PHYSIOLOGY AND HYGIENE OF LABOUR

PHYSIOLOGY AND HYGIENE OF LABOUR. PROPHYLAXIS OF OVERSTRAIN. PHYSICAL FACTORS OF PRODUCTION ENVIRONMENT. PROFESSIONAL DISEASE. CHEMICAL FACTOR OF PRODUCTION ENVIRONMENT. PROFESSIONAL POISONING.

 

Occupational hazards are often encountered in industry, agriculture, mining and other working environments. The major categories of environmental stress for a worker are: chemical agents; physical agents and conditions; biological agents and conditions; and psychosocial factors. They may act either singly or in combination.

 The result of occupational accidents are caused by both environmental and human factors as often, as each of factors separately. The interaction between man and his working environment may lead to improvement of health, when work is fully adapted to human needs and factors, or to ill health, if work stresses are beyond human tolerance. Occupational diseases and injuries result from specific exposures at work. In addition, work exposures may aggravate certain illnesses or be a factor of varying importance in causing diseases of multiple etiologies.

Psychosocial Factors

A high degree of mechanization may increase psychosomatic disorders, reduce job satisfaction, and contribute to a higher rate of absenteeism. Factors such as inter-personal relations at work, work stability, shift work, speed, and safety are important. Workers engaged in repetitive tasks, controlled by machines, derive less satisfaction from their work.

Shift work creates a psychosocial working environment that may adversely influence the health of a worker. Night work, and the change of working hours from one shift to another, may subject the workers to certain stresses. Such stresses affect the nervous system, increasing the frequency of peptic ulcer and of nervous symptoms, such as fatigue, nervousness, irritation, and insomnia. These nervous symptoms are usually related to the lack of sleep, which in turn may be related to housing conditions, and especially to disturbance of sleep by noise during the day, if the worker is on night shift .

Gastro-intestinal diseases are part of multiple etiology, and the work environment may be a contributing factor, especially where there is emotional or psychological stress at work. Shift workers may have a higher incidence of peptic ulcer than day workers. Chronic gastritis and, to some extent, peptic ulcer were found in Egypt among night shift workers, and were attributed to the stress of a shift work as well as to the dietetic habits.

Effects of Exposure to Combined Stress

Workers are often exposed to more than one kind of stresses;  then the outcome is complex. Human tolerance also varies. Workers may be easily affected by minor degrees of stress because of the lowered " vital " status of the exposed individuals. The environmental stress in this case does not cause the illness, but rather brings about, in vulnerable groups a rapid shift from the previously tolerated levels of existing illness, or of subclmical impairment, to a state of Usability. Such acute events have often occurred as a consequence of different environmental stress factors acting on individuals with quite different kinds of physiological handicaps. In developing countries, the employment of children, women, the elderly and the partially disabled is common. The degree of tolerance and susceptibility to psychological and physical stresses at work varies in these groups, and may result in health impairment and increased labour turnover.

The stress associated with night work was found, in a study carried out in Egypt, to contribute to a high incidence of high blood pressure; in this study of garage workers, exposure to toxic substances may have contributed to the high incidence of respiratory diseases that was found. In the viscose rayon industry, exposure to carbon disulfide has been associated with an increased incidence of atherosclerosis and cardiovascular diseases, in reports from studies carried out in different countries. The incidence of cardiac deaths among workers exposed to nitroglycol in the dynamite industry is reported to be higher than among the general population . Diet, smoking and mental strain may be a contributing factor in these diseases, although their importance in this connection remains to be determined.

Occupationally exposed groups are affected by the diseases prevailing in the community and, in some developing countries, by malnutrition. Exposure to dusts or gases, to heat stress, to the stress of physical effort, and to other conditions that are well tolerated by healthy individuals, may cause serious complications among workers suffering from, e.g., pulmonary tuberculosis, cardiovascular disease, damage to organs, such as the liver and the kidneys, as a result of parasitic diseases, or malnutrition. Tuberculous workers suffering from massive pulmonary fibrosis may develop silicosis more quickly than those who doesn't suffer from  lung disease. Cardiac patients are more liable to heart failure if they are required to exert considerable physical effort in a hot environment; the diabetic can suffer complications on night-shift work; and the worker whose liver and kidneys are affected by dysentery or other parasitic infestations may suffer from acute degenerative disease if exposed to carbon tetrachloride, mercury, and other toxic substances that might be tolerated by healthy individuals.

Appendix 1

Methods of assessment of work intensity and tension

Obligations of doctors of medical and sanitary departments of enterprises include necessity of assessment of work intensity, its physiological value, level of functional load of the working man organism, in other words to give quantitative evaluation of man’s work.

Such assessment is necessary when solving questions of working and rest conditions, duration of working time for women and adolescents, substantiation of working day duration, tariffication of work at substantiation of benefits concerning vacations and extra compensations, control of industrial environment factors.

Functional exertion of organism at work time may be characterized from two sides – energetic and informational. The first one prevails at physical and the second one at mental work.

         Characteristics of the work that requires intensive mental work during receiving and analyzing information, physiologists call “tension”; body burden at work that requires muscle force and correspondingly energy supply – “intensity”.

         As it was mentioned at the previous lecture, all types of work by their intensity are divided into light, medium complexity, heavy and very heavy, according to their tension – non-tensioned, slightly tensioned, tensioned and super tensioned.

         For assessment of level of the work intensity and tension, ergonometric and physiological methods are used.

Ergonometric characteristics of work intensity are characterized by lading weight, work intensity, kind of working posture, value of static load.  

Work power at physical labour is calculated by formula:

N = ,

where  N – work power in Wt;

 А – work in J;

 Т – work time in sec.

Work, as physical concept, is mass transfer in space, considering terrestrial attraction, and is calculated by following formula:

А = 9.8×(Р×Н +  +)×6,

where Р – mass, kg;

g – acceleration of gravity, = 9.8 m/sec² ,

Н – hoisting height of the load, m;

L –horizontal transfer distance, m;

6 and 9.8 – scaling factor in J.

Static load value is calculated by multiplication of force value and holding time, and is expressed in kg/sec.

Characteristics of working posture and transfer in space are based on observations, measurements of body angle, transfer distance, timing etc.

Ergonomic indices of labour tension:

1.     Number of objects under simultaneous observation.

2.       Duration of concentrated observation or time of activities (in % from overall time of the working day).

3.     Density of signals (announcements) per annum.

4.     Emotional stress.

5.     Interchangeability.

6.     Tension of analyzers’ functions.

7.     Memory volume required.

8.     Intellectual tension.

9.     Monotony etc.

Main indices of labour intensity are power and static load value as well as intensity (Density of muscular force per time unit).

Main indices of labour intensity definition are those ones of attention, density of processed information signals and emotional stress characteristics. Other criteria are additional.

To find out to which category belongs one work or another, it is necessary to use the most informative main indices, or two additional ones.

It is suggested to consider the level of physiological functions during work as physiological criteria of the level of intensity and tension of the work. Rating scale of intensity and tension of the work, developed by Kyiv Scientific and Research Institute of Occupational Hygiene and Diseases, provides for determination of pulse rate, energy expenditure, indicator of static force resistance, latent period of sensorimotor reactions, indicator of memory, attention etc. And at the same time physiological factors are determined at the beginning and at the end of the working day.

         Based on the change level of researched functions after completing the working day category of the work is determined (in %). Such factors as pulse rate and energy expenditure are evaluate in absolute values.

Appendix 2

Method for assessment of fatigability during physical labour

Dynamometry. To measure muscle strength of the hand, spring-type hand dynamometer is used. Maximum hand power is defined by dynamometer scale in kg. Static muscle endurance of the hand is measured by the period during which tested person is capable to keep fast dynamometer at 75 % of maximum hand strength (figure 32.1-а).

Muscle strength and static muscle endurance of the whole body is measured by stationary dynamometer, which is very easy in operation: power of the hand measured by “lifting” facility, fixed by legs (figure 32.1-b).

Figure. 32.1 Dynamometers (a – hand; b – stationary)

Dynamometric measurements are carried out at the beginning and at the end of the working shift. At the training – before and after load (20 squats with 10 kg load).

Ergography is defined as measurement of muscle efficiency using ergograph – device of desk-size. Еrgograph is twine sheave fixed on a special support, on one end of which hangs a load of a definite mass and another end has a loop for finger or a hand of the tested person. A twine is connected to a pen that records ergogram on a kymograph – frequency and flexion degree of a finger of a hand when lifting a load.

Decoding of ergograms that were taken at the beginning and at the end of the working shift allows determining muscle strength, fatigability resistance, fatigability, level of fatigability resistance resumption, content of done work and level of resumption of the done work content (fig. 32.2).

Fig. 32.2 Ergogram (1, 2) according to M.V. Lanyk

(average height of the second, third and fourth myograms at fulfillment of the first (ab) and the second (a₁b₁) works; fatigability resistance at the first (bc) and the second (b₁c₁) works )

 

These data are calculated according to depth of myograms in mm and their changes with time in seconds or minutes in the process of research.

Metering of strength and static endurance of muscles is also carried out by special device – dynamo-chromo-reflex meter. Force and duration of pressing hand dynamometer is registered by pointer microammeter (see fig 40.1.1а in “Hygiene of children and adolescents” section).

Physical working capacity and fatigability development are also determined by dynamic analysis of cardiovascular system:

-         heartbeat frequency (pulse) before and after load and its restitution;

-         systolic and diastolic blood pressure, systolic and minute blood volume, oxyhemometry.

Also electric cardiography is used (students study it in the department of physiology and in clinical departments) for determination of lung capacity, respiratory minute volume, respiration rate, ventilation of lungs by Douglas or Orsay-Fisher techniques, energy expenditure by means of the respiratory metabolism detection.

Electric tremormetry is detection of frequency amplitude of involuntary shaking of hands, inferior limbs allows to assess both level of physical fatigue and functional state of nervous system. Tremor of hands is determined using a special device ‑ electric tremormeter (fig. 32.3), which consists of metal plate of circa 20 х 30 cm area with narrow figured slots and metal probe with ebonite handle that are connected to voltage source and electric meter. Tested person conducts the probe along figured slots trying not to touch their edges and meter detects how many times the probe touched the plate during certain period of research.

Tremor of hands of not tired person is less than 3-5 swings (touches) per second, and of tired person ‑ 8-12 and even more swings per second.

Fatigue at mental and operator’s work is detected by series of psycho-physiological tests. (see Appendix 3).

Fig. 32.3 Electric tremormeter 

Appendix 3

Attention analysis by search of numbers

Method gives an idea of extent and tempo of psychical processes. Its principle of operation is: tested person must find out numbers in ascending (and descending) orders on the table, where they are placed random, to point them and to call them as quickly as possible.

         For the examination, it is necessary to have a stopwatch, a pointer and tables with numbers (fig. 32.4). A table is shown at the distance of 70 cm from the eyes at uniform illumination. The tested person obtains instruction: “You’ll see a table. On the table you must point at and pronounce aloud all numbers from 1 to 25 in turn. Try to do this as quickly as you can. Let’s start!” A researcher puts a table on and turns on the stop-watch. Then, he turns it off when 25 is pointed at. Further he demonstrates another table, three ones in total.

Fig. 32.4 Table for attention analysis by the search of numbers technique

 

Examination results are evaluated as follows. Numbers’ search in one table, on average less than 45 sec. is a good result, 45-55 sec. – satisfactory, more than 1 min. – unsatisfactory.

Examination of attention by search of numbers with switching

This method is aimed to determine an extent, switching and distribution of attention. Red and black tables with figures from 1 to 24 are demonstrated to the tested person. He must find out black and red figures, calling in turn first black figure than red one. He must find out black figures in ascending and red ones in descending orders (see fig. 40.2. in “Hygiene of children and adolescents” part).

The tested person obtains instruction:” You’ll see a table where 24 black and 24 red figures are located random. On the table you must point at and pronounce aloud all black figures in ascending order starting from one and all red figures in descending order starting from 24. No need to call the color Try to do this as quickly as possible”. An operator controls performance of the task with a stopwatch.

When assessing results, time of the task performance, number and character of mistakes are taken into consideration. Fulfillment of the task during 2 minutes shows adequate quality of attention, more than 3 minutes – insufficiency of attention functions. Mistakes in color are not serious if they are minor. More serious are mistakes of the order called figures. For example, some of the tested people in the middle of the table start calling figures of both number sequences in ascending or descending order. Such mistakes if the tested person does not correct them and continues to do them till the end of the examination testify about attention switch difficulties, i.e. about his physical or emotional fatigue.

Appendix 4

Examination of memory by memorization of geometric figures

This method is used for assessment of functional state of central nervous system (CNS) at the time of work when researches are carried out during the whole working day. At that it is necessary to underline that this test helps to study short-term memory capacity. This method allows determining extent of fatigue of the workers of operators’ professions.

The set of triangles with different hatch is shown to the tested person (fig. 32.5). His attention is paid to the difference between them. After that he is offered to remember 6 triangles with different geometric patterns during 8 seconds and after that to pick them out from the set that was shown at the beginning of the test.

Decrease of number of figures picked out correctly after 8-second remembering during working day may testify about dominance of inhibition processes in CNS as the result of growth of fatigue.

 

 

Fig. 32.5 Set of triangles

 

Appendix 5

Criteria of work classification according to its levels of intensity and tension

 

Appendix 6

Quantitative assessment of intensity of physiological functions

 

 

 

Heaviness and labor tension

Ergonomic and physiological metods are used to determine the heaviness and tensity of degree estimation of the labor .Ergonomic method allows defining a degree of psychophysiologocal loading on a man. Therefore they also use the ergonomic time-study of work process. Determine duration of separate elements of work operations in different periods of workday considering the condition of functional organism systems during labour activity. Main ergonomic labor heaviness indeces are: power of external work, translocating loads mass, size of static loading and description of work pose.

Leading ergonomic labor tension indeces are number of objects of simultaneous supervision, category of visual works, duration of concentrated supervision and active motions, number of objects of simultaneous supervision, signals (reports) density for a certain period of emotional and intellectual tension, labor monotony, which is determined by a number and repeating of discrete elements of work operations, duration of their execution and time of passive supervision.
As physiological criteria of heaviness and labor tensity degree estimation they use dynamics indeces changes of physiological functions during a workday. Physiological labor heaviness indeces are considered to be energy expense sizes, descriptions of physical capacity, static endurance and frequency of heart contractions. Labor tension is evaluated according to volume of operative memory, latent periods of general and differentiated visually- motoric reaction, switching and stability of attention .

Volume of efficient memory can be defined by a method of remembering of geometrical figures. Investigated person is proposed to view a set of triangles with different shading. He has to memorize 6 triangles during 6-8 seconds, then he has to choose triangles from a set of 36 triangles and compose them in same sequency .

Latent period of simple visually motored reaction is determined by chronoreflexometrs of different constructions. Time between serving of light signal and beginning of motion reaction is evaluated. Experiment is held 10 times and then middle time is estimated.

For determination of latent period of differentiated visually-motored reaction investigated person is proposed a stereotype irritants series, which consist of positive (for example, white and green) and negative (for example, red) irritants. Calculate a middle duration of latent reaction period and count up, amount of false decisions.

Study of attention functions by searching method allows to realize the condition of its switching speed. Investigated person is offered, to find , to show and to name 25 will placed numbers as soon as possible . Researches are repeated with three different tables and then the mean numbers of the searching time are determined. Labour heaviness (light, middle, difficult, very difficult) and tenacity (unstrained, strained, lustily strained) are determined by limitative indeces, the descriptions of labored activity, that indicate the greatest heaviness and tension.

MEMORY PROPERTIES

1. Research of shot duration memory

A Method is based on recreation of figures (two-digit ciphers). For the experiment the demonstration tables, with 12 two-digit ciphers, or rical figures are used. For each investigation a table is proposed , which a person attentively studies during 30 sec.

Later investigate is offered to cover the table and to recreate the ciphers. Investigated records on 12 figures cells, which it memorized into on advance prepared form with. For analysis amount of right named ciphers are taken into account. Percentage of right recreated ciphers is summer up.

2. Research of long-term memory

Investigated is offered to reproduce the ciphers, which were offered before on the following day. Among ciphers, which will be reproduced from memory only those, which a person memorized from the table are taken into account.Supply Form and results estimation are anagogic to previous.

3. Casting memory

Investigated is given a card with 10 couples of word written on it.

 For example: Lock-door,

                       Hour-day,

                       Lake-fence,

                      Animal-forest,

                      Eye-ear,

                      Night- star,

                      Pen - calculator,

                      Way-road,

                     arden-flowers,

                     Rain - umbrella.

On a table in front of investigated person there are cards, placed with blank side up, on which the first words of each words couple of are written. The Teacher reads out words couples and is proposes to students to tip over the cards with textual page and to add to each word a suitable couple. Experiment takes 30 sec. The Results are evaluated by amount of right reproduced couples. Record form and results estimation to previous task.

Results are recorded into beneath brought table.

Index of rich in content memory is a coefficient of verbally-logical imprinting, that is determined by dint of number dale right reproduced trace on amount of given words couples.

ATTENTION PROPERTIES

1. Attention steadiness

 Necessary for work is: Anfimov tables and stopwatch.

Investigated on extent of 2 min with most (possibly) speed and exactness must delete in form two certain letters, for example “k" and “е" not missing the lines. After command “start" task takes 2 min. After got through time an experimenter gives a command “stop".

The results are recorded into following table:

Determine work exactness (T) and work productivity (E).

Work exactness calculed by formula:  

                            T =A/(A+B+C)

Where A- amount of right marked signs;

           B- amount of wrong pretermited signs;

           C - amount of wrong deleted signs.

Work productivity calculed by formula:

                       E = P x T

Where P- general amount of looked over signs;

           T- work exactness.

2. Switching of attention

Work is hold by the means of Platonov-Shults table.

For experiment they use 3 tables with variously located red and black colored numbers.
For the 1 table the task is to find as quick as possible black ciphers in growth order.
On the ІІ table the investigated person must find the black ciphers in falling order.
For the ІІІ table the task is to find the black ciphers in falling order and red ones in growth order simultaneously.

For speed estimation of switching attention they use results of performed task. Fix time (A), that is used by investigated person on execution of task for finding of black ciphers in ascending order from 1 to 25. Time (B) expended on finding of red ciphers in falling order from 24 to 1 and time (C) expended on mix counting of black and red ciphers from 25 to 1, changing black and red cipher.
Switching (T) time is counted up by formula:

T =C - (A+B)

Where C- time expended on execution of task on mixed table “C";

           A- task execution time on table “A";

           B- task execution time on table “B".

3. Research of attention (Kholina`s test )

Investigated is offered 2 tables. One is on the table turned with clean side up the teacher keeps the other one. In each table ciphers from 1 to 16 in arbitrary order are recorded. Student is offered to draw 2 blanks with 16 cells - 4 in each row. On teachers command investigated open the table in front of them on the desk, other – in for general view. Turn by turn ciphers from 1 to 16 from first and second tables are transformed into provided forms are carried and recorded into suitable cells. The task last 30 sec. Result is evaluated by amount of right transformed ciphers. Estimation (in points) analogical to previous works.

HEAVINESS (light, middle, difficult, very difficult) and labor TENSITY (tense, little strained, strained, very strained) is determined by limit active indeces, meaning those descriptions of labored activity, that indicate on most considerable heaviness and tension.

There is great amount of other methods for evaluation of attention estimation, information alteration speed, different memory types and other, which can be found in psychological practical works and methods on study of physiology-hygienic aspects of professional people activity.

4. Determination of exactness and motions coordination with the help of phonotremometer
Takes into account a passing speed on labyrinth and amount of touches to walls.
Strikes off an index of phonotremometery ( I ).

I = (1/ passing time on labyrinth + 1/amount of touches to walls of labyrinth) x 100%
Criteria of an estimation of the basic psycho-physiological parameters at students

Occupational Accidents

Accidents result from both environmental hazards and human factors. The contributing environmental factors include the layout of the workplace, unsatisfactory machine guards, inadequate maintenance of equipment, defective lighting, excessive noise and vibration, unsuitable floors, walls, celeings, etc. On the the other side, we must include poor adaptation to the industrial mechanized environment, a casual attitude towards work, and incorrect methods of work. In addition, the physical and physiological capacities of the worker may not face the job requirements; thus his visual acuity may be inadequate, this worker may suffer from hearing loss or other forms of partial incapacitation, and his psychological state, particularly his alertness, may be unsatisfactory.Despite this,the failure to observe safe practices and to make proper use of mechanical safeguards and personal protective equipment account for many accidents. Most authorities consider human factors much more important than environmental hazards in accident causation, the former being possibly responsible for 85 % of all accidents.

Hygienic classification of work

(by indeces of harmfullness and danger of factors of industrial enviroment, hardness and effort of working process).Terms and determination of main definition used in classification.
Dangerous and harmful factors of working conditions can be physical, chemical, biological factors of industrial environment, psycho physiological factors in work organization, working places staff and equipment.

Harmful industrial factor is factor, which influence on the worker in the indicated condition can cause illness or firm decreasing of capacity.

Dangerous industrial factor is a factor, which influenced on the worker can cause trauma or other sudden worsening of health.

Difficulty (heaviness) of work – a line of working process, which reflexes loading on borne-muscular system and functional system (cardiovascular, respiratory, etc.), which provides its action.

Tensity of work – is a characteristic of working process, which reflects loading on the central nervous system.

Classification is necessary for hygienic estimation of real conditions and kind of work on working places, determining of priorities in holding of sanitary condition. The base of hygienic classification is presented by harmful factors of industrial environment, the lever of difficulty and tensity of working process.

Principal of condition differentiation and kind of work foresee degree deflection of sizes of industrial environment and working process from active hygienic norms and influence on functional state and health of workers.

There are three types of conditions and kinds of work.

I – optimal condition and kind of work, where unpleasant influence (on worker’s health) of harmful and dangerous industrial factors on worker’s health is absent. Apiaries condition for keeping high level of capacity (absent or according to level, which is good for population.

II – permissible conditions and kind of work when level of dangerous and harmful industrial factors don’t overcome hygienic norm on working place. And possible functional change caused by working process, renovate during Brea time, during working and home rest before beginning next shift and don’t cause unpleasant influenced in the next period on the health of working and their children.

III – harmful and dangerous conditions and kind of work due to which sanitary norm and rules possible influence of dangerous and harmful factors of industrial environment in the quantities which increased hygienic norm, psychophysiological factors of working action, which causes functional changes in the organism, which can lead to firm of decreasing capacity and disorders of working health.

There are three degrees of harmful and dangerous conditions of kind of work:

I – conditions and kind of work, which cause functional violations which have a reverse character during early indication and after interruption of influence.

II – conditions and kind of work, which cause functional violation, which assist increasing indexes of morbidity with temporary loosing of work capacity and in some cases appear ance of signs or easy form of professional diseases.

III – conditions and kind of work with increased danger of development of professional diseases, higher illness with temporary of working lass.

In case of presence of two or more dangerous and harmful industrial factors and factors of working action condition of work it is necessary to hold according estimation to higher class and degree.

Classification exclude work in extreme conditions during which combination of conditions and kind of work forro high risk of development of hard form of acute professional diseases, handicapness and danger for life. Degree of risk in extreme condition of work can not be characterized quantitative indeces of harmfullress, danger, difficulty and tensity of work.

 

Criterias classification of work according to difficulty and effort

http://www.britannica.com/eb/article-9108516/occupational-disease

Origin of the dust

 

1.1.     The dust sources in the air may be:

-            volcanic eruptions;

-            cosmic dust (meteorite combustion in the atmosphere);

-            dust storms – wood (Тibet, China), soil, sand;

-            agricultural dust – from harvesting and crop processing;

-            industrial – manufacturing emissions and meltdowns;

-            road dust;

-            marine (salt).

1.2. Domestic dust. The dust content in the air of living, industrial, public, educational, sport places may be caused by:

-            type and quality of the floor and furniture covering;

-            population density of the place;

-            character and quality of tidying up (dry, wet) and air exchange;

-            culture level of the inhabitants.

1.3. Industrial dust: the dust content in the industrial areas may be caused by:

-            type of industry;

-            mechanization level of the manufacture;

-            quality of dust-catching and ventilation facilities.

 

Classification of the dust

 

1.2.     By chemical composition (origin):

-       inorganic (silicon oxide, asbestos, salt, minerals of ores, metals, soul and others);

-       organic (plant, animal, synthetic organic materials, polymers, plastics, gum, colorants (dye-stuff));

-       microbiological (microorganisms, fungi).

-       mixed (different particles of inorganic, organic and biological nature);

1.3.     By influence on organism:

-       indifferent;

-       toxic;

-       dermatotropic;

-       pneumotropic;

-       allergenic;

-       cancerogenic and others.

1.4.     By form of the particles:

-       amorphous;

-       fibrous;

-       pointy (spiky) and others (see fig. 12.1).

1.5.          By size of the particles:

-       aerosuspensions – particles with size more than 100 micrometers;

-       aerosols:  large dispersible – sizes 100-10 μm. (proper dust)

medium dispersible – sizes 10 –0.1 μm. (cloud)

small dispersible – sizes less than 0.1 μm. (fume or smoke)

2.5. By formation mechanism:

-       disintegration aerosols (crashing and processing of the solid rocks and materials);

-       condensation aerosols (agglomeration of the atoms or molecules to dust particles)

 

3. Principles (rules) of aerosols and aerosuspensions behaviour in the air (Jibs-Stokes laws)

 

3.1. Aerosuspensions and large dispersible aerosols are accumulated from the air with acceleration: the gravity affects the dust particles greater than the air resistance.

3.2. Middle dispersible aerosols are accumulated from the air at the constant speed: gravity is in balance with the air resistance.

3.3. Small dispersible aerosols aren’t accumulated - they stay in the Brownian movement: the air resistance to the dust particle movement is greater than the gravity. Small dispersible particles conglomerate or absorb moisture on themselves, becoming heavier and only then accumulate.

 

 Respiratory tract anatomy and physiological laws on which the respiratory tract protection from the dust in the air is based

 

The respiratory tract is quite well protected from the dust getting into lung alveoli. This protection consists of the respiratory tract curvature: three nasal meati with curved bone lamella; bronchial tree with its branching helps the air turbulence, and that is why the aerosuspensions and large dispersible dust particles, in accordance to the law of inertia (Newton’s law), are thrown away from the respiratory tract by the centrifugal force; and then the dust is removed due to the ciliary epithelium with bronchial mucus. 

Middle dispersible aerosols penetrate deeper into bronchi. Small dispersible aerosols in accordance to the Brownian movement of the diminutive mass penetrate easily into alveoli with the air and may cause pneumoconiosis or other diseases. Some scientists have an opinion that a part of the small dispersible particles may be breathed away like the air molecules.

 

 Adverse events and diseases caused by the dust influence on the human organism

 

5.1. The dust content in the atmospheric air reduces the lighting, ultraviolet radiation intensity, causes the dull weathers (the dust particles are the moisture condensation centers), fogs and smog.

5.2. The dust influence on the skin and mucous membranes appears as the obstruction of excretory ducts of sebaceous and sweat glands, development of skin and mucous membranes maceration, causes pyodermia and allergy. Lipotropic dust components may be absorbed into skin, causing the general toxic reactions. The dust reduces ventilating function and decreases the vapor conduction contaminating the clothes and influencing the heat exchange and skin breathing negatively.

5.3. The dust influence on respiratory track may cause different pathological states:

-         general toxic reactions: the dust dissolved in water is absorbed from the lungs and mucous membranes, gets into the blood vessels and may cause different pathology depending on the troposity of the toxic substance (lead or saturnism, zinc, strontium poisonings and others):

-         allergic diseases: dispnea or breathlessness, chronic bronchitis, rhinitis, pharyngitis, tracheitis, bronchial asthma (plant or woolen dust, soot and others);

-         infectious diseases with inhalation transmission (tuberculosis, pneumonic plague and others);

-         pneumoconioses – fibrous lung diseases, caused by the prolonged influence of some types of inorganic dust (silicosis is caused by the silicon oxide, siderosis – by iron dust, asbestosis, anthracosis and others);

-         lung cancer – under the chrome dust, radionuclides, 3,4-benzpyrene, 5,6-dibenzanthracene and other carcinogens influence.

 Hygienic standards of the dust content in the air

The measuring methods of the dust content in the air may be classified: by the sampling technique – sedimentation and aspiration, by research results definition – weighting and calculation.

Table 1

Maximum allowable concentration (MAC) of the aerosols with the fibrogenic activity

 

Fig. 12.1 Morphology of dust particles.

A, B – wood dust; C – bristle dust; D – chamotte dust; G- hemp dust;

Н – conifers dust; J – coal dust; К – glassy dust; L – bronze dust; M – dust under foundry cleaning.

Appendix 2

Sedimentation methods

2.1. Sedimentation-weighting method is used to determine the quantity of the dust, that falls down from the atmospheric air onto the surface unit near the industrial areas, in the cities and others settlements.

The sampling is performed using: 1) flask method, the wide glassware (sedimentator) with distilled water is exposed on the open surface for 3-4 weeks or 2) sticky screen method (for radioactive aerosols collection), when the sedimentator’s bottom is lubricated with the glycerin or 3) snow sample method: the first snowfall date is noted and then, after 1.5-2 months, the snow block of certain area (e.g. 0.5 m²) is cut out to the clean layer of the first snowfall. Water, snow and glycerin fix the drop-out dust very well. The water from glassware or the snow water is evaporated to the solid residual after the exposition, the glycerin with fixed dust is collected with the ash-free tampon quantitatively. The solid residual is weighed (for radioactivity determination it is ashed) and is recalculated in g/m², and then in t/km². Several tons of dust per km² per year fall down in the industrial regions, according to this method.

2.2. Sedimentation-weighting method – the dust deposition on the object-plate. The object-plate (slide) is greased with glycerin, vaseline or 2% Canada balsam solution in xylol from the 10 cm air column to determine the form and size of the dust particles using the microscope and “dust formula” calculation. The “dust formula” is portions of the dust particles of each size in the air volume in percentage. The aspiration methods are also widely used for this purpose. (see appendix 3).

 

Appendix 3

Aspiration methods for determination of the dust content in the air

3.1. Aspiration-weighting method consists of drawing the certain air volume through the aerosol filter using the Migunov’s electrical aspirator or the hoover (vacuum cleaner) with rheometer (device for the aspiration speed determination). The aerosol filter АFА-В-18 (АФА-В-18) from Petrianov’s non-woven synthetic filter fabric (PFF) is fastened to the special bailer allonge (adapter) (fig. 12.2)

 

 

Fig. 12.2 Cassettes and allonges (adapters) with filters for the air sampling.

1 – filter with fabric PFF; 2 – plastic allonge (adapter) with filter;

3 – metal allonge (adapter); 4 – cassette case; 5 – cassette screw; 6 – filler ring.

The filter (without fixed paper ring) is weighed using the analytical or torsion balance before and after the air aspiration.

The air sampling duration depends on the dust content in the air, the air aspiration speed during sampling, the necessary minimal dust weight on the filter and may be calculated using the following formula:

,

where: Т –the air aspiration duration, min.;

  а – the necessary minimal dust weight on the filter, mg;

  C – MAC of the investigated dust, mg/m³;

  W – the air aspiration speed, l/min.

The maximum makeweight has to be not more than 25-50 mg if the own filter mass (to 100 mg) is not too big.

The dust concentration (mg/m³) may be calculated using the following formula:

_,

where: С – the dust concentration, mg/m³;

  q ₁ – the filter mass before air aspiration;

  q ₂ – the filter mass after air aspiration;

  V₀ – the sample air volume in standard conditions which is calculated using Gay-Lussac’s formula.

3.2. Aspiration-calculating method is used in two modifications.

Filters AFA used for determination of the mass dust content in the air are applied with filter surface to the object-plate (slide) and are held under acetone vapors for several minutes. The filter fabric melts to the transparent film and fixed dust particles can be seen through the microscope.

Samples received by both sedimentation and aspiration methods are studied using the microscope with ocular micrometer. The ocular micrometer is a scale on the round glass with diameter which is equivalent to the internal diameter of the microscope’s ocular.

The meaning of the scale interval of the micrometer has to be assigned before determination of the dust particles sizes. For this purpose the ocular micrometer with intervals from 0 to 50 is put in the ocular of microscope. The objective micrometer with scale interval of 10 μm is fixed on the microscope’s stage. Intervals of the ocular micrometer are combined with any interval of the objective micrometer. The scale interval is determined by the number of the ocular micrometer intervals which fit into the certain intervals of the objective micrometer (see fig. 12.3).

For example, 12 intervals of the ocular micrometer scale coincide with one interval of the objective micrometer scale which is 10 μm. One interval of the ocular micrometer thus equals to  = 0.83 μm.

The dust particle sizes are determined by the application of the slide with the dust instead of the object-micrometer to the same optical system. For example, the biggest dust particle coincides to three intervals of the ocular micrometer scale. That is why the dust particle size is 0.83×3 = 2.49 μm.

Sizes of 100-300 dust particles are determined by the microscope in different parts of its view and then dust particles are grouped in according to their sizes (the data are signed out in the table 2 and “dust formula” is calculated. The “dust formula” is the percentage of the dust particles of each size in the whole sample. The dust hazard rate for respiratory track may be estimated according to the “dust formula”: the greater the percentage of the small dispersible dust the greater the danger of pneumoconioses development and general toxic effect.

Table 2

Calculation of the “dust formula”

Fig. 12.3 Determination of the meaning of the scale interval of ocular micrometer.

1 – ocular micrometer scale; 2 – objective–micrometer

 

Appendix 4

Determination of the dust concentration with dustmeter VKP-1 (ВКП-1)

The device VKP-1 (ВКП-1) is used for the dust concentrations in the air of the heated indoor industrial areas from 0.1 to 500 mg/m³. The device function is based on the aerosol particles electrization in the negative alternative corona charge field, and the following determination of their total charge, induced on the walls of the cylindrical measuring camera of air-absorbing part of the device. Determined under this condition, the total charge is proportional to the aerosol concentration in the air which has passed through the charging camera.

Device (dustmeter) setup. The “OPERATING MODE” tumbler should be turned on, the tumbler “DIAPASONS” put in position 1. Plug the device into the electrical supply network. The device is grounded automatically with the tripolar plug. The “OPERATING MODE” tumbler must then be put in the “CALIBER” position. The microampermeter pointer on 50 scale division is set up with “CALIBRATION” handle.

Order of testing. The “OPERATING MODE” tumbler is put into the “MEASURE” position, the microampermeter data is read after 10 sec. The measuring sub-diapason should be taken into the account. The dust concentration in the air of the industrial areas is determined in accordance to the calibration characteristic. If it is necessary repeat the measuring in the different diapason.

Put the “OPERATING MODE” tumbler in “OFF” position and “DIAPASONS” tumbler in position “4” after finishing the measuring, unplug the device. 

The results of measuring using the device VKP-1 (ВКП-1) are assessed in accordance to the table 3.

 

Table 3

Table for the assessment of results measured with device VKP-1 (ВКП-1)

 

Physical characteristics and classification of noise

From physical point of view noise represents chaotic elastic air vibrations of different frequency, intensity and rhythm. (Music represents harmonious elastic air vibrations).

From hygienic point of view noise represents various sounds that hinder a person to work, rest, and sleep, and has negative, irritating effect on him.

Sound or vibration frequency is expressed in Hertz (Hz) – quantity of vibrations per second, and by octave – audio band, the upper level of which is 2 times bigger than the lower one (16-32 Hz; 100-200 Hz etc.). Perceived by human ear frequency is in the range of 16-20000 Hz that is enclosed in 10 octaves.

According to frequency noise is classified into: low frequency, medium frequency, high frequency, sonic frequency (when one single frequency sounds), narrow-band frequency (1-3 octaves sound), wideband frequency (4-6 octaves sound) and “white noise” (all frequencies sound).

Sound intensity depends on amplitude of air vibration and in sound pressure it is expressed by energy units and is measured in Newton per square meter (N/m²). Human ear perceives sound pressure in the range of 2-10^-5 - 2-10^1,5 N/m², includes about 1 million of those units and makes their use impossible for noise intensity measurement in practice.

Therefore, the level of intensity or sound pressure intensity – the ratio of given sound intensity in N/m² (Р) to its threshold value Р₀, equal 2-10^-5 and express in decibels (dB) – tenth part of logarithm (exponent) of sound pressure is used. Thus, level of upper (pain) threshold of sound pressure (L) is:

L = 20 lg = 20 lg^6.5 = 20×6.5 = 130 dB

Thus, if level of sound pressure increases by 2 dB, sound pressure in N/m² increases 2 times as much, by 3 dB - 3 times as much, by 7 dB - 7 times as much etc.

Ear perceives sounds of different frequency differently: low-frequency sounds of the same level of sound pressure are quieter, and high-frequency sounds are louder. Therefore physiological value of sound perception was introduced by volume, measurement unit of which is phon (decibels of volume). For conversion of decibels into phons and vice versa, special diagrams of Robinson and Dotson are used. They are given in the corresponding manuals (fig. 33.1).

Fig. 33.1 Diagram of Robinson and Dotson.

(horizontal lines – sound pressure level in dB; curves – sound volume in phons)

To compare: if volume threshold at 1 000 Hz is taken for 0 dB, then at З0 Hz it is higher by 63 dB, and at 4 000 Hz it is lower by 10 dB.

Also hourly noise classification exists, according to which noise is divided into uninterrupted (continuous), interrupted (rhythmic and arrhythmic) and impulse-type (percussion).

According to their impact, sounds of the same volume attack organism in the same way, depending on frequency: low-frequency sounds are less harmful and high-frequency sounds are more harmful than ones of medium frequency (Standard, 1 000 Hz). Thus lower threshold of sound harmful effect at 1 000 Hz comes to 30 dB, and at 60 Hz – to 65 dB, at 8 000 Hz – to 23 dB.

Therefore, both control objects (streets, lodgings, offices, study, medical and manufacturing premises) and noise frequency spectrum are put into the basis of noise sanitary regulation (table 1).

For detection of level of noises in medium-octave bands either noise spectrum analyzer or noise and vibration dosimeter are used. (see Appendix 4)

Based on measurement results and standard levels from table 1, noise spectrogram is made (fig. 33.2). This spectrogram allows to determine frequencies, at which actual noise exceeds maximum allowable levels in controlled areas, and to make sound conclusions.

Table 1

Maximum allowable level of noise on workplaces

(extract from State Sanitary Rules 3.3.6.037-99)

Fig. 33.2 Noise spectrogram

If there is no spectrum analyzer, then noise dosimeter is used for measurement (Appendix 3, fig. 33.3). The result is expressed using integral indices of noise level - decibels А (dBА) and evaluated according to last column of State Standard (Table 1).

Total noise level from different sources is calculated according to special formulas (Appendix 2).

Occupational exposures contribute to the morbidity and mortality of many diseases. However, occupational diseases continue to be underrecognized even though they are responsible for an estimated 860,000 illnesses and 60,300 deaths each year. Family physicians can play an important role in improving the recognition of occupational disease, preventing progressive illness and disability in their own patients, and contributing to the protection of other workers similarly exposed. This role can be maximized if physicians raise their level of suspicion for workplace disease, develop skills in taking occupational histories and establish routine access to occupational health resources.

The patient with a possibly work-related illness frequently seeks care initially from a family physician. The physician's recognition of a possible link between work and disease often determines the diagnostic tests that are performed and the treatment that is recommended. Early diagnosis of an occupational illness may prevent progressive morbidity and disability from conditions such as occupational asthma and may facilitate the reversal of adverse effects from exposures to substances such as lead.¹ The identification of an occupational illness in one patient also provides the physician with an opportunity to protect other patients with similar exposures.² Since much remains to be learned about the effects of toxins on health, the family physician is in a crucial position to contribute new information about occupational disease.

A variety of factors are responsible for the present underrecognition of occupational illnesses. Some of these factors include the difficulties physicians can encounter in dealing with the Workers' Compensation system, the reluctance of patients to connect a health problem with their work (primarily because they fear they will lose their jobs) and the present managed care environment, which reduces the time available to take a complete occupational history.

This article describes ways in which family physicians can improve the detection of occupational disease in their patients. In particular, physicians need to raise their level of suspicion for occupational disease, build skills for efficiently obtaining an occupational history and develop routine access to occupational medicine resources.

Raising the Level of Suspicion

Occupational disease is surprisingly common. An estimated 860,000 illnesses and 60,300 deaths from workplace exposures occur annually in the United States. Studieshave found that 75 percent of hospitalized and ambulatory primary care patients report hazardous exposures, and 17 percent suspect that their illness is linked to their job. Work-related illness is diagnosed in approximately 10 percent of these patients.

Since the spectrum of occupational diseases is extremely broad (Table 1), many conditions commonly encountered in primary care practice may be work related. The following illustrative case is but one example of an illness with an occupational source.

Illustrative Case

A 38-year-old man reported several weeks of generalized headaches. A diagnosis of stress-tension headache was made, and he was given an analgesic. Because he continued to have pain, computed tomographic (CT) scanning was performed. The CT scan was normal.

The patient was referred to a neurologist and then to a specialty headache clinic. Various treatments were applied without effect.

An occupational history revealed that he had been a spray painter for 11 months. While at work, he was routinely exposed to mixed organic solvents. When he was taken out of work for four weeks, his headaches cleared.

Musculoskeletal Disorders

Patients with musculoskeletal disorders involving the arm and neck frequently seek medical care. Work tasks contribute to symptoms in a significant proportion of these patients. More than 60 percent of reported occupational illnesses are work-related musculoskeletal disorders of various types.¹⁴ Specific diagnoses, such as localized nerve entrapment (e.g., carpal tunnel syndrome), tendinitis (e.g., lateral epicondylitis, de Quervain's tendinitis), muscle strain and less well-defined regional pain syndromes, have been associated with jobs in all sectors of the economy. Repetition, force, awkward or static postures, vibration, work speed and restricted tasks are job factors that may contribute to the development of these ailments.

Respiratory Diseases

A variety of respiratory diseases are also commonly occupational in origin. Pneumoconiosis due to inhalation of asbestos, silica or other nonorganic dust should be considered in patients who report progressive dyspnea and dry cough. Airway diseases, including rhinosinusitis, bronchitis and asthma, have been increasingly recognized as work related.

A widening array of exposures has been linked to occupational asthma related to possible exposure to allergens (e.g., grain dust), respiratory irritants (e.g., sulfur dioxide) or substances acting through other mechanisms (e.g., isocyanates). Less frequently, recurrent "flu" or "pneumonia" may actually be symptoms of hypersensitivity pneumonitis from exposure to mold, other organic materials or certain chemicals.

Neurologic Disorders

The nervous system is a frequent target of toxins, including organic solvents (e.g., toluene and chlorinated hydrocarbons), metals (e.g., lead and manganese) and pesticides (e.g., organophosphates). Peripheral polyneuropathy may be caused by agents such as lead, methyl butyl ketone and organophosphate pesticides. More commonly, chronic organic solvent exposure is responsible for a syndrome that includes headaches, fatigue, light-headedness, cognitive difficulties and depression.

Cancer and Heart Disease

Work exposures also contribute to a notable percentage of cancers and have been increasingly recognized as factors in the development of coronary artery disease.

Stress-Related Illnesses

Stress has also emerged as an important hazard in the contemporary workplace. It has been associated with a range of emotional and physical ailments, including coronary artery disease and myocardial infarction. The risk of stress-related illness is increased in jobs with high emotional/psychologic demands and low potential for control by the worker.

Work Conditions and Illness

As the focus of business has shifted from manufacturing to service in most industrialized countries, traditional notions of hazardous work have, by necessity, been expanded. Occupational illnesses continue to occur in manufacturing, construction and agricultural sectors, but they are also increasingly being recognized in the burgeoning service sector. For example, rapidly expanding computer use has been associated with musculoskeletal and eye problems in a growing number of office workers.

Today a significant proportion of occupational illnesses are related to building conditions, such as inadequate fresh-air ventilation, low humidity and the presence of cigarette smoke, volatile organic compounds and fibers, molds or other microbiologic materials.

Typically, workers with symptoms related to indoor air quality report upper airway and eye irritation, frequently accompanied by fatigue and difficulty concentrating. These symptoms generally occur in a group of workers in the same environment. Furthermore, the workers report rapid clearing of the symptoms when they leave the workplace. Other illnesses, including asthma, hypersensitivity pneumonitis and respiratory infections, have also been linked to specific building-related exposures.

Index of Suspicion

An occupational etiology should be considered if an illness fails to respond to standard treatment, does not fit the typical demographic profile (i.e., lung cancer in a 40-year-old nonsmoker) or is of unknown origin. Much is still unknown about the health effects of most workplace exposures. The introduction of new chemicals and other materials has far outpaced general knowledge of their potential toxicity. Consequently, family physicians continue to play a crucial role in recognizing unsuspected links between exposures and specific illnesses.

PROFESSIONAL DISEASES AND POISONING

Lead Poisoning Plumbism

 www.faqs.org/health/ Sick-V3/Lead-Poisoning.html

www.epa.gov/reg3wcmd/ lp-whyislead.htm

The best way to know if a person is being exposed to lead is to have a blood lead level (BLL) test.  In California, employers are required to provide blood lead testing for their employees who work with lead.  Laboratories that analyze BLL tests report the results to OLPPP, which operates the California Occupational Blood Lead Registry.  OLPPP uses information from the Registry to identify lead-poisoned workers for follow-up.

Purpose

OLPPP investigates and follows up on reported cases of lead poisoning in individual workers. The purpose of these investigations is to ensure that:

 

 

 

·         workers receive proper medical care

·         conditions in the workplace that resulted in lead poisoning are corrected

• workers do not carry lead contamination home and poison their families.

 

Case Investigation Activities

To achieve these goals, OLPPP:

• Calls the lead-poisoned worker to address concerns about his or her health, learn about the workplace, and identify household members and co-workers at risk;

• Talks to the employer to review the company’s lead safety measures and make recommendations on how to control lead exposure;

• Contacts the doctor who is treating the lead-poisoned worker to review the case and provide information and assistance.

Saturnism.

Synonyms.—Chronic Lead-poisoning; Saturnism.

Definition.—A chronic intoxication due to absorption of lead.

Etiology.—Individual susceptibility is much greater in some cases than in others, and sleeping in newly painted rooms, or drinking water flowing through lead pipes, has occasioned the disease.

The most common means of receiving the poison, however, is due to contact by workers in lead, such as paint manufacturers, painters, plumbers, workers in type-foundries, shot-makers, pottery-glaziers, lace-makers, calico-printers, glass-grinders, and the habit of dressmakers of biting off thread, some of which is lead-dyed.

It may be taken in the food, in which lead chromate is used to impart a rich yellow color, and may be found in bread, milk, butter, and candy. Chocolate, candy, and tobacco wrapped in lead-foil may also give rise to plumbism.

Women are more susceptible than men, and adults than children, though most likely on account of more frequent exposure rather than natural susceptibility.

Pathology.—The pathological changes occur in the peripheral nerves, muscles, kidneys, liver, mucous membranes, and bloodvessels.

The most constant changes are found in the peripheral nerves, the nerve-endings exhibiting a neuritis, to be followed by atrophy of the muscles. The cord is usually free from structural change, though degeneration may occur in patches, in the nerve-trunks. The atrophied muscles are pale in color, and, in advanced stages, show fibroid degeneration.

In lead-encephalopathy, arterio-sclerosis of the cerebral bloodvessels is found, which sometimes is followed by softening of the brain, and by hemorrhages. Parenchymatous degeneration of the kidneys and liver is common.

Symptoms.—The symptoms vary, depending upon individual susceptibility, amount of lead absorbed, and the length of time of exposure. Anemia is an early and characteristic symptom, and usually of the chlorotic type. The hemoglobin may be considerably diminished, though the erythrocytes are rarely less than 3,000,000. There is impaired nutrition, with consequent loss of flesh and strength.

An almost constant and characteristic symptom is a blue line at the juncture of the gums with the teeth, and is clue to the presence of lead sulphid, formed by the union of the lead in the blood with sulphuretted hydrogen, the latter resulting from the decomposition of tartar upon the teeth. If the patient's teeth be free from tartar, the blue line may be absent. The gums are frequently soft, swollen, and spongy, and there is a metallic taste, and the breath is fetid.

Gastro-intestinal symptoms are also characteristic, lead colic causing the most intense suffering. Commencing with an obscure pain near the navel, it radiates in every direction, until the entire abdomen seems involved. The pain is griping and excruciating in character, the patient not infrequently screaming in his agony. The pain may extend to the back, hip, thighs, and legs; in fact, no part of the body seems free from pain.

The abdominal walls are tense and hard, sometimes knotted, and the umbilicus is drawn inward. The bowels are not tender to pressure, neither does pressure alleviate the pain, as in some other forms of colic. The patient is frequently troubled with nausea and vomiting, the material thrown off the stomach being a slimy fluid, more or less mixed with acrid bile. The tongue is pale, broad, and flabby, and its movements controlled with difficulty; the skin is soft and moist, the pulse not at first affected, but when the disease is long continued and severe, it becomes soft, feeble, and increased in frequency.

The bowels are obstinately constipated; if anything passes, it is in hard scybalous masses, with a brownish water; the sphincters seem to be sometimes so contracted that neither urine nor feces can be passed, and it is v/ith greatest difficulty that we can introduce the nozzle of a syringe.

Paralysis is common, especially that affecting the extensor muscles of the forearm, producing wrist-drop. Less frequently the deltoid, the biceps, the brachialis and pectoral muscles are involved.

Saturnine arthralgia, pain in the articulations, is not an uncommon symptom.

Cerebral symptoms, or lead-encephalopathy, occur where large quantities of lead are absorbed, and it is characterized by convulsions, delirium, coma, neuro-retinitis, and sometimes insanity.

Diagnosis.—The history of exposure to lead-poisoning, the blue line on the margin of the gums, the wrist-drop, the anemic condition, and the lead-colic are such characteristic symptoms that the diagnosis is easily made.

Prognosis.—Unless degeneration of the heart and kidneys has taken place or severe cerebral symptoms develop, the prognosis is favorable.

Treatment.—"The first object of treatment is to mitigate the intense pain, and open the bowels, after which means to remove the lead should be immediately used. Among the most efficient means for the relief of pain is the administration of chloroform in doses of from twenty to thirty drops every half hour or hour; it may be administered in mucilage, water, rectified spirits, or, what is preferable to all, glycerin. I usually order it in the following" manner:

• Defined as persistent eating of non-nutritive material for 1 month or more

• Always search for lead lines in any child with an ingested foreign body

• Main source of lead intoxication is lead paint used in houses painted before 1980

• Absorption is greater in children than adults

• Lead may be inhaled as well as ingested

• Symptoms develop more quickly through GI tract

• Toxicity more severe with co-existing iron, zinc, or calcium deficiency

• Pathology

• Lead concentrates in metaphyses of growing bones

• Distal femur

• Both ends of tibia

• Distal radius leading to

• Failure of removal of calcified cartilaginous trabeculae in provisional zone

• Clinical findings

• Neurological

• Learning disability

• Decreased IQ

• Mental retardation

• Encephalopathy

• Motor deficits

• Seizures

• Cerebral edema

• Hearing loss

• Gastrointestinal

• Abdominal pain

• Nausea

• Vomiting

• Diarrhea

• Constipation

• Anorexia

• Metallic taste in mouth

• Ileus

• Renal

• Tubular damage

• Azotemia

• Gout

• Hematologic

• Affects blood synthesis

• Hemolysis

• RBC stippling

• Iron deficiency

• Musculoskeletal

• Muscle and joint pain

• Soft tissue

• Blue-black line in gum margins

• Endocrine

• Decreased stature

• Decreased growth hormone

• Decreased vitamin D levels

• Laboratory findings

• Predate bone changes on x-ray

• Serum Lead Level >1.2 umol/L

• Urine lead level elevated

• Peripheral Smear

• Stippled erythrocytes

• Complete Blood Count

• Microcytic Anemia

• Leukocytosis

• Urine microscopy of sediment or renal biopsy

• Acid-fast inclusion bodies in tubular nuclei

• Pathognomonic for lead poisoning

• Free Erythrocyte Protoporphyrin (FEP) > 0.6 umol/L

• Imaging findings

• Cerebral edema in acute lead intoxication

• Particles of lead in GI tract

• Bands of increased density at metaphyses of tubular bones (growing bone)

• Metaphyses of growing bones may be dense normally

• Lead lines more apt to be seen in proximal fibula and distal ulna where growth is not as great as other long bones

• Lead lines may persist

Frontal radiograph of both knees of a child with lead poisoning show dense metaphyseal bands
involving not only distal femurs and proximal tibias but proximal fibulas as well

• Bone-in-bone appearance

• Abnormalities in bone modeling

• Erlenmeyer flask appearance to distal femur

www.lead.org.au/ bblp/silent-epidemic.html

http://www.healthy.hartford.gov/Lead_Poisoning/PbIntro.htm

 

Pneumoconiosis

Pneumoconiosis is a disease of the lungs caused by long-term breathing of dust, especially certain mineral dusts. Forms of pneumoconiosis include black lung disease (coal worker's pneumoconiosis), silicosis, and asbestosis. The disease typically resultsfrom working in a mine for many years, but factory work and other occupations can expose people to the ill effects of breathing dusts. The term "pneumoconiosis" comes from the Greek pneumon, meaning lung, and konis, meaning dust.

What Causes Pneumoconiosis?

Only microscopic-size dust particles, about 1/5,000 of an inch across or smaller, are able to reach the tiniest air sacs (the alveoli) in the lungs. There they cannot be removed, and accumulate to cause a scarring and thickening of the lungs called fibrosis . Eventually, the lungs begin to lose their ability to supply oxygen to the body.

THE WAR AGAINST BLACK LUNG

The prevalence of black lung disease did not begin to decrease until it became clear that the cause was excessively high levels of coal dust in mines. Largely due to the efforts of coal miners' unions, occupational safety conditions improved.

In 1969, the Mine Health and Safety Act set standards in the United States for maximum allowable levels of coal dust in mines. The Act also provided compensation for miners who developed black lung disease. Death rates from pneumoconiosis have been declining since the Act was passed.

Breathing coal dust was an occupational hazard for coal miners, especially those who did not wear protective masks.

Corbis-Bettman.

Black lung disease is caused by breathing coal dust, usually in mines. Silicosis results from inhaling silica dust from sand and rock, primarily in mines, quarries, and in occupations such as sandblasting. Asbestosis comes from breathing tiny asbestos fibers in mining, building construction, and other industries. Less commonly, other kinds of dust are continuously inhaled in work-related situations and cause pneumoconiosis.

What Happens When People Have Pneumoconiosis?

Symptoms

Because pneumoconiosis usually takes 20 or 30 years to develop, workers often do not notice symptoms until they are over 50. The main symptoms are coughing and difficulty in breathing, which gradually increases. Complications include emphysema and increased risk of tuberculosis. Asbestosis patients are more likely to develop lung cancer, especially if they smoke cigarettes. Damaged lungs make the heart work harder, and heart problems can accompany severe cases of pneumoconiosis.

Diagnosis

Diagnosis is made by physical examination and through a medical history that tells the doctor which dusts patients have been exposed to. The doctor may also take chest x-rays and pulmonary (lung) function tests.

Treatment

There is no cure for pneumoconiosis, because the dust cannot be removed from the lungs. Even if it could, the damage done to the lungs from years of inflammatory reaction to the dust could not be undone. Except in a mild form called simple pneumoconiosis, the disease is progressively disabling. The only treatment is to avoid smoking and further exposure to dust, and to treat complications.

Prevention

Pneumoconiosis can be prevented by enforcing maximum allowable dust levels in mines and at other work sites, and by using protective masks. Regular medical examinations, including chest x-rays for people at risk, can detect pneumoconiosis during its earlier stages, before it becomes disabling.

See also

Emphysema
Environmental Diseases

Lung Cancer

Tuberculosis

COAL WORKERS PNEUMOCONIOSIS, COMPLICATED

 

This picture shows complicated coal workers pneumoconiosis. There are diffuse, small, light areas (3 to 5 mm) in all areas on both sides of the lungs. There are large light areas which run together with poorly defined borders in the upper areas on both sides of the lungs. Diseases which may explain these X-ray findings include complicated coal workers pneumoconiosis (CWP), silico-tuberculosis, disseminated tuberculosis, metastatic lung cancer, and other diffuse infiltrative pulmonary diseases

Taking the Occupational History

An illness that fails to respond to standard treatment, does not fit the typical demographic profile or is of unknown cause should raise suspicion of an occupational etiology. An illness that fails to respond to standard treatment, does not fit the typical demographic profile or is of unknown cause should raise suspicion of an occupational etiology.

A standardized set of questions asked of every patient is the single most important method of recognizing the link between illness and occupation. In a busy practice, a set of screening questions and a self-administered questionnaire can be helpful in obtaining an efficient occupational history.

Screening Questions

Key screening questions include the following:

1.     What type of work do you do?

2.     Do you think your health problems might be related to your work?

3.     Are your symptoms different at work and at home?

4.     Are you currently exposed to chemicals, dusts, metals, radiation, noise or repetitive work? Have you been exposed to chemicals, dusts, metals, radiation, noise or repetitive work in the past?

5.     Are any of your co-workers experiencing similar symptoms?

If the answers to one or more of these questions suggest that a patient's symptoms are job related or that the patient has been exposed to hazardous material, a comprehensive occupational history should be obtained.

Self-Administered Occupational History

Every patient's chart should include a self-administered occupational history form that the patient fills out before a visit. The completed form is then available for subsequent review and periodic updating by the family physician or office staff. A sample form for a self-administered occupational history is provided in Figure 1.

Comprehensive Occupational History

The elements of the comprehensive occupational history are listed in Table 2.

Job History. A job history, including employer names, dates of employment, job titles and major job duties, serves as the framework for assessing occupational exposures and the risk of illness. The job history should include a list of all positions held, because some occupational diseases, particularly work-related cancers, have long latent periods.

Job duties are distinguished from job titles because titles alone often provide little or misleading information about occupational exposures. Furthermore, workers with the same job title, even within the same company, may have vastly different exposures based on their job duties.

Military service should also be included in the job history. Hazardous exposures are common in military settings (e.g., asbestos exposure in naval shipyards and dioxin exposure in Vietnam).

Exposures. The second element of the history is an assessment of specific exposures. Major exposures should be listed for each job in the job history. The physician should ask for additional details about job tasks that appear relevant to the patient's current symptoms.

Exposures are recorded for each of the patient's various job duties. These exposures may include metals, chemicals, dusts, physical factors (i.e., repetitive motion, noise, radiation), microorganisms and stress. Both indirect and secondary exposures should be recorded because the patient's health can be affected by exposures originating in other parts of the workplace. For example, asthma in a woman assembling spark plugs may be exacerbated by exposure to volatilized products from a molding operation 20 feet away from her workstation.

Exposure dosage should also be assessed. Although a patient may present a list of numerous chemicals used in a workplace, some substances may be used infrequently or in very small amounts, whereas others may be used daily, gallons at a time.

The presence of exposure controls may significantly affect the extent of exposure. Ventilation is a crucial control and includes both general and local systems. The patient should be asked specific questions about general ventilation, including the presence of operable doors and windows, the location of walls and partitions that may affect air flow, and the configuration of the mechanical ventilation system. Workers are usually aware of a local exhaust ventilation system, such as a hood, a vacuum apparatus attached to a machine or exhaust slots on a tank. The patient should be asked whether the exhaust mechanisms are functioning.

Personal protective equipment such as respirators, gloves and earplugs are other commonly used exposure controls. To assess exposure dosage, the physician needs to know whether the patient uses the protective equipment consistently, whether the equipment fits correctly (especially a respirator), whether the equipment is appropriate for the exposure and whether the equipment is stored and maintained properly.

 

 

Temporal Relationship of Symptoms to Work. The timing of symptoms in relation to work is often crucial in the assessment of a potential occupational illness. A patient with asthma may state that symptoms appear soon after he or she arrives at work and then abate after the shift and on weekends. The timing of symptoms may be more specifically linked to the use of a certain substance, the activation of a specific process or a change of materials or other work conditions. However, it is important to recognize that as many job-related illnesses progress, the clear relationship of symptoms to work may be obscured by a lack of marked improvement away from work.

Symptoms Among Co-workers. The probability that work is contributing to a common illness is strengthened if the patient's co-workers are experiencing similar symptoms. When queried, patients with occupational illness commonly report others who are similarly affected.

Nonoccupational Exposures. Nonwork activities may also contribute to illness and therefore should be assessed as part of the comprehensive history. Tobacco smoking and excessive alcohol use contribute to a variety of diseases and may interact with occupational exposures to increase the risk of adverse health effects. Recreational activities, hobbies, unpaid work (e.g., home renovations) and drug use are other potential sources of hazardous exposure. For example, a miner may be exposed to noise both at work (drilling and blasting) and at home (snowmobiling and hunting) or a construction painter may be exposed to lead during bridgework and while scraping and repainting the house. The history should allow the physician to evaluate the relative contribution of exposures, both on and off the job, to an illness.

Additional Exposure Information

It is often desirable to supplement the occupational history with additional exposure data. Patients may have only partial knowledge of the specific substances to which they have been exposed.

With the patient's permission, the physician can request exposure information from the employer. The Occupational Safety and Health Administration's (OSHA) Hazard Communication and Access to Medical Record Standards mandate access to this information for both clinicians and workers.

Alternative strategies may be employed if the patient is reluctant to have the physician contact the employer. The patient may make the request for exposure information, or the physician may contact the manufacturer or distributor of the suspect materials. Labels from workplace containers provide the names of appropriate contacts. The patient can also ask representatives of a trade union, if present, to obtain exposure data. Employers are sometimes amenable to a site visit by the physician. This visit can provide valuable exposure information.

In response to a request for exposure data, the physician usually receives a material safety data sheet (MSDS) for each substance used in the workplace. The MSDS identifies the hazardous ingredients and notes potential health effects of the substance. The MSDS is often limited, however. Since many substances remain unstudied and their toxic effects are unknown, they have not been deemed harmful by OSHA. As a result, they are not covered in MSDS materials. The lack of toxicity data is also reflected in the emphasis the MSDS places on acute health effects. The potential effects of chronic lower level exposure often are not included in the MSDS. Therefore, the physician should view the MSDS as an informational starting point that frequently requires supplementation.

In addition to the MSDS, quantitative exposure data are often available. These data typically include levels of air contaminants that are compared to OSHA permissible exposure limits (PELs). However, if the air level of a substance is below the recommended PEL, it should not automatically be assumed that the substance carries no risk of adverse health effects. The limitations of monitoring techniques and OSHA's standard setting process frequently call this assumption into question.²² Consequently, even if air levels of various substances are below the PELs, a patient whose history is consistent with a work-related illness is likely to be experiencing the adverse effects of exposure.

Occupational Health Resources

The need for consultation or referral depends on the physician's skill, confidence and time, as well as the specifics of a given case. A telephone consultation or referral to an occupational medicine specialist can provide information on the extent of a patient's exposure, the likely health effects of the exposure, appropriate diagnostic tests, possible workplace interventions to reduce exposure and recommendations on the patient's return to work. Corroboration by an occupational medicine specialist may also increase the family physician's confidence in his or her professional assessment of the situation.

Many occupational health centers employ multidisciplinary teams that include industrial hygienists, nurses and social workers. This structure allows occupational illness to be addressed comprehensively. In addition, resources are available to conduct workplace evaluations, to provide educational programs and to help patients access appropriate benefits systems and cope with the emotional ramifications of an occupational disease.