Occupational medicine (job-related illnesses)

OCCUPATIONAL MEDICINE / JOB-RELATED ILLNESSES (see also Italian laws

)

The study of worker's diseases arise in 1650 with Bernardino Ramazzini (De morbis artificum). The figure of occupational physician arises in England in 1850-1870, during the industrial revolution. The figure of the igienist arises in 1910 in Italy as a specialization of the internal medicine, while in France it stems from legal medicine.

danger : the probability that a risk is created (e.g. the presence of asbestos within an intact wall)
risk : the probability that a damage is created (e.g. the rupture of a wall containing asbestos)

The damage to the worker may come from a ... :

work-related injury : during thw work, from a violent cause acting in a short time (e.g. a working turn)
work-related chronic risk factors :

direct and significant action (efficient cause : acute and repeated or chronic) => alteration of the health state => professional disease, e.g. :

hearing loss from excessive noises
irritant contact dermatitides (ICD) (e.g. cement, NiSO₄, CoSO₄, KSO₄)
occupational bronchopneumopathies

carcinogens
dusts

inorganic dusts

mineral sclerogenous dusts

silicosis

mineral metallic nonsclerogenous dusts

endotoxins

byssinosis
weaver cough
air-conditioner fever

allergic :

irritant gas chemical pneumonitis
COPD from irritants causing pulmonary scars

technopathies due to mechanical vibrations
excessive load over normal musculoskeletal structures or normal load over impaired musculoskeletal structures => diseases due to incongruous fixed or dynamic working posture : work-related musculoskeletal disorders (WMSD) and cumulative trauma disorders (CTD)

short-term (subjective) : fatigue, comfort,
long-term (objective) : involvement of muscular and articular groups

mild : 40-80 kg : increases intake of nutrients but impairs catabolyte expulsion
moderate : 80-300 kg : impaired intake and increased output; threshold value in healthy subjects
intense : 300-650 kg : possible microfractures of limiting plate, discoarthrosis; surveillance is required
heavy : > 650 kg : microfractures, severe discal degeneration; never go further

first grade :

cervical and lumbosacral
dorsal

second grade : whole rachid, paravertebral muscles, painful spinous apophyses
third grade : as above + reduced or painful motility + positive Lasegue's sign

structures in workplaces : incongruous posture, structural elements, postural variability, fragmentation of load weight, stockage height, mechanization)
time and pause distribution
educative interventions (correct alternating movements, physical exercise)
sanitary interventions (recognize predisposed workers)

professional or occupational cancers (only 4% of all cancers)

chemicals :

organic

PAH
alkylating agents (epoxides, bischloromethylether (BCME), nitrogen mustards)
nitrosocompounds
azocompounds (bladder cancer after exposure to aromatic amines)
benzene
liver angiosarcoma after exposure to monovinyl chloride (MVC)
paranasal sinus carcinoma after exposure to wood dust

inorganic

pleural mesothelioma and lung cancer after asbestos exposure
Cr , Ni (nose, paranasal sinuses, lungs)
As (lung)

physical

infectious

less direct and less clearly demonstrable action => alteration of the health state and multiple and complex aetiology, far less severe than previous disease but anyway able to cause working discomfort

psychosocial factors
individual factors
environmental factors
inadequate solution of ergonomic problems
excessive mental charge

work-related disease (WRD)

ischemic heart disease (IHD)
COPD
syndromes affecting locomotor apparatus

biomechanical overload in assembly-lines (De Quervain's disease, CTS, epicondylitis, scapulohumeral periarthritis) in bolt screwers, heavy material movers, toll-gate workers, postural and pschical discomfort in videoterminal workers (asthenopia is similar to study on paper and is reversible at rest)

psychical disorders (burn-out, mobbing , somatoform disorders )

occupational physiology (for heavy jobs) : study of effects of muscular and psychic work on functions of various organs and apparatuses (energetic working expenses)

nature of energy sources :

potential energy in foods (1 cal = quantity of heat that allows to rise by 1°C the temperature of 1 g at P = 1 atm, from 14.5°C to 15.5°C)

sugars : 1 g = 5 kcal
proteins : 1 g = 5 kcal
lipids : 1 g = 9 kcal

average calorie requirements

qualitative

50% sugars
30% proteins
20% lipids

quantitative :

mild work : 2000-2700 kcal
moderate work : 2700-3300 kcal
heavy work : 3300-4500 kcal

Lehmann-Muller resistance limit : 4 kcal/min = 2000 kcal/8 hrs

modality of transformation of potential energy into free energy

aerobic and anaerobic transformation : ATP =ATPases=> ADP + P_i => movement of myofibrils via actomyosin
aerobic oxidation (dismutation reactions coupled to coenzymes and oxidative phosphorylation) : creatine phosphate (CP) + ADP =CPK=> ATP + creatine
consumed O₂ in ATP resynthesis is a marker for consumed energy
O₂ energy equivalent : 1 L O₂ = 5 kcal = 20,000 J
1 metabolic equivalent (MET) = 3.5 mL O₂/kg/min/m² = 1 kcal/kg/hr = basal metabolic rate (BMR)

class I : < 2 MET = rest, sedentary activity

1.5 MET : working at a table, handling devices, drive the car
2 MET : to sew, walking at 2 miles per hour

class 2 : 2-4 MET = mild-intensity physical activity

2.5 MET : barman, archivist
3 MET : hand milking, working in a supermarket
3.5 MET : walking at 5 km/h without weights
4 MET : whitewashing, plastering, walking 6.5 km/h

class 3 : 4-6 MET = moderate-intensity physical activity

5 MET : walking at 4 miles per hour, level firm surface
6 MET : aerobics (moderate)

class 4 : 6-8 MET = vigorous-intensity physical activity

7 MET : to move weigths > 20 kg, hand sawing
8 MET : to cut down trees, to roll steel, tennis (singles), swimming (front crawl, moderate), cycling 21 km/h, jogging at 6 miles per hour
11 MET : running 11 km/h
12.5 MET : very vigorous effort on a stationary bike
16 MET : skin diving, fast

microclimate (temperature, humidity, and air velocity)

clothes
temperature
barometric pressure
humidity
air velocity

Laboratory examinations

thermometry
relative humidity

hair hygrometer
electrical conductivity hygrometer
psychrometer

ventilation :

hot wire anemometer
mechanical anemometer
katathermometer

radiating heat : globothermometer (black body)

effective corrected temperature (ECT) considering relative humidity and air velocity
wet bulbe globe thermometer (WBGT) = 0.7 WB + 0.3 GT

Mechanisms of thermoregulation

Laboratory examinations

metabolic barometers

at rest
while working

temperature : skin, rectum, esophagus, sublingual
sweat flow : whole body weight before and after working
heart rate (frequencymeter, Holter)
clothing insulation estimate
temperature of air kept within clothes

Maximum tolerable limits

physical :

TE (WHO) :

sedentary work (< 2 MET) : 31°C, < 200 W
mild work (2-4 MET) : 30°C, 200-400 W
moderate/heavy work (5-7 MET) : 29°C, > 300 W

TEC (air velocity) (WHO) :

sedentary work : 30°C
moderate work : 28°C
heavy work : 26°C

WBGT (ABGIM) :

sedentary work : 30°C
moderate work : 25°C
heavy work : 25°C

biological :

heart rate : 125 bpm
predicted 4 hours sweat rate (P4SR) : 3 L / 4 hrs
rectal temperature : 38.3°C

Hyperthermy

ergonomics : the science relating to humans and their work, embodying the anatomic, physiologic, psychologic, and mechanical principles affecting the efficient use of human energy, initially dealing with astronauts. It is an interdisciplinary science for the adaptation of methods, media, and workplaces to human requirements. Together with occupational physiology they study the man-machine and man-workplace systems to tend towards a physiological rationalization of human work

workers at videoterminals
manual movements of charges

ergonomics

ergometer (J)

rolling carpet
pedals
cranks

collection of signals of physiological engagement :

cardiorespiratory signs (heart rate, ventilation rate)
metabolic signs (lactacidemia )
electrophysiological signs
subjective perception

subjective effort perception (Borg's scale) :

6-8 : extremely mild
9-10 : very mild
11-12 : moderately mild
13-14 : a little hard
15-16 : hard
17-18 : very hard
19 : extremely hard

Fatigue

Aetiology

excessively heavy work
work involving only a few muscles
uncomforting position, adverse environment or not good health

heart rate
O₂ consumption
Flicner test : frequency of optic fusion of intermittent light stimuli
neurobehavioural tests

production of metabolic heat from chemical reactions :

at rest : 100% heat output
during work : 75% is converted in heat and 25% in mechanical energy

thermal exchanges of human body :

conduction
convection
irradiation

visible radiations (0.4-0.8 mm)
invisible

emission : l and I
absorption

evaporation

respiratory apparatus : pulmonary evaporation (PE)
skin : perspiratio insensibilis (PI)

1 g H₂O = 2.4 kJ absorbed
1 g H₂O = 2.4. kJ generated

untolerable cold : muscular work > 500 W
tolerable cold : muscular work < 500 W => Q = (PE + PI)

tolerable hot : sweat < 1 L/hour => Q = (PE+PI)
untolerable hot : sweat > 1 L/hour

unregulable heat (cell functioning)

basal metabolic rate (BMR) = 4.825 kcal/L/m²_BSA (multiply by 1.15 to convert into W/m²_BSA)
1 kJ = 50 mL O₂ = 2.2 W/m²_BSA

regulable heat (activity)

anaerobic
aerobic : maximal aerobic potency is measured with tapis-roulants or cycloergometer

rectangular assays
triangular assays
step assays

occupational psichology

attitudinal selection
professional orientation

industrial toxicology :

dose markers
effect markers

industrial hygiene (Certified Industrial Hygienist (CIH) and Certified Safety Professional (CSP)) : that branch of preventive medicine which is concerned with the protection of health of the industrial population (workplace) from ...

physical polluttants (noises, radiations)
chemical polluttants (gases, vapors, dusts, toxics, cancerogens)
biological contaminants (e.g. in hospitals)

work-related anamnesis
information on productive process

raw materials
intermediate products
end-products
fundamental technologies

collection of samples of noxious agents

Web resources

American Industrial Hygiene Association (AIHA)

Special Interest Groups (SIGs)

American Society For Testing and Materials (ASTM)

measurement of noxious agents

evaluation of results

risk
programmation of ameliorative measures

realization of ameliorative measures

Prevention

primary prevention : verification and bonification of workplace (not practiceable in medical environments, where patients cannot be removed !)
secondary prevention : protection and check-ups of humans (not only early diagnosis of disease, but also of hypersensitivity (e.g. hypersensitivity to CO at concentrations < 50 ppm, atopy, ...)
tertiary prevention : job reintegration

occupation and pregnancy

risk factors for reproduction may act

before pregnancy, leading to infertility by damaging (e.g. Cd, Pb, Mn, Hg, IR, ...)

gametogenesis
gametes liberation and transport

during pregnancy (fertilization, implantation, organogenesis, fetal-maternal metabolic exchanges), leading to :

extrauterine pregnancy
spontaneous abortion
premature delivery
natimortality
congential defects

R40 , R45 , R46 , and R49 chemicals : dibromochloropropane, ehtylene dibromide, chlordecan, PCBs , CS₂ , ethylene oxide , alkylating agents, antifolates, OCs, halogenated gases, N₂O , 2,4,5-T, ...
heat
chronic posture (upright posture decreases placental vascularization)
efforts

before wk 16 : librarian, archivist, emergency room nurse, odontotechnicians, store-keeper, forwarding agent, shopkeeper, alimentary drinks workers, metal and electronic employers
after wk 16 : supporting teacher, operating theatre nurse, radiology technicians, agriculture workers

after pregnancy

worsening of maternal disease
infant mortality
infant tumours (radionuclides passing into maternal milk may lead to infant thyroid cancers)

anemia, leukocytosis
decreased respiratory functions
susceptibility to aspecific bronchial irritants
forced position, unfavorable microclimate, hyperemesis gravidarum, delayed gastric emptying, postprandial sleepiness, forced osteoarticular positions, physical efforts, hyperalgesia, delayed reaction times, emotional liability

class I : certain causes of infertility or teratogenesis
class II : probable causes of infertility and teratogenesis
class III : suspected causes of infertility and teratogenesis
class IV : not evaluated causes of infertility or teratogenesis
class V : not dangerous for humans according to animal tests

As low as reasonably achievable (ALARA) is most often used in reference to chemical or radiation exposure levels. ALARA is not simply a phrase, but a work principle, a mindset, a culture of professional excellence. In an ideal world, one could reduce his exposure to hazardous materials to zero. In reality, reducing an exposure to zero is not always possible; certain social, technical, economic, practical, or public policy considerations will result in a small but acceptable level of risk. The best way to prevent this risk from increasing is to keep one's exposure ALARA. ALARA practices apply to virtually any substance, but are mandated for radiation workers by the U.S. Nuclear Regulatory Commission (NRC). One can never have "zero" radiation exposure because of the naturally occuring radioactivity that surrounds us - cosmic rays, natural isotopes in our body etc. Therefore, the best we can do is to add nothing to this background dose, i.e. we keep our exposure ALARA. The ALARA approach used by the NRC assumes that any exposure to ionizing radiation carries some risk. The risk is assumed to be linear, so as one's exposure increases, so does the risk of adverse health effects. Instead of operating at or just below permissible exposure limits, one must stay as far below the exposure limits as possible. This affords a wider margin of error should a control fail or malfunction - one's exposure level may rise but still stay below the acceptable limit. The OSHA Hazard Communication Standard 1910.1200 does not cover radioactive materials unless they also present a physical or health hazard. See the MSDS FAQ for more information. This term may appear in a discussion of PEL's, TLV's or other exposure limits on an MSDS. It will also appear on the MSDS for any substance that contains or is contaminated with a radioactive element. The personal protective equipment and other information on the MSDS should assist you in the task of keeping your exposure levels ALARA. New work practices and procedures can also help you in your quest for ALARA excellence. There are few laboratory chemicals without hazards so consider using ALARA practices with every chemical
Best available technology not entailing excessive cost (BATNEEC)
Best practicable environmental option (BPEO)
Environmental quality objective (EQO)
Environmental quality standard (EQS)
Web resources :

International Labour Organization (ILO)
National Institute for Occupational Safety and Health (NIOSH) is a part of CDC created by the Occupational Health and Safety (OHS) Act of 1970, the same Act that created OSHA

NIOSH cooperates with other world agencies in providing International Chemical Safety Cards which, while not strictly MSDS's, provide workers with succinct information about the hazards of chemicals.
NIOSH plays a role in establishing PEL, TLV and STEL's for a variety of chemicals.
The NIOSH Pocket Guide to Chemical Hazards (NPG).
NIOSH publishes Occupational Health Guidelines for Chemical Hazards listed by chemical.
The Registry for Toxic Effects of Chemical Substances (RTECS), a toxicology database containing over 140,000 chemicals substances, originally called the Toxic Substances List

Occupational Safety and Health Administration (OSHA)
Health Canada's Workplace Hazardous Materials Information System (WHMIS) is Canadian legislation covering the use of hazardous materials in the workplace. It has 6 broad hazard classifications:

Class A - Compressed Gas
Class B - Flammable and Combustible Material

Division 1: Flammable Gas
Division 2: Flammable Liquid
Division 3: Combustible Liquid
Division 4: Flammable Solid
Division 5: Flammable Aerosol
Division 6: Reactive Flammable Material

Class C - Oxidizing Material
Class D - Poisonous and Infectious Material

Division 1: Materials causing immediate and serious toxic effects

Subdivision A: Very toxic material
Subdivision B: Toxic material

Division 2: Materials causing other toxic effects
Subdivision A: Very toxic material
Subdivision B: Toxic material
Division 3: Biohazardous Infection Material

Class E - Corrosive material
Class F - Dangerously reactive material

Canadian Centre for Occupational Health and Safety (CCOHS)
Journals :

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