Occupational asthmaAsthma is a predisposition to chronic inflammation of the lungs in which the airways are reversibly narrowed. Asthma affects 7% of the population of the United States, and 300 million worldwide...
is an occupational condition defined as:
"a disease characterized by variable airflow limitation and/or airway hyper-responsiveness due to causes and conditions attributable to a particular occupational environment and not stimuli encountered outside the workplace".
Introduction
AsthmaAsthma is a predisposition to chronic inflammation of the lungs in which the airways are reversibly narrowed. Asthma affects 7% of the population of the United States, and 300 million worldwide...
is defined as a respiratory disease caused by narrowing of the air passages. It is synonymous with difficulty in
breathingBreathing is the process that takes oxygen in and carbon dioxide out of the body. Aerobic organisms require oxygen to release energy via respiration, in the form of the metabolism of energy-rich molecules such as glucose...
, tightness of chest, nasal irritation, coughing and wheezing. The first person to use it in reference to a medical condition was
HippocratesHippocrates of Cos or Hippokrates of Kos - Greek: ; Hippokrátēs was an ancient Greek physician of the Age of Pericles, and was considered one of the most outstanding figures in the history of medicine...
, and he believed that tailors, anglers and metalworkers were more likely to be affected by the disease. Although much research has been done since, the inflammatory component of asthma was recognized only in the 1960s.
Today,
asthmaAsthma is a predisposition to chronic inflammation of the lungs in which the airways are reversibly narrowed. Asthma affects 7% of the population of the United States, and 300 million worldwide...
affects as much as 15% of the Canadian population (and this is true of other developed countries too) and has increased four fold in the last 20 years. Various reasons can be identified for this increase - Of course better diagnosis and facilities along with a greater awareness regarding the disease have played a major role. But, one cannot deny the part of increased environmental pollution. Researchers have been working on the relation between the environment and human health since long and the air we breathe is the primary cause for lung diseases like
asthmaAsthma is a predisposition to chronic inflammation of the lungs in which the airways are reversibly narrowed. Asthma affects 7% of the population of the United States, and 300 million worldwide...
,
rhinitisRhinitis , commonly known as a runny nose, is the medical term describing irritation and inflammation of some internal areas of the nose. The primary symptom of rhinitis is nasal dripping. It is caused by chronic or acute inflammation of the mucous membrane of the nose due to viruses, bacteria or...
,
COPDChronic obstructive pulmonary disease refers to chronic bronchitis and emphysema, a pair of two commonly co-existing diseases of the lungs in which the airways become narrowed. This leads to a limitation of the flow of air to and from the lungs causing shortness of breath...
s, etc. that affect us today.
Approximately 10 to 15% of the adults affected by the disease report an aggravation of their symptoms while at work and an improvement when away, which implies that they may be suffering from Occupational Asthma. Thus, when an individual’s Asthma is caused, not aggravated, by workplace materials, it is defined as Occupational Asthma. In the USA, OA is considered the most common occupational lung disease.
At present, over 400 workplace substances have been identified as having asthmagenic or allergenic properties. Their existence and magnitude vary from region to region and the type of
industryAn industry is the manufacturing of a good or service within a category. Although industry is a broad term for any kind of economic production, in economics and urban planning industry is a synonym for the secondary sector, which is a type of economic activity involved in the manufacturing of raw...
and can be as varied as wood dust (
cedarCedar is a genus of coniferous trees in the plant family Pinaceae. They are most closely related to the Firs , and share a very similar cone structure...
,
ebonyEbony is a general name for very dense black wood. In the strict sense it is yielded by several species in the genus Diospyros, but other heavy, black woods are sometimes also called ebony...
, etc.), persulfates (Hairsprays),
zincZinc , also known as spelter, is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
or even seafood like prawns. For example, in
FranceFrance , officially the French Republic , is a country located in Western Europe, with several overseas islands and territories located on other continents. Metropolitan France extends from the Mediterranean Sea to the English Channel and the North Sea, and from the Rhine to the Atlantic Ocean...
the industries most affected in order of importance are Bakeries and cake-shops, automobile industry and hairdressers, whereas in Canada the principal cause is wood dust, followed by isocyanates.
Hypersensitivity pneumonitisHypersensitivity pneumonitis is an inflammation of the alveoli within the lung caused by hypersensitivity to inhaled organic dusts. Sufferers are commonly exposed to the dust by their occupation or hobbies.-Pathophysiology:Hypersensitivity pneumonitis involves inhalation of an antigen...
is a related condition, with many occupational examples (e.g. "Farmer's Lung", "Malt Worker's Lung" and "Humidifier Lung" etc.). However, although overlapping in many cases, hypersensitivity pneumonitis may be distinguished from
occupational asthma in that it isn't restricted to only occupational exposure, and involves
type III hypersensitivityType III hypersensitivity occurs when antigens and antibodies are present in roughly equal amounts, causing extensive cross-linking.-Presentation:...
and
type IV hypersensitivityType IV hypersensitivity is often called delayed type hypersensitivity as the reaction takes two to three days to develop. Unlike the other types, it is not antibody mediated but rather is a type of cell-mediated response....
rather than
type I hypersensitivityType I hypersensitivity is an allergic reaction provoked by reexposure to a specific type of antigen referred to as an allergen.Exposure may be by ingestion, inhalation, injection, or direct contact.-Pathophysiology:...
of asthma. Unlike asthma, hypersensitivity pneumonitis targets lung alveoli rather than bronchi.
History
In 1700,
Bernardino RamazziniBernardino Ramazzini was an Italian physician.Ramazzini was an early proponent of the use of cinchona bark in the treatment of Malaria...
, Doctor of Philosophy and Medicine from
ParmaParma is a city in the Italian region of Emilia-Romagna famous for its architecture and the fine countryside around it. It is the home of the University of Parma, one of the oldest universities in the world....
,
ItalyItaly , officially the Italian Republic , is a country located on the Italian Peninsula in Southern Europe and on the two largest islands in the Mediterranean Sea, Sicily and Sardinia. Italy shares its northern, Alpine boundary with France, Switzerland, Austria and Slovenia...
published the book “De Morbis Artificum Diatriba” (A Treatise on the Diseases of Workers). Although researchers like Olaus Magus had done work on diseases due to occupational causes as early as 1555, this was the first comprehensive work on work-related diseases. This volume described in detail the diseases of workers in 52 different occupations. Thus, it was the basis for the emergence of occupational medicine and even today, it is an important reference. Due to his important contribution to this field, Dr. Ramazzini is considered the father of occupational medicine.
Similarly, for his contribution to research on asthma in the workplace, Dr Jack Pepys is considered as the Father of Occupational Asthma. His work on the role of
AspergillusAspergillus is a genus of a few hundred molds found throughout much of nature worldwide. Aspergillus was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Micheli was reminded of the shape of an aspergillum , and named the genus...
species in pulmonary diseases as also on the cause of farmer’s lung have heavily influenced the emergence of OA as an occupational disease. And, thanks to his work on Specific Inhalation Challenge, the compensatible aspect of the disease was recognized.
Signs and symptoms
Less than five years of exposure to an occupational agent can be enough for the appearance of the first OA symptoms. This depends on whether the reason for the OA to occur was exposure to the causative agent over a period of time (with a latency period) or a single exposure to an irritant but at a very high concentration (without latency period). Both eventually result in OA. Coughing, wheezing, nasal irritation, difficulty in breathing, tightness of chest are the most common symptoms and can be recognized more easily by asking oneself the following questions:
- Are any of the above symptoms recurrent/chronic?
- Are they present at work?
- Do they worsen towards the end of the work day and/or end of the week?
- Does the employee/worker feel an improvement in his condition when away from work, on vacation or on weekends?
If these symptoms persist, the person is most likely suffering from OA. However, one must be aware that this could also be because the person is already suffering from asthma and his condition was simply aggravated by workplace irritants (Work-aggravated asthma). In this case, although he will suffer similar consequences as someone who is suffering from OA (loss of work, medical expenses, etc.), his disease cannot be considered as having an occupational origin.
Diagnosis
Like for any other disease correct diagnosis is important. According to Dr. Susan Tarlo:
“It is important to recognize, since if due to a workplace sensitizer and, if undetected and if the patient continues to work with even small exposure to the relevant sensitizing agent, the prognosis is worse”. She also concluded that, “the chance of eventual improvement in Asthma severity after stopping exposure decreases with the duration of exposure after the onset of the symptoms. The best chance of asthma clearing or significantly improving is associated with early diagnosis and early removal from ongoing exposure”.
However, the biggest challenge is the first step – Family doctors and patients alike do not have sufficient knowledge about Occupational Asthma - only 15% of the asthmatic patients are asked by their doctor if their symptoms are related to work. And often, patients do not mention this possibility due to the fear of losing their jobs or simply because they are not aware of the association between their work and asthma. What they do not realize is that if they continue working under such circumstances, not only are they sure to lose their job in the long run but their asthma will also reach an irreversible stage. Clearly, an incorrect diagnosis will have considerable medical, social and financial consequences.
Diagnosis of OA is a process and has to be done over a period of time. First, the patient’s occupational and clinical history is taken and his symptoms are charted (Charting is usually done at the end of a typical work week and within 24 hours of the occurrence of symptoms in order to get objective information). Once this has been established, the following
diagnostic methods are used:
Non-specific bronchial hyperreactivity
A non-specific bronchial hyperreactivity test involves testing with methacoline, after which the Forced Expiratory Volume in 1 second (FEV
1) of the patient is measured. This test is often used for measuring the intensity of a person's asthma and to confirm that the person needs to be treated for asthma. Other non specific tests could even require the patient to run in open air or on a treadmill for a few minutes at a continuous pace. In this case, the individual’s Peak Expiratory Flow Rate (PEFR) is measured. (The peak expiratory flow rate measures how fast a person can exhale) .
Skin prick tests
Although called skin prick test, it does not involve drawing blood, in fact, the skin is not even scratched. It is usually performed on the inner aspect of the forearm where grid is marked (using a simple marker) and a drop of the allergen that is to be tested is placed on the arm at the end of each line. All the allergens that need to be tested can be similarly placed on the grid. Once this has been done, the skin is pricked through the drop using a lancet. Reactions, if any, occur within 10 to 15 minutes and these results can then be analyzed.
IgE-specific tests
Immunoglobulin E is an antibody found in our blood and is effective against toxins. Since it can also trigger allergic reactions to specific allergens like
pollenPollen is a fine to coarse powder containing the microgametophytes of seed plants, which produce the male gametes . Pollen grains have a hard coat that protects the sperm cells during the process of their movement between the stamens to the pistil of flowering plants or from the male cone to the...
, the IgE test is performed to evaluate whether the subject is allergic to these substances.
Spirometric tests
Conventionally, a
spirometerA spirometer is an apparatus for measuring the volume of air inspired and expired by the lungs. It is a precision differential pressure transducer for the measurements of respiration flow rates. The spirometer records the amount of air and the rate of air that is breathed in and out over a...
can be defined as a device used to measure timed expired and inspired volumes. These volumes then enable us to measure how quickly the lungs can be emptied and filled and whether it is effective. These measurements need to be stated at body temperature, and the pressure will have to be saturated with water vapor to get the correct values. This is because, if the spirometer is dry the recorded volume of air displaced is lower than that actually displaced by the lungs.
Peak Expiratory Flow at work
This test uses the PEFR method. The only difference is that it measures the functioning of the patient's airways at his place of work and not necessarily in a controlled environment. The patient breathes into a Peak Expiratory Flow monitor (a hand-held device that has a mouth piece at one end and a scale with an indicator on the other).
Specific inhalation challenge
- Realistic method
“The Realistic Method” is a whole body sealed chamber where the patient is exposed to articles that are present in their workplace. This method has the advantage of being able to assess, albeit highly subjectively, ocular and nasal symptoms as well as a reduction in FEV1.
- Closed-circuit method
This test requires the patient to breathe aerosols of the suspected ‘asthmagens’ through an oro-facial mask. These ‘asthmagens’ are aerosolized using closed circuit chambers, and the quantities and concentrations administered being minute and extremely stable minimize the risk of exaggerated responses.
Of the above methods of doing a diagnosis, procedures such as monitoring of
spirometrySpirometry is the most common of the Pulmonary Function Tests , measuring lung function, specifically the measurement of the amount and/or speed of air that can be inhaled and exhaled...
or peak expiratory flow at work and Specific Inhalation Challenges (SIC) have been proved as the most objective and reliable methods.
Prevention and treatment
According to the
Canadian Centre for Occupational Health and SafetyThe Canadian Centre for Occupational Health and Safety is a Crown corporation owned by the Government of Canada.CCOHS functions as the primary national agency in Canada for the advancement of safe and healthy workplaces and preventing work-related injuries, illnesses and deaths...
(CCOHS) better education of workers, management, unions and medical professionals is the key to the prevention of OA. This will enable them to identify the risk factors and put in place preventive measures like masks or exposure limits, etc.
Recovery is directly dependent on the duration and level of exposure to the causative agent. Depending on the severity of the case, the condition of the patient can improve dramatically during the first year after removal from exposure.
Three basic types of procedures are used for treating the affected workers:
1) Reducing exposure
This method is most effective for those affected by irritant-induced OA. Thus, by reducing their exposure duration and level to the causative agent, the probability of suffering another reaction is lowered. But exposure can be reduced in other ways like making use of face masks or providing better ventilation. Now, more and more di-isocyanate free spray paints are available. Similarly, most hospitals and healthcare companies have exchanged latex gloves for other materials. Thus, reducing exposure to known asthmagens can also be used as a preventive measure.
2) Removal from exposure
Persons affected by OA that occurred after a latency period, whether a few months or years, must be immediately removed from exposure to the causative agent. This is their only chance of recovery. However, this entails severe socio-economic consequences for the worker as well as the employer due to loss of job, unemployment, compensation issues, quasi-permanent medical expenditures, hiring and re-training of new personnel, etc. Also, according to recent research the probability that those who suffer from OA remain unemployed longer than those who suffer from non-occupational asthma is higher. One solution to this problem is relocating the employee in the same company away from the causative agents.
3) Medical and pharmacological treatment
Anyone diagnosed with Asthma will have to undergo medical treatment. This is complementary to either removing or reducing the patient’s exposure to the causal agents. Two types of medication can be used:
- Relievers or bronchodilators
Short-acting beta-agonists like salbutamolSalbutamol or albuterol is a short-acting β
2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease...
or terbutalineTerbutaline is a β
2-adrenergic receptor agonist, used as a fast-acting bronchodilator and as a tocolytic to delay premature labour...
or long-acting beta-agonists like salmeterolSalmeterol is a long-acting beta2-adrenergic receptor agonist drug that is currently prescribed for the treatment of asthma and chronic obstructive pulmonary disease...
and formoterolFormoterol or eformoterol is a long-acting β
2-agonist used in the management of asthma and/or chronic obstructive pulmonary disease...
or anticholinergicAn anticholinergic agent is a substance that blocks the neurotransmitter acetylcholine in the central and the peripheral nervous system. An example of an anticholinergic is dicyclomine....
, etc. dilate airways which relieve the symptoms thus reducing the severity of the reaction. Some patients also use it just before work to avoid a drop in the FEV1.
- Preventers
Anti-inflammatory agents like corticosteroidCorticosteroids are a class of steroid hormones that are produced in the adrenal cortex. Corticosteroids are involved in a wide range of physiologic systems such as stress response, immune response and regulation of inflammation, carbohydrate metabolism, protein catabolism, blood electrolyte...
s, LKTRA or mast cell stabilizers can be used depending on the severity of the case.
Compensation issues
As mentioned earlier, when a person is diagnosed as having occupational asthma, it results in serious socio-economic consequences not only for the workers but also for the employer and the healthcare system. The employee has to be taken off job immediately to prevent any further damage to his health. And, the probability of being re-employed is lower for those suffering from OA as compared to those suffering from normal asthma. The employer not only pays compensation to the employee, but will also have to spend a considerable amount of time and energy and funds for hiring and training new personnel.
Occupations at risk
The following tables show occupations that are known to be at risk for occupational asthma, and main substances involved.
Yet, the riskiest occupations for asthma are: adhesive handlers (e.g.
acrylateThe acrylate ion is the ion of acrylic acid.Acrylates are the salts and esters of acrylic acid. They are also known as propenoates ....
), animal handlers and veterinarians (animal proteins), bakers and millers (cereal grains), carpet makers (gums), electronics workers (soldering
resinResin is a hydrocarbon secretion of many plants, particularly coniferous trees. It is valued for its chemical constituents and uses, such as varnishes and adhesives, as an important source of raw materials for organic synthesis, or for incense and perfume. Fossilized resins are the source of amber...
), forest workers, carpenters and cabinetmakers (wood dust), hairdressers (e.g.
persulfateThe term persulfate refers to ions or compounds with more oxygen than normal sulfates.These do not have sulfur in a different oxidation state; rather, they contain peroxide units, where two oxygens take the place of one in a normal sulfate; the oxygen atoms are in oxidation state −1.The main forms...
), health care workers (latex and chemicals such as
glutaraldehydeGlutaraldehyde is an organic compound with the formulat CH22. This pungent colorless oily liquid is used to disinfect medical and dental equipment...
), janitors and cleaning staff (e.g.
chloramine-T N-chloro tosylamide sodium salt, sold as chloramine-T, is a N-chlorinated and N-deprotonated sulfonamide used as a biocide and a mild disinfectant. It is a white powder that gives unstable solutions with water.-Chemistry:...
), pharmaceutical workers (drugs, enzymes), seafood processors, shellac handlers (e.g. amines), solderers and refiners (metals), spray painters, insulation installers, plastics and foam industry workers (e.g. diisocyanates), textile workers (dyes) and users of plastics and epoxy resins (e.g. anhydrides)
Grains, flours, plants and gums |
Occupation |
Agent |
Bakers, millers |
Wheat |
Chemists, coffee bean baggers and handlers, gardeners, millers, oil industry workers, farmers |
Castor beans |
Cigarette factory workers |
Tobacco dust |
Drug manufacturers, mold makers in sweet factories, printers |
Gum acacia |
Farmers, grain handlers |
Grain dust |
Gum manufacturers, sweet makers |
Gum tragacanthTragacanth is a natural gum obtained from the dried sap of several species of Middle Eastern legumes of the genus Astragalus, including A. adscendens, A. gummifer, and A. tragacanthus. Some of these species are known collectively under the common names "goat's thorn" and "locoweed". The gum is...
|
Strawberry growers |
Strawberry pollen |
Tea sifters and packers |
Tea dust |
Tobacco farmers |
Tobacco leaf |
Woollen industry workers |
Wool |
Animals, insects and fungi |
Occupation |
Agent |
Bird fanciers |
Avian proteins |
Cosmetic manufacturers |
CarmineCarmine , also called Crimson Lake, Cochineal, Natural Red 4, C.I. 75470, or E120, is a pigment of a bright red color obtained from the carminic acid produced by some scale insects, such as the cochineal and the Polish cochineal, and is used as a general term for a particularly deep red color of...
|
Entomologists |
Moths, butterflies |
Feather pluckers |
Feathers |
Field contact workers |
CricketCricket is a bat-and-ball team sport that is first documented as being played in southern England in the 16th century. By the end of the 18th century, cricket had developed to the point where it had become the national sport of England. The expansion of the British Empire led to cricket being...
s |
Fish bait breeders |
Bee moths |
Flour mill workers, bakers, farm workers, grain handlers |
Grain storage mites, alternariaAlternaria is a genus of ascomycete fungi. Alternaria species are known as major plant pathogens. They are also common allergens in humans, growing indoors and causing hay fever or hypersensitivity reactions that sometimes lead to asthma...
, aspergillusAspergillus is a genus of a few hundred molds found throughout much of nature worldwide. Aspergillus was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Micheli was reminded of the shape of an aspergillum , and named the genus...
|
Laboratory workers |
Locusts, cockroachCockroaches are insects of the order Blattaria. This name derives from the Latin name for the insect, Blatta....
es, grain weevils, rats, mice, guinea pigs, rabbits |
Mushroom cultivators |
Mushroom spores |
Oyster farmers |
HoyaHoya is a genus of 200-300 species of tropical climbing plants in the family Apocynaceae , native to southern Asia , Australia, and Polynesia. Common names for this genus are waxplant, waxvine, waxflower or simply hoya...
|
Pea sorters |
Mexican bean weevils |
Pigeon breeders |
Pigeons |
Poultry workers |
Chickens |
Prawn processors |
PrawnPrawns are Decapods, belonging to the sub-order Dendrobranchiata . They are similar in appearance to shrimp, but can be distinguished by the gill structure which is branching in prawns , but is lamellar in shrimp...
s |
Silkworm sericulturers |
Silkworms |
Zoological museum curators |
BeetleBeetles are the group of insects with the largest number of known species. They are classified in the order Coleoptera , which contains more described species than in any other order in the animal kingdom, constituting about 25% of all known life-forms...
s |
Chemicals/Materials |
Occupation |
Agent |
Aircraft fitters |
Triethyltetramine |
Aluminum cable solderers |
AminoethylethanolamineAminoethylethanolamine or AEEA is an organic base used in the industrial manufacture of fuel and oil additives, chelating agents and surfactants, among other things....
|
Aluminum pot room workers |
FluorineFluorine is the chemical element with atomic number 9, represented by the symbol F. Fluorine forms a single bond with itself in elemental form, resulting in the diatomic F 2 molecule. F 2 is a supremely reactive, poisonous, pale, yellowish brown gas. Elemental fluorine is the...
|
Autobody workers |
Acrylates (resins, glueThis is a list of various types of glue. Historically, the term "glue" only referred to protein colloids prepared from animal flesh. The meaning has been extended to refer to any fluid adhesive....
s, sealantA sealant is a viscous material that changes state to become solid, once applied, and is used to prevent the penetration of air, gas, noise, dust, fire, smoke or liquid from one location through a barrier into another. Typically, sealants are used to close small openings that are difficult to shut...
s, adhesiveAdhesive or glue is a compound in a liquid or semi-liquid state that adheres or bonds items together. Adhesives may come from either natural or synthetic sources. Some modern adhesives are extremely strong, and are becoming increasingly important in modern construction and industry...
s) |
Brewery workers |
Chloramine-T N-chloro tosylamide sodium salt, sold as chloramine-T, is a N-chlorinated and N-deprotonated sulfonamide used as a biocide and a mild disinfectant. It is a white powder that gives unstable solutions with water.-Chemistry:...
|
Chemical plant workers, pulp mill workers |
ChlorineChlorine Chlorine Chlorine ( , from the Greek word 'χλωρóς' (khlôros, meaning 'pale green'), is the chemical element with atomic number 17 and symbol Cl. It is a halogen, found in the periodic table in group 17 (formerly VII, VIIa, or VIIb). As the chloride ion, which is part of common salt and...
|
Dye weighers |
Levafix brilliant yellow, drimarene brilliant yellow and blue, cibachrome brilliant scarlet |
Electronics workers |
Colophony |
Epoxy resin manufacturers |
Tetrachlorophthalic anhydride |
Foundry mold makers |
FuranFuran, also known as furane and furfuran, is a heterocyclic organic compound. It is typically derived by the thermal decomposition of pentose-containing materials, cellulosic solids especially pine-wood. Furan is a colorless, flammable, highly volatile liquid with a boiling point close to room...
-based resin binder systems |
Fur dyers |
Para-phenylenediamine |
Hairdressers |
Persulphate salts |
Health care workers |
GlutaraldehydeGlutaraldehyde is an organic compound with the formulat CH22. This pungent colorless oily liquid is used to disinfect medical and dental equipment...
, latexLatex refers generically to a stable dispersion of polymer microparticles in an aqueous medium. Latexes may be natural or synthetic. Latex as found in nature is a milky sap-like fluid within many plants that coagulates on exposure to air. It is a complex emulsion in which proteins, alkaloids,...
|
Laboratory workers, nurses, phenolic resinPhenolic resin can include any of various synthetic thermosetting resins such as Bakelite, obtained by the reaction of phenols with simple aldehydes such as formaldehyde. Phenolics can be used to make molded products including pool balls, laboratory countertops, and as coatings and...
molders |
FormaldehydeFormaldehyde is a chemical compound with the formula CH2O. It is the simplest aldehyde. Formaldehyde also exists as the cyclic trimer trioxane and the polymer paraformaldehyde. It exists in water as the hydrate H2C2. Aqueous solutions of formaldehyde are referred...
|
Meat wrappers |
Polyvinyl chloridePolyvinyl chloride, commonly abbreviated PVC, is the third most widely used thermoplastic polymer after polyethylene and polypropylene. In terms of revenue generated, it is one of the most valuable products of the chemical industry. Around the world, over 50% of PVC manufactured is used in...
vapour |
Paint manufacturers, plastic molders, tool setters |
Phthalic anhydridePhthalic anhydride is the organic compound with the formula C6H42O. This anhydride of phthalic acid, a colourless solid, is an important industrial chemical, especially for the large-scale production of plasticizers for plastics.-Synthesis and production:Phthalic...
|
Paint sprayers |
DimethylethanolamineDimethylaminoethanol, also known as DMAE or dimethylethanolamine, is an organic compound. This compound also goes by the names of N,N-dimethyl-2-aminoethanol, beta-dimethylaminoethyl alcohol, beta-hydroxyethyldimethylamine and Deanol...
|
Photographic workers, shellacShellac is a resin secreted by the female lac bug to form a cocoon, on trees in the forests of India and Thailand. It is processed and sold as dry flakes , which are dissolved in denatured alcohol to make liquid shellac, which is used as a brush-on colorant, food glaze and wood finish much like a...
manufacturers |
Ethylenediamine |
Refrigeration industry workers |
CFCs |
Solderers |
Polyether alcohol, polypropylene glycolPolypropylene glycol or polypropylene oxide is the polymer of propylene glycol. Chemically it is a polyether. The term polypropylene glycol or PPG is reserved for low to medium range molar mass polymer when the nature of the end-group, which is usually a hydroxyl group, still matters...
|
Isocyanates and metals |
Occupation |
Agent |
Boat builders, foam manufacturers, office workers, plastics factory workers, refrigerator manufacturers, TDIToluene diisocyanate is an aromatic diisocyanate. It is produced for reaction with polyols to form polyurethanes. It exists in two isomers, 2,4-TDI and 2,6-TDI . 2,4-TDI is produced in the pure state, but TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers respectively...
manufacturers/users, printers, laminators, tinners, toy makers |
TDIToluene diisocyanate is an aromatic diisocyanate. It is produced for reaction with polyols to form polyurethanes. It exists in two isomers, 2,4-TDI and 2,6-TDI . 2,4-TDI is produced in the pure state, but TDI is often marketed as 80/20 and 65/35 mixtures of the 2,4 and 2,6 isomers respectively...
|
Boiler cleaners, gas turbine cleaners |
VanadiumVanadium is the chemical element with the symbol V and atomic number 23. It is a soft, silvery grey, ductile transition metal. The formation of an oxide layer stabilizes the metal against oxidation. Andrés Manuel del Río discovered vanadium in 1801 by analyzing the mineral vanadinite, and named it...
|
Car sprayers |
Hexamethylene diisocyanateHexamethylene diisocyanate is an organic compound in the class known as isocyanates. More specifically, it is an aliphatic diisocyanate. It is produced in relatively small quantities, accounting for only 3.4% of the global diisocyanate market in the year 2000...
|
Cement workers |
Potassium dichromatePotassium dichromate, K2Cr2O7, is a common inorganic chemical reagent, most commonly used as an oxidizing agent in various laboratory and industrial applications. As with all hexavalent chromium compounds, it is potentially harmful to health and must be handled and...
|
Chrome platers, chrome polishers |
Sodium bichromate, chromic acidChromic acid generally refers to a collection of compounds generated by the acidification of solutions containing chromate and dichromate anions or the dissolving of chromium trioxide in sulfuric acid. Often the species are assigned the formulas H2CrO4 and...
, potassium chromatePotassium chromate is a yellow chemical indicator used for identifying concentrations of chloride ions in a salt solution with silver nitrate...
|
Nickel platers |
Nickel sulphate |
Platinum chemists |
Chloroplatinic acid |
Platinum refiners |
Platinum salts |
Polyurethane foam manufacturers, printers, laminators |
Diphenylmethane diisocyanate |
Rubber workers |
Naphthalene diisocyanate |
Tungsten carbide grinders |
CobaltCobalt is a hard, lustrous, gray metal, a chemical element with symbol Co and atomic number 27. Although cobalt-based colors and pigments have been used since ancient times for making jewelry and paints, and miners have long used the name kobold ore for some minerals, the free metallic cobalt was...
|
Welders |
Stainless steelIn metallurgy, stainless steel, also known as inox steel or inox, is defined as a steel alloy with a minimum of 11% chromium content by mass. Stainless steel does not stain, corrode, or rust as easily as ordinary steel...
fumes |
Drugs and enzymes |
Occupation |
Agent |
Ampicillin manufacturers |
Phenylglycine acid chloride |
Detergent manufacturers |
Bacillus subtilisBacillus subtilis, known as the hay bacillus or grass bacillus, is a Gram-positive, catalase-positive bacterium commonly found in soil. A member of the genus Bacillus, B. subtilis is rod-shaped, and has the ability to form a tough, protective endospore, allowing the organism to tolerate extreme...
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Enzyme manufacturers |
Fungal alpha-amylaseα-Amylase is the major form of amylase found in humans and other mammals. It is also an enzyme present in seeds which reserves are made of starch, or in fungi...
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Food technologists, laboratory workers |
PapainPapain is a cysteine protease enzyme present in papaya and mountain papaya .-Structure:...
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Pharmacists |
Gentian powder, flaviastase |
Pharmaceutical workers |
MethyldopaMethyldopa is a psychoactive drug used as a sympatholytic or antihypertensive. Its use is now deprecated following introduction of alternative safer classes of agents...
, salbutamolSalbutamol or albuterol is a short-acting β 2-adrenergic receptor agonist used for the relief of bronchospasm in conditions such as asthma and chronic obstructive pulmonary disease...
, dichloramineDichloramine is a reactive inorganic compound. It has the formula . It is unstable and reacts with many materials. It is formed by a reaction between ammonia and chlorine or sodium hypochlorite. It is a byproduct formed during the synthesis of chloramine and nitrogen trichloride....
, piperazine dihydrochloride, spiramycinSpiramycin is a macrolide antibiotic. It is used to treat toxoplasmosis. Although used in Europe, Canada and Mexico, spiramycin is still considered an experimental drug in the United States, but can sometimes be obtained by special permission from the FDA for toxoplasmosis in the first trimester of...
, penicillinPenicillin is a group of antibiotics derived from Penicillium fungi. Penicillin antibiotics are historically significant because they are the first drugs that were effective against many previously serious diseases such as syphilis and Staphylococcus infections...
s, sulphathiazole, sulphonechloramides, chloramine-T N-chloro tosylamide sodium salt, sold as chloramine-T, is a N-chlorinated and N-deprotonated sulfonamide used as a biocide and a mild disinfectant. It is a white powder that gives unstable solutions with water.-Chemistry:...
, phosdrin, pancreatic extracts |
Poultry workers |
Amprolium hydrochloride |
Process workers, plastic polymer production workers |
TrypsinTrypsin is a serine protease found in the digestive system of many vertebrates, where it hydrolyses proteins. Trypsin is produced in the pancreas as the inactive proenzyme trypsinogen. Trypsin predominantly cleaves peptide chains at the carboxyl side of the amino acids lysine or arginine, except...
, bromelin |
Woods |
Occupation |
Agent |
Carpenters, timber millers, woodworkers |
Western red cedar, cedar of Lebanon, irokoIroko is a hardwood from tropical Africa. It is one of the woods sometimes referred to as African Teak, although it is not always suitable as a substitute for teak. Colour is initially yellow but darkens to a richer brown over time....
, California redwood, raminGonystylus, also known as ramin, is a genus of about 30 species of hardwood trees native to southeast Asia, in Malaysia, Singapore, Indonesia, Brunei, the Philippines, and Papua New Guinea, with the highest species diversity on Borneo...
, African zebrawood |
Sawmill workers, pattern makers |
Mansonia, oakAn oak is a tree or shrub in the genus Quercus , of which about 400 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
, mahoganyThe name mahogany is used when referring to numerous varieties of dark-coloured hardwood, it is an American Indian word originally used for the wood of the species Swietenia mahagoni, known as West Indian or Cuban mahogany. Mahogany it was next equally applied to the wood of Swietenia macrophylla,...
, abiruana |
Wood finishers |
Cocabolla |
Wood machinists |
Kejaat |
External links
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