Introduction to Industrial Hygiene

1. Introduction to Industrial Hygiene Safety Management TM 650 Carter J. Kerk Industrial Engineering Department South Dakota School of Mines Summer 2007

2. Introduction to Industrial Hygiene • Read Asfahl • Chapter 9, Health and Toxic Substances • Chapter 10, Environmental Control and Noise

3. Industrial Hygiene • Part science, part art • Industrial Hygiene is the application of scientific principles in the workplace to prevent the development of occupational disease or injury • Requires knowledge of chemistry, physics, anatomy, physiology, mathematics

4. Toxicology Occupational Health Standards Airborne Hazards Indoor Air Quality Skin Disorders Noise Exposure Radiation Thermal Stress Anatomy Biohazards Chemicals Illumination Personal Protective Equipment Ventilation Vibration Sampling IH Topics

5. History of IH • Disease resulting from exposure to chemicals or physical agents have existed ever since people chose to use or handle materials with toxic potential • In the far past, causes were not always recognized

6. Earliest Recordings • Lead poisoning among miners by Hippocrates, 4th century BC • Zinc and sulfur hazards by Pliny the Elder, 3rd century BC

7. The Original Metallica • Georgius Agricola published a 12 volume set in 1556, De Re Metallica • Town physician in Saxony • Silver mining • Described diseases of lungs, joints, eyes • Woodcuts (see next slides)

11. Metallica Quotes • “If the dust has corrosive qualities, it eats away at the lungs, and implants consumption in the body” • Later determined to be silicosis, tuberculosis, and lung cancer

12. Metallica Quotes • “there is found in the mines black pompholyz, which eats wounds and ulcers to the bone; this also corrodes iron . . . There is a certain kind of cadmia which eats away at the feet of workmen when they have become wet, and similarly their hands, and injures their lungs and eyes.” • Later recognized as manifestations of toxicity of arsenic and cadmium

13. Metallica cont. • A young American named Herbert C. Hoover and his wife, L.H. Hoover, translated Agricola’s work into English. • The translation was published in 1912 • Hoover graduated from Stanford in 1891 as a Mining Engineer • Hoover served as the 31st president of the US (1929 – 1933)

14. Paracelsus • Published work describing mercury poisoning of miners in 1567 • His famous quote, “All substances are poisons; there is none which is not a poison. The right dose differentiates a poison and a remedy.” • This provided the basis for the concept of the dose-response relationship.

15. Dose-Response Relationship • The toxicity of a substance depends not only on its toxic properties, but also on the amount of exposure, or the dose • Paracelsus differentiated between • Chronic (low-level, long-term) poisoning • Acute (high-level, short-term) poisoning

16. Bernardino Ramazzini (1633-1714) • Wrote a book, “De Morbis Artificum” (Diseases of Workers), starting the field of occupational medicine • Urged physicians to ask the question, “Of what trade are you?” • He described diseases associated with various lower-class trades, such as corpse carriers and laundresses.

17. Other Pioneers around 1770 • Sir George Baker • Linked “Devonshire colic” to lead in cider • Percival Pott • Linked soot exposure and scrotal cancer in chimney sweeps

18. The Mad Hatter • Lewis Carroll’s “Alice in Wonderland” (1865) • Mad Hatter exhibited symptoms of mercury poisoning, such as mental and personality changes marked by depression and tendency to withdraw • Mercury was used in processing hides made into hats • Bars were installed on windows at hat factories presumably to prevent afflicted workers from leaping during bouts of depression

19. Protection Starts to Arrive • English Factory Act, 1833, allows injured workers to receive compensation • English Factory Inspectorate, 1878 • US Workers Compensation started in 1908-1915 in several states (state programs, not federal) • Occupational Safety & Health Act enacted in 1970 creating OSH Administration • Created regulations, inspections, recordkeeping, enforcement, etc.

20. Birth of Industrial Hygiene • A few industrial hygienists were practicing in early 1900s • Physicians sometimes saw the industrial hygienist as a threat to their realm of expertise • Dr. Alice Hamilton was a pioneer Occupational Physician and female pioneer. She helped foster the field of IH in the US • American Industrial Hygiene Association (AIHA) formed in 1939

21. Industrial Hygiene • Other terms • Occupational Hygiene • Environmental Hygiene • Environmental Health

22. Professional Organizations • American Industrial Hygiene Association (AIHA), www.aiha.org, member organization • American Conference of Governmental Industrial Hygienists (ACGIH), www.acgih.org, member organization for government employees • American Board of Industrial Hygiene (ABIH), www.abih.org, independent organization that administers certification programs for industrial hygiene professionals • IHIT, Industrial Hygienist in Training • CIH, Certified Industrial Hygienist • Requires maintenance of certification

23. Scope of IH • Recognition, Evaluation, and Control of hazards or agents • Chemical Agents • Dusts, mists, fumes, vapors, gases • Physical Agents • Ionizing and nonionizing radiation, noise, vibration, and temperature extremes • Biological Agents • Insects, molds, yeasts, fungi, bacteria, viruses • Ergonomic Agents • Monotony, fatigue, repetitive motion

24. Control of Agents • Controls in this order of preference • Engineering Controls • Engineering changes in design, equipment, processes • Substituting a non-hazardous material • Administrative Controls • Reduce the human exposure by changes in procedures, work-area access restrictions, worker rotation • Personal Protective Equipment / Clothing • Ear plugs / muffs, safety glasses / goggles, respirators, gloves, clothing, hard-hats

25. 1. Recognition of health hazards • Walk-through survey with someone knowledgeable of the processes • Regular intervals, keep records • Planning stage reviews • Modification reviews • MSDS reviews

26. 2. Evaluation of hazards • Measurements • Air sampling, noise meters, light meters, thermal stress meters, accelerometers (vibration) • Calculation of dose • Level and duration of exposure • Keep records

27. 3. Control of Hazards (Prioritized) • 1 Engineering • Substitute a less hazardous material, local exhaust ventilation • 2 Administrative • Worker rotation, training • 3 Personal Protective Equipment • Respirators, gloves, eye protection, ear protection, etc.

28. 4. Recordkeeping • Important in all phases of the program • Often required by regulation • 29 CFR 1904 • Increase program effectiveness • Useful in legal challenges

29. 5. Employee training • Effective component if total program is implemented and engineering controls are first established • Often required by regulation • Right to Know or Hazard Communication Standard: 29 CFR 1910.1200 • Regular intervals • Keep it interesting and effective, use a variety of techniques • Keep records of dates, individuals, topics, effectiveness

30. 6. Program review • Regular intervals (~yearly, semi-annual) • Review the written program as well as the implementation • Updates for new regulations, new chemicals, new processes, or any changes • Audit components of the program • Internal “OSHA” inspection • Involve employees, consultants, management

31. Toxicology

32. Definitions • Toxicity: The ability of a substance to cause harm or adversely affect an organism • Toxicology: The science and study of harmful chemical interactions on living tissue

33. Occupational Toxicology • Workplace exposure to chemicals • You or someone you know has probably experienced an episode of toxicology • Injury or death due to: • Smoke inhalation • Confined space incident • Ingestion or absorption of a chemical

34. The Dose-Response Relationship • A time of exposure (dose) to a chemical, drug, or toxic substance, will cause an effect (response) on the exposed organism • If the amount or intensity of the dose increases, there will be a proportional increase in the response

35. Definitions • Dose: The amount of a substance administered (or absorbed), usually expressed in milligrams of substance per kilogram of the exposed organism (mg/kg) • Response: The effect(s) of a substance; may be positive or negative

36. Dose – Response Curve

37. Acute and Chronic Terminology: Exposure as well as Response • Acute exposure: short time / high concentration • Chronic exposure: long-term, low concentration • Acute response: rash, watering eyes, cough from brief exposure to ammonia • Chronic response: emphysema from years of cigarette smoking

38. Possible Response Levels • No response: at low dosage levels there may be no response at all • Threshold dose: the lowest level of dosage at which a response is manifested • NOAEL: no observed adverse effect level • NEL: no effect level • Above threshold dose: response can be positive up to a point and then could become toxic to the organism • Different people or organisms will exhibit a variety of responses

40. Indicators of Relative Toxicity • Toxicity: ability of a substance to cause harm or have an adverse affect • How much harm? • What aspect of the population? • Notation: • LD, lethal dose • LC, lethal concentration • ED, effective dose • EC, effective concentration

41. LD50 – a measure of relative toxicity • Most common toxicity notation • Determined in the lab and based on an acute exposure to adult test animal • Lethal dose that produces death in 50% of the exposed population • LD50, 35 mg/kg, oral, rat • 35 mg of dose per kg of rat’s body weight, when administered orally, produces death in 50% of exposed population • Comparing the LD50 between two substances gives the relative toxicity between the two substances

42. LD50 Relative Toxicity

43. Effect of route of administration

44. How can we interpret animal test? • Animal tests can give an indication of relative toxicity which can be extrapolated to humans • Problems • Toxicity variance between organisms • Animal doses (strength or time) may be higher than realistic human exposures • On a body weight basis, humans are usually more susceptible to toxic effects, sometimes by a factor of ten • Therefore, human interpretation requires use of a safety factor

45. Epidemiological Studies • Prospective epidemiological study • Take a cohort (or group of individuals) with a common exposure • Follow through time to see if they develop disease • Retrospective epidemiological study • Take a cohort with a disease and trace back through time to see if there is a common exposure • These are difficult with many confounding factors, but are quite valuable

46. Latency Period • Long delay between exposure and disease • Some diseases may not develop for many years • Lung cancer may occur as much as 30 years after exposure to asbestos • This makes animal studies and epidemiological studies even more difficult, but also very valuable

47. Routes of Exposure • Inhalation • Ingestion • Absorption through the skin • Less common • Injection • Absorption through eyes and ear canals

49. Inhalation • Most common route of entry into body • Therefore our area of highest concern • Lungs are designed for efficient gas exchange between the air and bloodstream • Lungs have up to 1000 square feet of exchange area (about 32 feet by 32 feet) • Normal day’s breathing volume: 8 cu ft • Therefore great potential for toxins to enter bloodstream