Introduction to Industrial Hygiene

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Introduction to Industrial Hygiene

• Safety Management
• TM 650
• Carter J. Kerk
• Industrial Engineering Department
• South Dakota School of Mines
• Summer 2009

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Introduction to Industrial Hygiene

• Read Asfahl
• Chapter 9, Health and Toxic Substances
• Chapter 10, Environmental Control and Noise

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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

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IH Topics

• 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

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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

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Earliest Recordings

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

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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 slide)

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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

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Metallica cont.

• A young American named Herbert C. Hoover and his
  wife, L.H. Hoover, translated Agricolas 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)

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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.

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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

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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.

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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

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The Mad Hatter

• Lewis Carrolls 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

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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.

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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

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Industrial Hygiene

• Other terms
• Occupational Hygiene
• Environmental Hygiene
• Environmental Health

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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

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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

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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

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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

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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.

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4. Recordkeeping

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

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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

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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

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Toxicology

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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

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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

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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

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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

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Dose Response Curve
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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

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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

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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

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Routes of Exposure

• Inhalation
• Ingestion
• Absorption through the skin
• Less common
• Injection
• Absorption through eyes and ear canals

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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 days breathing volume 8 cu ft
• Therefore great potential for toxins to enter
  bloodstream

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Skin Absorption (2nd most important route)

• Skin surface area is about 20 square feet (4.5 ft
  by 4.5 ft)
• Compare to 1000 sq ft for lungs
• Materials can be absorbed into blood stream just
  below the skin surface or toxins can be stored in
  fat deposits
• Obviously workers can easily expose their hands
  into solvents, oils, chemicals, etc., plus these
  materials can be sprayed or rubbed on other parts
  of the body
• Many chemicals are either soluble in water or in
  oil (fat, lipid)
• The skin easily absorbs lipid-soluble materials
• Solvents
• Water-soluble materials are not easily absorbed
• Lipid layer on skin provides a barrier

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Ingestion (3rd most important route)

• Ingestion is not usually intentional
• Unintentional ingestion
• Failure to wash hands and face before meals
• Eating/drinking in areas where airborne hazards
  exist
• Lighting cigarettes with dirty hands
• Application of cosmetics
• Use of chewing tobacco or gum in contaminated
  areas

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Ingestion

• The digestive tract is moist and designed for
  efficient absorption
• Surface area of intestines is greatly increased
  by small projections (villi)
• Thin surfaces, highly vascularized
• Materials easily transferred to bloodstream

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Injection

• Less common
• Possible hazards
• Outdoor work, construction sites, hazardous waste
  sites, plants, animals, reptiles, insects,
  abrasions, puncture wounds, cuts

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Absorption into eyes and ears

• Much less common but possible
• Moist surfaces

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Distribution of Toxins

• Once toxins are in the body, there are several
  mechanism of movement and action
• Inhalation
• Toxics may enter bloodstream
• Toxics may irritate or scar lung tissues directly
• Skin Absorption
• Toxics may enter bloodstream
• Toxics may irritate, corrode or burn skin directly

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Once absorbed into the body, toxins can move to
other tissues and organs through various ways

• Filtration
• Toxins move through membrane pores
• Diffusion
• Movement from higher concentration to lower
  concentration
• Active transport
• Movement across a membrane otherwise impermeable
  by a transport mechanism
• Chemical reaction or carrier molecule, requires
  energy
• Phagocytosis
• Toxins eat or engulf other cells or by use of
  white blood cells

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Liver

• Important in metabolism, energy storage, protein
  synthesis
• Receives blood from digestive tract and works to
  concentrate, transform, and excrete substance
  (both good and bad toxins)
• Thus produces bile (enriched) which is returned
  to the intestines

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Kidneys

• Receive 25 of cardiac output for filtration
• Primarily for elimination of water soluble
  molecules
• Large molecules (proteins) and lipid soluble
  materials are reabsorbed through the tubules of
  the nephron
• Nephron functional unit of the kidney (see next
  slide
• Materials pass by filtration, diffusion, active
  transport

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References

• Nims DK. Basics of Industrial Hygiene. John
  Wiley Sons, Inc., 1999. ISBN 0471-29983-9