The document discusses key concepts in toxicology and human anatomy related to occupational health hazards. It defines terms like toxicity, hazard, and risk. It also outlines several factors that can affect toxicity and risk, such as route of exposure, dose, and multiple exposures. The document then discusses concepts like target organs, toxic effects, and provides examples of hazards from different jobs or industries.

1. UNIT 2 INDUSTRIAL TOXICOLOGY AND HUMAN ANATOMY HPEO 408 Occupational Health Hazards

2. TOXICOLOGY TERMINOLOGY REVIEW

3. Toxicity – the degree a substance can harm humans, animals, or environment Hazard – is something that has the potential to cause harm if exposed to a certain set of circumstances Risk – is the probability that harm (i.e. adverse effect) will occur given exposure TOXICITY VS. HAZARD

4. Characteristics of hazard: Route of exposure Form Dose/concentration Absorption rate Exposure duration Surface area exposed Area exposed (ex. skin thickness) How hazard reacts within the body Distribution Metabolism Excretion Other exposures (i.e. mixtures) FACTORS AFFECTING TOXICITY AND RISK

5. Independent effects Occurs when the hazards are different in composition and act in a different manner and on different organ systems Additive effects The total effect is the sum of each independent effect Occurs when the hazards act in a similar way and produce the same effect Example: Chlorinated insecticides and halogenated solvents  liver toxicity. Potentiated effects When a substance causes an increase in harm that on its own does not elicit an effect Example: CO potentiates noise induced hearing loss from exposure to noise Synergistic effects Is an interaction where one hazard exacerbates the adverse effect of another. Example: asbestos exposure and smoking  lung cancer Antagonistic effects The effect of one substance cancels or reduce the effect of another Often related to enzyme function and metabolism Example: ethanol reduces effects of methanol exposure MULTIPLE EXPOSURES

6. How do we adjust for these when determining compliance or health risk? Independent effects Use TLVs as normal Additive effects Calculate TWA for mixtures (located in your text book) Antagonistic effects Use TLVs as normal Has reduced effects but don’t know to what level so take conservative approach Potentiated/ synergistic effects There is no clear method Indicates we must take extreme caution! MULTIPLE EXPOSURES II

7. TLV designation Indicates that skin exposure may be a significant contributor to overall dose Determined by: Studies showing significant absorption through skin or systemic effects Low dermal LD50 values with animal studies NOTE: TLVs/exposure limits are developed without considering skin exposure What does this mean for the OH professional? Systemic effects may occur due to dermal exposure over inhalation Identifies need for PPE or other controls to limit skin exposure Biological monitoring would be appropriate to monitor exposure SKIN NOTATION

8. Odor or mild irritation detectable BELOW levels that are hazardous Largely based on comparison of TLV to published odor thresholds If using odor thresholds should preform odor threshold tests on each worker Not good to use when: Odor threshold is over TLV Odor threshold is very low (i.e. well below action limit) Olfactory fatigue it common Worker is unable to detect odor WARNING PROPERTIES

9. Considerations using odor thresholds: Differences in odor thresholds across populations Effects of aging (decrease smell ability with age) Olfactory system can become fatigued (loose its sense of smell) Number of conditions that can result in olfactory dysfunction rhinitis, sinusitis, polyps, Inflammation and/or trauma to head exposure to some chemicals (ex. metallics) WARNING PROPERTIES II

10. NOAEL No Observed Adverse Effect Level Highest data point where there was no effect LOAEL Lowest Observed Adverse Effect Level Lowest data point where there was an effect NOAEL/LOEAL

11. Immediate vs. delayed effects Reversible vs. irreversible Local vs. systemic “ Local” - site of action of the agent is at the point of contact Absorption does not necessarily occur “ Systemic” - site of action other than the point of contact Absorption has taken place TOXIC EFFECTS CONSIDERATIONS

12. ANATOMY INTRODUCTION

13. Network of cells responsible for communication Contains high fat content  fat-soluble agents of concern and are more likely able to pass the blood-brain barrier Broken into two categories: The central nervous system (CNS) includes the brain and spinal cord The peripheral nervous system Includes the nervous structures (motor and sensory nerves) that do not lie in the CNS NERVOUS SYSTEM

14. Set of glands responsible for hormone production and regulation of the body using feedback systems Includes hypothalamus, adrenal, pituitary, pineal, and thyroid glands Most common/important regulation roles include regulation of: Metabolism Growth Development Reproductive cycles Mood ENDOCRINE SYSTEM

15. Responsible for distributing blood/lymph in the body Caries substances throughout the body and to and from cells nutrients, gases, hormones, enzymes, and waste Stabilizes body temperature and pH, and fights diseases Broken into two categories: The cardiovascular system I ncludes the heart, blood, and blood vessels The lymphatic system I ncludes the thymus, spleen, bone marrow, and lymphatic tissue CIRCULATORY SYSTEM

16. Primary function is to process/metabolize nutrients from the blood Also metabolizes other substances Considered the body’s detoxifier; therefore, susceptible to toxins Liver cells can regenerate after toxic damage, but prolonged/repeated exposure can lead to permanent liver damage Liver detoxification process can: Metabolize toxins into safe forms or metabolites Metabolize toxins into more toxic metabolites Methanol  formaldehyde  formic acid Metabolized by (1) alcohol and (2) aldehyde dehydrogenase enzymes LIVER

17. Includes kidneys, bladder, ureters, urethra, and sphincter muscles Responsible for producing, filtering, storing, and excreting urine Primary function is to excrete unwanted waste products including toxins Toxins typically have to be water soluble before they are excreted Non-water soluble toxins can be modified by liver to allow for excretion Kidneys – maintain fluid and electrolyte balance by filtration and selective re-absorption into the blood URINARY SYSTEM

18. HAZARD IDENTIFICATION EXAMPLES

19. A hazard is the actual chemical/biological/physical agent that may cause harm if exposed. This is what you are being asked to provide in questions asking you to identify the hazards involved with a job, task, or industry. Examples: detergents, dust, bacteria, non-ionizing radiation, vibration A health outcome/effect is the outcome that may occur due to exposure to the hazard. Examples: skin irritation, cancer, breathing difficulties, burns, hearing loss, amputations A source of exposure (or exposure source) is the vehicle or process the exposure is originating from. Examples: cleaning, grinding, smelting, mixing, blood , feces/sewage A route of exposure is the manner in which people are exposed to the agent, or the way the hazard enters the body. Examples: inhalation, skin contact/absorption, ingestion, injection HAZARD TERMINOLOGY REVIEW

20. To clarify, when asked to provide the hazards, we want the actual agent that causes the harm (i.e. the chemical, biological, or physical agent) Often students can get confused and provide health effects or sources of exposures  loss of marks on assignments/quizzes Sometimes this can be tricky, especially with physical hazards Correct answers will properly identify the hazard however, the best answer is to identify the hazard and include additional information such as the outcome, source/route of exposure to explain the hazard The next slide outlines examples of this where: The first row will name the hazard The second row will name the hazard and supplement it with explanatory information HAZARD IDENTIFICATION

21. Vibration exposure Whole body vibration from driving forklifts Noise exposure Hearing loss could occur due to exposure to noise from the operating equipment Temperature extremes Risk of heat stress occurring due to high/elevated temperatures. Wood dust Inhalation of wood dust from sawing operations Welding fumes Metal fume fever due to inhalation of welding fumes Mold Inhalation of fungal spores from water damaged ceiling tiles Hepatitis C virus Risk of contracting Hepatitis C from exposure to contaminated blood through a needle stick injury. HAZARD TERMINOLOGY EXAMPLES