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Toxicological effects - Irritants

Toxicological effects - Irritants. Irritation Inflammation or aggravation of tissue from contact Influenced by solubility Primary or secondary. Toxicological effects - Irritants. Primary irritant A material that exerts its effect at the site of action with little or no systemic effects

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Toxicological effects - Irritants

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  1. Toxicological effects - Irritants • Irritation • Inflammation or aggravation of tissue from contact • Influenced by solubility • Primary or secondary

  2. Toxicological effects - Irritants • Primary irritant • A material that exerts its effect at the site of action with little or no systemic effects • Acids, alkalis, etc. that produce burns on the skin but produce no other systemic effects

  3. Toxicological effects - Irritants • Secondary irritant • A material that still exerts an effect at the site of action but also has significant systemic effects • E.g. aromatic hydrocarbons: phenol causes skin irritation but systemically it poisons the body and can cause death

  4. Toxicological effects -Asphyxiants • Asphyxiants interfere with oxygenation • Anoxia – no oxygen in the blood: 3-5 min brain damage and death • Hypoxia – low levels of oxygen in the blood: can lead to brain damage or death • Simple • Exert effect by diluting or displacing oxygen

  5. Toxicological effects -Asphyxiants • Chemical asphyxiants disrupt oxygen metabolism or the body’s ability to control respiration • Effects O2 metabolism in the cell • Hydrogen sulfide (H2S) paralyzes the respiratory center of the brain and stops breathing

  6. Basis for workplace standards • Animal data • Appropriate animal models • Human epidemiological data • Descriptive studies • Retrospective studies • Prospective studies

  7. Workplace exposure limits • For any agent or condition, there is a level of exposure (concentration and time dependent) for which the effects are acceptable. Exposure limits are set at such levels

  8. ACGIH TLVs • American Conference of Governmental Industrial Hygiene (ACGIH) • Threshold Limit Value (TLV) • A time-weight average (TWA) conc. for a normal 8-hr workday and a 40-hr. work week, to which nearly all workers may be repeatedly exposed, day after day without adverse effect

  9. ACGIH TLVs • TLV-STEL (short-term exposure limit) • A 15 min. TWA exposure which should not be exceeded at any time during a workday even if the 8-hr TWA is within the TLV. Exposures < 15 min; not more than 4 x a day and be at least 60 min apart

  10. ACGIH TLVs • TLV-C (ceiling) • The conc. that should not be exceeded during any part of the working exposure

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