1. 1 Chemical and Biological Agents

2. 2 Introduction  Most occupational diseases such as asbestosis, silicosis, various types of dermatitis, spills, and burns are related to chemical or biological exposures  Chemical Agent  hazards created by one or more chemicals  Biological Agent  hazards created by exposure to biological materials.

3. 3 Chemical Agents  More than 70,000 chemicals are currently in use in North America  No toxicity data on about 80% of the chemicals  Certain industrial chemicals have been linked to: cancer, lung disease, blood abnormalities, nervous- system disorders, birth defects, sterility.

4. 4 Chemical Agents  80% of all occupational disease result from chemical exposures  Toxicity –  the ability to cause injury to human biological tissue.  Toxicity is the potential degree of seriousness of the hazard of exposure

5. 5 Toxicology  Toxicology  the scientific study of poisons  Routes of Entry for chemicals include:  Respiration (inhaling)  Skin absorption  Ingestion  Skin penetration (puncture wounds)

6. 6 Respiration (Inhalation) Most of the human exposure to chemicals comes from breathing airborne contaminants Levels of defense: –Nose –Interior of the nasal passage –Tiny hairs or cilia and mucus –Aerodynamic characteristics of the human lung

7. 7 Skin Absorption The ability of a chemical to easily pass through the skin is often closely associated with its level of toxicity Chemicals that are not rapidly absorbed may produce a localized irritation (dermatitis) which may cause the skin to become white and dry.

8. 8 Ingestion Many solvents enter through the mouth and digestive system This is not as important as those that enter through the skin or the lungs Ingested solvents may be absorbed into the bloodstream and carried to “target organs” where toxic effects can be produced.

9. 9 Penetration Penetration occurs when the skin is cut or punctured by any sharp object A knife or needle may be contaminated with a hazardous chemical Workers such as doctors, nurses, can easily be punctured by a hypodermic needle.

10. 10 Characteristics of Properties of Solvents The general characteristics that make solvents effective and hazardous are: Low Surface Tension the higher the wetting factor the more absorbent the chemical will be into the skin High Vapour Pressure can create an inhalation hazard Low Boiling Point the lower the boiling point the greater the risk of vapours in the air.

11. 11 Characteristics of Properties of Solvents Low Heat of Vaporization the lower the amount of heat necessary the greater the risk of exposure High Volatility the greater the chemical evaporation, the greater the risk of health & fire Ability to Dissolve Fat the more effect a chemical is at dissolving fat the more damage it can do to unprotected skin.

12. 12 Biological Agents –natural organisms or products of organizations that present a risk to humans Two well known diseases resulting from biological agents are: –Legionnaires’ disease and –HIV/AIDS

13. 13 Control of Exposure A number of control measure are available to minimize exposure to hazards: Engineering controls Work practices and procedures Administrative controls Personal protective equipment Personal hygiene practices Medical surveillance

14. 14 Engineering Controls The best way to reduce the risk of handling solvents is to find alternatives Areas should be properly enclosed with effective exhaust systems in place to prevent ignition, or human exposure to vapours.

15. 15 Work Practices All employees trained in – identification –handling of dangerous substances Spills must be properly contained and employees exposed to the hazard must wear personal protective equipment

16. 16 Administrative Controls education all employees in safe work practices Ongoing training Workers must be familiar with the (WHMIS) legislation.

17. 17 Personal Protective Equipment Because inhalation is the most common and hazardous route of entry, the most commonly used protective device is a respirator No single protective device, such as a facemask, will adequately address all conditions for all workers.

18. 18 Medical Surveillance Medical surveillance programs are implemented to ensure that workers who are exposed to agents are not subjected to situations in which their health may be jeopardized. X-Rays, pulmonary function tests and blood work are aspects of medical surveillance programs.

19. 19 Case 2. Unexpected gas (p164) What steps would you take to ensure that this event was never repeated?