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| Module 3: Toxicology - Section 3: Linking Chemical Exposures and Health Effects |
| TOX 3.6: Assessment and Monitoring of Exposure to Chemical Hazards |
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| Module 3: Toxicology - Section 3: Linking Chemical Exposures and Health Effects |
| TOX 3.6: Assessment and Monitoring of Exposure to Chemical Hazards |
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Assessment and monitoring of exposure to hazardous chemical substances is an important aspect of initial and ongoing risk assessment and control. The primary prevention strategy should always be to prevent exposure to agents associated with toxic effects. When it is not possible to prevent such exposures, then the appropriate strategy is to limit exposure and minimise the possibility of adverse health effects. Exposure monitoring encompasses two basic techniques viz. environmental air monitoring (occupational hygiene) and biological monitoring. Environmental and biological monitoring are ways of investigating different problems and should be seen as complementary procedures. A practical approach in setting up an exposure monitoring programme for hazardous chemical substances is outlined in Table 3.
| Table 3. A stepwise approach to developing an exposure monitoring programme for hazardous chemical substances | |
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| Step 1 | What is the nature of the job? - outline the various activities. |
| Step 2 | Identify the hazardous chemicals associated with exposure to chemicals in the various activities. |
| Step 3 | Identify the potential routes of exposure to the particular hazardous chemical substance. |
| Steps 1-3 are part of the risk assessment process. If a potential health risk is identified, proceed to Step 4. | |
| Step 4 | If the exposure route is mainly airborne, proceed to environmental monitoring (EM). |
| Step 5 | If the exposure route is mainly through non-inhalation routes (skin, ingestion) or if major reliance on personal protective equipment, proceed to biological monitoring (BM). |
| Step 6 | Develop a sampling strategy for EM and/or BM based on exposure zone characterisation (groups of workers performing similar activities). For EM, it is preferable to do personal sampling. The timing of the sampling strategy for BM is based on the biological half-life of the substance in the sample medium (blood, urine) concerned. Conduct sampling in a standardised manner. Ensure that samples are appropriately stored after collection. |
| Step 7 | Identify the appropriate analytical test that has a high degree of validity, and a quality- certified laboratory that will conduct the analysis of samples. |
| Step 8 | Decide beforehand the criteria to be used to define an abnormal test result using the DOL/ ACGIH/NIOSH OELs for airborne substances or Department ofLabour (DOL)/ACGIH BEIs for BM samples. |
| Step 9 | |
| Step 10 | Outline the procedure for notification of employer, worker (ongoing worker notification procedures) and enforcement agency (notify incident to DOL) as to the outcome of the exposure assessment. |
| Step 11 | Ensure input of the information obtained in this process into systems and procedures in assessing the efficacy and improvement of existing control measures such as engineering controls, work procedures, education and training. |
| Step 12 | Ensure evaluation and audit of the programme on a regular basis. |
Postgraduate Diploma in Occupational Health (DOH) - Modules 3: Occupational Medicine & Toxicology (Basic) by Profs Mohamed Jeebhay and Rodney Ehrlich, Health Sciences UCT is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 2.5 South Africa License. Major contributors: Mohamed Jeebhay, Rodney Ehrlich, Jonny Myers, Leslie London, Sophie Kisting, Gail Todd, Neil White. Source available from here. For any updates to the material, or more permissions beyond the scope of this license, please email healthoer@uct.ac.za or visit www.healthedu.uct.ac.za.
Last updated Jan 2007.
Disclaimer note: Some resources and descriptions may be out-dated. For suggested updates and feedback, please contact healthoer@uct.ac.za.