Block 4: Toxicology - Section 6: Pesticides
TOX 6.4: Monitoring

MONITORING:

Monitoring of pesticide exposure can be done either by blood or urine analysis. Blood monitoring is either through plasma or red blood cell (RBC) cholinesterase activity. Plasma cholinesterase reflect current absorption while RBC cholinesterase reflects the concurrent effect on the neurological system. 4

Before commencing blood cholinesterase monitoring baseline cholinesterase values for workers must be established. This is indicated in the table below 4.

Level of Decline for Baseline Appropriate Action
Plasma Cholinesterase
15-25% Retest worker
25-40% Retest worker, investigate safety conditions
>40% Remove workers from exposure, investigate safety conditions
Red Cell Cholinesterase
15-25% Retest worker
25-30% Retest worker, investigate safety conditions
>30% Remove workers from exposure, investigate safety conditions

Measuring pesticide metabolites in urine maybe a cheaper method and more acceptable to workers as apposed to blood monitoring. It is not complicated by individual variability of enzyme function as happens with blood monitoring. The disadvantages are that it requires urine that is formed over the period of toxicant absorption. There are uncertainties about specificity of some metabolites as products of pesticide metabolism.

Read the review article given to you on "Organophosphate and carbamate poisoning" and answer the following questions: Note from GRD: In what form is this article? Perhaps we can get in in electronic format and link to it.

  1. Discuss the symptomatic treatment of organophosphate poisoning and note the dose of atropine used.
  2. Discuss the routes of absorption of organophosphates and the likely order in which toxic effects present.
  3. Give examples of organophosphates and their uses and therefore possible causes of poisoning.
  4. Discuss the properties of the compounds which may have an effect on the severity of the poisoning.
  5. Discuss the pre-hospital treatment of organophosphate-poisoning.

INTERACTIVE EXAMPLES

Example 1

REFERENCES:

  1. Goodman and Gilman or Katzung and Bardin PG. Van Eeden SF and Joubert JR. Intensive care management of acute organophosphate poisoning. S Afr Med J 1987 72:593-597.
  2. Environmental and Occupational Medicine. W N Rom. 3rd Edition. Chapter 83. Pages 1157 to 1171.
  3. London L, Myers J. Critical Issues for Agrichemical Safety in South Africa. American Journal of Industrial Medicine.1995. Vol 27. P 1-14.
  4. Steenland K, Jenkins B. Chronic Neurological Sequelae to Organophosphate Pesticide Poisoning. American Journal of Public Health. 1994. Vol 84. No 5. P731-736.
  5. L London. Biological monitoring of workers exposed to organophosphate pesticides: Guidelines for filed application.1995. Occupational Health Southern Africa. 1(4). 13-17.
  6. http://www.pesticideinfo.org/Index.html



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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, Rajen Naidoo, Saloshni Naidoo. 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.
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