Table 1 Definition of pattern of use and action required Definition of pattern of use Action required Baseline Baseline measurement should be carried out – two are desirable – at a time when there has been at least four weeks without exposure. Very occasional use If use of organophosphate pesticides is only half a day every month or less, then this is very occasional use. Use should be recorded. No test is needed unless the worker has symptoms which could be related to organophosphate pesticides during or after use, or there has been an ‘exposure incident’ leading to symptoms. Intermittent use If use of organophosphate pesticides is for two to three days at a time, all day with gaps of time of a month or more between use, then this is intermittent use. Use should be recorded. Test during the period of peak exposure/use. Testing provides valuable information on the effectiveness of controls. Controls must be updated if levels of exposure indicate high work-related exposure. No further testing is needed unless the worker has symptoms which could be related to organophosphate pesticides during or after use, there has been an ‘exposure incident’ leading to symptoms, or there is concern ‘overexposure’ may have occurred. Seasonal use If use of organophosphate pesticides is say four days a week, and extends over a long season then, this is seasonal use. Use should be recorded. For heavy or seasonal use, testing should occur during the period of peak exposure/use. Workers exposed should be tested at the end of the work shift on the last day of a work week, early in the season, once work practices have settled, in order to check the effectiveness of work practices and controls. Adjustments to controls can then be made if necessary. Workers should be advised of their results (percentage depression of cholinesterase from their baseline values). The timing of further tests, should be based on the nature of the work and previous test results. A worker having greater than 20% depression from baseline values should be retested at an early stage. No further test is needed unless the person has symptoms which could be related to organophosphate pesticides during or after use, there has been an ‘exposure incident’ leading to symptoms, or there is concern ‘overexposure’ may have occurred. Table 2 Signs and symptoms of organophosphate poisoning Nervous tissue and receptors affected Site affected Manifestations
APPENDIX 2 LIST OF ORGANOPHOSPHATE PESTICIDES The following list of cholinesterase-inhibiting organophosphate chemicals are approved for use in Australia, as of March 2012). To be legally used in Australia products must be registered by the Australian Pesticides and Veterinary Medicines Authority (APVMA). Since product registrations change over time, the person conducting the business or undertaking should check the product label and safety data sheet to determine whether the chemical products used contain cholinesterase inhibiting (anti-cholinesterase) compounds. Organophosphate pesticides Acephate Azamethiphos Azinphos-methyl Cadusafos Carbofuran Chlorfenvinphos Chlorpyrifos Chlorpyrifos-methyl Coumaphos Cythioate Diazinon Dichlorvos Dimethoate Disulfoton Ethion Fenamiphos Fenitrothion Fenthion Maldison (Malathion) Methamidophos Methidathion Mevinphos Naled Naphthalophos Omethoate Oxydemeton-methyl Parathion Parathion-methyl Phorate Phosmet Pirimiphos-methyl Profenofos Propetamphos Prothiofos Temephos Terbufos Tetrachlorvinphos Thiometon Trichlorfon