Application for the Reassessment of a Hazardous Substance under ...

4.3 EnvironmentIdentification of adverse effects (risks and costs)4.3.1 At all steps in the lifecycle (Table 9) there is potential for dichlorvos to enter theenvironment.4.3.2 Dichlorvos is very toxic to aquatic life, terrestrial vertebrates and terrestrialinvertebrates and harmful to soil organisms. Exposure of the environment couldtherefore result in significant effects.Assessment of potentially significant adverse effects (risks and costs)4.3.3 ERMA New Zealand assesses the significance of adverse effects by comparing theenvironmental exposure with existing controls in place to the concentration causingeffects.4.3.4 Given the default controls, any incidents would be likely to be localised and could beof no more than moderate magnitude if waterways became contaminated bysignificant quantities of dichlorvos. The likelihood of such effects resulting fromincidents/spills during repackaging, local transport, storage or disposal of dichlorvosproducts is considered to be highly improbable. This combination of likelihood andmagnitude indicates suggests a negligible risk 4 .4.3.5 The environmental effects that may arise from outdoor public health use (UseScenario 30) would be localised in extent and duration and therefore would beconsidered moderate in magnitude. ERMA New Zealand considers the likelihood ofmoderate effects to be unlikely, given the comparatively small areas that would betreated and the rapid dissipation of dichlorvos. This combination of likelihood andmagnitude also suggests a low risk.4.3.6 ERMA New Zealand considers that tthe magnitude of effects to the environment thatmay arise from dichlorvos use in biosecurity fruit fly monitoring traps (Use Scenario31) are minimal. The likelihood of environmental effects resulting from isconsidered highly improbable given the enclosed nature of the traps and thespecificity of the lures that attract pests to them. This combination of likelihood andmagnitude suggests a negligible risk.4.3.7 ERMA New Zealand modelled likely exposure during the use of dichlorvosaccording to the scenarios in Table 7. In determining exposure, ERMA NewZealand made no allowance for buffer zones around fields. L. Stulich (pers. comm.)indicated that 5 - 10 m hedging buffer zones are used, Horticulture New Zealandsuggested 4-6 m shelter belts are used for tamarillos, but ERMA New Zealand doesnot know if this is standard practice.4.3.8 Details of the environmental exposure modelling are presented in Appendix C.4The ERMA New Zealand qualitative risk matrix based on evaluation of likelihood and magnitude of risk isgiven in Appendix JDichlorvos reassessment – application Page 41 of 436