Acute toxicity The precautionary principle

Public Health Significance of Urban Pests 485

14.2.2.4. Basing risk and exposure assessments on use patterns

Pesticide data sets and requirements, including risk and exposure assessments, are based on the pattern of use, and the safety database of the technical grade AI manufacturer is large. Most regulatory agencies also refer to these data as generic or core safety data. Application formatting requirements for pesticides are detailed, but are not harmonized between different regulatory agencies, although efforts continue to harmonize them. Also, testing protocols must be approved and testing conducted in facilities that comply with Good Laboratory Practices – a system of management controls for laboratories and research organizations to ensure the consistency and reliability of results.

14.3. Toxicology

4 This section covers two major areas: pesticide hazard identification and six groups of pes- ticides. In the WHO urban pests and health project, the primary focus is on exposure of residential bystanders and residential areas, not on professional pesticide applicators or food handling establishments. Hazards related only to the pesticides used most frequently for urban-pest management and pet treatments are considered.

14.3.1. Pesticide hazard identification

Pesticides are unique among chemical products, since a lot of toxicological information is available before marketing. Available data are mainly from tests on animals and this poses some problems in extrapolating and applying these data to people. These tests may not always be the most sensitive indicators of human response, but test data on people are limited, given that pesticides are toxicants. Bridging toxicology test results from one species to another is not foolproof. However, procedures have been devised to take this into account when assessing the risk to people of pesticide exposures. This section deals mostly with existing general toxicological information on pesticide poisoning and known toxic effects. Emphasis is on data that relate to people; when such data are absent or mini- mal, a summary of animal toxicological data is provided.

14.3.1.1. Acute toxicity

WHO classifies pesticides according to the acute risk to health – that is, the risk of sin- gle or multiple exposures over a relatively short period of time – that might be encoun- tered accidentally by any person handling the product, in accordance with the manufac- turer’s directions for handling or in accordance with the rules laid down for storage and transportation by competent international bodies. The classification distinguishes bet- ween the more and the less hazardous forms of each pesticide, in that it is based on the toxicity of the technical compound and on its formulations. In particular, allowance is made for the lesser hazards presented by solids, compared with liquids. The classification Pesticides: risks and hazards 484

14.2.2.1. The precautionary principle

The precautionary principle is the all-embracing principle and so-called force behind the regulation of chemicals. T he principle is the foundation of regulating chemicals in Europe, and although federal level regulatory authorities in the United States and Canada have never adopted this principle as a formal creed per se, it is gaining popula- rity with some local authorities in the United States. Expressed in another way, when scientific certainty is lacking, precaution should be applied to the breadth of regulatory concerns. All regulatory agencies and authorities that register pesticides conduct thorough and extensive health and environmental reviews of pesticides before allowing their initial or continued use in the environment. Perhaps the best understood reason for applying pre- caution to pesticide regulation originates in the general abstinence from conducting or permitting tests with pesticides on human subjects. Therefore, toxicology data are brid- ged from animal testing to assess the risk of adverse effects on people. Also, computer models are used to refine exposure and risk assessment. Moreover, the special considera- tion now given to children’s health in the pesticide risk assessment process enhances pre- cautionary measures and is at the forefront of regulatory considerations.

14.2.2.2. The substitution doctrine