Integrated Human and Ecological Risk Assessment: A Case Study of Organophosphorous Pesticides in the Environment

This study was chosen as an example of integrated risk assessment because organophosphorous esters (OPs) share exposure characteristics for different species, including human beings and because a common mechanism of action can be identified. The "Framework for the integration of health and ecological risk assessment" is being tested against a deterministic integrated environmental health risk assessment for OPs used in a typical farming community. It is argued that the integrated approach helps both the risk manager and the risk assessor in formulating a more holistic approach toward the risk of the use of OP-esters. It avoids conclusions based on incomplete assessments or on separate assessments. The database available can be expanded and results can be expressed in a more coherent manner. In the integrated exposure assessment of OPs, the risk assessments for human beings and the environment share many communalities with regards to sources and emissions, distribution routes and exposure scenarios. The site of action of OPs, acetylcholinesterase, has been established in a vast array of species, including humans. It follows that in the integrated approach the effects assessment for various species will show communalities in reported effects and standard setting approaches. In the risk characterization, a common set of evidence, common criteria, and common interpretations of those criteria are used to determine the cause of human and ecological effects that co-occur or are apparently associated with exposure to OPs. Results of health and ecological risk assessments are presented in a common format that facilitates comparison of results. It avoids acceptable risk conclusions with regard to the environment, which are unacceptable with regard to human risk and vice versa. Risk managers will be prompted to a more balanced judgement and understanding and acceptance of risk reduction measures will be facilitated.