ABSTRACT
This chapter is devoted to the scientific methodology in human health research. It deals with multiple perspectives for viewing toxic causation and the diversity of strategies that investigators follow to establish or negate a link between absorption of a chemical compound and neuropsychological deficits in humans. Toxic causation sometimes is established on the basis of observation of single cases even when little documentation is available to support facts. Toxic causation can also be established when a dose—response relationship between the environmental chemical compound and the neuropsychological function is found. The case-control paradigm is the strategy of choice when no other environmental or biological indicator of neurotoxic exposure is available. Studies of contrasts have also been used for the assessment of the important truth that psychometric techniques sometimes provide subclinical evidence of neuropsychological dysfunction.
