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Review: neurotoxicity of lead.

'Lead and its compounds are potentially toxic; the element has no known physiological function; it is widely distributed in nature and as a result of man's activities' (Lawther Report: DHSS 1980). Concern grew in the late 1970s that even low levels of exposure to lead caused adverse changes in children's adjustment and academic attainment. This paper traces the rapid developments of the past decade in investigating the relationship between body lead burden and relevant outcome measures. Research strategies moved from small-scale, clinical-descriptive studies to large-scale epidemiological studies; from cross-sectional studies to longitudinal ones. Agreement had to be reached on how to measure body lead burden. Decisions had to be made on which outcome measures to use. Measures of global intelligence were complemented by measures of academic attainment, emotional adjustment and hyperactivity, as well as by experimental measures of more basic psychophysiological functioning. Ways had to be found of dealing experimentally and statistically with socioeconomic factors which acted as confounds. The investigations were marked by tremendous collaboration between investigators, between national agencies and across countries. The methodological issues are relevant to the investigation of other toxins and they define a field of developmental behavioural toxicology. This case study can act as a model for investigating the effects of other environmental toxins and hazards.