We identified industrial chemicals that have caused neurotoxic effects in man from the hazardous substances data bank of the US National Library of Medicine, supplemented by fact sheets by the US Agency for Toxic Substances and Disease Registry, and the integrated risk information system of the US Environmental Protection Agency. We searched for the terms “neurotoxic”, “neurological”, and “neuro”. For all neurotoxic substances identified, we then used synonyms, commercial names, and CAS
ReviewDevelopmental neurotoxicity of industrial chemicals
Section snippets
Vulnerability of the developing brain
The developing human brain is inherently much more susceptible to injury caused by toxic agents than is the brain of an adult.12 This susceptibility stems from the fact that during the 9 months of prenatal life, the human brain must develop from a strip of cells along the dorsal ectoderm of the fetus into a complex organ consisting of billions of precisely located, highly interconnected, and specialised cells. Optimum brain development requires that neurons move along precise pathways from
Recognition of neurotoxicity
Developmental neurotoxicity in children exposed to industrial chemicals is often first identified through recognition of obvious functional abnormalities after high-dose exposure that clearly caused poisoning. Good quality research later documented the presence of less striking, but nonetheless serious adverse effects at low doses of exposure (figure 1). This sequence of discovery led to the recognition that environmental pollutants exert a range of adverse effects—some are clinically evident,
Identification
Studies in animals support the notion that a wide range of industrial chemicals can cause developmental neurotoxicity at low doses that are not harmful to mature organisms.26, 27 Such injury seems to result in permanent changes in brain function that might become detectable only when the animal reaches maturity. Because developmental neurotoxicity might not be apparent from routine toxicology tests,28 identification of neurotoxic chemicals often rests on clinical and epidemiological data.
To
Emerging neurotoxic substances
Documentation of developmental effects in human beings for the other compounds listed in the panel is poor. However, three obvious candidate substances deserve particular attention, including two that have not seemed to cause neurotoxicity in adults.
Effects of developmental neurotoxicity
The five substances recognised as causes of developmental neurotoxicity show similar patterns in the development of scientific documentation of their risks. This pattern of discovery started in each instance with recognition of adult neurotoxicity, typically in people with occupational exposure, and of episodes of acute, high-dose poisoning in children. The next stage was the accumulation of epidemiological evidence of neurobehavioural deficits in children with prenatal exposures at
Prevention
A pandemic of neurodevelopmental toxicity caused by industrial chemicals is, in theory, preventable. Testing of new chemicals before allowing them to be marketed is a highly efficient means to prevent toxicity, but has been required only in recent years. Of the thousands of chemicals used in commerce, fewer than half have been subjected to even token laboratory testing for toxicity testing.24 Nearly 3000 of these substances are produced in quantities of almost 500 000 kg every year, but for
Search strategy and selection criteria
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