The Declaration of Brescia on Prevention of the Neurotoxicity of Metals

On 17–18 June, 2006, the Scientific Committee on Neurotoxicology and Psychophysiology and the Scientific Committee on the Toxicology of Metals of the International Commission on Occupational Health (ICOH) convened an International Workshop on Neurotoxic Metals: Lead, Mercury, and Manganese—From Research to Prevention (NTOXMET) at the University of Brescia. Scientists and physicians from 27 nations participated. Data were presented for each of the three metals on environmental sources, fate and distribution; human exposure; clinical, subclinical, and developmental neurotoxicity; epidemiology; risk assessment; and prospects for prevention. Ongoing and future studies were described and discussed. For each of the metals, initial recognition of neurotoxicity occurred in the context of high-dose exposure. For example, lead poisoning was first recognized in miners, smelters, and type setters, methylmercury poisoning in inhabitants of the fishing community of Minamata, and manganese poisoning in miners and ferroalloy workers. Subsequent development of more sensitive and sophisticated analytical instruments led to the recognition of subclinical toxicity and developmental neurotoxicity at progressively lower levels of exposure. In each case, the extent of toxicity was much greater than initially appreciated and the size of the affected population much larger. Many decades typically elapsed between the initial recognition of neurotoxicity and the initiation of programs for prevention. Early warnings were frequently ignored and even actively resisted. The historical observation that long delays had typically elapsed before the initiation of prevention prompted extensive discussion at the Workshop about the need to develop more effective strategies. From this discussion, a series of recommendations emerged on future directions for research and prevention of the neurotoxicity of metals. At the closing session of the International Workshop at Brescia, the following recommendations on the prevention of the Neurotoxicity of Metals were adopted by consensus: Intensified attention must be paid to early warnings of neurotoxicity. Clinical observations or toxicological data suggesting the existence of neurotoxicity including subclinical and developmental toxicity must be taken very seriously. Such observations should prompt consideration of prudent preventive action. All uses of lead including recycling should be reviewed in all nations and uses contributing to environmental and human exposures, such as uses in toys, paint, water pipes, building materials, solder, electronics, medications, and cosmetics ended. The transfer of these products from one country to another should also be avoided. This approach has been adopted successfully in the EU and needs to be extended worldwide. In particular, tetraalkyllead must be eliminated without delay from the gasoline supplies of all nations. The removal of organic lead from gasoline has produced declines of>90% in population mean blood lead levels in industrially developed nations, and this success is now being repeated in some of the developing nations. This action represents one of the great public health triumphs of the late 20th century and needs urgently to be extended to all nations. Current exposure standards for lead need urgently to be reduced. Current standards were established many years ago and do not reflect recent advances in scientific knowledge about toxic effects at levels of exposure below these standards. The Brescia Workshop recommends that: