Persistent organic pollutants: potential health effects?

It is not a point of debate that the Stockholm Convention for the prevention of further accumulation of persistent organic pollutants (POPs) should be ratified and implemented by all countries. However, in their article, Schafer and Kegley present an unbalanced "worst case scenario". Approximately 20% of the food supply of the US is contaminated with POPs at extremely low levels; these levels are comparable to those found in many other countries. Furthermore, there is no scientific consensus that these levels are hazardous to most humans. More information is needed to determine the actual risks of extremely low levels of POPs to human health.

Human biomonitoring: research goals and needs.

Epidemiological studies have taken advantage of a number of strategies to monitor human populations for mortality, incidence, and exposure to hazardous environmental agents. These studies have been compromised by the lack of individual exposure assessment data that precisely quantified internal dose. As methods improve in analytical chemistry and molecular biology, direct biological monitoring of exposed populations is possible. Biomarkers have been developed and validated in exposed populations that quantify individual exposure, susceptibility, and early markers of health effects and can be used to study relationships between exposures and environmentally induced diseases. This paper provides background on the state of the art of human populations monitoring and, through a series of case studies, provides examples of novel biomarkers of exposure, susceptibility, and effect that highlight new opportunities for biomonitoring. Prevention of human disease due to environmental contaminants can be accomplished by implementing strategies such as those discussed to monitor exposure and early health effects in human populations.

Assessing the neurotoxic potential of chemicals--a multidisciplinary approach.

Since 1981, the development of methodology to assess the neurotoxic potential of chemicals has been a high priority within the International Programme on Chemical Safety (IPCS). Following the completion of an in-depth review of the scientific principles and methods for the assessment of neurotoxicity associated with chemical exposures, IPCS started to develop a multidisciplinary and comprehensive approach for neurotoxicity testing of chemicals. In view of the complexity of the nervous system and the variety of effects caused by chemicals, no single test or approach will be appropriate. Initially, IPCS evaluated neurobehavioral tests as well as in vitro procedures as screening tests, and an international collaborative study of neurobehavioral tests appropriate for screening chemicals for neurotoxicity is now in progress. Possible integration of higher level neurobehavioral tests with neurophysiological, biochemical, and pathological procedures in future testing strategies are discussed.

The third United States-Japan meeting on the Toxicological Characterization of Environmental Chemicals.

This report summarizes the discussion of the Third U.S.-Japan Meeting on the Toxicological Characterization of Environmental Chemicals held under the auspices of the U.S.-Japan cooperative in research and development in science and technology. Recent data on the interrelationships between toxicity, cell proliferation, and carcinogenicity are presented.

U.S.-Japan joint meeting on the toxicological characterization of environmental chemicals of mutual interest.

The paper describes deliberations of a meeting between scientists from the U.S. National Toxicology Program and the National Institute of Hygienic Sciences, Tokyo, Japan. The scientific approaches and experimental processes used by each organization in designing, conducting, and evaluating the short-term and long-term toxicity/carcinogenicity of environmental chemicals were evaluated.

Toxicity of polybrominated biphenyls (PBBs) in Domestic and laboratory animals.

The composition, environmental fate, and effects of the polybrominated biphenyls (Firemaster BP-6 or FF-1) involved in the accidental contamination of cattle feed in Michigan in 1973 are reviewed. Toxic effects referred to in this report are limited to those occurring in domestic and laboratory animals and include general toxicity, neurobehavioral toxicity, immunotoxicity, reproductive toxicity, mutagenicity and carcinogenicity. The absorption, distribution, biotransformation and elimination of these polybrominated biphenyls are discussed along with the interactions with other chemicals and drugs.

Neurochemistry and toxicology: overview.

We have witnessed a tremendous increase in our knowledge of the molecular and biochemical mechanisms which underly the activities of the nervous system. Such knowledge is essential in order to determine the basic mechanisms involved in neurotoxic events. An overview of how neurotoxins could conceivably interfere with some basic neurochemical processes is presented, along with a specific example of how an understanding of such processes can contribute to the detection of neurotoxicity and to the development of predictive testing techniques.

Environmental chemicals and nervous system dysfunction.

Selected examples of associations between nervous system diseases and exposures to occupational and environmental chemicals have been reviewed. Recent outbreaks of human neurotoxicity from both wellknown and previously unknown toxicants reemphasize the need for the medical community to give increased attention to chemical causes of nervous system dysfunction.

Toxicological properties of lead.

The pathological effects of lead on the renal, nervous, reproductive, endocrine, and immune systems have been reviewed. Emphasis is placed on reported subclinical effects due to chronic, low-level lead exposure. The crucial issue of whether subtle behavioral, intellectual, and developmental impairment occurs in young children, as a result of lead-induced CNS damage is discussed in detail. This issue remains unresolved. Further studies are needed in order to determine the long-term health effects of continuous, low-level lead exposure.

Effects of handling and etherization on incorporation of [3H] lysine into protein of mouse brain and liver.

A standardized handling experience of 20 sec duration elevated the amount of radioactive lysine incorporated into brain total proteins during a 10 min labeling period begun either 10 min or 30 min after the handling. Etherization for 20 sec produced similar metabolic changes. Incorporation of [3H] lysine into liver proteins was minimally affected by handling, while slightly altered by etherization. The metabolic changes detected in the brain after handling did not appear to be side-effects of changes in blood-borne radioactivity. The results indicate that laboratory stresses often thought to be of minor importance can have large effects on ordinary assays of protein metabolism in brain.