Anthropogenic acute chemical exposures have become an important socioeconomic and environmental factor on the national, regional and global level. They present an actual or potential danger to vital activity and health of large population groups and normal operation of the Biosphere and natural components. Hence a problem of prevention and elimination of acute technogenic exposures hazardous for human health has expanded beyond the medical competence and grown to a major environmental issue.
Newer data from human epidemiologic studies of methylmercury (MeHg) poisoning in which perinatal exposure occurred are available from four distinct populations. The results of an Iraqi grain-consuming population are compared to results from studies performed in fish-consuming groups in the Faroe Islands, the Seychelles Islands and in Peruvian fishing villages. A comparison of the results indicate that the Iraqi population does not represent a sensitive subpopulation within a perinatal group, but rather the relative lower threshold identified from this study was the results of confounders. Use of this benchmark dose for regulatory purposes may place a severe limitation upon fish consumption in the United States that is not fully supported by the scientific data.
Adverse health effects following prenatal exposures to methylmercury (MeHg) have been apparent from several prospective cohort studies conducted in a fish-eating population. A prospective study in a Faroese birth cohort documented subtle deficits of several functional domains at prenatal MeHg exposure levels previously thought to be safe. Recent additional studies also showed neurobehavioral deficits associated with exposures to polychlorinated biphenyls (PCBs) with concomitant MeHg poisoning. In contrast, a prospective study in the Seychelles did not detect a similar association between MeHg exposure and neurodevelopmental deficits; children of the highest MeHg exposure group showed better scores in some developmental tests than those of the lower exposure groups for both prenatal and postnatal MeHg exposures. This paradoxical difference between both studies is summarized herein. The primary source of human exposure to MeHg is fish. Since a considerable number of pollutants, including polychlorinated biphenyls (PCBs) and pesticides, are also present in fish, and since some organochemical substances including PCBs are also well documented to be neurotoxic to the developing brain from epidemiological studies, the combined effects of these pollutants should be considered in discussing the neurotoxicity of MeHg. In this article, therefore, major prospective cohort studies focusing on the exposures to PCBs were reviewed.
Developmental origins of environmentally induced disease and dysfunction. Proceedings of the International Conference on Foetal Programming and Developmental Toxicity. Tórshavn, Faroe Islands. May, 20-24, 2007.
Previous studies have reported alarmingly high levels of organochlorines (OCs), particularly polychlorinated biphenyls (PCBs), in free-ranging polar bears (Ursus maritimus). In this study plasma concentration of PCBs ranged from 14.8 to 200 ng/g wet weight. The aim of the study was to investigate associations between OCs and lymphocyte proliferation after in vitro stimulation with different mitogens and antigens. In 1998 and 1999, 26 and 30 free-ranging polar bears from Svalbard and Churchill, Canada, respectively, were recaptured 32-40 d following immunization with inactivated tetanus toxoid and hemocyanin from keyhole limpets (KLH) to sensitize lymphocytes. At recapture, blood was sampled for determination of plasma levels of PCBs and organochlorine pesticides (OCPs) and lymphocyte proliferation after in vitro stimulation with specific mitogens--phytohemagglutinin (PHA), pokeweed mitogen (PWM), concanavalin A (Con A), lipopolysaccharide (LPS), and purified protein derivative of Mycobacterium avium subsp. paratuberculosis (PPD)--and antigens: tetanus toxoid and KLH. The combinations of sum(PCBs) (sum of 12 individual PCB congeners), sum(OCPs) (sum of 6 OCPs), and their interactions contributed up to 15% of the variations in the lymphocyte responses. By using multiple regression analyses, followed by classical mathematic function analyses, thresholds for immunomodulation were estimated. Depending on the lymphocyte proliferation response studied, the estimated thresholds for significant immunomodulation were within the concentration ranges 32-89 ng/g wet weight (ww) and 7.8-14 ng/g ww for sum(PCBs) and sum(OCPs), respectively. Thus, this study demonstrated that OC exposure significantly influences specific lymphocyte proliferation responses and part of the cell-mediated immunity, which also is associated with impaired ability to produce antibodies (Lie et al., 2004).
Centers for Disease Control and Prevention, National Center for Environmental Health, Division of Environmental Hazards and Health Effects, Health Studies Branch, Atlanta, GA 30333, USA. CRubin@cdc.gov
Developed nations share similar challenges to human health from commercial and agricultural chemicals that are released into the environment. Although Russia and the United States are historically distinct and unique, both countries are geographically large and economically dependent on emission-producing surface transportation. This paper describes U.S.-Russian collaborative activities that grew from a 1995 conference in Moscow that brought together environmental health investigators from both countries to discuss common concerns about the human health impact of environmental pollutants. Lead, pesticides, volatile organic compounds, and mercury were identified as contaminants of greatest concern. Collaborative studies were initiated that included collecting blood and hair samples and splitting samples for analyses in both countries, and introducing and sharing new portable blood and environmental sample analyses instruments. The findings demonstrated that hair analysis was not a good predictor of BLL and that Russian children in the first city sampled had a mean BLL of 7.7 microg/dl. Although higher than the U.S. mean, this level was below the 10.0 microg/dl CDC level of concern. This manuscript summarizes additional study results and describes their impacts on Russian policy. On-going collaborative environmental investigations are described.
The bright, fluorescent pink-colored remains of a polar bear were found on an Alaskan island with the gravel and snow adjacent to the bear colored bright purple. Traces of fox urine and feces found nearby were also pink. The pink and purple colors were due to rhodamine B, and ethylene glycol (EG) was present in the soil under the carcass. Evidence is given to suggest the bear consumed a mixture of rhodamine B and EG commonly used to mark roads and runways during snow and ice periods. Such wildlife losses could be prevented by substituting propylene glycol for the EG in such mixtures.
The burden of persistent organic pollutants (POPs) in Arctic peoples has been monitored for some years. In 1997, the Alta Declaration extended the mandate of the Arctic Assessment and Monitoring Programme (AMAP) to cover assessment of the combined effects of environmental stressors. The AMAP Phase I assessment report (Assessment report: Arctic pollution issues. Arctic monitoring and assessment programme (AMAP), Oslo Norway, xii+859 pp. Vol xii + 859 pp. Oslo, Norway, 1998) gave an overview of the classical toxicology of contaminants. Only recently a programme for measuring the potential biological effects of these contaminants has been established: The AMAP Human Health Effect Monitoring Programme. Body burden data alone are not enough to assess the health risks associated with exposure to environmental contaminants in Arctic peoples. Furthermore, laboratory studies of the effects of single chemicals or chemical mixtures in laboratory animals and cell cultures cannot fully elucidate the human health risks. Integration of epidemiological health research and effect-biomarker studies on humans from exposed populations in the Arctic is needed in order to obtain information about the real health risks resulting from exposure to the accumulated mixtures of contaminants in the Arctic. The present text aims to give a short account of background literature on known and suspected effects of environmental chemicals on endocrine regulated processes with special emphasis on Arctic conditions. Following the evaluation of existing knowledge, a survey of the recently started Human Health Effect Biomarker Programme in Greenland is given.
Various environmental pollutants of industrial or agricultural origin such as persistent organic pollutants (POCs) are causing great concern owing to their toxicity to humans and animals. At the Stockholm Convention on POCs in 2001, 12 of these pollutants, i.e. dioxins, PCBs (polychlorinated biphenyls) and DDT were referred to as "the dirty dozen". Conclusion: Collaborative studies by scientists from Canada, Russia, Scandinavia and other countries representing different fields such as environmental chemistry, ecology and medical sciences may increase our knowledge about the present threat of toxic chemicals to ecology and human health in the Arctic region. It is hoped that improved understanding will promote preventive political decisions.
Comment On: Acta Paediatr. 2003 Nov;92(11):1255-6614696844
Is the decline of the increasing incidence of non-Hodgkin lymphoma (NHL) in Sweden and other countries a result of cancer preventive measures? The yearly age-standardized incidence of NHL increased significantly in Sweden during 1971-1990, for men an average of 3.2% and for women 3.1%. The corresponding figures for 1991-2000 were -0.8% and -0.2%, respectively. A decline of the increasing incidence has also been seen in other countries, such as the United States, Finland, and Denmark. Immunosuppression is one established risk factor for NHL, possibly with interaction with Epstein-Barr virus. Phenoxyacetic acids and chlorophenols, both pesticides, have been associated with NHL. Use of these chemicals was banned in Sweden in 1977 and 1978, respectively. Also, persistent organic pollutants such as polychlorinated biphenyls, hexachlorobenzene, chlordanes, and dioxins have been shown to increase the risk. Exposure of the whole population occurs predominantly through the food chain. Exposure to such chemicals was highest in the 1960s and 1970s. Because of regulation in the 1970s, exposure has declined substantially in the population. The change in incidence of NHL in Sweden and other countries may serve as a good example of how prohibition and limitation of exposure may be reflected in cancer statistics some decades later.