Developing Countries and Environmental Decline
In developing countries in Africa and Latin America, disease, pestilence, war, famine, and death are commonplace. These countries also have some of the highest birth rates and lowest life expectancies of any in the world. In the struggle to address these problems and develop economically, environmental health problems are both created and exacerbated. Two articles in the Focus section (p.1018) examine issues of population, water resources, waste disposal, air pollution, pesticide use, and worker safety in sub-Saharan Africa and Latin America. While economics and politics continue to drive social issues and block progress in the quality of the environment, organizations are being formed and funding is being sought to improve health and welfare in these countries.
Global Report Card
Although many environmentalists agree that 1994 was not a banner year for the environment, and the U.S. Congress failed to pass any major environmental legislation this session, around the world advances were made in the past year in addressing environmental health problems. The Spheres of Influence (p. 1030) summarizes some of the major international conferences held and legislation passed concerning issues of population, biodiversity, global warming, environmental justice, chemical and pesticide use, and world trade and looks ahead to 1995 to identify potential developments in the environmental health arena.
p53 Molecular Model
Utilization of state-of-the-art X-ray crystallography, combined with computer-assisted modeling, has enabled scientists to construct the shape and content of the active site of p53, one of the most important genes associated with cancer. The Innovations article (p. 1034) describes the role of the p53 tumor-suppressor gene and the discovery of its molecular structure. There is hope that developments in molecular medicine will enable scientists to improve cancer diagnosis, prognosis, and treatment with new drug designs based on these techniques.
Asbestos and Colon Cancer
Gamble (p. 1038) reviews the evidence suggesting that asbestos is a potential cause for colon cancer using epidemiological data from occupational exposure, case-control studies, animal bioassays, and other related data. Gamble found an association between high exposure to asbestos and colorectal cancer, but no exposure-response gradient among the cohorts where trends for lung cancer were observed. Because there was no consistent risk associated with asbestos exposure in population-based case-control studies and no evidence of increased incidence of colon cancer in animal models, Gamble asserts that only very high exposure to asbestos increases the risk of colon cancer.
Immunogenicity of Lead-Altered Neuroproteins
Neuroproteins were incubated with lead and then mice were injected with unaltered neuroproteins or lead-altered proteins to determine immune responsiveness. Waterman et al. (p. 1052) showed that lead enhances the immunogenicity of the neural proteins myelin basic protein and glial fibrillary acidic protein, suggesting that these responses are involved in a mechanism of immunologically mediated progression of lead-induced neurotoxicity.
Intake of Dietary Cadmium
Berglund et al. (p. 1058) investigated the potential influence of high-fiber diets on the intake and absorption of dietary cadmium in Swedish women. Blood and urinary samples were assayed for cadmium, hemoglobin, ferritin, and zinc. Absorption of cadmium was weakly associated with high fiber content in the diet and strongly associated with age. Because there was also a strong inverse correlation between blood cadmium concentration and iron reserves in the body, the authors suggest that premenopausal women might be at greater risk from dietary cadmium ingestion.
Ozone Alters Cell Barriers in Lung
Yu et al. (p. 1068) grew canine bronchial epithelial cells in culture and exposed them to ozone. They report changes in mannitol flux and transcellular electrical resistance, which indicates a loss of integrity in the cellular barrier. These adverse effects were directly related to the dose and after 18 hours were reversible in cells exposed to two lower doses, but were progressively enhanced at the highest dose of ozone exposure. The antioxidants vitamins E and A were capable of attenuating the ozone-induced changes in cytoskeletal dysfunction, suggesting ozone acted as a direct oxidant on the cellular membrane.
Nasal Toxicity in Mexico City
Calderone-Garcidueñas et al. (p. 1074) investigated the effects of atmospheric pollution in Mexico City on the respiratory health of healthy males. The data suggest that cumulative exposure to elevated ozone concentrations as high as 10 ppm for 10 hours per day for 2 weeks was associated with adverse respiratory symptoms and severely irritated nasal mucosa. The toxicity was observed as early as 2 days after exposure, and persisted for up to 2 weeks after departure.
Chloroform from Indoor Pools
Levesque et al. (p. 1082) measured chloroform concentrations in air and water from an indoor pool after increasing the water chloroform concentration from 159 to 538 µg/l over seven days. The body burden of chloroform in swimmers was strongly associated with the water and air concentration in the pool and was enhanced by exercise. Because the dose of chloroform can be 100 times greater from swimming in chorinated pools for one hour compared to that from drinking tap water, indoor pools represent an important route of exposure that may exceed acceptable levels of trihalomethanes for sensitive individuals.
Pesticide Risks and Regulations
Risk analyses of occupational pesticide exposure were evaluated by Woodruff et al. (p. 1088) in the state of California, based on dose estimates of 41 chemicals compared to standard indices of acute and chronic toxicity. Broad ranges of absorbed daily doses and lifetime cancer risks were calculated for each pesticide, and for these chemical exposures the risks of toxic chronic effects were greater than those from acute toxic effects. Woodruff et al. believe that ongoing pesticide regulatory programs are ineffective and suggest that novel policy strategies to offer immediate worker protection are warranted.
Last Update: June 4, 1998
