Radical Departure
The NIEHS News (p. A66) continues its Under the Scope series of profiles of areas of research at the NIEHS with a look at the topic of free radicals, antioxidants, and oxidative stress. NIEHS scientist Ron Mason explains his group's novel use of electron spin resonance to study biological, pharmacological, and toxicological problems in vivo.
Dealing with Leftovers
With cleanup costs estimated at some $200 billion, nuclear waste presents a fearsome challenge to the Department of Energy and other federal agencies. The Focus (p. A68) looks at the government's strategy for cleaning up the debris of decades of nuclear weapons production while safeguarding public health.
This Is the Environment on Drugs
The use of illegal drugs exacts a heavy toll on human health, and costs society billions in medical expenses and lost productivity. The eradication of illegal drug production may also exact a toll on the environment. The Spheres of Influence (p. A74) examines the environmental effects of illegal drug production and outlines government plans for addressing this multifaceted problem.
MicroCAT and Mouse
The MicroCAT system, a recent advance in X-ray computed tomography technology, is described in the Innovations (p. A78). MicroCAT allows scientists to examine the soft tissue and skeletal details of live laboratory animals over time and generations, which may provide information to researchers studying human genetic mutations and diseases such as arthritis.
Estrogens and Development
The red-eared slider turtle, which exhibits temperature-dependent sex determination, was used by Bergeron et al. (p. 93) as an in vivo model for testing developmental effects of estrogenic chemicals. Low doses of 17ß-estradiol were synergistic when administered with a single low dose of estriol. A dose-response study by Sheehan et al. (p. 155) indicated that there was no apparent threshold dose of 17ß-estradiol for temperature-dependent sex-reversal in the red-eared slider turtle, suggesting that there may be risk of environmental effects from even low concentrations of estrogenic chemicals.
El Niño and Disease
The relationship between reported incidences of dengue fever and the El Niño southern oscillation in 14 island nations of the South Pacific were reported by Hales et al. (p. 99). Unlike the initiation of epidemics, the transfer of dengue fever between islands appears to be independent of interannual climate variations, but is more dependent on factors such as population density and travel for disease transmission.
Chlorinated Products in Water
Disinfection of water by chlorination is necessary to destroy infectious microbes, but the process yields disinfection by-products, some of which could be toxic. Weisel et al. (p. 103) evaluated biomarkers for exposure and show that urinary trichloroacetic acid excretion rate and creatinine-normalized concentrations were useful.
Lead Chelation by DMSA
The meso and racemic forms of dimercaptosuccinic acid were examined for their lead-chelating ability in human adenocarcinoma cells by Pigman et al. (p. 111). Proton-induced X-ray emission assays indicated that the racemic form of dimercaptosuccinic acid may be more effective in chelating lead from within the cell, and that the racemic form is transported across the cell monolayer more readily than the meso form.
Copper and Intestinal Toxicity
Pizzaro et al. (p. 117) examined acute gastrointestinal effects in 60 human volunteers who drank water containing 1-5 mg/l copper. Gastrointestinal disturbances were directly related to copper concentrations, and the threshold for symptoms (diarrhea, pain, nausea, vomiting) was 3 mg/l copper. Most symptoms disappeared when copper consumption was discontinued.
Exposure to Radon
In some areas of Iowa and Minnesota, Steck et al. (p. 123) found that outdoor radon concentrations exceeded the national average indoor levels. In this region, outdoor radon exposure can be a substantial fraction of total exposure and should be considered in risk estimations.
Dermatitis and Electrophilicity
Rosenkranz et al. (p. 129) evaluated the role of electrophilicity in the induction of allergic contact dermatitis in humans. Electrophilicity accounted for about 30-40% of allergic contact dermatitis-inducing ability, indicating that identification of these moieties could be used to further the understanding of this disease.
Exposure to MTBE
A study of personal exposure to methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME) in Finnish self-service gasoline stations was conducted by Vainiotalo et al. (p. 133). There was a wide log-normal distribution of values, with low exposures being most frequent. The mean concentrations in individual samples were 2.4-3.9 mg/m3 MTBE, 1.7-2.2 mg/m3 TAME, and 0.90 mg/m3 benzene at two stations; these concentrations are well below the short-term limits for toxicity.
Contaminants in Mustelids
Carcasses of mink and otters obtained from commercial trappers in northwest America were evaluated by Harding et al. (p. 141) to determine residues of organochlorine pesticides, PCBs, PCDDs, and PCDFs. Liver concentrations were higher in 1994-1995 and 1995-1996 samples than in those from 1990-1992. Although there was no relationship between body burden of contaminants and body condition, baculum length in male juvenile mink was inversely related to total PCBs.
Air Pollution in Korea
Lee et al. (p. 149) examined the relationship between air pollution and daily mortality for 1991-1995 in Korea. There were positive associations between daily mortality and sulfur dioxide, ozone, and total suspended particulates. The estimated mortality associated with sulfur dioxide and ozone occurred at levels below the current WHO recommendations for these air pollutants.
Cyclosiloxane Toxicity in Mice
Lieberman et al. (p. 161) investigated the toxicity of cyclosiloxanes in mice injected intraperitoneally with a distillate containing four different oligomers of dimethylsiloxane. Mortality, inflammatory lesions in the lung and liver, and elevated serum enzymes indicated that the toxicity of octamethylcyclotetrasiloxane was comparable to that of carbon tetrachloride or trichloroethylene.
Last Updated: January 25, 1999