Emerging Disease Threats
Twenty-nine diseases and microbes have emerged since 1973 including HIV, Cryptosporidium, and Vibrio cholera, and 20 diseases have reemerged in the last two decades including tuberculosis, dengue, and malaria. The first Focus describes how environmental changes resulting from human activities may be contributing to the emergence and spread of disease world-wide.
Hazards of New Technologies
As society approaches the 21st century, technology seems to advance at an almost breathtaking pace. For centuries, however, people have realized that with the benefits technology brings there usually come problems or limitations as well. The second Focus describes three major areas of technological advances: fiber and fine particles, computer-related technologies, and transgenics, and the real and potential hazards they pose to human health.
Eliminating Medical Waste
The Innovations describes how new hospital products, such as gowns and surgical drapes, made from polyvinyl alcohol can cut down on hazardous medical waste, reduce incinerator emissions, and save money.
Enzyme Induction in Rats Given PCB/PCDFs
A 2-day prepubertal female rat bioassay was used by Li and Hansen to estimate both dioxinlike and non-dioxinlike biological responses from extracts of an Illinois landfill contaminated by polychlorinated biphenyls and polychlorinated dibenzofurans. Several metabolic enzymes in rat liver were induced, serum total thyroxine was reduced, and there was a 35% increase in uterine weight, suggesting that a comprehensive approach that uses both biochemical and endocrinological endpoints might improve assessments of risk for complex mixtures.
Global Warming and the Asian Sandfly
A discriminate analysis model was used to simulate global warming and predict seasonal and geographic distribution of the sandfly in Soutwest Asia. This insect serves as a vector responsible for the endemic transmission of leishmaniasis and sandfly fever. Cross and Hyams report that with an increase of 1°C, 14 locations could become endemic with disease transmission, 17 more with a 3°C increase, and 12 more with a 5°C increase. The model also predicted that seasonality for disease would be extended throughout 12 months in 7 locations with at least a 3°C rise in temperature and in 29 locations with a 5°C rise.
Cancer and Mortality in Alachlor Workers
Acquavella et al. examined mortality and cancer rates between 1968 and 1993 in Iowa workers potentially exposed for about 17,000 worker years to alachlor, the active ingredient in a family of pre-emergent herbicides.The authors report lower mortality than expected and cancer incidences no higher than the overall rate for Iowa, suggesting that there was no appreciable effect of alachlor even though pesticide exposure at the production facility greatly exceeded that characteristic of agricultural operations.
Dioxin Bioassays for Trichloro-ethylene Incineration Products
Medaka embryo cardiotoxicity, antiestrogenicity in trout liver cell cultures, and guinea pig Ah receptor assays were used by Villalobos et al. to evaluate dioxin-like responses to an incompletely combusted trichlorethylene aerosol, a toxic by-product that mimics transient incinerator emissions. Extracts of the soot aerosol caused embryotoxicity, induced cytochrome P450 and metabolic enzyme activity, reduced estradiol-dependent vitellogenin synthesis, and enhanced Ah receptor binding. TCDD and dibenzofuran were not detected in the by-products, suggesting that unknown components associated with incomplete combustion of trichloroethylene may pose health risks through dioxinlike mechanisms.
Tissue Repair in Rat Liver
Mangipudy et al. used an animal model to investigate thioacetamide toxicity and the role of cell proliferation in tissue repair. The authors report complete survival of thioacetamide-treated rats in the absence and complete mortality in the presence of colchicine doses that block cell division, but found sustained and stimulated tissue repair when colchicine doses are used that incompletely block cell division, emphasizing the critical role of tissue repair in toxicity responses.
Air Pollution and Lung Cancer Risk in Italy
Spatial models were used to evaluate sources of pollution around Trieste, Italy. Based upon autopsy registrys, Bigerri et al. report that there was a moderate risk for lung cancer in relation to the city center or to proximity of an incinerator and suggest that air pollution may have been a causal factor in tumor development.
PCDD/PCDF/PCBs in Norwegians Eating Contaminated Crabs
Johansen et al. determined whole blood concentrations of 2,3,7,8-substituted polychlorinated dibenzo-p-dioxins and polychlorinated-p-dibenzofurans and 19 different PCB congeners from men ingesting different amounts of crab from a Norway fjord polluted with organochlorine compounds from a Mg-production plant. There were stronger correlations between crab consumption and the sum of PCDDs and PCDFs in blood and a weaker correlation between crab consumption and some of the highly chlorinated PCBs or with urine cadmium concentration.
PCB/DDT Metabolites in Human Milk
Norén et al. sampled human milk in Stockholm at seven intervals between 1972 and 1992 for methylsulphonyl metabolites of chlorinated biphenyls and methylsulphonyl metabolites of p,p'-DDE. Concentrations of metabolites of chlorinated biphenyls decreased from about 9 to 2 ng/g lipids, and those of p,p'-DDE from about 5 to 0.4 ng/g lipids, and were correlated with the levels of total PCB or of total p,p'-DDE. The major metabolite in milk was from p,p'-DDE, while PCB methylsulfones with 5 and 6 chlorine atoms were predominant.
P450 in Crabs in Japan
Ishizuka et al. measured cytochrome P450 content in hepatopancreas of the fresh water crab, Eriocheir japonicus, as well as activities of several metabolic enzymes, and found some correlation with polycyclic aromatic hydrocarbon (PAH) pollution in the Tone river. The activities of benzo[a]pyrene 3-hydroxylase, ethoxycoumarin O-deethylase, ethoxyresorufin O-deethylase, imipramine 2-hydroxylase, bunitrolol 4-hyroxylase, and metabolic activation of benzo[a]pyrene appeared to be useful indicators of levels of PAH in the environment.
Last Update: July 9, 1997
