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Biomedical subjects

M Mehlman

Publications and source records attributed to M Mehlman.

6 recordsLinked to original sources
PubMed1989

Health effects of gasoline refueling vapors and measured exposures at service stations.

Liquid gasoline is a complex mixture of at least 150 hydrocarbons with about 60-70% alkanes (paraffins), 25-30% aromatics, and 6-9% alkenes. In order to evaluate the potential for health effects from inhaling gasoline vapors, it is essential to understand the major differences in the composition of vapors versus liquid gasoline. The small chain, low carbon-numbered components are more volatile and thus in higher percentages in the vapor phase than the larger and heavier molecules. It is noteworthy that the concentrations of aromatics (the more toxic of the gasoline components), are depleted to about 2% in the vapor phase, with the light paraffins (the less toxic) enriched to about 90%. Actual measurements of vapor exposure at service stations confirm that the vapor composition is primarily to low weight alkanes although benzene is also emitted and represents the chemical of greatest concern. A perceived health concern from inhaling gasoline vapors is the potential for carcinogenicity based on the induction of kidney tumors in male rats and liver tumors in female mice exposed to wholly-vaporized gasoline. However, the results of the animal studies are of questionable relevance for human risk assessment due to the unique mechanism operative only in the male rat and since the exposure was to wholly-vaporized gasoline rather than the gasoline vapor mixture to which humans are exposed. Recent research supports the hypothesis that branched-chain-alkanes bind to a globulin specific to make rats, alpha 2-u-globulin. The protein complex can not be degraded in the usual manner so that protein accumulation occurs in renal cells, leading to cytotoxicity, death, proliferation, and with prolonged exposure, kidney cancer. The results of epidemiology studies fail to link an increase in cancer to exposure to gasoline vapors.

Air Pollutants↗
PubMedDate not supplied

Role of exposure databases in epidemiology.

At present, exposure databases record data primarily for regulatory purposes; they have not focused on serving the needs of epidemiologists or public health. However, the modification of exposure databases could facilitate their use in epidemiology. Characteristics necessary to enhance the use of all databases include easy access by users; documentation of methods, sampling bias, error, and inconsistences; widespread coverage in time and space; and methods and measures for estimating exposure of individuals as well as populations. Also needed are exposure scenarios and models to estimate exposures for geographic areas and time intervals not currently sampled. Multidisciplinary teams are needed to examine current databases, to review strategies for improving data collection, and to suggest and help implement appropriate changes. A long-term goal is to develop and validate data from exposure scenarios and models using data on the relationship of exposure to doses measured in humans.

Databases, Factual↗
PubMedDate not supplied

Enhancing cognition in the intellectually intact.

As science learns more about how the brain works, and fails to work, the possibility for developing "cognition enhancers" becomes more plausible. And the demand for drugs that can help us think faster, remember more, and focus more keenly has already been demonstrated by the market success of drugs like Ritalin, which tames the attention span, and Prozac, which ups the competitive edge. The new drug Aricept, which improves memory, most likely will join them. Whether such drugs are good for individuals, or for society, is an open question, one that demands far more public discussion.

Brain Diseases↗