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Biomedical subjects

V Lawrence

Publications and source records attributed to V Lawrence.

8 recordsLinked to original sources

Links between passive smoking and disease: a best-evidence synthesis. A report of the Working Group on Passive Smoking.

We reviewed the toxicologic, clinical, and epidemiologic evidence on the health effects of environmental tobacco smoke (ETS). For each type of exposure to environmental tobacco smoke we have sought articles in the English language reporting studies of effects on human health. Formal criteria that stressed study design, quality of execution and generalizability of results were used to select 116 scientifically admissible reports from over 2,900 articles. We concluded that: (a) there is strong evidence of an association between residential exposure to environmental tobacco smoke and both respiratory illness and reduction of lung function, and also between maternal smoking and reduced birth weight; (b) the weight of evidence is compatible with an association between active maternal smoking during pregnancy and increased infant mortality, and also between residential exposure to environmental tobacco smoke (primarily spousal smoking) and the risk of lung cancer; (c) there is evidence consistent with a relationship between exposure to environmental tobacco smoke in the workplace and respiratory symptoms, (d) the evidence is insufficient to implicate residential exposure to environmental tobacco smoke in relation to other forms of malignant disease or congenital malformations; (e) there is no evidence in the literature of an association between nonresidential exposure to environmental tobacco smoke and any form of cancer. Further studies are required to address the effects of exposure to environmental tobacco smoke, especially nonresidential exposure, in carcinogenesis and as a risk factor for atherosclerosis. Further work is also needed to improve measurement of exposure in such studies and to assess the importance of confounding factors.

Adolescent

The effect of sub-lethal doses of dieldrin on the ventilatory and cardiac activity in two species of shrimps.

The effect of dieldrin on the heart and ventilatory activity in the shrimps Macrobranchium faustinum and Macrobrachium amazonicum was studied over 4 and 7 day exposure periods, respectively. In M. faustinum, ventilatory rate increased by 43% and heart rate by 14.4%. In M. amazonicum, the ventilatory and heart rates decreased by 21 and 6%, respectively. In M. amazonicum ventilatory reversal frequency, an index of respiratory stress, was 6.7 times higher than the control values. All the changes, except for M. amazonicum heart rate were significant at the 0.01 level of probability.

Animals

The effect of sub-lethal doses of dieldrin on resting and active metabolism in two species of shrimps.

The effects of dieldrin on the active (VaO2) and resting (VrO2) oxygen consumption rates of the shrimps Macrobrachium faustinum (De Sassure) and Macrobrachium amazonicum (Heller) were studied during exposure for 4 days at 0.01 p.p.b. and 7 days at 0.0002 p.p.b., respectively. The VrO2 of M. faustinum increased significantly (P less than 0.01) by 48% but the VaO2 decreased by 13%. The VrO2 and VaO2 decreased by 43 and 70%, respectively, in M. amazonicum. Thus, in both species the aerobic metabolic scope for activity decreased. The increased resting metabolic rate of the indigenous M. faustinum is ascribed to energy consuming responses which allow compensation for the effects of the stressor. The stressor may be said to have moved this species into a metabolic "zone of compensation". The decreased resting metabolic rate of the pond-cultured M. amazonicum is ascribed to greater susceptibility, more extensive metabolic breakdown and failure of compensatory responses. This species might be said to have been forced by the stressor into a metabolic "zone of collapse".

Animals

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Economics, Nursing