Suchergebnisse

MTBE is a volatile organic compound used as an oxygenating agent in gasoline. Inhalation from fumes while refueling automobiles is the principle route of exposure for humans, and toxicity by this route has been well studied. Oral exposures to MTBE exist as well, primarily due to ground‐water contamination from leaking stationary sources, such as underground storage tanks. Assessing the potential public health impacts of oral exposures to MTBE is problematic because drinking water studies do not exist for MTBE, and the few oil‐gavage studies from which a risk assessment could be derived are limited. This paper evaluates the suitability of the MTBE database for conducting an inhalation route‐to‐oral route extrapolation of toxicity. This includes evaluating the similarity of critical effect between these two routes, quantifiable differences in absorption, distribution, metabolism, and excretion, and sufficiency of toxicity data by the inhalation route. We conclude that such an extrapolation is appropriate and have validated the extrapolation by finding comparable toxicity between a subchronic gavage oral bioassay and oral doses we extrapolate from a subchronic inhalation bioassay. Our results are extended to the 2‐year inhalation toxicity study by Chun et al. (1992) in which rats were exposed to 0, 400, 3000, or 8000 ppm MTBE for 6 hr/d, 5 d/wk. We have estimated the equivalent oral doses to be 0, 130, 940, or 2700 mg/kg/d. These equivalent doses may be useful in conducting noncancer and cancer risk assessments.

Two views about the amount of opportunity available through technical education are contrasted. In popular discussions the system figures as an `alternative route' to middle class occupations. In sociological literature, however, it is dismissed as a significant source of opportunity. A review is presented of important but neglected changes in the organization of courses and the recruitment of young men to them. It is shown that both class and educational differentials do reduce the proportion of places on advanced and full time courses which are available for early leavers and for boys of working class origin. On the other hand an analysis of long run trends in terms of (i) the participation of each social class in technical education, (ii) transition rates between different levels of study, (iii) the link between qualification and occupational rewards, suggests that attempts to discount technical colleges as a source of opportunity may be premature. It is concluded that any discussion of the effect of increasing educational opportunity upon social mobility entails the examination of the institutional mechanisms through which individuals are prepared and trained for occupational roles.

Drawing on the empirical articles in this special issue and posing further questions, I suggest how movement scholars might move forward in identifying and accounting for movements' cultural impacts. I argue for comparing cases in which movements did and did not have cultural influence, for developing new approaches to public opinion as a measure of movements' influence, for mining theoretical traditions associated with a wider array of cultural concepts than we routinely use, and for paying attention to the institutional norms that mediate movements' impacts—impacts within politics as much as outside it.