Are brominated flame retardants endocrine disruptors?

Brominated flame retardants (BFRs) are a group of compounds that have received much attention recently due to their similarity with "old" classes of organohalogenated compounds such as polychlorinated biphenyls (PCBs), in terms of their fate, stability in the environment and accumulation in humans and wildlife. Toxic effects, including teratogenicity, carcinogenicity and neurotoxicity, have been observed for some BFR congeners, in particular the brominated diphenyl ethers (BDEs). This concise review focuses on the potency of BFRs and to disrupt endocrine systems, and attempts to answer the question whether or not BFRs are endocrine disruptors. Evidence is provided on the disruption of the thyroid hormone system by BFRs, with particular emphasis on the BDEs, as most recent data is available on this class of flame retardants. Similar to the hydroxylated PCBs, in vitro mechanistic studies as well as animal experiments have demonstrated the effects of BDEs on thyroid hormone transport and metabolism. An overview of possible effects of BFRs on the estrogen system is also provided. Research gaps are outlined, as well as ongoing and future studies in the European community aimed at contributing to comprehensive risk assessments based on the endocrine-disrupting effects of BFRs.     

CAGED FISH AS MONITORS OF POLLUTION: EFFECTS OF CHLORINATED EFFLUENT FROM A WASTEWATER TREATMENT PLANT1

ABSTRACT: Fish confined to cages were used to determine the effects of effluent from a wastewater treatment plant (WWTP). Control fish were kept in cages in an aquaculture pond. Acute effects of the effluent entering the final oxidation pond of the WWTP were determined by confining channel catfish (Ictalurus punctatus) at the pond inlet; the mean total residual chlorine (TRC) concentration was 0.9 mg/l during this exposure. After 8 h, 42 percent of the fish had died and survivors had severe lesions of the skin and gills. During the first two weeks of exposure, channel catfish at the outlet of the final oxidation pond (mean TRC=0.1 mg/l) were predisposed to bacterial infection but lost the parasitic trematodes that were on the gills when the fish were placed in cages. After several weeks, exposed fish had histologic lesions, enlarged livers, and reduced growth. The presence of unidentified carcinogen(s) in the effluent of this WWTP was indicated by papillomas developing on caged black bullheads (Ictalurus melas) and hepatic-enzyme induction in channel catfish. In situ exposure of caged fish was advantageous because storage and pretreatment of water samples were not required, and exposure levels corresponded to those present in the environment. The use of cages for containment of fish during field exposure allowed confinement to the location of interest and convenient sampling of the fish. Unlike wild fish, the caged fish could be compared to control fish with the same pre-exposure history.     

Achievement motive and entrepreneurial orientation: a structural analysis

In this study we have attempted to assess the achievement motive of students of small business, considered as having high entrepreneurial orientations, and students of business and economics, considered as having lower entrepreneurial orientations. Based on a facet definition of achievement motive we analyzed the structure of achievement motive for both samples. As hypothesized, results reflected the three facets of achievement motive: type of confrontation, time perspective related to task performance, and behavior modality. As hypothesized, small business students were found to score higher than their business and economics colleagues on most of the achievement items. Considerable differences between the samples were found on four achievement components: the readiness to face uncertainty, calculating risk, undertaking personal responsibility, and solving problems. The discussion focused on the advantages of the multifaceted approach to achievement motive and implications for assessing it in various settings. Copyright © 1999 John Wiley & Sons, Ltd.     

Surface ozone-temperature relationships in the eastern US: A monthly climatology for evaluating chemistry-climate models

We use long-term, coincident O₃ and temperature measurements at the regionally representative US Environmental Protection Agency Clean Air Status and Trends Network (CASTNet) over the eastern US from 1988 through 2009 to characterize the surface O₃ response to year-to-year fluctuations in weather, for the purpose of evaluating global chemistry-climate models. We first produce a monthly climatology for each site over all available years, defined as the slope of the best-fit line (m_O3-T) between monthly average values of maximum daily 8-hour average (MDA8) O₃ and monthly average values of daily maximum surface temperature (T_max). Applying two distinct statistical approaches to aggregate the site-specific measurements to the regional scale, we find that summer time m_O3-T is 3–6 ppb K^?1 (r = 0.5–0.8) over the Northeast, 3–4 ppb K^?1 (r = 0.5–0.9) over the Great Lakes, and 3–6 ppb K^?1 (r = 0.2–0.8) over the Mid-Atlantic. The Geophysical Fluid Dynamics Laboratory (GFDL) Atmospheric Model version 3 (AM3) global chemistry-climate model generally captures the seasonal variations in correlation coefficients and m_O3-T despite biases in both monthly mean summertime MDA8 O₃ (up to +10 to +30 ppb) and daily T_max (up to +5 K) over the eastern US. During summer, GFDL AM3 reproduces m_O3-T over the Northeast (m_O3-T = 2–6 ppb K^?1; r = 0.6–0.9), but underestimates m_O3-T by 4 ppb K^?1 over the Mid-Atlantic, in part due to excessively warm temperatures above which O₃ production saturates in the model. Combining T_max biases in GFDL AM3 with an observation-based m_O3-T estimate of 3 ppb K^?1implies that temperature biases could explain up to 5–15 ppb of the MDA8 O₃ bias in August and September though correcting for excessively cool temperatures would worsen the O₃ bias in June. We underscore the need for long-term, coincident measurements of air pollution and meteorological variables to develop process-level constraints for evaluating chemistry-climate models used to project air quality responses to climate change.