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Bisphenol A (BPA) is a monomer used in the manufacture of a multitude of chemical products, including epoxy resins and polycarbonate. The objective of this study was to evaluate the effects of BPA on male sexual development. This study, performed in CF-1 mice, was limited to the measurement of sex-organ weights, daily sperm production (DSP), epididymal sperm count, and testis histopathology in the offspring of female mice exposed to low doses of BPA (0, 0.2, 2, 20, or 200 microg/kg/day), by deposition in the mouth on gestation days 11-17. Male sexual development determinations were made in offspring at 90 days-of-age. Since this study was conducted to investigate and clarify low-dose effects reported by S. C. Nagel et al., 1997, Environ. Health Perspect. 105, 70-76, and F. S. vom Saal et al., 1998, Toxicol. Indust. Health 14, 239-260, our study protocol purposely duplicated the referenced studies for all factors indicated as critical by those investigators. An additional group was dosed orally with 0.2 microg/kg/day of diethylstilbestrol (DES), which was selected based on the maternal dose reported to have maximum effect on the prostate of developing offspring, by F. S. vom Saal (1996, personal communication), vom Saal et al. (1997, Proc. Natl. Acad. Sci. U S A 94, 2056-2061). Tocopherol-stripped corn oil was used as the vehicle for BPA and DES, and was administered alone to control animals. No treatment-related effects on clinical observations, body weight, or food consumption were observed in adult females administered any dose of BPA or DES. Similarly, no treatment-related effects on growth or survival of offspring from dams treated with BPA or DES were observed. The total number of pups born per litter was slightly lower in the 200-microg/kg/day BPA group when compared to controls, but this change was not considered treatment-related since the litter size was within the normal range of historical controls. There were no treatment-related effects of BPA or DES on testes histopathology, daily sperm production, or sperm count, or on prostate, preputial gland, seminal vesicle, or epididymis weights at doses previously reported to affect these organs or at doses an order of magnitude higher or lower. In conclusion, under the conditions of this study, the effects of low doses of BPA reported by S. C. Nagel et al., 1997 (see above) and F. S. vom Saal et al., 1998 (see above), or of DES reported by F. S. vom Saal et al., 1997 (see above) were not observed. The absence of adverse findings in the offspring of dams treated orally with DES challenges the "low-dose hypothesis" of a special susceptibility of mammals exposed perinatally to ultra-low doses of even potent estrogenic chemicals. Based on the data in the present study and the considerable body of literature on effects of BPA at similar and much higher doses, BPA should not be considered as a selective reproductive or developmental toxicant.

Zooplankton samples were collected from 0 to 50 m depth at 2 stations in Jones Sound and 1 in Baffin Bay in August and September of 1983. Levels of chlorophyll and phaeopigment were measured in several stages of Calanus hyperboreus and Calanus glacialis at 4 h intervals, to examine diurnal feeding behavior in copepods which do not vertically migrate on a daily basis. All stages examined for each of the 2 species showed diurnal variations in feeding activity. In addition, different stages and species always started to feed synchronously, although timing of onset of evening feeding was different at each of the 3 stations. On each occasion feeding started when incident light intensity decreased to < 4 W m-2. Cessation of feeding in the morning, however, was not linked to a particular intensity of incident light and may be controlled by satiation of appetite. Levels of 3 digestive enzymes -protease, laminarinase, and amylase -were measured in 2 stages of C. hyperboreus and C. glacialis at 4 h intervals over a 48 h time series at the second of the Jones Sound stations. There were no rhythmic changes in amounts of enzymes in any of the stages. Maximum levels of gut pigment within any 1 stage were not necessarily correlated with ambient chlorophyll concentrations, which varied by a factor of 4 among stations.

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The arctic copepod Pseudocalanus can be highly aggregated in the first few centimeters under landfast ice during spring in concentrations up to 10/(6) per cubic meter. Chlorophyll-derived pigments in the water, the abundance of animals, and their gut pigment index show fluctuations that may be tidally related. Short-term grazing experiments performed at -1.7 degrees C, in which ice algae was used as food, yielded feeding rates comparable to the highest known for the genus. Arctic Pseudocalanus seem to feed opportunistically near the ice-water interface, either directly on the attached epontic (under ice) algae or as it erodes from the ice.

Chlorophyll destruction by Calanus spp. grazing on phytoplankton (diatoms and Phaeocystis) was assessed at stations in the Labrador Sea and off Labrador and Newfoundland (Canada). Copepods were fed at natural or diluted food concentrations over several (4 to 8) sequential 12 h feeding periods. Initial chlorophyll concentrations were between 0.2 and 19 pg I -' , and degrees of chlorophyll destruction were between 20 and 100%. For replicate incubations, degrees of chlorophyll destruction were similar. Over all experiments degrees of destruction were generally high and variable at low ingestion rates (<50 ng chl mg-' h-'), decreasing to a limit of about 4 5 % at higher ingestion rates. The relationship between ingestion rate and degree of chlorophyll destruction was not obviously affected by differences in in situ conditions (e.g. stage of the spring bloom). Filtration rates, by contrast, did vary, decreasing in the presence of an apparently noxious food (Phaeocystis) and sometimes increasing during experiments, perhaps in response to increasing hunger. Faecal pellets, collected from copepods fed at natural food concentrations, did not leak pigment over a 4 d period, and neither chlorophyll nor phaeopigment was lost as copepods with food in their guts were alloived to defecate for 3 h in filtered seawater. These results suggest that most chlorophyll destruction occurs at an early stage of feeding, and that phaeopigments are not intermediates. When we assumed in a simple model that the 'bleaching' reaction was enzymatically mediated, we found that enzyme activity varied linearly with initial ingestion rate, with a positive y-intercept. One interpretation of this is that there are 2 pools of enzyme activity: one associated with the copepods and the other with the phytoplankton. The algal enzymes are normally latent, but are activated by the physical break-up of cells during ingestion. At low ingestion rates the copepod enzyme can destroy all, or most, of the ingested chlorophyll, whereas at higher ingestion rates more of the destruction is due to the algal enzymes. The high variability in degrees of chlorophyll destruction reported here and elsewhere can be explained partly by differences between algal foods (e.g. differences in levels of the bleaching enzyme), partly by differences in copepod behaviour (e.g. effects on filtration rates), and partly by differences in experimental conditions, which affect the range of ingestion rates exhibited during an incubation (e.g. density of copepods, duration of incubation).