摘要:

AbstractPrevious attempts at structure/biodegradability relations (SBRs) and available biodegradation data are reviewed and it is concluded that (1) not enough rate data on large numbers of chemicals are available to develop quantitative SBRs and (2) attempted qualitative SBRs have suffered from either poor documentation of the biodegradation evaluation or they have used limited biodegradation test data. Because of the poor reproducibility of biodegradation tests, a weight‐of‐evidence evaluation procedure is proposed. A system for collecting and evaluating biodegradation data from screening tests, biological treatment simulations, grab sample tests and field studies is described and study‐specific and summary biodegradability codes in combination with reliability codes are developed that can be used for structure/biodegradability rela

ISSN:0730-7268    

DOI:10.1002/etc.5620060101

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractDissolved organic matter (DOM) in aquatic systems is known to reduce the bioavailability of heavy metals. Recent studies have shown similar reductions in bioavailability of organic contaminants. The mechanism for reduction, with Aldrich humics, was to reduce the freely dissolved, bioavailable, xenobiotic concentration by partitioning to DOM. This mechanism was also found to apply to organic contaminants in the presence of DOM from interstitial waters. A reverse‐phase separation technique was used to measure the sorbed xenobiotic, and by difference from the total, the freely dissolved concentration of a contaminant permitting the calculation of a partition coefficient (Krp). Equilibrium partitioning of selected polycyclic aromatic hydrocarbon and poly‐chlorinated biphenyl congeners to the DOM, in interstitial waters from several geographical sources, ranged over several orders of magnitude for a single compound. The reduction in bioavailability was measured by reduction in the conditional uptake rate constant for organic xenobiotics in the presence of DOM, for the amphipodPontoporeia hoyi(the major benthic invertebrate in the Great Lakes). Reduction in the conditional uptake rate constant versus controls was used to calculate a biologically determined partition coefficient (Kb). The logKrpwas well correlated with logKb, logKb= 1.54(0.15) + 0.723(0.03) logKrp(r2= 0.74,n= 195) over a range of three orders of magnitude in measured partition coefficient for individual compounds using DOM from different sour

ISSN:0730-7268    

DOI:10.1002/etc.5620060102

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractMacrobenthic animal communities that colonized uncontaminated and fenvalerate‐contaminated sand (0.1, 1 and 10 μg/g dry weight, nominal) in boxes placed for 8 weeks in an estuary were compared to assess effects of fenvalerate on community structure. As much as 27% of initial concentrations of this synthetic pyrethrin persisted in sediment at the end of the test. The average number of species (35.6) in communities in five replicates exposed to 10 μg/g was significantly less than that in the control (47.8) and lower concentrations (45.0 and 46.2). Of the dominant phyla collected (Annelida, Mollusca, Chordata and Arthropoda), abundance of chordates only (primarily lancelets,Branchiostoma caribaeum) was reduced by 10 μg fenvalerate/g. Biological indices applied to the data showed the greatest structural differences for communities exposed to the highest concentration, but these did not differ substantially from those for the control. Effective concentration for exposure via the sediment was five orders of magnitude greater than that for waterborne exposure determined in earlier benthic community stu

ISSN:0730-7268    

DOI:10.1002/etc.5620060103

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractLobsters,Homarus americanus, were exposed in a flow‐through system to a sublethal concentration of zinc (Zn++) for 4 d and then transferred to flowing unspiked sea water for 7 d. The concentrations (μg/g dry weight) of Zn++after the four days of exposure were in the order gill>green gland>haemolymph>hepatopancreas>crusher tissue>crusher muscle>pincer tissue>shell>testes>heart>pincer muscle>abdominal (tail) muscle. After 7 d in unspiked water the concentration of Zn++in each of the tissues decreased, but did not return to pre‐exposure levels. In terms of the total tissue burden the level of Zn++in only the hepatopancreas continued to increase during the depuration phase. The data were analysed using a four‐compartment model with haemolymph as the “central” compartment. The exchange of Zn++between gills and water was rapid, between gills and haemolymph was somewhat slower, and between haemolymph and tail muscle was extr

ISSN:0730-7268    

DOI:10.1002/etc.5620060104

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractProadifen HCl (SKF‐525A), a hepatic microsomal enzyme inhibitor, was evaluated as a synergist for eight chemicals that produced temporary immobilization (TI) at sublethal levels in birds. Probit analysis showed that Proadifen HCl administered orally and concurrently at 100 mg/kg to quail (Coturnix coturnix japonica) with four of the test chemicals (alpha‐chloralose, chlordiaz‐epoxide, nicotine sulfate and phencyclidine) significantly lowered (p= 0.05) the estimated median lethal (LD50) and/or temporary immobilization response (TI50). Proadifen HCl reduced the LD50 dose foralpha‐chloralose 1.56‐fold and the TI50 2.03‐fold; the TI50 dose for chlordiazepoxide HCl 2.47‐fold; the LD50 dose for nicotine sulfate 4.10‐fold and the TI50 2.98‐fold; and the LD50 dose for phencyclidine HCl 2.35‐fold and the TI50 27.5‐fold. The synergism exhibited by Proadifen HCl with metomidate and tribromoethanol was less or negative. The LD50 of metomidate was reduced 1.96‐fold, but the TI50 was not affected. The LD50 of tribromoethanol was increased 1.15‐fold, but the TI50 was reduced by a factor of 1.48. There was no synergism between Proadifen HCl and methiocarb or pentobarbital. These data show that the LD50 and/or TI50 of temporary immobilizing agents for birds can be affected by the use of a synergist such as Proadifen HCl, and indicate that synergism between bird control chemicals or pesticides and drugs could be used to improve efficacy, lower application rates and reduce en

ISSN:0730-7268    

DOI:10.1002/etc.5620060105

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractFood and water avoidance experiments were conducted on mallards (Anas platyrhynchos L.) and northern bobwhite (Colinus virginianus L.) exposed to a range of dietary carbofuran concentrations. A dietary avoidance concentration 50 (analogous to an LC50) was calculated for each avoidance experiment. This statistic describes the dietary toxicant concentration threshold at which, when exceeded, exposed animals are likely to discriminate between untreated and treated feed or water. The food avoidance concentration 50s (FAC50s) for mallards and bobwhite were 10 and 159 ppm, respectively. The water avoidance concentration 50 (WAC50) for mallards was 3 ppm. For bobwhite the WAC50 for carbofuran was estimated to exceed 50 ppm.

ISSN:0730-7268    

DOI:10.1002/etc.5620060106

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractVariations in oyster mutagenicity were monitored in a series ofin siturelocation experiments and compared with tissue concentrations of polycyclic aromatic hydrocarbons (PAHs). Oysters (Crassostrea virginica) were relocated among three rivers in the southern Chesapeake Bay and sampled over a 2‐week exposure period. Extracts of oyster tissues were assayed for mutagenic activity by theSalmonella typhimuriummicrosomal test and analyzed for selected PAHs by gas chromatography. Oysters relocated to the polluted Elizabeth River (Norfolk, VA) from a pristine site (Ware River, VA) accumulated mutagenic activity and PAHs within 3 d following relocation. Mutagenicity increased over a 14‐d period while tissue levels of most PAHs stabilized or declined after 3 d. Extracts of native oysters from the Elizabeth River exhibited comparable levels of mutagenic activity as 14‐d relocated oysters. In elimination experiments, PAH levels and mutagenic activity of Elizabeth River oysters decreased following relocation to the Ware River and were not detected after 14 d. Regression analyses did not detect a significant association between slopes of mutagenicity dose‐responses and tissue levels of PAHs. Marginal associations with numbers ofSalmonellarevertants per plate were detected in comparisons with sums of PAH tissue levels, and with tissue levels of benzofluor

ISSN:0730-7268    

DOI:10.1002/etc.5620060107

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

摘要:

AbstractA protocol for determination of “no‐effect” concentrations on hatch and survival in the zebrafish (Brachydanio rerio) has been evaluated at five laboratories for variability using chromium (K2Cr2O7) and zinc (ZnSO4× 7H2O) as toxicants. Repeatability (r) and reproducibility (R), expressed as C.V. (coefficient of variation), for logarithmic median survival time ranged between 1% and 9% forrand between 1% and 29% forRdepending upon concentration of toxicant. Variability increased at high concentrations, especially for zinc. For logarithmic median hatching time, C.V. forrranged from 6% to 24% and forRbetween 11% and 27% for the various concentrations of chromium and zinc. Estimated logarithmic “no‐effect” concentrations on survival of zinc and chromium had a C.V. forrbelow 10% and a C.V. forRbelow 15% for zinc and below 25% for chromium. Zinc delayed the time to hatch at lower concentrations than those that reduced survival time, for the estimated logarithmic “no‐effect” concentrations of zinc on hatchrwas around 75% andRaround 100%. The “no‐effect” concentrations based on all nine or ten tests from the five laboratories were 15 mg Cr/L and 0.5 mg Zn/L. Because of the cumulative toxicity of chromium in fish the chronic “safe” concentration may be considerably lower, but the “no‐effect” concentration of 0.5 mg Zn/L for effects on hatching time is consistent with the chronic “safe” concentration found in other species of fish at the same

ISSN:0730-7268    

DOI:10.1002/etc.5620060108

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY

ISSN:0730-7268    

DOI:10.1002/etc.5620060109

出版商:Wiley Periodicals, Inc.    

年代:1987

数据来源: WILEY