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This risk assessment applied a framework for determining probable co-occurrence of juvenile spring Chinook salmon (Oncorhynchus tshawytscha) with agricultural pesticides in the Willamette Basin, Oregon (Teply et al. this issue2012) to characterize risk to the threatened population. The assessment accounted for spatial and temporal distribution of 6 acetylcholinesterase-inhibiting insecticides in salmonid habitat within the basin and their relative contributions to mixture toxicity estimated from chemical monitoring data. The 6 insecticides were chlorpyrifos, diazinon, malathion, carbaryl, carbofuran, and methomyl. Seasonal distributions of the juvenile salmon prey base across the basin were determined and compared to co-occurrence with the insecticide mixture to determine the probability of prey reduction and reduced production of juvenile fish. Probability of effect on freshwater aquatic invertebrates was based on acute toxicity species sensitivity distributions (normalized to the most potent compound, chlorpyrifos) using a novel approach to apply the toxicological concept of concentration addition to species sensitivity distributions with differing slopes. The chlorpyrifos distribution was then used to determine relative sensitivity among various species tested within the important taxa making up the prey base. A prey base index was devised, incorporating diet composition and prey availability, to evaluate the indirect effects of the insecticide mixture on juvenile salmon production occurring as a result of a reduction in the prey base. Our analysis targeted fish use of backwater and off-channel habitat units, because they generally coincide with agricultural lands in lowlands and represent shallow habitat with limited water exchange. The percentage of agricultural land use within 300 m of critical habitat stream reaches was used to scale chemical measurement data from a site with high agricultural land use across the full extent of the basin to provide estimates of chemical exposure in each reach. Seasonal impacts were evaluated from mean monthly concentrations. Stressor impact on 5 key taxa was evaluated at each time step and for each reach, and the outcome was compared to a conservation threshold assigned to the prey base index. Only 13% of juveniles reared in backwater, off-channel habitat within 300 m of agricultural land. Percent reduction of carrying capacity as a consequence of reduced prey was estimated to be 5% over the entire brood year. This can be considered lost capacity that is probably compensated elsewhere via increased occupancy (emigration to other habitat units within the reach), which is not accounted for in the model. Integr Environ Assess Manag 2012; 8: 285–300. © 2011 SETAC

A collection of 12 microbial cultures, known to contain cytochrome P-450 monooxygenase or other degradative enzymes, was screened for their ability to degrade the Novartis Crop Protection Inc. developmental fungicide cyprodinil (CGA-219417; 4-cyclopropyl-6-methyl-N-phenyl-2-pyrimidinamine). Ten of the 12 cultures produced a monohydroxylated metabolite in yields ranging from 1.2 to 35.6%. The filamentous fungus, Beauveria bassiana ATCC 7159, produced a methoxylated glycoside of the monohydroxylated metabolite with a yield of 80%. Dihydroxylated metabolites and a molecular cleavage product, 4-cyclopropyl-6-methyl-2-pyrimidamine, were also detected in certain cultures. The overall results of the study indicated that cyprodinil was readily metabolized by a variety of microbial species. Metabolites generated by these cultures can potentially be used as analytical reference standards to support animal, plant, and soil metabolism studies. Keywords: Cyprodinil; microbial transformations; metabolite identification...

Biotransformation of the environmental pollutant chrysene 1 by resting cells of a mutant strain (B8/36) of the soil bacterium Sphingomonas yanoikuyae produces (+)-cis-3,4-dihydroxy-3,4-dihydrochrysene 4 which has been assigned (3S,4R) absolute configuration by stereochemical correlation with (-)-(3S,4R)-cis-3,4- dihydroxy-1,2,3,4-tetrahydrochrysene 6. Both cis-3,4-diol 6 and cis-1,2-dihydroxy-1,2,3,4- tetrahydrochrysene 12 are obtained in enantiopure form after chromatographic separation of the individual bis(2-methoxy-2-phenyl-2-trifluoromethylacetyl) (bis-MTPA) diastereoisomers of compound 6 and the MTPA diastereoisomers of bromohydrin 19, respectively, followed by hydrolysis. A new general synthetic route to cis-dihydrodiols, from the corresponding cis-tetrahydrodiol cyclic carbonates, is used to obtain both racemic and enantiopure forms of the bay-region diol 4, and the non-bay region diol 5. 1 H NMR and CD spectra of the cis- and trans-dihydrodiols of chrysene are described.

Bluegill sunfish (Lepomis macrochirus) were continuously exposed to 0.1 μg/ml of uniformly radiolabeled [ 14 C]3-chloro-p-toluidine hydrochloride (CPTH) for 28 d, after which the fish were transferred to flowing untreated water for a 28-d depuration period. At periodic intervals during the treatment and depuration periods, samples of water and fish were analyzed for [ 14 C] residues to determine the degree of CPTH absorption. Samples of bluegill that were exposed to the radiolabeled chemical for 28 d were analyzed to determine the distribution of the radiolabel and to isolate and identify possible metabolites. The steady-state concentrations in the bluegill tissues were reached by day 7 of exposure to the radiolabeled compound, with mean concentrations in the edible, nonedible, and whole-body tissues determined to be 2.9, 12.0, and 7.5 μg/g of tissue, respectively. Bioconcentration factors of 33x, 150X, and 88x were calculated for the three types of tissues. About 64% of the accumulated radiolabeled CPTH and metabolites were eliminated from the fish on day 28 of depuration. The distribution of radioactivity was found to be similar in all tissue groups. One metabolite was confirmed as N-acetyl-3-chloro-p-toluidine, with two metabolites suggested to be 4-acetamido-2-chlorobenzoic acid and 4-amino-2-chlorobenzoic acid. The N-acetylated breakdown product has been previously reported to occur in both mammals and birds ; thus, the metabolism of CPTH in fish may parallel that observed in these other species. Although the effects of biomagnification cannot be fully assessed at this time, we can conclude that when bluegill sunfish are continuously exposed to sublethal levels of CPTH, bioconcentration will not occur to an appreciable extent, and that residues will be rapidly excreted upon removal of the fish from the CPTH source. Furthermore, published information pertaining to various aquatic organisms indicates that bioaccumulation will not be a problem if the bioconcentration factor is below 100.

The adsorption of the herbicide 14C-atrazine to the marine fungus Dendryphiella salina was studied using sodium azide as an inhibitor of active uptake. Adsorption of atrazine (94 ppb) was found to reach equilibrium within six hours. Adsorption as a function of concentration (9.4 to 468 ppb) conformed to the empirically derived Freundlich equation giving a K value of 6.2. Atrazine on the fungal cell surface was easily desorbed by successive artificial seawater washes indicating a relatively loose binding. The ability of the marine fungus D. salina to remove 14C-atrazine from an artificial seawater medium suggests an environmental role in the transport and redistribution of atrazine in estuaries.

The influence of glucose and NH4NO3 on the degradation of the herbicide atrazine was studied with the marine fungusPericonia prolifica Anastasiou. The bioaccumulation of14C-atrazine by fungal cultures was substantially increased at increased concentrations of glucose. Overall, 34.1% of the initial atrazine concentration was removed from the culture filtrate of the cultures grown in 0.5% (w/v) glucose and 0.007% (w/v) NH4NO3, and 40.4% of the initial atrazine concentration was removed when the same media contained 0.08% (w/v) NH4NO3. The majority of internalized radioactivity from both sets of cultures could be extracted from the mycelia as undegraded atrazine. However, examination of both the culture filtrates and mycelia of cultures grown under 0.5% (w/v) glucose and 0.08% (w/v) NH4NO3 revealed the presence of both dealkylated and dechlorinated hydrolysis products of atrazine. The fungal cultures, compared with uninoculated controls, showed a 5-fold increase in 2-chloro-4-ethylamino-6-amino-striazine (deisopropylatrazine), a 1.9-fold increase in 2-hydroxy-4-ethylamino-6-isopropylamino-s-triazine (hydroxyatrazine), and a 1.5-fold increase in other metabolites not extracted into ethyl acetate, suggesting two separate degradation pathways caused by a combination of metabolic and physicochemical interactions. Although mineralization of [ring-14C] atrazine did not occur under the conditions employed, considerable radioactivity was found in an unextractable form associated with cell fragments ofPericonia cultures indicating further metabolism of the initial degradation products.

Microbial transformation of the tetrazolinone herbicide F5231 was accomplished with the filamentous fungus Absidia pseudocylindrospora Hesseltine et Ellis (ATCC 24169). The fungus converted the herbicide to six metabolites which were identified spectrally by mass, infrared, and nuclear magnetic resonance spectroscopy.