Forgot your password?
New user?
New Window Opens on the Secret Life of Microbes: Scientists Develop First Microbial Profiles of Ecosystems
CAS announces the release of SciFinder Scholar for Mac OS X
Press Releases
Press Releases
| Check out our New Publishers' Select for Free Articles |
Archives of Environmental Contamination and Toxicology (v.41, #3)
Development of the Fragment Constant Method for Estimating the Partition Coefficients of Nonionic Organic Mixtures by Z. Lin; H. Yu; S. Gao; J. Cheng; L. Wang (pp. 255-260).
The fragment constant model for estimating partition coefficient of nonionic organic mixtures is developed based on group contribution theory. For 60 mixtures randomly composed of eight substituted benzenes, the C18-Empore™ disks/water partition coefficients (K MD) are determined. Establishment of a model between these K MD and the mole fraction of the fragments (Cl, Br, I, NO2, CH3) acquires the fragments constants for K MD. The significant linear regression equation, between these fragment constants and that of Hansch, provides an approach for calculating K MD of untested nonionic organic mixtures by using the fragment constants of Hansch.
Gridded Usage Inventories of Technical Hexachlorocyclohexane and Lindane for China with 1/6° Latitude by 1/4° Longitude Resolution by Y. F. Li; D. J. Cai; Z. J. Shan; Z. L. Zhu (pp. 261-266).
China banned the use of technical HCH (BHC: 1,2,3,4,5,6-hexachlorocyclohexane) in 1983; lindane has been used in this country since 1991. The total production was around 4 million t for technical HCH from 1952 to 1984, and 11,400 t for lindane between 1991 and 2000. Though the total produced technical HCH was considered to be used in China, only 3,200 t of lindane were used between 1991 and 2000 with the rest for export or on unused stack. Annual usage of these two compounds was located into each province first and then broken for different crops. Inventories of gridded usage of both technical HCH and lindane with 1/6° by 1/4° latitude/longitude resolution have been created by different gridded cropland data sets as surrogate data. The intensive use of technical HCH on croplands was concentrated in the southeastern part of China, but the use of lindane was concentrated in the northern part of China.
Aerobic and Anaerobic Metabolism of Glutaraldehyde in a River Water–Sediment System by H.-W. Leung (pp. 267-273).
Material balance studies of glutaraldehyde in a river water–sediment system demonstrate that glutaraldehyde preferred to remain in the water phase. Glutaraldehyde was metabolized rapidly under both aerobic and anaerobic conditions. The pseudo-first-order half-life of catabolism, based on the loss of glutaraldehyde from the water phase, was 10.6 h aerobically and 7.7 h anaerobically. In contrast, under sterile conditions at pH 5 or 7, no appreciable degradation of glutaraldehyde was observed over a 31-day period. At pH 9, about 30% of the glutaraldehyde degraded over the same period. The major degradate was identified as 3-formyl-6-hydroxy-2-cyclohexene-1-propanal, a cyclicized dimer of glutaraldehyde. The extrapolated half-life of abiotic degradation was 508 days at pH 5, 102 days at pH 7, and 46 days at pH 9. Under aerobic conditions, glutaraldehyde was first biotransformed into the intermediate glutaric acid, which then underwent further metabolism ultimately to carbon dioxide. Metabolism of glutaraldehyde under anaerobic conditions did not proceed ultimately to methane, but terminated with the formation of 1,5-pentanediol via 5-hydroxypentanal as an intermediate.
Nitrogen, Phosphorous, and Organic Carbon Removal in Simulated Wetland Treatment Systems by R. G. Hunter; D. L. Combs; D. B. George (pp. 274-281).
Effects of vegetation, wastewater drawdown, hydraulic retention time (HRT), and media depth on removal of nitrogen, phosphorous, and organic carbon in microcosms were investigated. Synthetic wastewater was added daily to 28 microcosms, and effluent was sampled every 12 days for 132 days. Effluent was analyzed for ammonium (NH4 +-N), nitrate (NO3 −-N), orthophosphate (PO4 3−-P), and total organic carbon (TOC). Average percent removal of NH4 +-N was significantly greater in microcosms containing plants (67%) than in those without plants (29%). Percent removal of PO4 3−-P was also significantly greater in microcosms with plants (42%) than in microcosms without plants (20%), but no significant difference was found for TOC removal between microcosms with plants (67%) and those without plants (74%). Average removal was significantly lower in microcosms with wastewater drawdown than in those without wastewater fluctuation for both NH4 +-N (51% versus 83%) and PO4 3−-P (14% versus 71%). Percent NH4 +-N removal was significantly greater in microcosms with a 6-day retention time (80%) than in those with a 2-day retention (53%), and PO4 3−-P removal was also significantly greater with a 6-day retention time (55%) than a 2-day retention (29%). No differences were seen in TOC removal due to any of the treatments but HRT, where removal was greater microcosms with a 2-day HRT (76%) than in those with a 6-day HRT (60%). Media depth did not have a significant effect on nutrient removal. Results of this study demonstrate that required design parameters are different depending on the nutrient being removed in systems simulated by these microcosms.
Effects of Experimental Manipulation of pH and Salinity on Cd2+ Uptake by the Sponge Microciona prolifera and on Sponge Cell Aggregation Induced byCa2+ and Cd2+ by R. B. Philp (pp. 282-288).
Marine sponges (Microciona prolifera) collected in St. Joseph Bay, Florida panhandle, were exposed for 2 h to pH/salinity unit combinations of 7.4/30, 6.3/30, 7.4/11, and 6.3/11. Cell suspensions from these were aggregated with 24 μM of either CaCl2 or CdCl2. Cells exposed to the low/low (11/6.3) combination aggregated spontaneously (no added stimulus) in 8/11 experiments, suggesting a significant disturbance of normal function, possibly involving disrupted ion uptake. In all other combinations aggregation proceeded normally and there were no statistically significant differences among the groups. CdCl2 was as effective an aggregation stimulus as CaCl2. The calcium channel blocker verapamil (100 μM) reduced calcium-induced aggregation by 15% but had no effect on cadmium (Cd)-induced aggregation, indicating that L-type calcium channels do not play a major role in aggregation induced by these divalent cations. Sponge tissue was exposed for 48 h to the same pH/salinity combinations but containing Cd (15 or 150 μg/ml) and then dried and analyzed for Cd. All sponges concentrated Cd but those exposed to low salinity concentrated it most (in one case ×13). Low pH alone had no appreciable effect but appeared to increase the effect of low salinity. One sponge with a native Cd content of 47.2 μg/g dry weight had the highest acquired Cd content. The results of this study indicate that low levels of salinity and pH, similar to those we recorded in the study area, facilitate the accumulation of Cd, but not via L-type calcium channels, and disrupt normal aggregation responses of the cell. These results may help explain a previous observation that cells from M. prolifera from this area, with high native levels of Cd, failed to aggregate in response to CaCl2[Philp RB (1999) Comp Biochem Physiol 124C:41–49] and also the frequent die-offs of Microciona that have virtually eliminated this sponge from its local habitat.
Chemical Contamination and Toxicity of Sediment from a Coastal Area Receiving Industrial Effluents in Kuwait by M. U. Beg; S. Al-Muzaini; T. Saeed; P. G. Jacob; K. R. Beg; M. Al-Bahloul; K. Al-Matrouk; T. Al-Obaid; A. Kurian (pp. 289-297).
The Shuaiba coastal area (12.5 × 1.5 km) was examined for contamination with total organic carbon, volatile organic matter, total petroleum hydrocarbons, polycyclic aromatic hydrocarbons, cadmium, chromium, copper, lead, nickel, vanadium, and zinc in sediment; their desorption by aqueous elution; and toxicity to aquatic biota. The pollutants were mainly accumulated in the upstream area facing Mina Al-Ahmadi refinery to Shuaiba harbour. Solid-phase Microtox assays showed severe toxicity, and the LC50 was negatively correlated with most of the chemical parameters, suggesting that toxicity was the function of collective effects of the pollutants present in sediment. Sea water elutriation showed poor desorption of pollutants from sediment, and the elutriates were not found toxic to Microtox and brine shrimp larvae. Whole sediment suspension in sea water reduced the survival of fingerlings in fish bioassays. Action from Shuaiba Area Authority is required to reduce pollutant accumulation in identified depositional area on the Shuaiba coast by facilitating unrestricted water flow in the area and restricting pollutant discharge at source.
Sediment Toxicity Identification Evaluation (TIE) Studies at Marine Sites Suspected of Ordnance Contamination by R. S. Carr; M. Nipper; J. M. Biedenbach; R. L. Hooten; K. Miller; S. Saepoff (pp. 298-307).
A sediment quality assessment survey and subsequent toxicity identification evaluation (TIE) study was conducted at several sites in Puget Sound, Washington. The sites were previously suspected of contamination with ordnance compounds. The initial survey employed sea urchin porewater toxicity tests to locate the most toxic stations. Sediments from the most toxic stations were selected for comprehensive chemical analyses. Based on the combined information from the toxicity and chemical data, three adjacent stations in Ostrich Bay were selected for the TIE study. The results of the phase I TIE suggested that organics and metals were primarily responsible for the observed toxicity in the sea urchin fertilization test. In addition to these contaminants, ammonia was also contributing to the toxicity for the sea urchin embryological development test. The phase II TIE study isolated the majority of the toxicity in the fraction containing nonpolar organics with high log K ow, but chemical analyses failed to identify a compound present at a concentration high enough to be responsible for the observed toxicity. The data suggest that some organic or organometallic contaminant(s) that were not included in the comprehensive suite of chemical analyses caused the observed toxicological responses.
Development of Marine Toxicity Data for Ordnance Compounds by M. Nipper; R. S. Carr; J. M. Biedenbach; R. L. Hooten; K. Miller; S. Saepoff (pp. 308-318).
A toxicity database for ordnance compounds was generated using eight compounds of concern and marine toxicity tests with five species from different phyla. Toxicity tests and endpoints included fertilization success and embryological development with the sea urchin Arbacia punctulata; zoospore germination, germling length, and cell number with the green macroalga Ulva fasciata; survival and reproductive success of the polychaete Dinophilus gyrociliatus; larvae hatching and survival with the redfish Sciaenops ocellatus; and survival of juveniles of the opossum shrimp Americamysis bahia (formerly Mysidopsis bahia). The studied ordnance compounds were 2,4- and 2,6-dinitrotoluene, 2,4,6-trinitrotoluene, 1,3-dinitrobenzene, 1,3,5-trinitrobenzene, 2,4,6-trinitrophenylmethylnitramine (tetryl), 2,4,6-trinitrophenol (picric acid), and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The most sensitive toxicity test endpoints overall were the macroalga zoospore germination and the polychaete reproduction tests. The most toxic ordnance compounds overall were tetryl and 1,3,5-trinitrobenzene. These were also the most degradable compounds, often being reduced to very low or below-detection levels at the end of the test exposure. Among the dinitro- and trinitrotoluenes and benzenes, toxicity tended to increase with the level of nitrogenation. Picric acid and RDX were the least toxic chemicals tested overall.
A Bioassay for the Measurement of Insecticide Concentration by R. J. Grant (pp. 319-324).
A bioassay was developed to measure insecticide residues using fruit flies (Drosophila melongaster). After adding a known volume of sampling solution, the time at which 50% of the flies were dead (LT50) was recorded and cross-referenced to the appropriate calibration curve. Using known standards, comparable results were obtained using the bioassay and GC-MS. The bioassay allows concentrations of synthetic pyrethroids as low as 1 pg L−1 to be measured with a variance of < 5%. The bioassay can be used reliably over a wide range of temperatures and it is tolerant to a range of pH and surface tensions of the test solution. The whole bioassay is compact, physically robust, and simple to use; hence, it could be of use in the field as a quick preliminary assessment of water contamination.
Toxicity of Fipronil and Its Degradation Products to Procambarus sp.: Field and Laboratory Studies by D. Schlenk; D. B. Huggett; J. Allgood; E. Bennett; J. Rimoldi; A. B. Beeler; D. Block; A. W. Holder; R. Hovinga; P. Bedient (pp. 325-332).
Fipronil is a phenylpyrazole insecticide that is the active ingredient in the pesticide Icon 6.2 FS™ which is applied to rice seeds targeting the rice water weevil. An arthropod-selective insecticide, fipronil blocks the GABA-gated chloride channel and is unique in that several of its degradation products have been indicated to be equal or more potent than fipronil. After application of rice seeds (2–3 days postplant) to flooded ricefields, water is typically pumped from the ricefields and can be used for the culture of crayfish (Procambarus sp.). Because fipronil is selective for arthropods, is transported via organic sediment, and crayfish consume organic sediment, 96-h LC50 experiments were conducted with fipronil and three of its environmental derivatives in crayfish under conditions without carrier solvents in water of similar pH, alkalinity, and hardness as observed in south Louisiana crayfish culture ponds. Measured LC50s for fipronil to red swamp (Procambarus clarkii) and white river (Procambarus zonangulus) crayfish were 14.3 (95% CI; 5.1–23.4) and 19.5 (95% CI; 11.1–27.9) μg/L, respectively. LC50s of fipronil sulfone (11.2; 9.2–13.2 μg/L), fipronil sulfide (15.5; 13–18 μg/L); and the photoproduct, desulfinyl fipronil (68.6; 46–95.2 μg/L) displayed very high toxicity in crayfish. In situ toxicity studies using caged crayfish in culturing ponds receiving effluent from drained ricefields indicated that effluent from ricefields planted with Icon-treated seed was significantly more toxic compared to untreated surface water (40% survival compared to 83% survival). Hazard quotient comparisons using measured water concentrations in the field and laboratory-based LC50s indicated that fipronil and its metabolites in water resulting from Icon-treated rice seed planting poses a significant risk to crayfish survival.
Toxicity of Cadmium and Copper on Larval and Juvenile Stages of the Estuarine Crab Chasmagnathus granulata (Brachyura, Grapsidae) by L. S. López Greco; M. V. Sánchez; G. L. Nicoloso; D. A. Medesani; E. M. Rodríguez (pp. 333-338).
The toxicity of cadmium and copper were assayed in the estuarine crab Chasmagnathus granulata. Acute assays were made on the first larvae stage, and both acute and chronic assays were made on juvenile crabs. The acute lethal toxicity of the assayed heavy metals was three orders of magnitude higher in larvae than in juveniles. Cadmium proved to be more toxic than copper in most cases; this difference was more evident in the chronic assays on juveniles, according to the nonphysiological feature of cadmium and its persistent accumulation in organisms. During these chronic assays, cadmium produced both a significant mortality and a clear retardation of molting, in accordance with its inhibitory effect on the molting process as previously reported. Copper only caused a molting acceleration during chronic assays, perhaps as a detoxifying mechanism. Heavy metal concentrations having effects in the chronic assays have been reported in some sectors of the estuary where the assayed species lives.
Analysis and Occurrence of Polybrominated Diphenyl Ethers in Washington State Freshwater Fish by A. Johnson; N. Olson (pp. 339-344).
A method is described for analyzing polybrominated diphenyl ethers (PBDEs) in fish tissue using gas chromatography with atomic emission detection (GC/AED) and quantitation by compound independent calibration (CIC). The method has the advantage of an element-selective response, including selectivity between bromine and chlorine. An analysis of fish tissue samples from selected locations in Washington State showed total PBDE concentrations ranged from 1.4 μg/kg (wet weight) in rainbow trout from a remote spring-fed stream to 1,250 μg/kg in mountain whitefish from the urbanized Spokane River. Tetra and penta isomers were the major compounds present. There appear to be substantial between-species differences in the ability of fish to metabolize PBDEs.
Effect of Endosulfan on Antioxidants of Freshwater Fish Channa punctatus Bloch: 1. Protection Against Lipid Peroxidation in Liver by Copper Preexposure by S. Pandey; I. Ahmad; S. Parvez; B. Bin-Hafeez; R. Haque; S. Raisuddin (pp. 345-352).
Effect of a single exposure of endosulfan (5 ppb) on catalase (CAT), glutathione peroxidase (GPx), glutathione S-transferase (GST), and reduced glutathione (GSH) of liver, kidney, and gill of a freshwater fish (Channa punctatus Bloch) were evaluated after 24 h of treatment. Endosulfan exposure resulted in a significant induction (p < 0.05–0.001) of GPx, GST activity, and GSH levels in all the organs. However, CAT activity was found to be significantly decreased (p < 0.01–0.001). Lipid peroxidation (LPO) values were also determined in liver, kidney, and gill and a significant increase in LPO values (p < 0.05–0.01) was observed in all the organs. We also investigated whether preexposure to low concentration of copper (10 ppb) for 4 weeks has any protective effect against endosulfan-induced oxidative damage. In copper-acclimatized endosulfan-exposed fish, a significant decrease in GPx (p < 0.001), GST (p < 0.05), GSH (p < 0.001) levels, and LPO (p < 0.01) was observed in the liver, whereas CAT activity was increased significantly (p < 0.001). However, kidney and gill did not show any significant alterations in antioxidant levels. The results of this study demonstrate that endosulfan induces peroxidative damage in liver, kidney, and gill in response to which levels of antioxidant were modulated. However, when fish preacclimatized to copper were exposed to endosulfan, protection against oxidative damage was observed only in the liver. It is proposed that measurement of antioxidants in fish tissues may prove to be useful in biomonitoring of exposure to aquatic pollutants.
Accumulation Profiles of Persistent Organochlorines in Waterbirds from an Estuary in Korea by J. W. Choi; M. Matsuda; M. Kawano; B. Y. Min; T. Wakimoto (pp. 353-363).
Persistent organochlorine pollutants (POPs), such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and organochlorine (OC) pesticides such as DDTs (dichlorodiphenyltrichloroethane), HCHs (hexachlorocyclohexane isomers), CHLs (chlordane compounds) and HCB (hexachlorobenzene), were measured in subcutaneous fat of resident and migratory birds collected from the Nakdong River estuary (NRE) in Korea. Black-tailed gull, a resident bird from the NRE, contained greater concentrations of PCDD/Fs and PCBs than the migratory birds collected in the estuary. For example, mean concentrations of PCDD/Fs in black-tailed gull (395.5 pg/g fat weight) were higher than those in migratory birds, such as greenshank (198.3 pg/g fat weight), common gull (90.9 pg/g fat weight) black-headed gull (84.2 pg/g fat weight), and common tern (47.1 pg/g fat weight). However, concentrations of DDTs and/or HCHs were great in some migratory species, such as little tern (mean DDT 6,200 ng/g fat weight) and black-necked grebe (HCHs 475 ng/g fat weight). This suggested that contamination of PCDD/Fs and PCBs in resident gulls are due to intake of locally contaminated fish near the NRE. Elevated OC pesticide levels in migratory birds indicated that these birds have been exposed to DDTs and HCHs during their migration in Southeast Asian countries where chlorinated pesticides are still used. 2,3,7,8-Tetrachloro dibenzo-p-dioxin equivalents (TEQs) were calculated using the toxic equivalency factors (TEFs) reported by World Health Organization in 1998. Four of the 2,3,7,8-substituted congeners of PCDD/Fs contributed over 90% of the TEQs.
Lead Poisoning of Waterfowl by Contaminated Sediment in the Coeur d'Alene River by L. Sileo; L. H. Creekmore; D. J. Audet; M. R. Snyder; C. U. Meteyer; J. C. Franson; L. N. Locke; M. R. Smith; D. L. Finley (pp. 364-368).
The Coeur d'Alene River basin in Idaho has been contaminated by mine tailings that have impaired the health of wildlife since the early 1900s. In other parts of the world, virtually all lead poisoning of waterfowl is caused by the ingestion of manmade lead artifacts, primarily spent lead shotshell pellets or, occasionally, fishing sinkers. However, in the Coeur d'Alene River basin in Idaho, nonartifactual lead poisoning was the ultimate cause of death of most of 219 (77%) of 285 waterfowl carcasses that had been found sick or dead from 1992 through 1997. The majority of these 219 waterfowl (172 tundra swans [Cygnus columbianus], 33 Canada geese [Branta canadensis], and 14 other species) were poisoned by ingesting river sediment that was contaminated with lead. The next most common cause of death (20 instances, 7%) was lead poisoning accompanied by ingested shotshell pellets. The remaining 46 waterfowl succumbed to trauma, infectious diseases (aspergillosis, avian cholera, tuberculosis), or miscellaneous problems, or the cause of death was not determined.
Secondary Effects of the Pesticide Bacillus thuringiensis kurstaki on Chicks of Spruce Grouse (Dendragapus canadensis) by M. L. Norton; J. F. Bendell; L. I. Bendell-Young; C. W. LeBlanc (pp. 369-373).
The objective of this study was to determine if application of the biological pesticide Bacillus thuringiensis kurstaki (B.t.k.) had secondary effects on spruce grouse (Dendragapus canadensis) chicks in the southern boreal forest of Ontario, Canada. B.t.k. kills larvae of Lepidoptera that might otherwise be food. This may affect types of food ingested and influence chick growth rates by reducing the availability of a high-protein food. Amount of ingested grit, which is diet-dependent, may also be influenced, which could alter exposure to anthropogenic toxic metals, such as cadmium (Cd) and lead (Pb), associated with the grit. Chick growth rate from 0 to 14 days of age was determined, and gizzard contents were analyzed for types of foods and levels of macronutrients and trace metals in chicks raised in a plot treated with B.t.k. compared to chicks raised on a control plot. Chick growth rates were significantly different (p < 0.05); chicks from the treatment plot increased body mass 30% less as compared to chicks raised on the control plot. Control chicks contained on average 2.5-fold the mass (in g) of grit and nearly twofold the mass of food, which included larvae, in their gizzards compared to those exposed to B.t.k. whose diets were dominated by spiders and ants. Concentrations of magnesium (Mg), calcium (Ca), phosphorous (P), iron (Fe), manganese (Mn), sulfur (S) and the trace metals zinc (Zn), copper (Cu), nickel (Ni), and chromium (Cr) did not differ between experimental and control birds (p > 0.05). In contrast, control chicks had higher levels of aluminum (Al), Cd, cobalt (Co), and Pb in their gizzards than chicks from the sprayed area (p < 0.05), attributed to greater amounts of consumed grit. Although birds from the sprayed area had lower levels of the toxic metals Pb and Cd in their gizzards, a protein-deficient diet could have been a factor that contributed to decreased rates of growth in B.t.k.-exposed birds as compared to those birds held on nonsprayed sites. Reduced growth during the first 2 weeks of avian development has important consequences at the population level, and it is recommended that this secondary effect be considered for all species who rely on Lepidoptera larvae as a food resource prior to wide spread application of B.t.k. for insect control.
Effects of Mercury on the Contractile Activity of the Right Ventricular Myocardium by F. N. Cunha; G. P. S. de Assis; C. E. C. Silva; I. Stefanon; V. D. Pinto; D. V. Vassallo (pp. 374-380).
The increase in right ventricular systolic pressure observed in vivo after the administration of mercury opposes to the idea that the metal depresses the cardiac pump performance. We then investigated the effects of HgCl2 (0.1 to 2.5 μM) on the contractile activity of the right ventricular myocardium, measuring isometric and tetanic contractions of right ventricular isolated strips, right ventricular isovolumic systolic and diastolic pressures, and the coronary perfusion pressure (0.03 to 3 μM) in constant-flow Langendorff-perfused rat hearts. The results presented here suggest that the acute effects of mercury on the right ventricular myocardium are distinct. When isolated strips of right ventricular wall are used, the contractile depression produced by mercury is manifested. However, when mercury is administered to isolated perfused hearts or in vivo this depressant effect is not revealed. The possible reasons for this behavior are the increased coronary perfusion pressure, which promotes a positive inotropic effect, manifested during the infusion of increasing concentrations of mercury, or the putative stretch of the ventricular fibers, which might cause the increment of diastolic pressure. An interesting finding is that the mechanical activity of the preparations, in which mercury is administered via coronary circulation, is not depressed and, even more, it can increase systolic pressure. However, the nature of this protective effect of coronary circulation cannot be explained by the results presented here.
Hepatic Enzyme Induction and Acute Endocrine Effects of 2,2′,3,3′,4,6′-Hexachlorobiphenyl and 2,2′,3,4′,5′,6-Hexachlorobiphenyl in Prepubertal Female Rats by M.-H. Li; P.-C. Hsu; Y. L. Guo (pp. 381-385).
Polychlorinated biphenyls (PCBs) with the liable 2,3,6-substitution are important components of certain commercial mixtures and frequently detected in biota, but little is known about their enzyme induction abilities and possible endocrine-disrupting effects. CB 132 (2,2′,3,3′,4,6′-hexachlorophenyl) and CB 149 (2,2′3,4′,5′,6-hexachlorophenyl) were investigated in weanling female rats dosed intraperitoneally on days 21 and 22 and killed on day 24 of age. Uterotropic response, serum thyroid hormone, and hepatic enzyme induction were examined in prepubertal female rats treated with these two environmentally relevant 2,3,6-substituted chlorobiphenyl (CB) congeners from 8 mg/kg to 96 mg/kg. The readily metabolized CB 132 did not cause any significant increase in all endpoints measured in the present study. On the other hand, CB 149 was a weak PROD and BROD inducer and a modest depleter of serum thyroxine in prepubertal female rats. The finding of thyroid hormone disruption by CB 149 may lead to biologically significant neurobehavioral and neurochemical changes in developing animals via milk lactation.
Organochlorines and 8-Hydroxy-2′-Deoxyguanosine (8-OHdG) in Cancerous and Noncancerous Breast Tissue: Do the Data Support the Hypothesis That Oxidative DNA Damage Caused by Organochlorines Affects Breast Cancer? by M. J. Charles; M. J. Schell; E. Willman; H. B. Gross; Y. Lin; S. Sonnenberg; M. L. Graham (pp. 386-395).
A study was conducted to test the hypothesis that oxidative DNA damage caused by exposure to organochlorines is an important risk factor in breast cancer. This is the first study that evaluates this hypothesis by measuring 8-hydroxy-2′-deoxyguanosine (8-OHdG), a biomarker of oxidative DNA damage, polychlorinated biphenyl (PCB) congeners, and isomers of bis (4-chlorophenyl)-1,1,1-trichloroethane (DDT) and bis (4-chlorophenyl)-2,2,2-dichloroethane (DDE) in cancerous and noncancerous tissue. We measured these compounds in 44 primary tumors (cancerous) and 21 benign breast biopsy (noncancerous) tissues. Overall, no significant differences were observed in the level of the organochlorines between the tissues. The median concentration for 8-OHdG was 10.5 fmol/mg DNA (1.7/105 deoxyguanosine residues), and 8.5 fmol/mg DNA (1.4/105 deoxyguanosine residues) in cancerous and noncancerous tissue, respectively. These values are similar to background levels. No significant differences were observed in 8-OHdG levels in cancerous versus noncancerous tissue, and no correlation was demonstrated between the organochlorines and 8-OHdG. The data thus do not support the hypothesis that oxidative DNA damage caused by exposure to organochlorines is an important risk factor in breast cancer.