Accumulation of environmental contaminants in wood duck (Aix sponsa) eggs, with emphasis on polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans.

We measured polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), organochlorine pesticides, and mercury in wood duck (Aix sponsa) eggs collected near a North Carolina (USA) bleached kraft paper mill. Samples were taken a decade after the mill stopped using molecular chlorine. Using avian toxic equivalency factors, 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalent (TEQ) concentrations were 1-30 pg/g fresh wet weight in eggs (n = 48) collected near the mill in 2002-2005 and were significantly higher than those from a reference site (<1 pg/g) 25 km away. Geometric mean wood duck egg TEQs (6 pg/g) were one-fifth those measured at this site prior to the cessation of molecular chlorine bleaching. Concentrations of mercury in wood duck eggs from nests of the Roanoke River sites ranged from 0.01 to 0.14 microg/g (geometric mean, 0.04 microg/g) and were significantly higher than those from the reference site, where concentrations did not exceed 0.04 microg/g (geometric mean, 0.02 mug/g). All concentrations were lower than those associated with adverse effects in birds. The congener profiles, lack of contamination in reference site eggs, and decline in contaminant concentrations after process changes at the mill provide strong evidence that mill discharges influenced contamination of local wood duck eggs. Collectively, the results indicate that the wood duck is an effective sentinel of the spatial and temporal extent of PCDD, PCDF, and mercury contamination.

National contaminant biomonitoring program: Residues of organochlorine chemicals in U.S. Freshwater Fish, 1976-1984.

The U.S. Fish and Wildlife Service periodically determines concentrations of organochlorine chemicals in freshwater fish collected from a nationwide network of stations as part of the National Contaminant Biomonitoring Program (NCBP, formerly a part of the National Pesticide Monitoring Program). From late 1984 to early 1985, a total of 321 composite fish samples were collected from 112 stations and analyzed for organochlorine chemical residues. The mean concentrations of total DDT did not change from 1980-81 to 1984, following a period of steady decline through the 1970's; however, the mean concentrations ofp,p'-DDT declined significantly. The most persistent DDT homolog (p,p'-DDE) was detected at 98% of the stations sampled in 1984, and constituted 73% of total DDT residues, up from 70% in 1974-79. Collectively, these findings indicate a low rate of influx and continued weathering of DDT in the environment. Residues of polychlorinated biphenyls (PCBs) also remained widespread, but a significant downward trend in total PCBs was evident, and early eluting PCB components were present at fewer stations than in the past. Mean concentrations of dieldrin have not changed since 1978-79; concentrations remained highest in Hawaii and in the Great Lakes. Toxaphene concentrations declined from 1980-81 to 1984, especially in the Great Lakes, and the incidence of toxaphene declined from 88% of the stations sampled in 1980-81 to 69% in 1984. Mean chordane concentrations did not change from 1980-81 to 1984, following a period of decline; however,trans-nonachlor replacedcis-chlordane as the most abundant component, suggesting a lower influx of chlordane to the aquatic environment. Residues of other organochlorines-mirex, pentachloroanisole (PCA), benzene hexachloride (BHC) isomers, endrin, heptachlor, hexachlorobenzene (HCB), and Dacthal(®) (DCPA)-were either found at relatively few (<25%) of the stations sampled in 1984 or were characterized by relatively low concentrations. In general, organochlorine concentrations were lower in 1984 than at any time reported previously.

Contaminated sediments from tributaries of the Great Lakes: chemical characterization and carcinogenic effects in medaka (Oryzias latipes).

Sediments from four inshore industrial sites and a reference site in the Great Lakes were extracted with organic solvents to produce a crude extract, which was separated on alumina into two fractions: predominantly polycyclic aromatic hydrocarbons; and predominantly nitrogen-containing polycyclic aromatic compounds. Crude extracts were redissolved in acetone and analyzed by gas chromatography and gas chromatography-mass spectrometry. The acetone-redissolved crude extracts from the four industrialized sites contained 5.6-313.3 micrograms total polycyclic aromatic compounds/g sediment and 3.0-36.4 micrograms other compounds/g sediment. In addition to the typical EPA priority pollutants, a substantial amount (228.7 micrograms/g sediment) of alkyl-polycyclic-aromatic compounds was detected in sediments from one of the industrialized sites. Extracts from the reference site contained 1.55 micrograms total polycyclic aromatic compounds/g sediment. Medaka (Oryzias latipes) were exposed to multiple pulse doses of acetone-redissolved extracts and fractions. Medaka were also exposed to a known carcinogen, methylazoxymethanol acetate, to verify that chemicals produced tumors in the test fish. Acetone-redissolved extracts and fractions from contaminated sediments were toxic to medaka. Fin erosion and non-neoplastic liver abnormalities were more prevalent in medaka after exposure to acetone-redissolved extracts and fractions from contaminated sediments. Neoplasms previously associated with chemical exposure in wild fishes were induced in medaka exposed to acetone-redissolved extracts and fractions from two of the contaminated sites, but not from the reference site or controls. These findings further support the hypothesis that chemical contaminants in sediments are involved in epizootics of neoplasms in wild fishes at contaminated sites.