Factors influencing persistent organic pollutant concentrations in the Atlantic white-sided dolphin (Lagenorhynchus acutus).

Assessing the trends of persistent organic pollutants (POPs) in cetaceans is difficult because of age and gender influences on accumulation. Persistent organic pollutants bioaccumulate and are poorly metabolized; hence, concentrations may increase with age in males while females reduce their POP burden through parturition and lactation. Age and gender effects on contaminant concentrations are species specific because of life history and reproductive strategies. These influences must be understood in order to elucidate and assess lifetime POP exposure. The objectives of this study were to determine baseline POP concentrations in blubber samples from the Atlantic white-sided dolphin (Lagenorhynchus acutus) and to investigate life history and other influences, such as metabolism, on these concentrations. Forty-seven L. acutus blubber samples collected from mass stranding events in Massachusetts, USA (1993-2000), and archived in the National Marine Mammal Tissue Bank at the National Institute of Standards and Technology (Gaithersburg, MD, USA) were analyzed for 55 polychlorinated biphenyl congeners (PCB; 55 congeners), five polybrominated diphenyl ether (PBDE) congeners, and organochlorine pesticides (toxaphene, DDT and metabolites, mirex, dieldrin, chlordanes, hexachlorocyclohexanes, hexachlorobenzene, and endosulfans) by gas chromatography/mass spectrometry (GC-MS). Ages for 19 animals were determined from growth layer groups on decalcified, stained thin tooth sections. Total PCBs (sigmaPCB; sum of 55 congeners) were the contaminants present in the highest concentrations in all age classes (0.5-63 microg/g wet mass) followed by sum of DDTs (0.50-43 microg/g wet mass), toxaphene (0.055-31 microg/g wet mass), chlordanes (0.30-24 microg/g wet mass), and PBDEs (0.12-4.0 microg/g wet mass). Body length had a greater statistical influence than age on contaminant burdens in L. acutus. Contaminant burdens decreased with length in both male and female L. acutus, suggesting metabolic elimination and/or growth dilution in males and off-loading via lactation in females.

Persistent organic pollutants in two dolphin species with focus on toxaphene and polybrominated diphenyl ethers.

Assessing trends of persistent organic pollutants (POPs) in marine mammals is difficult due to age, gender, and metabolism influences on accumulation. To help elucidate these effects in dolphins, POP concentrations were determined in the Atlantic white-sided dolphin, Lagenorhynchus acutus, a pelagic delphinid inhabiting North Atlantic waters, and in the rough-toothed dolphin, Steno bredanensis, a pelagic delphinid inhabiting tropical and subtropical waters. The specific objectives of this study were to determine baseline POP concentrations in L. acutus and S. bredanensis blubber samples and to examine the effects of age, gender, and metabolism on POP concentrations in dolphin blubber. Focus was aimed at contaminants of emerging concern, specifically, toxaphene and polybrominated diphenyl ethers (PBDEs). Samples collected from L. acutus (n = 47) stranding events in Massachusetts (1993--2000) and S. bredanensis samples (n = 15) were analyzed for PCBs, toxaphene, and other organic pesticides by gas chromatography/mass spectrometry (GC/MS). Age and gender influences were similar between the two species, with adult females having significantly lower POP concentrations as compared to adult males and juveniles. Mean sigma toxaphene concentrations were highest in juvenile L. acutus, 13.0 (6.7) microg/g wet mass (1 SD), and lowest in adult female S. bredanensis, 1.49 (1.4) microg/g wet mass. sigma PBDE (sum of congeners 47, 99, 100, 153, and 154) concentrations were highest in juvenile L. acutus, 2.41 (1.2) microg/g wet mass, and lowest in adult female S. bredanensis, 0.51 (0.6) microg/g wet mass. POP concentrations did not significantly differ between adult males and juveniles, suggesting metabolism of congeners and/or dilution with growth. PBDE concentrations in juvenile white-sided dolphins were not significantly related to collection year, suggesting that there may be a lag period for higher concentrations to be detected in pelagic marine mammals such as L. acutus or that concentrations have already peaked in this species prior to the first collection in 1993.

Polybrominated diphenyl ether congeners and toxaphene in selected marine standard reference materials.

Polybrominated diphenyl ether (PBDE) congeners and components of the complex mixture toxaphene are stable in the environment and readily bioaccumulated into wildlife and human tissues. PBDEs are presently used in large quantities worldwide as flame retardants in textiles, furniture, computer equipment, and cables. Toxaphene is a complex mixture of chlorinated bornanes and bornenes that was the most heavily used pesticide in the United States until it was banned in 1982; however, some countries continue to use toxaphene. The National Institute of Standards and Technology has quantified PBDE congeners and toxaphene in several available Standard Reference Materials (SRMs) using methods of gas chromatography with electron impact mass spectrometry (GC-EI-MS) and GC negative chemical ionization (NCI) MS, respectively. SRM 1588a Organics in Cod Liver Oil and SRM 1945 Organics in Whale Blubber were examined for PBDE congeners 47, 99, 100, 153, and 154, total toxaphene, and toxaphene congeners 26, 50, and 62. SRM 1946 Lake Superior Fish Tissue was also examined for total toxaphene and toxaphene congeners. The sum of the PBDE congeners (mean, (1 SD) wet basis) for SRM 1945 was 150 ng g(-1) (7 ng g(-1)). The concentration of PBDE 47 in SRM 1588a was 82.7 ng g(-1) (2.8 ng g(-1)). Other PBDEs were detected in SRM 1588a but were not quantified due their low levels. The total toxaphene (wet mass basis) was 1,210 ng g(-1) (127 ng g(-1)), 1,960 ng g(-1) (133 ng g(-1)), and 3,980 ng g(-1) (248 ng g(-1)) in SRMs 1945, 1946, and 1588a, respectively. The values for PBDEs and toxaphene determined in the SRMs, while not certified, indicate that the SRMs will be suitable control materials for PBDE and toxaphene analyses.