Environ. Sci. Technol. 2006, 40, 6919-6927
Dioxins and Related Compounds in Albatrosses from the Torishima Island, Japan: Accumulation Features by Growth Stage and Toxicological Implications TATSUYA KUNISUE,† SHIGEYUKI NAKANISHI,† NARIKO OKA,‡ FUMIO SATO,‡ MIYAKO TSURUMI,‡ AND S H I N S U K E T A N A B E * ,† Center for Marine Environmental Studies (CMES), Ehime University, Bunkyo-cho 2-5, Matsuyama 790-8577, Japan, and Yamashina Institute for Ornithology, Konoyama Abiko 115, Chiba 270-1145, Japan
Concentrations of dioxins and related compounds (DRCs), such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and coplanar polychlorinated biphenyls (Co-PCBs), were determined in eggs, nestlings, and adults of black-footed albatross (BfA; Diomedea nigripes) and short-tailed albatross (StA; Diomedea albatrus) collected from the Torishima Island in Japan during 2002, which is one of their breeding grounds. Observed DRC concentrations, especially PCDFs and nonortho Co-PCBs, in eggs of BfA and StA were relatively higher than those in other oceanic, coastal, and inland wild birds reported recently and were comparable to those in a pooled BfA egg from Midway Atoll in 1993, implying continuous input of these contaminants into open ocean and possible albatross-specific exposure. Concentrations of PCDDs except 12378-P5CDD and high-chlorinated PCDFs in 3-month-old BfA nestling were lower than those in 1-monthold nestling, indicating their developmental dilution. On the other hand, higher levels of T4-H6CDFs and Co-PCBs, especially low-chlorinated congeners such as 2378-T4CDF and T4CB77, were found in 3-month-old BfA nestling, suggesting specific exposure to these contaminants, possibly due to their higher transportability than high-chlorinated congeners. Estimated biomagnification factors of almost all the congeners in adults were apparently greater than those in nestlings, except 2378-T4CDF, T4CB77, and H7-O8CDD/Fs. This could be due to preferential metabolism of 2378T4CDF and T4CB77 and lower uptake efficiency of highchlorinated congeners through the gastrointestinal tract in adults. Toxic equivalents in BfA and StA eggs estimated using WHO-avian toxic equivalency factors exceeded some toxicity thresholds for avian embryos, indicating possible adverse effects of DRCs to albatross embryos.
Introduction Dioxins and related compounds (DRCs) have been found in wildlife and humans because of their persistency in the * Corresponding author phone/fax: +81-89-927-8171; e-mail:
[email protected]. † Ehime University. ‡ Yamashina Institute for Ornithology. 10.1021/es061153a CCC: $33.50 Published on Web 10/10/2006
2006 American Chemical Society
environment and highly bioaccumulative nature (1). Especially, higher-trophic wildlife such as raptorial and piscivorous birds accumulate DRCs predominantly and hence their toxic impacts are of great concern (1, 2). Actually, in previous studies on wild avian species, significant DRC concentrationdependent relationships were observed for biochemical alternation and reduced reproductive success (3-6). A recent study using chickens (Gallus domesticus) indicated that 2,3,7,8-tetrachlorinated dibenzo-p-dioxin (TCDD) treatment at an earlier developmental stage of the embryo was more sensitive for embryonic toxic effects (7). Therefore, determination of DRC levels in wild bird eggs is one of the key criteria in understanding toxicological risk. A number of monitoring surveys on DRC concentrations in eggs of coastal and inland water birds have been conducted mainly in developed countries, and it is found that the residue levels have been decreasing (8). On the other hand, little information on DRCs in eggs of oceanic birds is available; especially the temporal trend is unclear. We previously elucidated the contamination status of DRCs in breast muscle of albatrosses (Diomedeidae), which are the biggest oceanic birds and wander in the open ocean during most of their lives (9). It has been demonstrated that residue levels in albatross populations from the remote North Pacific Ocean were significantly higher than those from Southern Ocean and comparable to or higher than those in terrestrial and coastal birds from contaminated areas in developed nations, suggesting specific exposure and accumulation routes of DRCs to albatrosses of the northern hemisphere (9). In addition, previous studies have reported that albatrosses also accumulate high levels of persistent organic pollutants (POPs) such as PCBs, DDTs, and toxaphene, indicating that this species can be considered as a useful bioindicator for monitoring marine pollution and exploring clues for understanding possible toxic implications of POPs on wildlife in remote open oceans (10-13). However, limited studies on POPs in albatross eggs and nestlings from their breeding grounds have been conducted. Only one study is available on DRCs in three pooled samples of eggs collected from Midway Atoll during 1993-1994 (black-footed albatross [Diomedea nigripes] n)1, Laysan albatross [Diomedea immutabilis] n)2) (14), and hence recent levels are not known. Recently, our group cloned and sequenced two distinct aryl hydrocarbon receptor (AhR) isoforms from the liver of blackfooted albatross (BfA) (15). Furthermore, we demonstrated significantly positive correlations between polychlorinated dibenzo-p-dioxin/furan (PCDD/DF) congener-specific concentrations and ethoxyresorufin-O-deethylase (EROD) activity in the livers of BfAs (16). These results indicate that albatross might be at high risk by dioxin-induced toxic effects. Consequently, it is very important for assessing the toxicological risk to elucidate the contamination levels of DRCs accumulated in albatross embryos (eggs) and nestlings, which are considered to be highly sensitive to dioxin toxicity more so than adults are. In the present study, concentrations of DRCs were determined in eggs, nestlings, and adults of BfA and shorttailed albatross (StA) collected from the Torishima Island in Japan during 2002, and accumulation features by growth stage were characterized. In addition, DRC levels in stomach contents, which were spat out by BfA nestlings, were also measured; congener-specific biomagnification factors (BMFs) were evaluated in BfA nestlings and adults. Furthermore, toxic equivalent (TEQ) concentrations in eggs of these albatross species were estimated to evaluate the toxic VOL. 40, NO. 22, 2006 / ENVIRONMENTAL SCIENCE & TECHNOLOGY
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potential of DRCs. This is the first study on the residue levels of DRCs in eggs, nestlings, and adults of StA.
Materials and Methods Samples. Egg (nonembryo: n)7, embryo: n)5) and nestling (n)2) samples of black-footed albatross (BfA; Diomedea nigripes) and egg (nonembryo: n)1) nestling (n)1) and adult (n)2) samples of short-tailed albatross (StA; Diomedea albatrus), which were unhatched and naturally died, were collected from the Torishima Island, one of their breeding grounds, in Japan in February and May, 2002 (Figure S1). Biometric data are shown in Table S1. Breast muscles were obtained from adult and nestling specimens; egg contents were homogenized. Albatross nestlings had a habit of spitting their stomach contents, when researchers approached them. Five samples of such stomach contents spat out by BfA nestlings were also collected. All the samples were stored in Environmental Specimen Bank (es-BANK) for Global Monitoring, Ehime University at -20 °C until analysis. According to Tickell (17), BfAs disperse widely in Pacific Ocean as marine and pelagic species and breed in Midway Atoll, Izu, Bonin, and South Ryukyu Islands. Many breeders return to the colonies late in October and lay eggs by the end of November. They eat mainly fish and also squid and crustaceans and sometimes scavenge discarded offal and garbage from vessels. StAs disperse widely in North Pacific Ocean as pelagic species but breed only in the Torishima Island in Izu Islands and Minami-kojima in South Ryukyu Islands. Their breeding starts in October. They mainly eat squid, fish, and crustaceans. StA is a rare species and classified under criteria I in CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora). Chemical Analysis. DRCs were analyzed following the method described previously (9). Briefly, the wet sample of breast muscle (15-20 g), homogenized egg (5 g), or stomach content (5 g) was ground with anhydrous sodium sulfate and extracted in a Soxhlet apparatus with dichloromethane (DCM). The extract was concentrated, and an aliquot of the extract was used for lipid determination by a gravimetric method. 13C12-labeled DRCs were spiked into the remaining extract as internal standards. Lipid in this solution was removed by gel permeation chromatography (GPC) packed Bio-Bead S-X 3(Bio-Rad Laboratories, Hercules CA). The first fraction containing lipid was discarded, and the next timed fraction containing DRCs was collected, concentrated, and passed through activated silica gel (Wako-gel S-1: Wako Pure Chemical Industries Ltd., Japan) packed in a glass column. DRCs were eluted with hexane. After concentration, the cleaned up extract was spiked onto activated alumina (Aluminum oxide 90 active basic: Merck, Germany) packed in a glass column. The first fraction eluted with hexane contained most of the mono-ortho PCBs, and the second fraction eluted with 50% DCM in hexane contained the remaining mono-ortho PCBs, non-ortho PCBs, and PCDD/ DFs. Then the second fraction was passed through activated carbon-dispersed silica gel (Kanto Chemical Co. Inc., Japan) packed in a glass column. The first fraction was eluted with 25% DCM in hexane for obtaining the remaining monoortho PCBs and combined with the first fraction separated by an alumina column. Non-ortho PCBs and PCDD/DFs were eluted with toluene as the second fraction. Both fractions were concentrated to near dryness, and then 13C12-labeled injection spikes were added. Identification and quantification were performed using a gas chromatograph (GC: Agilent 6890 series) with an autoinjection system and a bench-topped double-focusing mass selective detector (MS: JEOL GC-Mate II) with a resolving power of more than 3000 for mono-ortho PCBs and a high-resolution MS (JEOL JMS-700D) with a resolving power of more than 10 000 for non-ortho PCBs and PCDD/ 6920
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DFs. DRCs were monitored by selective ion monitoring (SIM) mode at the two most intensive ions of the molecular ion cluster among [M]+, [M + 2]+, and [M + 4]+ except for P5CDD monitored at [M]+ and [M + 2]+. All the congeners were quantified using the isotope dilution method to the corresponding 13C12-congeners, when the isotope was within 15% of the theoretical ratio and the peak area was more than 10 times of noise. Recoveries for the 13C12-labeled DRCs were within 60-110%. Toxic Equivalents. The toxic equivalent (TEQ) was estimated using the toxic equivalency factor (TEF) for birds proposed by WHO (18).
Results and Discussion Residue Levels and Comparison with Other Data. Concentrations of DRCs in BfA eggs and nestlings were higher than those in StAs, while the levels of DRCs in both species were in the following order: mono-ortho PCBs > non-ortho PCBs > PCDFs > PCDDs (Table 1). Also in mature specimens, the DRC levels in BfAs, which were collected off the coast of the Ogasawara Islands during 1999, analyzed previously by our group (9) (Table S2), were higher than those in StAs analyzed in this study. It is likely that higher accumulation levels of DRCs in BfAs compared with those in StAs is due to their different feeding habits. BfAs eat mainly fish and also human refuse, while StAs eat mainly squid, suggesting a higher position for BfA than StA in the food web. In addition, as discussed in previous studies (9, 13), another possible reason might be the feeding of BfAs in POPs contaminated areas containing higher levels of DRCs. Observed PCDD/DF and Co-PCB concentrations in eggs of BfAs and StA from the Torishima Island were compared with those in other wild birds reported recently (Table S3). Among oceanic birds, BfA and StA eggs contained greater concentrations than other species collected off the California coast (19) and in the Canadian Arctic (20). Additionally, the DRC levels in BfA and StA eggs were relatively higher than those in coastal and inland water bird eggs from Japan (21), Canada (8), and the Great Lakes (22, 23) and comparable to those in cormorants from the Great Lakes (23), although concentrations of PCDDs and mono-ortho PCBs were lower than those in cormorant and heron eggs from Galveston Bay, TX, an area contaminated by DRCs (24). Greater accumulation of DRCs in mature BfAs compared with other wild avian species was also observed in our previous study (9). Long life span and plastic ingestion of this species could be two important factors that may account for elevated levels of DRCs (9, 12). These results indicate that albatrosses have been exposed to high levels of DRCs and also transfer large amounts of these contaminants to their eggs. Especially, it is noteworthy that wet basis concentrations of PCDFs in BfA and StA eggs were the highest among wild avian species compared (Table S3). We previously reported that higher PCDFs/PCDDs concentration ratios in albatrosses than those in birds inhabiting terrestrial and coastal areas were observed, indicating oceanic bird-specific exposure to PCDFs, possibly because of the fact that PCDFs may have higher transportability by air and water than PCDDs (9). In our recent study using skipjack tuna as a bioindicator, we demonstrated that PCDFs were found in open sea specimens but not PCDDs and suggested the following possible reasons: higher vapor pressure (PL) and lower octanol-air partition coefficient (KOA) of PCDFs than PCDDs and/or release of PCDFs from international vessels which used technical PCB, in which PCDFs are contained as impurities as antifouling paints in the past (25). Jones et al. (14) analyzed DRCs in a pooled BfA egg (ten samples were pooled) collected from Midway Atoll during 1993 and reported that wet basis concentrations of PCDDs, PCDFs, non-ortho PCBs (CB77+126+169) and mono-ortho
TABLE 1. Concentrations (pg/g lipid wt) of Dioxins and Related Compounds in Muscles, Eggs, and Stomach Contents of Albatrosses from the Torishima Islande black-footed albatross
mature (M)a lipid (%)
5.5
mature (F)a 5.5
(nestling (F)a, (1)b 13
egg including embryo (n)5)
egg (n)7)
short-tailed albatross egg 12
nestling-1 (F)a, (1)b 4.9
nestling-2 (F)a, (3)b
mean ( SD
range
30 180 38 210 55 55 27
2.8 15 6.2 23 6.5 6.4 9.5
16 110 20 130 25 11 15
9.3 35 16 52 19 27 29
7.5 46 9.8 38 13 14 7.9
2,3,7,8-T4CDF 1,2,3,7,8-P5CDF 2,3,4,7,8-P5CDF 1,2,3,4,7,8-H6CDF 1,2,3,6,7,8-H6CDF 1,2,3,7,8,9-H6CDF 2,3,4,6,7,8-H6CDF 1,2,3,4,6,7,8-H7CDF 1,2,3,4,7,8,9-H7CDF O8CDF
150 170 280 120 150 12 190 19 15 23
110 160 220 140 110 18 200 18 6.1 20
28 26 27 20 17
