In ovo exposure to polychlorinated biphenyls: reproductive effects on second-generation American kestrels

The reproductive success of wild birds has been affected by exposure to multiple contaminants. Reproduction of captive American kestrels (Falco sparverius) was suppressed when adult birds were exposed to dietary polychlorinated biphenyls (PCBs). In this study, the reproductive effects of in ovo exposure to PCBs is explored, along with determining effects on reproduction in second-generation birds indirectly exposed to PCBs. Reproductive changes in this subsequent generation are examined separately in male and female birds. Captive American kestrels (F. sparverius) were hatched from clutches with eggs containing environmentally relevant levels of total PCBs (34.0 μg/g whole egg WW versus 0 μg/g controls); parent birds had been fed PCB-spiked (Aroclor 1248:1254:1260) food (7 mg/kg BW day⁻¹) for 100 days until their eggs hatched. In 1999, the second-generation PCB birds were paired with unexposed kestrels having reproductive experience. In ovo PCB exposure suppressed egg laying completely in 25% of PCB females and resulted in delays in clutch initiation and smaller clutch sizes for PCB male and female pairs. There was no evidence in this study of in ovo PCB treatment effects on fertility or hatching success. The decline in reproductive success was also reflected in the reduced fledging success and higher incidence of complete brood mortality of PCB nestlings. Differences between in ovo–exposed PCB males and females but not between controls were evident in reproductive success. In ovo PCB exposure appears to have had greater effects on female kestrels until clutch completion, with a greater time lag between pairing and egg laying, reduced numbers of pairs laying eggs, and smaller clutches being laid. In ovo PCB exposure has greater effects later in the breeding season on male kestrels, which had poorer hatching and fledging success relative to the PCB females. Possible behavioral and physiological mechanisms involved in these reproductive changes are discussed. Received: 25 July 2000/Accepted: 8 December 2000     

Diet exposure to technical hexabromocyclododecane (HBCD) affects testes and circulating testosterone and thyroxine levels in American kestrels (Falco sparverius)

Hexabromocyclododecane (HBCD) is a high-production-volume, brominated flame-retardant that is used in items such as polystyrene foams. HBCD has been detected in the environment, wildlife tissues and in humans globally with some of the highest recorded levels in predatory birds. This study examined the effects of exposure to environmentally relevant levels of HBCD on the reproductive physiology of captive male American kestrels (Falco sparverius), a predatory bird. Two sets of males were used: one group not housed with females (unpaired: n_c=12, n_HBCD=10) and the second group housed with females (breeding: n_c=10, n_HBCD=20). All treatment birds were exposed to 0.51 μg HBCD/g kestrel/day technical HBCD, and controls to safflower oil only, injected into their food during seasonal testicular development. Unpaired males were exposed for 3 weeks and euthanized for testicular analysis. Breeding males were exposed for 3 weeks prior to pairing and throughout the courtship period. The HBCD-exposed unpaired males had heavier testes (p≤0.017) and a trend towards more seminiferous tubules containing elongated spermatids (p=0.052). There was also a moderate increase in plasma testosterone concentrations (p=0.056) compared to controls. In breeding males, testosterone levels increased during courtship to culminate in higher levels than controls by the time the first egg was laid (p=0.010) and circulating free and total T₄ was reduced throughout. The number of sperm cells reaching the perivitelline layer of the first egg for breeding males did not differ between the two groups. This study is the first report that HBCD exposure at environmentally relevant levels alters reproductive physiology in male birds and suggests that birds may be more sensitive to HBCD than mammals.     

Hexabromocyclododecane (HBCD) Stereoisomers in U.S. Food from Dallas, Texas

Background: Hexabromocyclododecane (HBCD) is a brominated flame retardant used in polystyrene foams in thermal insulation and electrical equipment. The HBCD commercial mixture consists mainly of α, β, and γ stereoisomers. Health concerns of HBCD exposure include alterations in immune and reproductive systems, neurotoxic effects, and endocrine disruption. Stereoisomer-specific levels of HBCD have not been measured previously in U.S. food.Objectives: We measured HBCD stereoisomer levels in U.S. foods from Dallas, Texas, supermarkets.Methods: Convenience samples of commonly consumed foods were purchased from supermarkets in Dallas in 2009-2010. Food samples included a wide variety of lipid-rich foods: fish, peanut butter, poultry, pork, and beef. Thirty-six individual food samples were collected in 2010 and analyzed for α-, β-, and γ-HBCD stereoisomers using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Ten pooled food samples previously collected in 2009 for a study of total HBCD levels using gas chromatography-mass spectrometry (GC-MS), were reanalyzed for α-, β-, and γ-HBCD stereoisomers using LC-MS/MS.Results: Of the 36 measured individual foods, 15 (42%) had detectable levels of HBCD. Median (ranges) of α- and γ-HBCD concentrations were 0.003 (< 0.005-1.307) and 0.005 (< 0.010-0.143) ng/g wet weight (ww), respectively; β-HBCD was present in three samples with a median (range) of 0.003 (< 0.005-0.019) ng/g ww. Median levels (range) for α-, β-, and γ-HBCD, in pooled samples were 0.077 (0.010-0.310), 0.008 (< 0.002-0.070), and 0.024 (0.012-0.170) ng/g ww, respectively.Conclusions: α-HBCD was detected most frequently and at highest concentrations, followed by γ-, and then β-HBCD, in food samples from Dallas, Texas. Food may be a substantial contributor to the elevated α-HBCD levels observed in humans. These data suggest that larger and more representative sampling should be conducted.     

Developmental toxicity of in ovo exposure to polychlorinated biphenyls: II. Effects of maternal or paternal exposure on second-generation nestling american kestrels

The development of second-generation nestling American kestrels (Falco sparverius) was altered by in ovo exposure of only one parent to polychlorinated biphenyls (PCBs). Polychlorinated biphenyls appear to alter nestling development through both maternally and paternally mediated effects. In 1998, F0 parent kestrels consumed approximately 5 to 7 microg total PCBs/g bird/d (Aroclors 1248:1254: 1260) for approximately 100 d prior to eggs hatching; these eggs, containing total PCB concentrations of 34.1 microg/g, produced 13 F1 offspring, which were then paired in 1999 with unexposed kestrels to examine developmental effects of maternal or paternal in ovo PCB exposure. Using a toxicokinetics model, eggs from the maternally exposed group had predicted PCB levels of 0.03 to 0.34 microg/g, with enriched higher chlorinated congeners. Polychlorinated biphenyl concentrations in eggs of all generations have recently been found in eggs and nestlings of free-ranging eagles. Consistent with the first generation, maternally exposed F2 females generally were larger, had altered growth rates, and delayed maximal growth and fledging compared with control females. Maternally exposed F2 males were heavier but had shorter bones, grew more quickly and earlier, and fledged 2 d later than control males. In the maternally exposed group, concentrations of plasma triiodothyronine were elevated in F2 females but suppressed in F2 males. Paternally exposed F2 hatchlings of both sexes were comparable in size to controls with the exception of having longer tarsi bones, but subsequently showed slower, delayed growth (both sexes) and fledging (females) and lower thyroxine concentrations (males). The alterations in thyroid hormones in the F2 generation are discussed in light of the enrichment of higher chlorinated PCB congeners and hydroxylated PCB congeners. The developmental changes in the kestrel nestlings are likely a function of several possible mechanisms involving maternal PCB deposition, parental behavior, and neurobehavioral and endocrine-thyroid function in nestlings.     

上海某医院产妇乳汁中六溴环十二烷水平及新生儿经母乳日摄入量的监测分析

目的 测定上海市某医院产妇乳汁中六溴环十二烷(hexabromocyclododecane,HBCD)含量水平,并估算新生儿每日经母乳HBCD摄人量.方法 于2006年9月至2007年4月在上海市城郊地区某三级甲等医院对分娩后的产妇进行问卷调查,并收集母乳样品48个,产妇均为单胎妊娠,排除高血压、糖尿病、HIV 感染和不良用药史.采用液相色谱-电喷雾离子源-串联三重四极杆质谱法测定α-HBCD,β-HBCD,γ-HBCD 3种非对映异构体的含量,并通过模型估算新生儿经母乳HBCD日摄入量.结果 上海市某医院产妇母乳中总HBCD浓度范围为0.11-37.75 ng/g脂重(lipid weight,1w),中位数为1.42 ng/g 1w,在79%(38/48)的样品中被检出.其中α-HBCD含量最高,浓度中位数为1.24 ng/g 1w,在77%(37/48)的样品中检出;其次为γ-HBCD、β-HBCD,浓度中位数均小于检测限,分别在13%(6/48),17%(7148)的样品中检出.新生儿经母乳总HBCD日摄人为:0.71-243.46 ng/kg.结论 上海市某医院产妇母乳中HBCD含量水平较高,其对婴幼儿健康的影响值得进一步研究.

Abstract：

Objective To explore the level of hexabromocyclododecane(HBCD)in human breast milk of delivery women in a Shanghai hospital.and estimate the daily intake of newborns from breast milk.Methods Forty-eight delivery women in a Shanghai suburb hospital(Class A,Grade 3)were surveyed by questionnaires.and their breast milk samples were collected from September 2006 to April 2007.All the delivery women were singleton pregnancies,excluding high blood pressure,diabetes,HIV infection and adverse medical history.Three diastereoisomers(α-HBCD,β-HBCD,γ-HBCD)were measured by the liquid chromatography-electrospmy ion source-tandem mass spectrometry.and then esitmated the daily intake of the newborns from the breast milk.Results The total HBCD concentration of breast milk,which was detected in 79%(38/48)of samples,ranged from 0.11 ng/g lipid weight(1w)to 37.75 ng/g 1w,with the median at 1.42 ng/g 1w.The most abundant diastereoisomer was α-HBCD which detected in 77%(37/48)of samples,with a median of 1.24,g/g 1w;followed by γ-HBCD and β-HBCD,detected in 13%(6/48)and 17%(8/48)of samples respectively,whose median were both under the limit of detection (LOD).The daily intake of the newborns from the breast milk ranged from 0.71 ng/kg to 243.46 ng/kg.Conclusion The concentrations of HBCD in breast milk of delivery women in a Shanghai hospital have been in a high level.and the influence on newborns'health need to be further studied.     

In vitro studies of DDT,DDE, and ATPase as related to avian eggshell thinning

Interspecific and inter-tissue differences were found in thein vitro sensitivity of oligomycin sensitive Mg²⁺ATPase (O.S.-ATPase) from avian mitochondrial homogenates to DDE. The enzyme from the target tissue, the shell gland of kestrels, which lay thin-shelled eggs on exposure to DDE, showed significantly greater sensitivity to DDE than O.S.-ATPase in muscle and brain preparations. The O.S.-ATPase from chicken shell gland was about nine times less sensitive than that from the kestrel. DDT, in contrast to DDE, was highly effective on O.S.-ATPase in all tissues tested from the three species of birds. In contrast to the high sensitivity of O.S.-ATPase, O.Ins.-ATPase and Na⁺-K⁺ATPase were not significantly affected by DDE or DDT. In addition, Ca²⁺-ATPases from mitochondrial and microsomal preparations from shell gland of kestrels were only minimally affected by DDT and DDE at concentrations over 20 times greater than those which inhibited O.S.-ATPase. The selectivity of DDE action in the eggshell thinning of kestrel is correlated with its action on shell gland O.S.-ATPases. However, because DDT effectively inhibits O.S.-ATPase from all tissues studied a combined effect is possible. Both would cause a reduction in ATP synthesis affecting energy-linked calcium transport. The need forin vivo studies including mitochondrial calcium transport is emphasized.Paper No. 11877, Scientific Journal Series, Minnesota Agricultural Experiment Station, University of Minnesota, St. Paul, MN 55108     

Hexabromocyclododecane in consumer fish from South China: implications for human exposure via dietary intake

Levels of hexabromocyclododecane (HBCD) were determined in 12 consumer fish species from South China. The concentrations of the sum of HBCD diastereoisomers (ΣHBCD) ranged from nondetectable to 194 pg/g wet weight, with a detectable frequency of 70%. This was at the low end of the concentration range globally observed. Carnivorous fish species contained higher HBCD concentrations than herbivorous and detritivorous ones, suggesting the potential for biomagnification of HBCDs via the trophic chain. Moreover, ΣHBCD concentrations were higher in both freshwater and seawater farmed fish than in wild marine fish, indicating that human activities were probably an important input source of HBCD in aquaculture. Among the three diastereoisomers, α-HBCD dominated in most samples, with a mean relative abundance of 70%. In agreement with previous studies, a difference in the diastereomer patterns was observed from commercial products and several environmental media to biota samples. For farm-raised snubnose pompano, the concentrations of ΣHBCD were moderately linearly correlated with lipid contents but were not significantly correlated with fish body lengths and weights. In the worst-case exposure, the mean estimated daily intake of ΣHBCD via fish consumption for residents of South China ranged from 13 to 16 pg/kg body weight/d for various age groups, much lower than its lowest observed adverse effect level derived from a two-generation reproductive toxicity study on rats.     

Reproduction success of American kestrels exposed to dietary polychlorinated biphenyls

While reproduction of wild birds is adversely affected by multiple environmental contaminants, we determined that polychlorinated biphenyls (PCBs) alone alter reproduction. Captive American kestrels (Falco sparverius), fed PCB-spiked (Aroclor 1248:1254:1260) food (7 mg/kg body weight/d) prior to and during the first breeding season only (100 d) laid eggs with environmentally relevant levels of total PCBs (34.0 microg/g whole egg wet wt vs 0 microg/g for controls). Reproduction changed during, not after, PCB exposure in this two-year study. The PCB-exposed pairs laid smaller clutches later in the season and laid more totally infertile clutches. Hatching success was reduced in PCB-exposed pairs, and 50% of PCB nestlings died within 3 d of hatching. Nearly 60% of PCB-exposed pairs with hatchlings failed to produce fledglings. Higher levels of total PCB residues and congeners were associated with later clutch initiation and fewer fertile eggs, hatchlings, and fledglings. We suggest that nonpersistent PCB congeners have a greater influence on reproduction than do persistent congeners.     

Secondary poisoning hazard of fenthion to American kestrels

The possibility that fenthion, an organophosphorus pesticide, could represent a secondary poisoning hazard to birds of prey was tested, using American kestrels (Falco sparverius) and house sparrows (Passer domesticus) as representative models of a naturally occurring predator-prey interaction. Fourteen kestrels were presented with live sparrows exposed previously to perches containing Rid-A-Bird 1100^® solution (11% fenthion active ingredient). Eleven kestrels died within twenty-four h after consuming one fenthion-exposed sparrow. Two kestrels died after consumption of a second fenthion-exposed sparrow on day 2, and a final kestrel died after partially consuming a third fenthion-exposed sparrow on day 3. Brain cholinesterase (ChE) activity in kestrels was depressed to levels diagnostic of poisoning by a ChE-inhibiting compound. The majority of fenthion contamination of sparrows was external, with the highest amounts measured on the feet. The detection of fenthion residues in kestrel gastro-intestinal tracts confirmed secondary fenthion poisoning.     

Embryonic exposure to o,p'-DDT causes eggshell thinning and altered shell gland carbonic anhydrase expression in the domestic hen

The mechanism for contaminant-induced eggshell thinning in wild birds remains to be clarified. It is generally assumed, however, that it results from exposure of the adult laying female. We have reported that embryonic exposure to the synthetic estrogen ethynylestradiol (EE2) results in eggshell thinning in the domestic hen. The objective of this study was to investigate whether eggshell thinning can be induced following in ovo exposure to a bioaccumulating estrogenic environmental contaminant, o,p'-DDT. Ethynylestradiol was used as a positive control. Domestic hens exposed in ovo to o,p'-DDT (37 or 75 microg/g egg) or EE2 (60 ng/g egg) laid eggs with thinner shells than the control birds. The hens from these exposure groups also had a significantly reduced frequency of shell gland capillaries with carbonic anhydrase (CA) activity, a key enzyme in eggshell formation. The decreased number of capillaries with CA activity suggests that a developmentally induced disruption of CA expression in the shell gland was involved in the eggshell thinning found in this study. Egg laying was not affected in hens exposed embryonically to 37 or 75 microg o,p'-DDT/g egg, whereas it was inhibited in hens exposed to higher doses. Decreased lengths of the left oviduct and its infundibulum were seen after embryonic treatment with o,p'-DDT or EE2. In addition, o,p'-DDT exposure resulted in right oviduct retention. The results support our hypothesis that eggshell thinning in avian wildlife can result from a functional malformation in the shell gland, induced by embryonic exposure to estrogenic substances.     

Reproductive impairment in zebra finches (Taeniopygia guttata)

The effects of polychlorinated biphenyls (PCBs) as compounds that may disrupt endocrine activity and, consequently, alter reproductive performance were investigated in altricial zebra finches (Taeniopygia guttata). The breeding performance and breeding cycle of zebra finches differed significantly between nonexposed birds and those experimentally pulse-exposed to Aroclor 1248, a PCB compound (40 microg/bird). Aroclor-exposed birds showed significantly increased numbers of clutches laid, nests constructed per pair, incubation time per pair, and percentage of hatchling mortality compared to controls. Not all reproductive parameters were affected. Those traditionally regarded as indicators of reproductive capacity (number of eggs laid per clutch, number of eggs laid per pair, hatchlings per clutch, and fledglings per clutch) did not differ statistically between exposed and control birds. Findings support the hypothesis that very low PCB doses may be associated with endocrine disruption. It is suggested that evaluation of reproductive parameters related to parental care is more adequate to assess endocrine disruption than is evaluation of reproductive success parameters. Given its short breeding cycle, altricial breeding behavior, and other advantages not possessed by precocial birds, we propose using the zebra finch for evaluations of chemicals with endocrine-disruptive activity.     

Copper Pellets Simulating Oral Exposure to Copper Ammunition: Absence of Toxicity in American Kestrels (<Emphasis Type="Italic">Falco sparverius</Emphasis>)

To evaluate the potential toxicity of copper (Cu) in raptors that may consume Cu bullets, shotgun pellets containing Cu, or Cu fragments as they feed on wildlife carcasses, we studied the effects of metallic Cu exposure in a surrogate, the American kestrel (Falco sparverius). Sixteen kestrels were orally administered 5 mg Cu/g body mass in the form of Cu pellets (1.18–2.00 mm in diameter) nine times during 38 days and 10 controls were sham gavaged on the same schedule. With one exception, all birds retained the pellets for at least 1 h, but most (69%) regurgitated pellets during a 12-h monitoring period. Hepatic Cu concentrations were greater in kestrels administered Cu than in controls, but there was no difference in Cu concentrations in the blood between treated and control birds. Concentration of the metal-binding protein metallothionein was greater in male birds that received Cu than in controls, whereas concentrations in female birds that received Cu were similar to control female birds. Hepatic Cu and metallothionein concentrations in kestrels were significantly correlated. Histopathologic alterations were noted in the pancreas of four treated kestrels and two controls, but these changes were not associated with hepatic or renal Cu concentrations, and no lesions were seen in other tissues. No clinical signs were observed, and there was no treatment effect on body mass; concentrations of Cu, hemoglobin, or methemoglobin in the blood; or Cu concentrations in kidney, plasma biochemistries, or hematocrit. Based on the parameters we measured, ingested Cu pellets pose little threat to American kestrels (and presumably phylogenetically related species), although the retention time of pellets in the stomach was of relatively short duration. Birds expected to regurgitate Cu fragments with a frequency similar to kestrels are not likely to be adversely affected by Cu ingestion, but the results of our study do not completely rule out the potential for toxicity in species that might retain Cu fragments for a longer time.     

Reproductive and morphological effects of o,p′-dicofol on two generations of captive American kestrels

A two-generation laboratory study was conducted on a captive population of American kestrels (Falco sparverius) to investigate the possible reproductive and teratogenic effects of the pesticide dicofol. Paired females were exposed to three levels of dicofol: 0, 5, and 20 mg/kg. Integrity of the reproductive tract of the resulting embryos was examined. Viable eggs were hatched, and these birds were permitted to breed the following year. Breeding performance for these birds was measured based on their ability to form pair bonds and exhibit normal behavior in the presence of a mate. Clutch completion, fertility, hatchability, and number of hatchlings reared to the fledging were used as reproductive parameters. Females dosed with 20 mg/kg of dicofol laid eggs with shells that were significantly (p<0.05) thinner than those of the control birds. Residue levels of dicofol in the form of dichlorobenzophenone were detected in the first and second clutch eggs of the 20-mg/kg dose group only. Male embryos from females dosed with 5 and 20 mg/kg of dicofol had gonads that were significantly different (p<0.05) from the control chicks. Feminization of male embryos was confirmed by the presence of primordial germ cells in the male gonad. Second-generation adult 5-mg/kg females showed a significantly (p<0.05) greater number of eggs and hatched chicks lost when compared to second-generation control females. Similar results were found in second-generation 5-mg/kg males paired with normal females and had a significant (p<0.05) number of chicks die posthatching. Results of second-generation breeding parameters indicate a negative effect on reproductive behavior.     

Effects of methylmercury on reproduction in American kestrels

Sixty breeding pairs of captive American kestrels (Falco sparverius) were exposed to a range of sublethal dietary concentrations of mercury (Hg), in the form of methylmercuric chloride, and their subsequent reproduction was measured. Egg production, incubation performance, and the number and percent of eggs hatched decreased markedly between 3.3 and 4.6 mg/kg dry weight of Hg (1.2 and 1.7 mg/kg wet wt), in the diet. The number of fledglings and the percent of nestlings fledged were reduced markedly at 0.7 mg/kg dry weight (0.3 mg/kg wet wt) and declined further between 2 and 3.3 mg/kg dry weight (0.7 and 1.2 mg/kg wet wt). Dietary concentrations of >or=4.6 mg/kg dry weight (1.7 mg/kg wet wt) were associated with total fledging failure. The estimated decline in fledged young per pair (24%, Bayesian regression) for kestrels consuming 0.7 mg/kg dry weight (0.3 mg/ kg wet wt) raises concerns about population maintenance in areas subject to high inputs of anthropogenic Hg. Mercury concentrations in 20 second-laid eggs collected from all groups were related to dietary concentrations of Hg, and the Hg concentrations in 19 of these eggs were related to eggs laid and young fledged. Concentrations of Hg in eggs from the highest diet group (5.9 mg/kg dry wt; 2.2 mg/kg wet wt) were higher than egg concentrations reported for either wild birds or for captive birds (nonraptors) fed dry commercial food containing 5 mg/kg methylmercury. Accumulation ratios of Hg from diets to eggs were higher than those reported for feeding studies with other species.     

Courtship Behavior of Captive American Kestrels (Falco sparverius) Exposed to Polychlorinated Biphenyls

Polychlorinated biphenyls (PCBs) adversely affect reproduction in birds. Captive adult male and female American kestrels (Falco sparverius) were studied to investigate the potential behavioral and hormonal alterations during the courtship period resulting from clinical exposure to PCBs. American kestrels ingested 7 mg/kg/body weight/bird/day of a 1:1:1 mixture of Aroclors 1248, 1254, and 1260 through their diet of day-old cockerels. The dietary dosage of Aroclors resulted in environmentally relevant total PCB residues in the eggs, averaging 34.1 μg/g wet weight (geometric mean). There was no difference between treatment and control birds in the circulating levels of total androgens (p = 0.44) or in 17β-estradiol (p = 0.29), one week following pairing. Male kestrels exposed to dietary PCBs exhibited significantly more sexual behaviors (p = 0.034) and flight behaviors (p = 0.026) than the control males. Sexual behaviors of male kestrels included; nest-box inspections, solicitation of copulation, the offer of food to the female, and giving the female food. The flight behaviors of the male included; flying from one perch to another and aerial display. In addition, the frequency of male sexual behaviors were correlated (r = 0.605, p = 0.001) with total PCB residues in the eggs of their mates. A concurrent study found that these same PCB-exposed kestrels experienced a delay in clutch initiation as well as a greater number of completely infertile clutches. Received: 22 September 2000/Accepted: 19 March 2001     

Organochlorine contaminants in a terrestrial foodweb on the Niagara Peninsula,Ontario, Canada 1987–89

During 1987–89, organochlorine contaminant levels were measured in American kestrel (Falco sparverius) eggs and in other components of the terrestrial ecosystem in Ontario, Canada. The extent to which these samples were contaminated with DDE varied geographically. Wet weight levels of DDE were greater in eggs from American kestrels (10.8 mg/kg), American robins (Turdus migratorius) (17.3 mg/kg), European starlings (Sturnus vulgaris) (8.8 mg/kg), and eastern bluebirds (Sailia sailis) (7.6 mg/kg) and in samples of earthworms (Lumbricus sp.) (0.6 mg/kg), soil (0.3 mg/kg) and vegetation (8.7 g/kg) originating from the northern portion of the Niagara Peninsula than elsewhere in southern Ontario. This area is an intensive fruit growing region which received heavy applications of DDT in the past. DDT and its metabolites persist in the soil of this area and are transferred to the biotic community via trophic interactions. DDE may continue to pose a regional hazard to wildlife as a result of these toxic hot-spots. In 1987 and 1988, kestrel reproductive success was lower on the northern Niagara Peninsula than at a site in southwestern Ontario. However, it was not possible to attribute this reduced reproductive success to environmental contaminants.     

Occurrence,Spatial Distribution and Health Risk of Hexabromocyclododecane (HBCD) in Source Water in the Lower Yangtze River,China

The occurrence and health risk of hexabromocyclododecane (HBCD), a brominated flame retardant with its three diastereoisomers, in drinking water sources in the lower Yangtze River in China was investigated. Its concentration ranged from 0.58 to 3.71 ng/L and averaged at 1.18 ng/L. Among the three diastereoisomers of α-, β- and γ-HBCD, γ-HBCD was the dominant one accounting for 44% (ranging 27–82%) to the total concentration. Source of HBCD in the contaminated site was discussed according to its spatial distribution and diastereoisomer profile. The margin of exposure (MOE) approach was applied to evaluate the health risk of HBCD through drinking water by estimated exposure and derived reference dose. The MOE was 17 for adults and 12 for children in the worst-case scenario, suggesting a trivial health concern.

     

Reduced reproduction of wedge-tailed shearwaters exposed to weathered Santa Barbara crude oil

Wedge-tailed Shearwaters breeding on Manana Island, Hawaii were treated with 0.1–2.0 ml weathered Santa Barbara crude oil either by external application to the breast plumage or by oral dose in gelatin capsules approximately 30 days prior to egg laying. Applications of oil caused reduced lay, lowered hatching success, and reduced breeding success. Two ml applied externally to the breast plumage resulted in a greatly reduced number of eggs laid and complete hatching failure of 60 pair of exposed birds. Oral doses of oil in gelatin capsules reduced laying and breeding success, but to a lesser extent than external exposure. Oil exposure did not change the length of the prelaying exodus or cause birds to move to new areas of the breeding colony, but resulted in abandonment and reduced incubation attentiveness. Growth rates of chicks of oral dosed birds were not different from controls, although survival of chicks of dosed birds was reduced. Long-term effects of external application of 2.0 ml of oil were demonstrated by a decreased number of birds returning to the colony in the year after dosing and reduced breeding success one year after oil exposure.     

Thyroid hormone suppression and cell-mediated immunomodulation in American kestrels (Falco sparverius) exposed to PCBs

Exposure to environmental contaminants can induce physiological changes in animals through various mechanisms. One manifestation of subclinical toxicity from polychlorinated biphenyl (PCB) exposure is the disruption of normal immune function described in numerous species, including American kestrels (Falco sparverius). In 1998, 152 mature male and female kestrels were fed either a mixture of Aroclor 1248:1254:1260 (approximately 7 mg/kg kestrel/day) through their food items, or control diets. Offspring produced by 50 breeding pairs (thus, half received in ovo PCB exposure only) were also studied. Total and differential white blood cell counts, the phytohemagglutinin (PHA) skin response, as well as thyroid hormone levels were tested in vivo in nonbreeding adults (1998 only) and nestlings (1998 and 1999). In 1999, nestlings came from three parental groups; adults exposed in 1998, birds produced by PCB-exposed parents, and unexposed birds. In 1998, directly exposed males but not females had increased total white blood cell counts driven by lymphocytosis, plus a decreased heterophil-to-lymphocyte ratio relative to controls. PCB-exposed birds had a significantly greater response to PHA than did controls, with sex as a significant factor and plasma triiodothyonine (T(3)) as a significant covariate. Levels of T(3) were significantly depressed in PCB-exposed birds of both sexes. The 1999 nestlings (F1 generation with respect to PCB exposure) did not show any effect of parental treatment group on the PHA skin response, yet T(3) remained as a significant covariate. Immunological effects are discussed in light of the antibody-mediated immunotoxicity found in the same birds and reported previously.     

Reproductive and morphological effects of halogenated dimethyl bipyrroles on captive American kestrels (Falco sparverius)

Sixty-four adult captive American kestrels (Falco sparverius) were exposed to a dietary source of halogenated dimethyl bipyrroles (HDBPs), a group of organohalogens proposed to have a natural origin. Adult kestrels were assigned to four treatment groups that were administered a different dose of HDBPs [high, 140 microg/(bird x d); medium, 4.3 microg/(bird x d); low, 0.13 microg/(bird x d); control, 0 microg/(bird x d)]. Exposure began prior to pairing and continued during breeding until approximately 28 d after hatching of the final eggs. Juvenile and adult kestrels accumulated HDBPs in carcass tissue, plasma, and liver. In addition, HDBPs were transferred to yolks during egg development. Low dietary absorption efficiencies (0.011-0.029) indicated that HDBPs were effectively cleared from kestrels either from increased elimination, metabolism, or a combination of the two processes. Reproductive and morphological endpoints examined for HDBP-induced changes included egg volume, egg mass, eggshell thickness, egg fertility, clutch size, liver and whole body mass, antebrachium, central retrice, tarsus, ninth primary, and wing cord lengths. Few statistically significant dose-dependent effects were observed. Hepatic tissue samples from selected individuals underwent histomorphological evaluation. Although the hepatic function was not evaluated specifically in these birds, no clinical signs suggestive of liver disease or gross hepatic anomalies were observed. Only minor histomorphological changes were detected in the hepatic tissue. The lack of serious effects suggests that HDBPs are not an acute reproductive threat to avian populations.