Organohalogen Contaminants Research Articles

Thyroid hormones and deiodinase activity in plasma and tissues in relation to high levels of organohalogen contaminants in East Greenland polar bears (Ursus maritimus)

Previous studies have shown relationships between organohalogen contaminants (OHCs) and circulating levels of thyroid hormones (THs) in arctic wildlife. However, there is a lack of knowledge concerning the possible functional effects of OHCs on TH status in target tissues for TH-dependent activity. The relationships between circulating (plasma) levels of OHCs and various TH variables in plasma as well as in liver, muscle and kidney tissues from East Greenland sub-adult polar bears (Ursus maritimus) sampled in 2011 (n=7) were therefore investigated. The TH variables included 3.3′,5.5′-tetraiodothyronine or thyroxine (T4), 3.3′,5-triiodothyronine (T3) and type 1 (D1) and type 2 (D2) deiodinase activities. Principal component analysis (PCA) combined with correlation analyses demonstrated negative relationships between individual polychlorinated biphenyls (PCBs) and their hydroxylated (OH–) metabolites and T4 in both plasma and muscle. There were both positive and negative relationships between individual OHCs and D1 and D2 activities in muscle, liver and kidney tissues. In general, PCBs, OH-PCBs and polybrominated dipehenyl ethers (PBDEs) were positively correlated to D1 and D2 activities, whereas organochlorine pesticides and byproducts (OCPs) were negatively associated with D1 and D2 activities. These results support the hypothesis that OHCs can affect TH status and action in the target tissues of polar bears. TH levels and deiodinase activities in target tissues can be sensitive endpoints for exposure of TH-disrupting compounds in arctic wildlife, and thus, tissue-specific responses in target organs should be further considered when assessing TH disruption in wildlife studies.

Environmental monitoring of organo-halogenated contaminants (OHCs) in surface soils from Pakistan

Extensive monitoring of organo-halogenated contaminants (OHCs) from surface soils of different land-use types from Pakistan was carried out during 2010. The concentrations (ngg−1; dry weight) and profiles clearly indicated the dominance of ∑DDT contaminants followed by the ∑HCHs, ∑30PCBs, chlordanes, and ∑10PBDEs in descending order. Concerning the spatial patterns of occurrence, industrial soils exhibited relatively higher concentration of DDTs, heavy PCBs, and PBDEs (noticeably BDE-47 and -99 congeners), while the urban soils were characterized by high total PCBs (with relatively higher levels of light PCBs), following the agricultural soils. Compared to available criterion guidelines, the current results suggested that 10% of soil samples from industrial sites exhibited slightly higher levels (>50ngg−1) of DDTs. The ∑TEQ levels for mono-ortho DL-PCBs ranged from 0.7 to 5.65 (1.9) pgTEQg−1 dw in all the studied samples and PCB-118 contributed significantly towards the total calculated TEQs. The results of this study will contribute to the environmental management of OHCs contaminated areas of Pakistan.

Human dietary intake of organohalogen contaminants at e-waste recycling sites in Eastern China

This study reports concentrations and human dietary intake of hexabromocyclododecanes (HBCDs), polychlorinated biphenyls (PCBs) as well as selected “novel” brominated flame retardants (NBFRs) and organochlorine pesticides, in ten staple food categories. Samples were sourced from areas in Taizhou City, eastern China, where rudimentary recycling and disposal of e-waste is commonplace, as well as from nearby non-e-waste impacted control areas. In most instances, concentrations in foods from e-waste recycling areas exceeded those from control locations. Concentrations of 2-ethylhexyl-2,3,4,5-tetrabromobenzoate (EH-TBB) and bis-(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (BEH-TBP) in samples from e-waste sites were 3.09–62.2ng/g and 0.81–16.3ng/g lipid weight (lw), respectively; exceeding consistently those in foods acquired from control sites by an order of magnitude in many cases. In contrast, while concentrations of HBCD in some foods from e-waste impacted areas exceed those from control locations; concentrations in pork, shrimp, and duck liver are higher in control samples. This highlights the potential significance of non-e-waste sources of HBCD (e.g. building insulation foam) in our study areas. While concentrations of DDT in all foods examined except pork were higher in e-waste impacted samples than controls; our exposure estimates were well below the provisional tolerable daily intake of 0.01mg/kgbw/day derived by the Joint FAO/WHO Meeting on Pesticide Residues. Concentrations of ΣPCBs resulted in exposures (650 and 2340ng/kgbw/day for adults and children respectively) that exceed substantially the Minimal Risk Levels (MRLs) for ΣPCBs of 20ng/kgbw/day derived by the Agency for Toxic Substances & Disease Registry. Moreover, when expressed in terms of dioxin-like toxicity equivalency based on the four dioxin-like PCBs monitored in this study (DL-PCBs) (PCB-105, 118, 156, and 167); concentrations in e-waste impacted foods exceed limits set by the European Union in 6 of the 8 food groups studied and result in dietary exposures for children (10.2pgTEQ/kgbw/day) that exceed the WHO tolerable daily intake of 1–4pgTEQ/kgbw/day.

The relationship between land use and emerging and legacy contaminants in an Apex predator, the bottlenose dolphin (Tursiops truncatus), from two adjacent estuarine watersheds

BackgroundPersistent organohalogen contaminant (POC) exposure is of concern in marine mammals due to the potential for adverse health effects. Studies have examined POCs in marine mammals on a regional scale; however, limited data exists on POC concentrations relative to land use and watersheds. ObjectiveExamine geographical variation of POC concentrations in bottlenose dolphins as it relates to land, and watershed, use. MethodsPOC (PCBs, DDTs, and PBDEs) concentrations were measured in blubber of bottlenose dolphins (n= 40) sampled in estuarine waters near Charleston, SC. Photo-identification sighting histories were used to assess the dolphins′ use of estuarine waters in two adjacent watersheds (Cooper Subbasin and Stono Subbasin) in the study area and to determine land use (developed, forested, agriculture, and wetland) associations. ResultsDolphins with ≥75% of their sightings in the Cooper Subbasin, which is characterized by a higher degree of developed land use, exhibited higher levels of PCBs, PBDEs, and total pesticides than those with ≥75% of their sightings in the Stono Subbasin. Observed differences were significant for ΣPBDEs and ΣDDTs/ΣPCBs ratio. Significant positive correlations were observed between ΣPBDEs and developed land use and between ΣDDTs/ΣPCBs and wetland land use. A significant negative correlation was observed between ΣDDTs/ΣPCBs and developed land use. ConclusionThe spatial pattern of PBDEs and the ΣDDTs/ΣPCBs detected in dolphin blubber was shown to vary significantly with adjacent watersheds and land use associations.

Organohalogen contaminants and trace metals in North-East Atlantic porbeagle shark (Lamna nasus)

The North-East Atlantic porbeagle (Lamna nasus) population has declined dramatically over the last few decades and is currently classified as ‘Critically Endangered’. As long-lived, apex predators, they may be vulnerable to bioaccumulation of contaminants. In this study organohalogen compounds and trace elements were analysed in 12 specimens caught as incidental bycatch in commercial gillnet fisheries in the Celtic Sea in 2011. Levels of organohalogen contaminants were low or undetectable (summed CB and BDE concentrations 0.04–0.85mgkg−1wet weight). A notably high Cd concentration (7.2mgkg−1wet weight) was observed in one mature male, whereas the range observed in the other samples was much lower (0.04–0.26mgkg−1wet weight). Hg and Pb concentrations were detected only in single animals, at 0.34 and 0.08mgkg−1wet weight, respectively. These contaminant levels were low in comparison to other published studies for shark species.

The effect of organohalogen contaminants on western Steller sea lion survival and movement in the Russian Far East

The western stock of Steller sea lions (Eumetopias jubatus) have experienced dramatic declines since the 1960s, particularly in the western Alaskan and Asian portions, which have continued to decline or stabilized at low levels. Multiple causes for this decline have been proposed and may include anthropogenic contamination from organohalogen contaminants (OCs). These include polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT), which have not been ruled out as a potential cause for the lack of recovery. The objective of this study was to determine the effects of OCs on survival and movement probabilities estimated in program MARK using resighting data collected from 2003 to 2009. PCBs and DDTs were measured in whole blood from 136 (74 males and 62 females) individually marked, free-ranging pups from four Russian Far East rookeries. The mean concentration of ∑PCB and ∑DDT was 4.25±5.12 and 3.22±4.28ngg−1 ww (n=136), respectively, and the average ∑PCB and ∑DDT concentration for those above the aggregate mean (n=44) was 9.25±6.55 and 7.65±5.21ngg−1 ww, and those below the aggregate mean (n=92) the concentration was 1.86±0.89 and 1.11±0.65ngg−1 ww, respectively. The lowest estimated probabilities of survival occurred in the first year, ranging from 38% to 74%, but increased for ages 1–9, ranging from 82% to 94%. The greatest movement occurred from Medny Island west toward the Kamchatka Peninsula (33%) and to Bering Island (18%), and low movement estimates for other natal rookeries was largely due to minimal resighting effort. The estimated probabilities of resighting varied by location (48%–87%), but had greater precision than survival or movement parameters. Survival and movement were most affected by age and location rather than OCs.

Altered vitamin D status in liver tissue and blood plasma from Greenland sledge dogs (Canis familiaris) dietary exposed to organohalogen contaminated minke whale (Balaenoptera acuterostrata) blubber

This study compared vitamin D3 (vitD3) and 25-OH vitamin D3 (25OHD3) status in Greenland sledge dogs (Canis familiaris) given either minke whale (Balaenoptera acuterostrata) blubber high in organohalogen contaminants (OHCs) or clean porcine (Suis scrofa) fat for up to 636 days. A group of six exposed and six control sister bitches (maternal generation) and their three exposed and four control pups, respectively, were daily fed 112g whale blubber (193µg ∑PCB/day) or porcine fat (0.17µg ∑PCB/day). Mean level of ∑PCB in adipose tissue of exposed bitches and their pups was 3106 and 2670ng/g lw, respectively, which was significantly higher than the mean concentration of 53ng/g lw for all controls (p<0.001). The vitamin analyses showed that 25OHD3 in liver of maternal exposed bitches were significantly lower than in controls (p=0.004) while vitD3 was significantly highest in liver of exposed pups (p<0.003). Regarding blood plasma concentrations, exposed F generation pups had significantly higher concentrations of 25OHD3 than controls (p=0.009). Correlation analyses showed that blood 25OHD3 decreased significantly with increased adipose tissue concentrations of ∑PCB in exposed dogs (R2=0.64, p=0.005) and a similar trend was found for liver 25OHD3 (R2=0.32, p=0.08). The results indicate that the homeostasis and metabolism of vitamin D compounds may respond differently to the dietary composition of fatty acids and OHC exposure. It is unknown if the lower level of 25OHD3 in the liver of exposed dogs would have any negative effects on immunity and reproduction and more focus should be conducted on this compound in Arctic wildlife.

Machine learning approaches to investigate the impact of PCBs on the transcriptome of the common bottlenose dolphin (Tursiops truncatus)

As top-level predators, common bottlenose dolphins (Tursiops truncatus) are particularly sensitive to chemical and biological contaminants that accumulate and biomagnify in the marine food chain.This work investigates the potential use of microarray technology and gene expression profile analysis to screen common bottlenose dolphins for exposure to environmental contaminants through the immunological and/or endocrine perturbations associated with these agents. A dolphin microarray representing 24,418 unigene sequences was used to analyze blood samples collected from 47 dolphins during capture-release health assessments from five different US coastal locations (Beaufort, NC, Sarasota Bay, FL, Saint Joseph Bay, FL, Sapelo Island, GA and Brunswick, GA). Organohalogen contaminants including pesticides, polychlorinated biphenyl congeners (PCBs) and polybrominated diphenyl ether congeners were determined in blubber biopsy samples from the same animals. A subset of samples (n = 10, males; n = 8, females) with the highest and the lowest measured values of PCBs in their blubber was used as strata to determine the differential gene expression of the exposure extremes through machine learning classification algorithms. A set of genes associated primarily with nuclear and DNA stability, cell division and apoptosis regulation, intra- and extra-cellular traffic, and immune response activation was selected by the algorithm for identifying the two exposure extremes. In order to test the hypothesis that these gene expression patterns reflect PCB exposure, we next investigated the blood transcriptomes of the remaining dolphin samples using machine-learning approaches, including K-nn and Support Vector Machines classifiers. Using the derived gene sets, the algorithms worked very well (100% success rate) at classifying dolphins according to the contaminant load accumulated in their blubber. These results suggest that gene expression profile analysis may provide a valuable means to screen for indicators of chemical exposure.

Organo-halogenated contaminants (OHCs) in the sediments from the Soan River, Pakistan: OHCs(adsorbed TOC) burial flux, status and risk assessment

In this study, regression analysis revealed that TOC is the principal factor in controlling the fate of organo-halogenated contaminants (OHCs: PCBs, PBDEs, OCPs) in Soan River, Pakistan. The OHCs(adsorbed TOC) burial flux (OHCs(adsorbed TOC)Bf; mg/cm2·yr) was calculated in the following ranges: ∑PCBs (0.07–0.31), ∑PBDEs (0.005–0.029), ∑HCHs (0.015–0.046) and ∑DDTs (0.007–0.039). Apart from OHCs(adsorbed TOC)Bf, the levels of OHCs were in the following order: PCBs>DDTs>PBDEs>HCH>Chlordane>HCB. PBDEs and PCB congener patterns showed following order respectively: BDE-149>-153>-18>-138>-44 and PCB-149>-153>-18>-138>-44. DDT isomers and metabolites' pattern were p,p′-DDT>p,p′-DDD>p,p′-DDE>o,p′-DDT>o,p′-DDD>o,p′-DDE and HCHs were β-HCH>α-HCH>γ-HCH>δ-HCH. PBDE composition had similarities to penta-BDE and DE-71 mixtures and PCBs with commercial products Aroclor-1254 and -1260. (DDE+DDD)/∑DDTs and p,p′-DDT/p,p′-DDE suggested the recent input of DDTs in sediments while α/γ-HCH indicated past usage of lindane and technical mixtures. Risk assessment suggested that Soan River and its tributaries are potentially at risk against most of the OHCs.

Organohalogen contamination in passerine birds from three metropolises in China: Geographical variation and its implication for anthropogenic effects on urban environments

Contamination of organohalogen pollutants (OHPs), including dichlorodiphenyl trichloroethane and its metabolites (DDTs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), decabromodiphenylethane (DBDPE), hexabromocyclododecanes (HBCDs), and dechlorane plus (DP) in three metropolises of China, Beijing, Wuhan, and Guangzhou, and a reference rural site were determined using terrestrial residential passerine species as bioindicator. DDTs dominated in Wuhan whereas flame retardants dominated in Guangzhou and Beijing. No geographical variation was found for PCB levels but it exhibited different homologue profiles among different sites which could be attributed to different dietary sources of birds. Industry characteristics of the sampling location contributed to the geographical differences in the occurrence and contamination profile of OHPs. The transformation of traditional agriculture characterized contamination profiles to industry characterized profiles in Beijing and Guangzhou implicates significantly environmental concern on the flame retardants contamination in non-hot-spot regions of China.

Steroid hormones in blood plasma from Greenland sledge dogs (Canis familiaris) dietary exposed to organohalogen polluted minke whale (Balaenoptera acuterostrata) blubber

Persistent organic pollutants such as polychlorinated biphenyls (PCB) are known to disrupt steroidogenesis and subsequent concentrations of circulating endogenous hormones. This is also suspected to occur in Arctic predatory species, such as polar bears (Ursus maritimus) and a study was therefore conducted in Greenland sledge dogs (Canis familiaris) as a sentinel species for adverse effects on steroid homeostasis. The control and exposed groups were composed of four sister-bitches all fed pork fat (Suis suis) and organohalogen contaminated minke whale (Balaenoptera acutorostrata) blubber, respectively, for 321–576 days. In the exposed group, this constituted a mean daily intake of 128 μg ∑PCBs (5 μg/kg/day). At the end of the study, organohalogen contaminant (OHC) were measured in adipose tissue and hormone levels in blood of sledge dogs. The hormones included 11 products of the steroidogenesis, which were ∑Androgen (dehydroepiandrosterone, androstenedione, testosterone, and dehydrotestosterone), ∑Estrogen (estrone, 17α-estradiol and 17β-estradiol), and ∑Progestagen (pregnenolone, progesterone, 17-OH-pregnenolone, and 17-OH-progesterone) concentrations. This allowed us to study the mechanisms underlying possible disruption of blood steroid concentrations. Results showed that exposed bitches had significantly higher concentrations of all OHC compounds. Unexpectedly, ∑Androgen, ∑Estrogen and ∑Progestagen concentrations were also significantly higher in exposed dogs. Data indicated that daily OHC contaminant exposure were concomitant with elevation in concentrations of steroid hormones in blood plasma of exposed sledge dogs. Based on these unexpected results, data suggest that more investigations should be focused on steroid endocrine disruption and potential health effects in Arctic top predators including domesticated dogs.

Assessment of concentrations and effects of organohalogen contaminants in a terrestrial passerine, the European starling

European starlings (Sturnus vulgaris) are a valuable model species for the assessment of concentrations and effects of environmental contaminants in terrestrial birds. Polybrominated diphenyl ethers (PBDEs) are found in birds throughout the world, but relatively little is known of their concentrations or effects in free-living terrestrial passerines. We used a nest box population of European starlings to 1) measure the variation in egg concentrations of persistent organohalogen contaminants at an agricultural site, and 2) assess whether individual variation in PBDE concentrations in eggs was related to reproductive parameters, as well as maternal or nestling characteristics including body condition, thyroid hormones, oxidative stress, and hematocrit. As PBDEs were the main contaminant class of interest, we only assessed a subset of eggs for other organohalogen contaminants to establish background concentrations. Exposure to organohalogen contaminants was extremely variable over this relatively small study area. Geometric mean wet weight concentrations (range in brackets) of the major contaminants were 36.5 (12–174) ng/g ΣDDT (n=6 eggs) and 10.9 (2–307) ng/g ΣPBDEs (n=14). ΣPCBs at 3.58 (1.5–6.4) ng/g (n=6) were lower and less variable. There were low levels of other organochlorine (OC) pesticides such as dieldrin (2.02ng/g), chlordanes (1.11ng/g) and chlorobenzenes (0.23ng/g). The only form of DDT detected was p,p′-DDE. The congener profiles of PBDEs and PCBs reflect those of industrial mixtures (i.e. DE-71, Aroclors 1254, 1260 and 1262). For all of the contaminant classes, concentrations detected in eggs at our study site were below levels previously reported to cause effects. Due to small sample sizes, we did not assess the relationship between ΣPCBs or ΣOCs and adult or chick condition. We observed no correlative relationships between individual variation in PBDE concentrations in starling eggs and reproductive success, maternal condition, or nestling condition in the corresponding nests.

Temporal trend and age-dependent serum concentration of phenolic organohalogen contaminants in Japanese men during 1989–2010

The temporal trend in serum concentrations of phenolic organohalogen contaminants (POCs) were investigated in two age groups of men from Kyoto, Japan, from 1989 to 2010. These concentrations and trends were compared with neutral contaminants including polychlorinated biphenyls (PCBs) and pesticides. Serum concentrations of pentachlorophenol (PenCP) and 4-hydroxy-PCB187 were age-dependent and decreased to approximately one-half during the two decades, whereas no contamination trends were observed for 2,4,6-tribromophenol (TriBP), tetrabromobisphenol A (TBBPA) and 6-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether (6-OH-BDE47). 6-OH-BDE47 was found in all samples (up to 3000 pg/g wet weight), whereas TBBPA was detected in 17 of 60 serum samples (up to 950 pg/g wet weight). The concentrations of TriBP, TBBPA and 6-OH-BDE47 were not correlated to those of PenCP or 4-OH-PCB187 in either age group, suggesting the different kinetics on exposure routes and fate between these brominated and chlorinated POCs.

Organohalogen contaminants and total mercury in forage fish preyed upon by thick-billed murres in northern Hudson Bay

Twelve marine fish species collected from a thick-billed murre (Uria lomvia) breeding colony in northern Hudson Bay in the Canadian Arctic during 2007–2009 were analyzed for legacy organochlorines (e.g. PCBs, DDT), polybrominated diphenyl ethers (PBDEs), perfluorinated carboxylates (PFCAs) and sulfonates (PFSAs), and total mercury (Hg). No one species of prey fish had the highest levels across all contaminant groups analyzed. For the two pelagic fish species sampled, concentrations of the major organochlorine groups (e.g. Σ21PCB, ΣDDT, ΣCHL, ΣCBz), ΣPBDE, ΣPFCA and Hg were consistently higher in Arctic cod (Boreogadus saida) than in capelin (Mallotus villosus). Biomagnification factors from whole fish to thick-billed murre liver across all species were generally higher for Σ21PCB and ΣDDT. ΣPBDE did not biomagnify.

Dietary exposure to phenolic and methoxylated organohalogen contaminants in relation to their concentrations in breast milk and serum in Japan

This study investigated human exposure to neutral, phenolic, and methoxylated organohalogen contaminants (OHCs) in a duplicate diet study to evaluate their concentrations in breast milk and serum of Okinawan people from Japan during 2004–2009. Dietary intakes of phenolic OHCs were predominantly 2,4,6-tribromophenol (TriBP), followed by tetrabromobisphenol A (TBBPA), and 6-hydroxy-2,2′,4,4′-tetrabromodiphenyl ether (6-OH-BDE47). After exposure, TriBP and TBBPA were transferred to breast milk, whereas 6-OH-BDE47 was selectively retained in serum. Despite a lower dietary exposure to pentachlorophenol and 4-hydroxy-CB187, both were retained in serum. For the methoxylated OHCs, 2,4,6-tribromoanisole (TriBA) and 6-methoxy-BDE47 were the predominant dietary contaminants, of which TriBA was present in both breast milk and serum, whereas 6-methoxy-BDE47 was selectively transferred to breast milk. These findings suggest that dietary exposure to phenolic and methoxylated OHCs may result in differential partitioning between breast milk and serum with different pharmacokinetic or exposure routes.

Comparative Study of Organohalogen Contamination Between Two Populations of Eastern Atlantic Loggerhead Sea Turtles (Caretta caretta)

We evaluated the presence of 37 organohalogen contaminants in plasma samples from 162 juvenile and 197 adult loggerhead turtles (Caretta caretta) from the archipelagos of the Canary Islands and Cape Verde, respectively, and compared the contamination profiles found. We detected five organochlorine pesticides (OCP) and 16 polychlorinated biphenyls (PCBs). The concentrations of the two groups of contaminants were higher in turtles from the Canary Islands (OCPs, 1.04 vs. 0.37ng/mL; PCBs, 1.92 vs. 0.08ng/mL). We also observed a different profile of PCB contamination between the two populations. In addition, there was a negative correlation between body size and the total concentration of PCBs in the Canary Islands turtles, but not in turtles from Cape Verde. The present study presents the first data on the organochlorine contaminants (OCs) of live turtles from Canary Islands. In addition, we perform a comparison of the levels and profiles of OCs between these two different groups of loggerhead sea turtles from the Eastern Atlantic.

Dynamics of Organohalogenated Contaminants in Human Serum from Obese Individuals during One Year of Weight Loss Treatment

We investigated the dynamics of several organohalogenated contaminants (OHCs) and their metabolites in an obese population during weight loss. Serum samples from obese individuals were taken before patients lost weight and after three, six, and twelve months. Samples were also collected from a matched lean control population. Analyzed OHCs were polychlorinated biphenyls (PCBs) and their hydroxylated metabolites (HO-PCBs), pentachlorophenol (PCP), polybrominated diphenyl ethers, and organochlorine pesticides (OCPs). Significantly lower concentrations of major PCBs, their metabolites, and PCP were measured in obese individuals at the initial moment of their enrolling in the project. While dilution differences might be responsible for the lower concentrations in the neutral OHCs, we suggest that a lower CYP-mediated metabolic activity can partially explain the data for the HO-PCBs. Additionally, lower chlorinated substituted PCBs had a higher percentage contribution to the sum PCBs in obese individuals, while higher chlorinated PCBs had a higher contribution for the controls. Increasing serum levels for all OHCs were observed during weight loss. The release from adipose tissue seemed dependent on the octanol-water partition coefficient, since OHCs with higher log Kow values displayed a higher release in serum. This also influenced the HO-PCBs profile after weight loss with lower chlorinated HO-PCBs increasingly gaining importance. Although weight loss is beneficial, it also influences the release of OHCs from adipose tissue and their metabolism. Therefore, the increase in the levels of compounds with endocrine effects might be of concern.

Is the bone tissue of ring-billed gulls breeding in a pollution hotspot in the St. Lawrence River, Canada, impacted by halogenated flame retardant exposure?

Bone metabolism is a tightly regulated process that controls bone remodeling and repair in addition to maintaining circulating calcium and phosphate levels. It has been shown that certain organohalogen contaminants may adversely impact bone tissue metabolism and structure in wildlife species. However, exceedingly few studies have addressed the bone-related effects of organohalogen exposure in birds. The objective of the present study was to investigate the associations between markers of bone metabolism and structural integrity, and concentrations of established and current-use halogenated flame retardants (FRs) in ring-billed gulls (Larus delawarensis) nesting in a known FR hotspot area in the St. Lawrence River (Montreal, Canada). Bone metabolism was assessed using plasma calcium and inorganic phosphate levels, and alkaline phophatase activity, while bone (tarsus; trabecular and cortical sections) structure quality was examined using the percentage of bone tissue comprised in the total bone volume (Bv/Tv) and bone mineral density (BMD). Bv/Tv and BMD of the tarsus tended (not significant) to be positively associated with circulating calcium levels in male ring-billed gulls. Moreover, concentrations of FRs in male bird liver (brominated diphenyl ether (BDE)-154, -183, -201, and -209) and plasma (BDE-209) were negatively correlated with trabecular and cortical BMD of the tarsus. These correlative associations may suggest light demineralization of bone tissue associated with FR exposure in male ring-billed gulls. Present findings provide some evidence that bone (tarsus) metabolism and mineral composition may be impacted in high FR-exposed (mainly to PBDEs) ring-billed gulls breeding in the highly urbanized Montreal region.

Size and density of East Greenland polar bear (Ursus maritimus) skulls: Valuable bio-indicators of environmental changes?

There is an increasing interest in assessing the relationship between climatic oscillations, environmental contaminants and the modelling of animal physiological and morphological responses. We therefore undertook a study of skull condylobasal length (CBL; reflecting body size) and bone mineral density (BMD) in 87 East Greenland male polar bears (Ursus maritimus) sampled in the time period of 1892–2010. The purpose of the study was to investigate if these measures are potential candidates as indicators for stress associated with climate change and long-range transported toxic industrial chemicals. The analyses showed that both BMD and CBL in polar bears sampled in period 4 (1999–2010, n=57) were significantly lower when compared with period 2 (1920–1936, n=19) (both p<0.02). Groups of persistent organohalogen contaminants (PCBs [polychlorinated biphenyls], DDT [dichlordiphenyltrichlorethane], HCH [hexachlorocyclohexane], HCB [hexachlorobenzene], chlordanes, dieldrin, PBDEs [polybrominated diphenyl ethers]) were measured in period 4 and multiple regression analyses controlling for age showed that dieldrin had a significant negative effect on BMD (p=0.03, n=52) while significant positive correlations with CBL were found for DDT, dieldrin and PBDE (all p<0.05, n=52). When testing the correlation with the North Atlantic Oscillation climate index no significant relationship was found for BMD (p=0.97, r=−0.01, n=27) nor CBL (p=0.31, r=−0.2, n=27). We therefore suggest that BMD and body size have decreased in East Greenland polar bear males over the past 120 years and that exposure to organohalogen contaminants may explain the BMD reductions. It is, however, not entirely clear if and how climatic oscillations affected the reductions in body size and BMD mainly because of the limited sample size in period 2 and lower mean age in period 4. Therefore, precautions should be taken towards a final conclusion on BMD and CBL as bioindicators for climate oscillations and exposure to toxic environmental chemicals. It is recommended that the sampling and archiving of East Greenland polar bear skulls continue in order to further explore how CBL and BMD reflect individual and population response upon exposure to environmental stress.

Organohalogenated contaminants (OHCs) in human serum of mothers and children from Pakistan with urban and rural residential settings

This study aimed to provide first data on the concentrations of different classes of organohalogenated contaminants (OHCs) in human serum from Pakistan, an area with limited information on environmental pollution. Serum samples (N=85) were collected from mothers (N=34; age ranged 23–51years), their children (N=34; age 3–10years) and general group (N=17; age 13–65years) with rural and urban residential settings. The concentrations of studied OHCs in serum decreased as follows: organochlorinated pesticides (OCPs)>polychlorinated biphenyls (PCBs)>polybrominated diphenyl ethers (PBDEs). Novel brominated flame retardants (NBFRs) were not detected, except for 1,2-bis(2,4,6-tribromophenoxy)-ethane (BTBPE)<0.2–8ng/g lipid weight (lw). Low levels of HO-PCBs (<0.2–20ng/glw) were detected, while HO-PBDEs were <0.2ng/glw. ∑PCBs (2–105ng/glw) together with ∑PBDEs (0.2–6.7ng/glw) contributed ~5% of the total OHCs body burden. The concentration(s) of major contributors (>80%) of OCPs ranged from <1–3645ng/glw for 1,1′-bis-(4-chlorophenyl)-2,2-dichloroethene (p,p′-DDE), <1–445ng/glw for β-hexachlorocyclohexane (β-HCH) and from 5 to 200ng/glw for pentachlorophenol (PCP). p,p′-DDE, the major OHC, was significantly higher (p<0.05) in rural children than in all other groups. In serum of rural children, the major OHCs were significantly higher (p<0.05) than the mothers. The current study indicates continuous exposure to humans with already regulated OHCs and highlights the need for further monitoring of these OHCs in the region.