Hair as an indicator of endogenous tissue levels of brominated flame retardants in mammals

Accumulation of background levels of persistent organochlorine and organobromine pollutants through the soil-earthworm-hedgehog food chain

The bioaccumulation of persistent organic pollutants (POPs), such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and DDT and metabolites, was investigated in the soil-earthworm-hedgehog food chain. Concentrations of selected POPs were measured in soil and earthworms collected in grassland and open woodland and in hair and blood of hedgehogs foraging in two parks containing these habitats. Despite background concentrations in soil (ranging from 1.3 to 9.3 ng/g for DDTs, 2.3 to 6.5 ng/g for PCBs and 0.08 to 0.20 ng/g for PBDEs), biota-soil accumulation factors (BSAFs) indicated that earthworms accumulated POPs (0.48-1.70 for DDTs, 1.09-2.76 for PCBs and 1.99-5.67 for PBDEs) and that animals feeding on earthworms are potentially exposed to higher concentrations of pollutants. BSAFs decreased with increasing soil concentrations for the three groups of compounds, suggesting that steady-state equilibrium was not reached in soil or earthworms. Positive, but low, log-linear relationships were found for DDT (r(2)=0.23, p<0.05 for Brasschaat and r(2)=0.63, p<0.01 for Hoboken) and PCB (r(2)=0.13, p<0.05 for both parks) concentrations between soil and earthworms. In order to relate earthworm to hedgehog POP concentrations, the foraging behavior of each individual was taken into account. The use of hair as a potential biomonitoring tissue in exposure and risk assessment of POPs was evaluated by examining the relationship between PCB and p,p'-DDE levels in hedgehogs' hair and blood. Contaminant profiles were used to gain insight into biotransformation of the studied compounds in each step of the investigated food chain and in the blood of hedgehogs, as well as the consequences thereof for their incorporation in hair. The absence of a discernable relationship between POP concentrations in earthworms and hair is possible due to variation in individual foraging behavior and POP uptake. Our results suggest that POPs in tissues should be measured from an adequate number of individuals per population instead of relying on indirect estimates from levels in soil or prey items.

Metabolism of 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) in chickens

Polybrominated diphenyl ethers (PBDEs) are an important class of persistent, organic pollutant that, based on previous studies in rodents, are poorly metabolized and bioaccumulate in lipophilic stores of the body. Because humans typically consume the fat and skin of chicken, a single (14)C-radiolabeled dose (2.7 mg/kg; 5.64 mumol/kg) of the most common PBDE in the environment, that is, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47), was administered to determine its metabolic disposition in male broiler chickens. Orally dosed BDE-47 was readily absorbed from the gut of chickens and was estimated to be 73% bioavailable. Cumulative tissue retention at 72 h was 60.2% of the dose. BDE-47 was deposited preferentially in lipophilic tissues, and the decreasing rank order of concentration on a wet weight basis was adipose tissue, skin, gastrointestinal tract, lung, carcass, muscle, liver, and kidney. When concentrations were adjusted for lipid content, the levels of BDE-47 in the principal edible tissues in chicken, that is, adipose tissue, skin, liver, and white and dark meat, were very similar to one another. Excretion of unbound metabolites in excreta was <1% of the dose, but bound radioactivity was a major component of excreta at >12% of the dose. Alkaline hydrolysis of bound material yielded a hydroxylated tetrabromo metabolite. The metabolic pathway of BDE-47 in chicken included mono-oxidation, mono-oxidation/debromination, and debromination. The present results suggest that trimming the fat and skin from chicken would substantially reduce human exposure to PBDEs during the consumption of chicken.

Residues of polybrominated diphenyl ethers in frogs (Rana limnocharis) from a contaminated site, South China: tissue distribution, biomagnification, and maternal transfer

Environmental pollutants are suspected to be a cause of global declines in amphibian populations, but few data are available on the bioaccumulation of polybrominated diphenyl ethers (PBDEs) in amphibians. To examine the tissue distribution, biomagnification potential, and maternal transfer of PBDEs in frogs, eighteen PBDE congeners were measured in the muscle, liver, and egg tissues of rice frogs (Rana limnocharis) and insects collected from an electronic waste (e-waste) recycling site in South China. PBDE levels in the frogs ranged from 0.63 to 11.6, 4.57 to 56.2, and 10.7 to 125 ng/g wet wt in the muscles, livers, and eggs, respectively. The frogs exhibited a unique congener profile, compared to those in aquatic and terrestrial species, with BDEs 99, 153, 183, 209, and 47 as the dominant congeners, intermediating between aquatic and terrestrial species. Most of the PBDE congeners in general showed higher affinity to liver than to muscle tissue. Except for BDEs 28, 47, 66, 138, and 206, the average biomagnification factors (BMFs) for all PBDE congeners were greater than 1.0, providing clear evidence of their biomagnification from insects to frogs. A parabolic relationship between log BMFs and bromine atom numbers or log Kow of PBDEs was observed, with the maximum BMF values for PBDEs with 6 bromine atoms (or at a log K(ow) of approximately 8.0). Relatively higher levels of 3-MeO-BDE 47 were found in male frogs, suggesting that male frogs in the present study might have higher metabolic capacity for PBDEs compared to female frogs. The ratio of levels in egg/female liver, indicating mother-to-egg transfer capacity, increased with increasing bromine atom numbers up to 7 and then declined as the bromine atom numbers rose. This indicated that the physicochemical properties of the congeners (e.g., K(ow), molecular sizes, and structures), resulting in different affinities to transport proteins, might impact their maternal transfer in frogs.

Organochlorine pesticide and polychlorinated biphenyl in feathers of resident and migratory birds of South-west iran

Persistent organochlorine pesticides (OCPs), such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), alpha-, beta-, and gamma-hexachlorocyclohexane (HCH) isomers, together with polychlorinated biphenyl (PCB) congeners (IUPAC Nos. 28, 52, 101, 138, 153, and 180) were determined in tail feathers from 35 birds belonging to 15 species, all originating from the southwest of Iran (Khuzestan, coast of the Persian Gulf) and kept in museum collections. The patterns of organochlorine contaminants (OCs) in birds varied depending on their migratory behavior. Resident birds contained higher median PCB concentrations (<LOQ-151 ng/g feather) than HCHs, DDTs, and HCB. Locally migrating birds had higher median concentrations of HCHs (19-83 ng/g feather). In contrast, long-distance migrants had lower concentrations of HCB and HCHs. A positive correlation was observed among OCs in these birds, suggesting that trophic level, feeding strategy, and taxonomic group are influencing factors for the OC concentrations in bird feathers. An estimate of the risk associated suggests that levels of OCPs and PCBs were lower or close to the threshold reported to affect reproduction in 1990s.

Tissue distribution of polybrominated diphenyl ethers in male rats and implications for biomonitoring

Polybrominated diphenyl ethers (PBDEs) are a class of widely used flame retardants which have been found to persist, bioaccumulate, and potentially affect development in animals. Exposure to PBDEs can be through both diet and the environment and is generally estimated by measuring PBDEs in blood, adipose tissue, muscle, or milk samples. Using rats as a model, we investigated tissue distribution of PBDEs after oral administration and evaluated a suitable matrix for body burden estimation. Male rats were administered dust or corn oil containing 8 or 6 microg PBDEs kg(-1) body wt, respectively, in the diet for 21 days (N=4 rats per treatment), and the concentration of 15 PBDEs were measured in various tissues, plasma, and feces. PBDEs were found in all tissues, including the brain, and showed no difference in distribution patterns between treatments for most PBDEs. Tri- to hexa-BDEs comprised >80% of the total PBDEs in the adipose, brain, kidney, lung, and residual carcass, but <40% in the liver and plasma. The ratio of the lipid-weight concentration of tri- to hexa-BDEs in adipose tissue, residual carcass, and plasma was 1:1:2. For the hepta- to nona-BDEs, lipid-weight concentrations increased from adipose tissue to residual carcass to plasma in the ratio 0.3:1:>4. BDE-209 was the dominant congener in the liver and plasma, but was not detected in the adipose tissue or carcass. In summary, the lower brominated congeners tended to distribute equally into lipids implying both adipose tissue and plasma would be suitable matrices for biomonitoring. Plasma was the best matrix for detection of the higher brominated congeners (especially BDE-209), although on a lipid-weight basis tended to overestimate the total body burdens.

Levels and trends of HBCD and BDEs in the European and Asian environments, with some information for other BFRs

In this paper, we review recent data for brominated flame retardants (particularly BDEs, HBCD and TBBP-A) in samples from the European and Asian environments, including recent temporal trend studies. Research is active and we cite over 100 studies published during 2005-2007. Environmental compartments studied comprise the atmosphere, indoor and outdoor air, sewage sludges, soils and sediments and a variety of biological samples and food chains. Findings include that the lack of reference materials for use in analytical quality control and method validation identified earlier has been addressed, and certified concentrations are now available for a number of BDE congeners in six pre-existing and one new reference materials. BDE209 was certified in three samples of indoor dust. The analysis of BDE209 remains problematic, but suitable methods for its determination are available and need to be applied. The contamination of indoor environments with BFRs has been recognised as representing a significant uptake pathway, particularly via dust. Additional data for TBBP-A are needed from areas, where it is produced and used, primarily Asia, as the worst-case scenario. As a reactive flame retardant it is less likely to leach from finished products. Also, issues regarding the importance of e-waste recycling as a source of BFRs to the local populations and the local environment require urgent study, certainly in China and possibly elsewhere. Generally, trends show a levelling in concentrations of BDEs and increases in concentrations of HBCD wherever determined and BDE209 in Asia.

Hair-biomonitoring of organic pollutants

This report reviews past research on hair analysis development for organic contaminants from the point of view of analytical procedures, successful applications and their limitations. For the past 20 years, hair analysis for organic pollutants has received more and more attention, since it is non-invasive, easily available and ethically not prioritized. New methods such as SFE, SPME and INAA have been developed to make the analysis more accurate and reliable. Furthermore, the correlation of contamination levels between hair samples and ambient air or internal tissues has been found by hair analysis and short-term and long-term exposure assessment in combination. However, there are still some limitations of hair analysis to be a validated risk assessment tool for many compounds. Some limitations had been of the past, some have not been fully investigated and need still further study. In this way, hair analysis can be the key to successfully biomonitor organic contaminations.

Organochlorine contaminants in hair of adolescents from Iassy, Romania

Human hair samples (n=42) from Iassy county (Eastern Romania) collected in 2002-2003 from adolescents were analyzed for hexachlorocyclohexane (HCH) isomers, p,p'-DDT and its metabolites, hexachlorobenzene (HCB), chlordane and metabolites and 5 polychlorinated biphenyl (PCB) congeners. Very low levels were found for HCB and oxychlordane (0.8 and 2.5 ng g(-1)) indicating a low usage of these pesticide formulations in the studied area. In case of HCHs, gamma-HCH isomer was measured at higher median concentrations (79 ng g(-1) hair) compared to the beta-HCH isomer (55 ng g(-1)), which generally is the most prevalent from HCHs. The DDTs profile consisted in p,p'-DDE and p,p'-DDT which levels correspond to 81% of sum DDTs. Very high median concentrations measured for p,p'-DDT (192 ng g(-1)) combined with lower values for p,p'-DDE/p,p'-DDT of 0.4 (from 0.20 to 2.0) in all hair samples suggest recent exposure to "fresh" DDT. When gender was considered, significantly higher concentrations for most of the investigated contaminants were found in girls hair compared to boys. Very high levels were found in the present study for HCHs and DDTs compared to samples from Greece, Western Europe and China. In case of PCBs, the levels found in Romanian samples were found to be in the same range compared to other previously published data.

Contaminant exposure in terrestrial vertebrates

Here we review mechanisms and factors influencing contaminant exposure among terrestrial vertebrate wildlife. There exists a complex mixture of biotic and abiotic factors that dictate potential for contaminant exposure among terrestrial and semi-terrestrial vertebrates. Chemical fate and transport in the environment determine contaminant bioaccessibility. Species-specific natural history characteristics and behavioral traits then play significant roles in the likelihood that exposure pathways, from source to receptor, are complete. Detailed knowledge of natural history traits of receptors considered in conjunction with the knowledge of contaminant behavior and distribution on a site are critical when assessing and quantifying exposure. We review limitations in our understanding of elements of exposure and the unique aspects of exposure associated with terrestrial and semi-terrestrial taxa. We provide insight on taxa-specific traits that contribute, or limit exposure to, transport phenomenon that influence exposure throughout terrestrial systems, novel contaminants, bioavailability, exposure data analysis, and uncertainty associated with exposure in wildlife risk assessments. Lastly, we identify areas related to exposure among terrestrial and semi-terrestrial organisms that warrant additional research.

Is external contamination with organic pollutants important for concentrations measured in bird feathers?

Although there is increasing evidence that bird feathers can be used as a non-destructive biomonitoring tool for organic pollutants [such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and p,p'-dichlorodiphenyl-trichloroethane and metabolites (DDTs)], the importance of external contamination of these organic pollutants onto the feathers has not been considered. Here we examine to which extent external contamination of organic pollutants occurs onto the feathers of a predatory bird. We have analysed primary wing feathers of 16 common buzzards (Buteo buteo) collected in Belgium. In order to study differences in external contamination within and among wing feathers, the vane and the shaft of each feather were separated and were analysed in parallel, pooled for the three inner and the three outer primary wing feathers. Most organic pollutants could be measured in these pooled samples of both the vane and the shaft. Concentrations of hexachlorobenzene (HCB), DDTs, PCBs and PBDEs were significantly higher in the vane compared to the shaft. The profiles of PCBs and PBDEs in the shaft closely resembled the profiles in liver and muscle tissue, in contrast with the profile of the vane. The PBDE congeners 47, 99 and 153 had a similar contribution in shafts of primary feathers of common buzzards. Although these results suggest that external contamination could be important on the vane, no differences in the profile of PBDEs or PCBs were found between the inner and outer (more exposed) primary feathers. Furthermore, correlation coefficients with internal tissues were not univocally distinct between the shaft and the vane. Therefore our results indicate that the higher concentrations found in the vane in comparison to the shaft do not originate from external contamination via the air, but that other factors such as structure and chemical properties of the feathers may be of importance. The lack of significant external contamination onto the feather surface is an additional asset for the use of feathers as a non-destructive biomonitor for organic pollutants.

Recent developments in the analysis of brominated flame retardants and brominated natural compounds

This article reviews recent literature on the analysis of brominated flame retardants (BFRs) and brominated natural compounds (BNCs). The main literature sources are reviews from the last five years and research articles reporting new analytical developments published between 2003 and 2006. Sample pretreatment, extraction, clean-up and fractionation, injection techniques, chromatographic separation, detection methods, quality control and method validation are discussed. Only few new techniques, such as solid-phase microextraction (SPME) or pressurized liquid extraction (PLE), have been investigated for their ability of combining the extraction and clean-up steps. With respect to the separation of BFRs, the most important developments were the use of comprehensive two-dimensional gas chromatography for polybrominated diphenyl ethers (PBDEs) and the growing tendency for liquid-chromatographic techniques for hexabromocyclododecane (HBCD) stereoisomers and of tetrabromobisphenol-A (TBBP-A). At the detection stage, mass spectrometry (MS) has been developed as well-established and reliable technology in the identification and quantification of BFRs. A growing attention has been paid to quality assurance. Interlaboratory exercises directed towards BFRs have grown in popularity and have enabled laboratories to validate analytical methods and to guarantee the quality of their results. The analytical procedures used for the identification and characterization of several classes of BNCs, such as methoxylated polybrominated diphenyl ethers (MeO-PBDEs) (also metabolites of PBDEs), halogenated methyl or dimethyl bipyrroles (DBPs), are reviewed here for the first time. These compounds were generally identified during the routine analysis of BFRs and have received little attention until recently. For each topic, an overview is presented of its current status.

Evaluation of the usefulness of bird feathers as a non-destructive biomonitoring tool for organic pollutants: a comparative and meta-analytical approach

In this study, we investigated whether bird feathers can be used as a non-destructive biomonitor for organic pollutants. We analysed the outermost tail feathers of 8 terrestrial and aquatic bird species from Belgium (8 species, n=108) for polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and organochlorine pesticides (OCPs). Every compound class could be quantified in one single tail feather of the birds under study (sum PCBs ranging from 5.5 to 510 ng/g feather, sum PBDEs from 0.33 to 53 ng/g feather, sum DDTs from 1.5 to 730 ng/g feather), except for PBDEs in feathers of the common moorhen (Gallinula chloropus). Further, we calculated Pearson correlations between concentrations of organic pollutants in feathers and concentrations in corresponding muscle or liver tissue from the birds. Correlations were found significant in half of the cases of the terrestrial species, but were found not significant for the aquatic species, with the exception of a significant correlation of sum PCBs in the common moorhen. Only for the common buzzard (Buteo buteo) (n=43) all correlations were found significant (0.32<r<0.77). In order to cope for low statistical power, we performed a meta-analysis on all bird species together. This led to significant correlations between levels in feathers and corresponding levels in muscle or liver for all terrestrial birds (p<0.05 in all cases, effect size 0.59 (p,p'-DDE) to 0.71 (Sigma PCB) for levels in feather and muscle). When correlations were recalculated excluding the birds that had died due to starvation, correlation coefficients for the terrestrial birds were found even higher (effect size up to 0.83 (Sigma PCB)). These results have important implications for non-destructive and retrospective biomonitoring. Although our results suggest that exact concentrations in the body cannot be predicted using feathers, bird feathers can give a good estimate of contamination levels in a population and as such are a potential non-destructive biomonitoring tool for organic pollutants. Outermost tail feathers and muscle tissue were also examined for nitrogen (delta15N) and carbon (delta13C) stable isotope content in the different bird species. However, delta15N/delta13C signatures in feather or muscle were not significantly correlated with the corresponding levels of organic pollutants in these tissues. Various confounding factors (such as habitat, condition, age, sex) may have masked a relationship between delta15N values and organic pollutant levels in the birds under study.

Non-destructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): IV. Hair versus soil analysis in exposure and risk assessment of organochlorine compounds

Few ecotoxicological studies on mammals use non-destructive methodologies, despite the growing ethical concern over the use of destructive sampling methods. In the present study we assessed exposure of hedgehogs (Erinaceus europaeus) to polychlorinated biphenyls (PCBs), dichloro-diphenyl-trichloroethanes (DDTs), hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB), by investigating concentrations of these compounds in soils and hedgehog hair from seven study sites around the urban area of Antwerp, Belgium. No relationships were observed between organochlorine compound concentrations in soils and hair from the different study areas. Furthermore, the individual variation of contamination levels in hair within study sites was high, especially for HCHs and HCB, and hair and soil had different relative profiles for PCBs, DDTs and HCHs. Our results show that concentrations of organochlorine compounds in soils alone are not predictive of the risk of these pollutants to hedgehogs and that tissue analyses are preferred to soil analyses in exposure and risk assessment studies.

Can predatory bird feathers be used as a non-destructive biomonitoring tool of organic pollutants?

The monitoring of different types of pollutants that are released into the environment and that present risks for both humans and wildlife has become increasingly important. In this study, we examined whether feathers of predatory birds can be used as a non-destructive biomonitor of organic pollutants. We demonstrate that polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and polybrominated diphenyl ethers (PBDEs) are measurable in one single tail feather of common buzzards (Buteo buteo) and that levels in this feather and internal tissues are significantly related to each other (0.35 < r < 0.76 for all 43 buzzards; 0.46 < r < 0.84 when excluding 17 starved birds). Our findings provide the first indication that feathers of predatory birds could be useful in non-destructive biomonitoring of organic pollutants, although further validation may be necessary.

Biomagnification of PBDEs in three small terrestrial food chains

Eight polybrominated diphenyl ethers (PBDE) congeners (IUPAC nos. 28, 47, 99, 100, 153, 154, 183, and 209) were measured in passerines (great tits--Parus major), wood mice (Apodemus sylvaticus), and bank voles (Clethrionomys glareolus). These data were combined with previously obtained data on PBDEs in common buzzards (Buteo buteo), sparrowhawks (Accipiter nisus), and red fox (Vulpes vulpes). This enabled estimation of the biomagnification potential of PBDEs in the following three terrestrial food chains: great tit--sparrowhawk, small rodents--buzzard, and small rodents--fox. Biomagnification of BDE 209 could not be assessed because levels of this congener were below the LOQ in the prey species. All other congeners, except BDE 28, were biomagnified in both predatory bird species. Biomagnification of BDE 28 could not be observed from rodents to buzzard. Biomagnification factors (BMFs) were calculated as the ratio between the lipid-normalized concentrations in the predator and in the prey. BMFs ranged from 2 to 34 for the sum of PBDEs in predatory bird food chain. Although the fox is a top-predator, this is not reflected in the PBDE concentrations that were measured in its tissues. In the small rodent-fox food chain, no biomagnification could be observed. This observation is most likely related to the high metabolic capacity of the fox with regard to organohalogens and should be taken into account when selecting species for environmental monitoring purposes. Not all top-predators will give a representative reflection of the pollution of their habitat, but confounding factors, such as metabolism, can influence the results to a great extent and can therefore lead to misinterpretations.

Non-destructive pollution exposure assessment in the European hedgehog (Erinaceus europaeus): II. Hair and spines as indicators of endogenous metal and As concentrations

The role of hair and spines of the European hedgehog as non-destructive monitoring tools of metal (Ag, Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Zn) and As pollution in terrestrial ecosystems was investigated. Our results showed that mean pollution levels of a random sample of hedgehogs in Flanders are low to moderate. Yet, individual hedgehogs may be at risk for metal toxicity. Tissue distribution analyses (hair, spines, liver, kidney, muscle and fat tissue) indicated that metals and As may reach considerable concentrations in external tissues, such as hair and spines. Positive relationships were observed between concentrations in hair and those in liver, kidney and muscle for Al, Co, Cr, Cu, and Pb (0.43 < r < 0.85). Spine concentrations were positively related to liver, kidney and muscle concentrations for Cd, Co, Cr, Cu and Pb (0.37 < r < 0.62). Hair Ag, As, Fe and Zn and spine Ag, Al, As and Fe were related to metal concentrations in one or two of the investigated internal tissues (0.31 < r < 0.45). The regression models presented here may be used to predict metal and As concentrations in internal tissues of hedgehogs when concentrations in hair or spines are available. The present study demonstrated the possibility of using hair and spines for non-destructive monitoring of metal and As pollution in hedgehogs.

Remarkable findings concerning PBDEs in the terrestrial top-predator red fox (Vulpes vulpes)

In the present study, we have analyzed muscle, liver, and adipose tissue of 33 red foxes from Belgium for their content of polybrominated diphenyl ethers (PBDEs). Median sums of seven tri- to hepta-BDEs (BDE 28, BDE 47, BDE 99, BDE 100, BDE 153, BDE 154, and BDE 183) were 2.2, 2.4, and 3.4 ng/g lipid weight in adipose tissue, liver, and muscle, respectively. These levels were lower than those found in various species of voles and mice, the main prey species of the red fox. This is probably related to the high capacity of the foxes to metabolize and eliminate lower brominated congeners. BDE 209 generally dominated the PBDE congener profiles in the red fox samples. In samples containing BDE 209, this congener contributed, on the average, approximately 70% to the total PBDE content. BDE 209 was measured in concentrations as high as 760 ng/g lipid weight in the liver, but the detection frequency was not more than 40%. In animals with the highest BDE 209 levels, this congener was detected in muscle, liver, as well as in adipose tissue. Other abundant congeners were BDE 153 and BDE 47, which prevail in other terrestrial species. The particular PBDE congener profile observed in the red fox resembles that seen in grizzly bears from Canada, but differs from those previously reported for terrestrial avian species. Our data confirms unambiguously that BDE 209 does bioaccumulate in terrestrial top predators, such as the red fox.