DDE Levels Research Articles

Dyslipidemia causes overestimation of plasma mitotane measurements.

SummaryMitotane (o,p′-DDD) is the standard treatment for advanced adrenocortical carcinoma (ACC). Monitoring of plasma mitotane levels is recommended to look for a therapeutic window between 14 and 20mg/L, but its positive predictive value requires optimization. We report the case of an ACC patient with a history of dyslipidemia treated with mitotane in whom several plasma mitotane levels >30mg/L were found together with an excellent neurological tolerance. This observation led us to compare theoretical or measured o,p′-DDD and o,p′-DDE levels in a series of normolipidemic and dyslipidemic plasma samples to explore potential analytical issues responsible for an overestimation of plasma mitotane levels. We demonstrate an overestimation of mitotane measurements in dyslipidemic patients. Mitotane and o,p′-DDE measurements showed a mean 20% overestimation in hypercholesterolemic and hypertriglyceridemic plasma, compared with normolipidemic plasma. The internal standard p,p′-DDE measurements showed a parallel decrease in hypercholesterolemic and hypertriglyceridemic plasma, suggesting a matrix effect. Finally, diluting plasma samples and/or using phospholipid removal cartridges allowed correcting such interference.Learning pointsHypercholesterolemia (HCH) and hypertriglyceridemia (HTG) induce an overestimation of plasma mitotane measurements.We propose a routine monitoring of lipidemic status.We propose optimized methodology of measurement before interpreting high plasma mitotane levels.

Organochloride pesticides induced hepatic ABCG5/G8 expression and lipogenesis in Chinese patients with gallstone disease.

BackgroundOrganochlorine pesticides (OCPs) are one kind of persistent organic pollutants. Although they are reported to be associated with metabolic disorders, the underlying mechanism is unclear. We explored the association of OCPs with gallstone disease and its influence on hepatic lipid metabolism.Materials and MethodsOCPs levels in omentum adipose tissues from patients with and without gallstone disease between 2008 and 2011 were measured by GC-MS. Differences of gene expression involved in hepatic lipid metabolism and hepatic lipids content were compared in liver biopsies between groups with high and low level of OCPs. Using HepG2 cell lines, the influence on hepatic lipid metabolism by individual OCP was evaluated in vitro.ResultsIn all patients who were from non-occupational population, there were high levels of β-hexachlorocyclohexane (β-HCH) and p',p'-dichloroethylene (p',p'-DDE) accumulated in adipose tissues. Both β-HCH and p', p'-DDE levels were significantly higher in adipose tissues from patients with gallstone disease (294.3± 313.5 and 2222± 2279 ng/g of lipid) than gallstone-free controls (282.7± 449.0 and 2025±2664 ng/g of lipid, P< 0.01) and they were strongly related with gallstone disease (P for trend = 0.0004 and 0.0138). Furthermore, higher OCPs in adipose tissue led to increase in the expression of hepatic cholesterol transporters ABCG5 and G8 (+34% and +27%, P< 0.01) and higher cholesterol saturation index in gallbladder bile, and induced hepatic fatty acids synthesis, which was further confirmed in HepG2 cells.ConclusionOCPs might enhance hepatic secretion of cholesterol into bile via ABCG5/G8 which promoting gallstone disease as well as lipogenesis.

Serum levels of organochlorine pesticides in the general population of Thessaly, Greece, determined by HS-SPME GC–MS method

In this study, exposure levels of organochlorine pesticides (OCs) were determined in general population residing in Larissa, central Greece. Serum samples from 103 volunteers were analyzed by optimized headspace solid-phase microextraction gas chromatography–mass spectrometry, to detect and quantify OC levels. The most frequently detected analytes were p,p′–DDE (frequency 99%, median:1.25ng/ml) and Hexachlorobenzene (HCB) (frequency 69%, median: 0.13ng/ml). Statistical analysis revealed a significant relationship of p,p′–DDE and HCB levels with age.

Body burden of persistent organic pollutants on hypertension: a meta-analysis.

Except the known risk factors for hypertension, several studies have suggested that exposure to persistent organic pollutants (POPs), endocrine disrupting chemicals, could be associated with an increased risk of hypertension. In this study, we performed a meta-analysis to summarize the existing epidemiological studies to investigate the association between POPs concentration and risk of hypertension. Based on comprehensive literature search results (PubMed, EMBASE, and KoreaMed), a meta-analysis of 11 articles was performed using a random-effects model. While we observed no significant association between the sum of non-dioxin-like PCBs and the risk of hypertension (OR = 1.00; 95% CI 0.89, 1.12), the sum of dioxin-like PCBs was associated with a significantly increased risk of hypertension (OR = 1.45; 95% CI 1.00, 2.12). High p,p'-DDE level was also significantly associated with the increased risk of hypertension. When subgroup analyses were carried out for studies which analyzed POPs concentrations using high-resolution gas chromatography/high-resolution mass spectrometry, the overall pooled estimate ORs increased with decreased heterogeneity, providing it as a possible heterogeneity source (OR = 1.36; 95% CI 1.21, 1.52; I (2) = 42.8%; p = 0.045). This study suggested that the concentration of certain POPs, especially dioxin-related compounds, was associated with the risk of hypertension.

Assessment of exposure to mixture pollutants in Mexican indigenous children.

The aim of the present work was to complete an exposure assessment in three Mexican indigenous communities using the community-based health risk assessment, which is the first step in the CHILD framework. We used 1-hydroxypyrene (1-OHP) as an exposure biomarker to polycyclic aromatic hydrocarbons (PAHs) and trans, trans-muconic acid (t,t-MA) as an exposure biomarker to benzene, persistent organic pollutants (POPs), lead, manganese, arsenic, and fluoride. Anthropometric measurements were also taken. In these communities, high percentages of children with chronic malnutrition were found (28 to 49%) based on their weight and age. All communities showed a high percentage of children with detectable levels of four or more compounds (70 to 82%). Additionally, our results showed that in indigenous communities, children are exposed to elevated levels of certain environmental pollutants, including manganese with 17.6, 16.8, and 7.3μg/L from SMP, TOC, and CUA, respectively. Lead and HCB levels were similar in the indigenous communities (2.5, 3.1, and 4.2μg/dL and 2.5, 3.1, and 3.7ng/mL, respectively). 1-OHP and t,t-MA levels were higher in TOC (0.8μmol/mol of creatinine, 476μg/g of creatinine, respectively) when compared with SMP (0.1μmol/mol of creatinine, 215.5μg/g of creatinine, respectively) and CUA (0.1μmol/mol of creatinine, 185.2μg/g of creatinine, respectively). DDE levels were 30.7, 26.9, and 9.6ng/mL in CUA, SMP, and TOC, respectively. The strength of this study is that it assesses exposure to pollutants with indications for the resultant risk before an intervention is made by the CHILD program to manage this risk in the indigenous communities. Considering the large number of people, especially children, exposed to multiple pollutants, it is important to design effective intervention programs that reduce exposure and the resultant risk in the numerous indigenous communities in Mexico.

The metabolic fingerprint of p,p′-DDE and HCB exposure in humans

BackgroundDichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB) are organochlorine pesticides with well-known endocrine disrupting properties. Exposure to p,p′-DDE and HCB concerns human populations worldwide and has been linked to metabolic disorders such as obesity and type 2 diabetes, but details about these associations in humans from the general population are largely unknown. ObjectivesWe investigated the associations between p,p′-DDE and HCB exposure and global metabolomic profiles in serum samples from 1016 participants from the Swedish population-based Prospective Investigation of the Vasculature in Uppsala Seniors (PIVUS) study. MethodsHCB and p,p′-DDE levels were determined using gas chromatography coupled to high-resolution mass spectrometry (GC–HRMS). Metabolite levels were determined by using a non-targeted metabolomics approach with ultra-performance liquid chromatography coupled to time-of- flight mass spectrometry (UPLC–TOFMS). Association analyses were performed using multivariate linear regression. ResultsWe found circulating levels of p,p-DDE and HCB to be significantly associated with circulating levels of 16 metabolites following adjustment for age, sex, education level, exercise habits, smoking, energy intake, and alcohol intake. The majority of the 16 metabolites belong to lipid metabolism pathways and include fatty acids, glycerophospholipids, sphingolipids, and glycerolipids. Overall, p,p′-DDE and HCB levels were found to be correlated to different metabolites, which suggests that different metabolic fingerprints may be related to circulating levels of these two pesticides. ConclusionsOur findings establish a link between human exposure to organochlorine pesticides and metabolites of key metabolic processes mainly related to human lipid metabolism.

4,4′-DDE and Endosulfan Levels in Agricultural Soils of the Çukurova Region, Mediterranean Turkey

Mediterranean Turkey has long been at the forefront of Turkish agriculture and the use of organochlorinated pesticides (OCPs) in this area rose considerably between the 1940s and 1980s. This study aimed to determine OCP residue levels in agricultural soils collected from the Mersin and Adana Districts, Çukurova Basin in Mediterranean Turkey. Most soil samples were contaminated with one, or both, of two OCP metabolites; 4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE) and endosulfan sulfate. 4,4'-DDE occurred in 27 of the 29 samples and ranged from 6 to 1090µgkg(-1)-dry soil (ds)(-1), while six samples contained endosulfan sulfate ranging between 82 and 1226µgkg(-1)-ds(-1). Generally, horticultural and corn-planted soils contained only 4,4'-DDE, whereas greenhouse cultivation appeared to accumulate both residues. This study indicated that 4,4'-DDE occurred above acceptable levels of risk in agricultural soils of Mersin District and further studies on the qualitative and quantitative assessment of OCPs in other agricultural regions with intensive pesticide use are necessary to fully understand the impact of OCPs on agricultural soil in Turkey.

Influence of Breastfeeding Time on Levels of Organochlorine Pesticides in Human Milk of a Mexican Population.

This study was conducted with the objective of determining whether there is a depuration of organochlorine pesticides in breast milk according to breastfeeding time. In total, 171 samples from mothers that lived in the State of Guerrero, Mexico were analyzed. There was a weak negative relationship between pp'DDE (r = -0.216) and Σ-DDT (r = -0.222) concentrations with the days of lactation. In a comparison analysis, a statistically significant decrease of pp'DDT and pp'DDE levels was observed, as well as the Σ-DDT from the first to the fifth week of lactation. A reduction of 0.188 mg/kg lipid of pp'DDE and 0.181 mg/kg lipid of Σ-DDT per week was obtained. HCB, β-HCH and op'DDT concentrations were low and had no major fluctuations between subgroups. The low levels found and the observed reduction in time involve less exposure to the infant to these pollutants. Through this methodology changes in levels of certain organochlorine pesticides in various stages of human milk production may be shown.

Prenatal DDT and DDE exposure and child IQ in the CHAMACOS cohort

Although banned in most countries, dichlorodiphenyl-trichloroethane (DDT) continues to be used for vector control in some malaria endemic areas. Previous findings from the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) cohort study found increased prenatal levels of DDT and its breakdown product dichlorodiphenyl-dichloroethylene (DDE) to be associated with altered neurodevelopment in children at 1 and 2years of age. In this study, we combined the measured maternal DDT/E concentrations during pregnancy obtained for the prospective birth cohort with predicted prenatal DDT and DDE levels estimated for a retrospective birth cohort. Using generalized estimating equation (GEE) and linear regression models, we evaluated the relationship of prenatal maternal DDT and DDE serum concentrations with children's cognition at ages 7 and 10.5years as assessed using the Full Scale Intelligence Quotient (IQ) and 4 subtest scores (Working Memory, Perceptual Reasoning, Verbal Comprehension, and Processing Speed) of the Wechsler Intelligence Scale for Children (WISC). In GEE analyses incorporating both age 7 and 10.5 scores (n=619), we found prenatal DDT and DDE levels were not associated with Full Scale IQ or any of the WISC subscales (p-value>0.05). In linear regression analyses assessing each time point separately, prenatal DDT levels were inversely associated with Processing Speed at age 7years (n=316), but prenatal DDT and DDE levels were not associated with Full Scale IQ or any of the WISC subscales at age 10.5years (n=595). We found evidence for effect modification by sex. In girls, but not boys, prenatal DDE levels were inversely associated with Full Scale IQ and Processing Speed at age 7years. We conclude that prenatal DDT levels may be associated with delayed Processing Speed in children at age 7years and the relationship between prenatal DDE levels and children's cognitive development may be modified by sex, with girls being more adversely affected.

Exploring the associations between microRNA expression profiles and environmental pollutants in human placenta from the National Children's Study (NCS)

The placenta is the principal regulator of the in utero environment, and disruptions to this environment can result in adverse offspring health outcomes. To better characterize the impact of in utero perturbations, we assessed the influence of known environmental pollutants on the expression of microRNA (miRNA) in placental samples collected from the National Children's Study (NCS) Vanguard birth cohort. This study analyzed the expression of 654 miRNAs in 110 term placentas. Environmental pollutants measured in these placentas included dichlorodiphenyldichloroethylene (DDE), bisphenol A (BPA), polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), arsenic (As), mercury (Hg), lead (Pb), and cadmium (Cd). A moderated t-test was used to identify a panel of differentially expressed miRNAs, which were further analyzed using generalized linear models. We observed 112 miRNAs consistently expressed in >70% of the samples. Consistent with the literature, miRNAs located within the imprinted placenta-specific C19MC cluster, specifically mir-517a, mir-517c, mir-522, and mir-23a, are among the top expressed miRNA in our study. We observed a positive association between PBDE 209 and miR-188–5p and an inverse association between PBDE 99 and let-7c. Both PCBs and Cd were positively associated with miR-1537 expression level. In addition, multiple let-7 family members were downregulated with increasing levels of Hg and Pb. We did not observe DDE or BPA levels to be associated with placental miRNA expression. This is the first birth cohort study linking environmental pollutants and placental expression of miRNAs. Our results suggest that placental miRNA profiles may signal in utero exposures to environmental chemicals.

Novel Chryseobacterium sp. PYR2 degrades various organochlorine pesticides (OCPs) and achieves enhancing removal and complete degradation of DDT in highly contaminated soil

Long term residues of organochlorine pesticides (OCPs) in soils are of great concerning because they seriously threaten food security and human health. This article focuses on isolation of OCP-degrading strains and their performance in bioremediation of contaminated soil under ex situ conditions. A bacterium, Chryseobacterium sp. PYR2, capable of degrading various OCPs and utilizing them as a sole carbon and energy source for growth, was isolated from OCP-contaminated soil. In culture experiments, PYR2 degraded 80–98% of hexachlorocyclohexane (HCH) or 1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane (DDT) isomers (50 mg L−1) in 30 days. A pilot-scale ex situ bioremediation study of highly OCP-contaminated soil augmented with PYR2 was performed. During the 45-day experimental period, DDT concentration was reduced by 80.3% in PYR2-augmented soils (35.37 mg kg−1 to 6.97 mg kg−1) but by only 57.6% in control soils. Seven DDT degradation intermediates (metabolites) were detected and identified in PYR2-augmented soils: five by GC/MS: 1,1-dichloro-2,2-bis (4-chlorophenyl) ethane (DDD), 1,1-dichloro-2,2-bis (4-chlorophenyl) ethylene (DDE), 1-chloro-2,2-bis (4-chlorophenyl) ethylene (DDMU), 1-chloro-2,2-bis (4-chlorophenyl) ethane (DDMS), and dichlorobenzophenone (DBP); and two by LC/MS: 4-chlorobenzoic acid (PCBA) and 4-chlorophenylacetic acid (PCPA). Levels of metabolites were fairly stable in control soils but varied greatly with time in PYR2-augmented soils. Levels of DDD, DDMU, and DDE in PYR2-augmented soils increased from day 0 to day 30 and then decreased by day 45. A DDT biodegradation pathway is proposed based on our identification of DDT metabolites in PYR2-augmented systems. PYR2 will be useful in future studies of OCP biodegradation and in bioremediation of OCP-contaminated soils.

Effect of prolonged exposure to sublethal concentrations of DDT and DDE on protein expression in human pancreatic beta cells

Pollution of the environment represents one of less explored potential reasons for the worldwide epidemic of type 2 diabetes. One of the most prevalent organochlorine pollutants remains the pesticide DDT and its degradation product DDE. Despite some epidemiologic correlations between levels of DDT and DDE in human organism and the prevalence of diabetes, there is almost no information about the exact targets of these compounds inside pancreatic beta cells. To detect functional areas of pancreatic beta cells that could be affected by exposure to DDT and DDE, we analyzed changes in protein expression in the NES2Y human pancreatic beta cell line exposed to three sublethal concentrations (0.1μM, 1μM, 10μM) of DDT and DDE for 1 month. Protein separation and identification was achieved using high-resolution 2D-electrophoresis, computer analysis and mass spectrometry. With these techniques, four proteins were found downregulated after exposure to 10μM DDT: three cytoskeletal proteins (cytokeratin 8, cytokeratin 18 and actin) and one protein involved in glycolysis (alpha-enolase). Two proteins were downregulated after exposure to 10μM DDE: cytokeratin 18 and heterogenous nuclear ribonucleoprotein H1 (HNRH1). These changes correlate with previously described effects of other stress conditions (e.g. exposure to palmitate, hyperglycemia, imidazoline derivative, and cytokines) on protein expression in pancreatic beta cells. We conclude that cytoskeletal proteins and their processing, glucose metabolism, and mRNA processing may represent targets affected by exposure to conditions hostile to pancreatic beta cells, including exposure to DDT and DDE.

Inverse correlation among organochlorine pesticide levels to total lipid serum contents: a preliminary study in Veracruz, México.

Organochlorine pesticides, due to their hydrophobic nature and persistence, accumulate in tissues rich in lipids, which had been used as a biomarker for environmental pollution. In humans, organochlorine pesticides are continuously circulating and equilibrating among body compartments. The objective of the study was to evaluate the concentrations of organochlorine pesticides in blood serum and compare their levels to the total lipid contents in Veracruz, México inhabitants. Our hypothesis is that concentrations of organochlorine pesticides will increase just as lipid concentrations. Levels of organochlorine pesticides were divided in ascending tertils according to their total lipid content. The linear trend model applied surprisingly reveals that the average level of all organochlorine pesticides decreases as the lipid concentration increases. From one tertil to the next β-HCH, it shows a decrease of -3.19mgkg(-1) on lipid basis, pp.'DDE levels decrease by -3.70mgkg(-1) on lipid basis and pp.'DDT levels decrease -1.13mgkg(-1) on lipid basis. We conclude that the levels and the orderly sequence of organochlorine pesticide distributions in the blood serum maintain an inverse relationship to total lipid blood serum concentrations.

Impact of wastewater on fish health: a case study at the Neckar River (Southern Germany) using biomarkers in caged brown trout as assessment tools.

The present work describes a field survey aiming at assessing the impact of a sewage treatment plant (STP) effluent on fish health by means of biomarkers. Indigenous fish were absent downstream of the STP. To elucidate the reason behind this, brown trout (Salmo trutta f. fario) were exposed in floating steel cages up- and downstream of a STP located at the Neckar River near Tübingen (Southern Germany), for 10 and 30 days. A combination of biomarker methods (histopathological investigations, analysis of the stress protein Hsp70, micronucleus test, B-esterase assays) offered the possibility to investigate endocrine, geno-, proteo- and neurotoxic effects in fish organs. Biological results were complemented with chemical analyses on 20 accumulative substances in fish tissue. Even after short-term exposure, biomarkers revealed clear evidence of water contamination at both Neckar River sites; however, physiological responses of caged brown trout were more severe downstream of the STP. According to this, similar bioaccumulation levels (low μg/kg range) of DDE and 12 polycyclic aromatic hydrocarbons (PAHs) were detected at both sampling sites, while up to fourfold higher concentrations of four PAHs, methyl-triclosan and two synthetic musks occurred in the tissues of downstream-exposed fish. The results obtained in this study suggest a constitutive background pollution at both sites investigated at the Neckar River and provided evidence for the additional negative impact of the STP Tübingen on water quality and the health condition of fish.

Survival rate and breeding outputs in a high Arctic seabird exposed to legacy persistent organic pollutants and mercury

Chronic exposure to pollutants may represent a threat for wildlife. We tested whether adult survival rate, breeding probability and breeding success the year of sampling and the following year were affected by blood levels of mercury or persistent organic pollutants in Svalbard black-legged kittiwake Rissa tridactyla, by using capture–mark–recapture models over a five-year period. Survival rate was negatively linked to HCB levels in females, to chlordane mixture and oxychlordane, tended to decrease with increasing PCBs or DDE levels, but was unrelated to mercury. Breeding probability decreased with increasing mercury levels during the sampling year and with increasing CHL or HCB levels during the following year, especially in males observed as breeders. Surprisingly, the probability of raising two chicks increased with increasing HCB levels. Although levels of these legacy pollutants are expected to decline, they represent a potential threat for adult survival rate and breeding probability, possibly affecting kittiwake population dynamics.

Levels of organochlorine pesticides in the blood of people living in areas of intensive pesticide use in Sudan.

Ninety-six human blood samples were collected from six locations that represent areas of intensive pesticide use in Sudan, which included irrigated cotton schemes (Wad Medani, Hasaheesa, Elmanagil, and Elfaw) and sugarcane schemes (Kenana and Gunaid). Blood samples were analyzed for organochlorine pesticide residues by gas liquid chromatography (GLC) equipped with an electron capture detector (ECD). Residues of p,p'-dichlorodiphenyldichloroethylene (DDE), heptachlor epoxide, γ-HCH, and dieldrin were detected in blood from all locations surveyed. Aldrin was not detected in any of the samples analyzed, probably due to its conversion to dieldrin. The levels of total organochlorine burden detected were higher in the blood from people in the irrigated cotton schemes (mean 261 ng ml(-1), range 38-641 ng ml(-1)) than in the blood of people from the irrigated sugarcane schemes (mean 204 ng ml(-1), range 59-365 ng ml(-1)). The highest levels of heptachlor epoxide (170 ng ml(-1)) and γ-HCH (92 ng ml(-1)) were observed in blood samples from Hasaheesa, while the highest levels of DDE (618 ng ml(-1)) and dieldrin (82 ng ml(-1)) were observed in blood samples from Wad Medani and Kenana, respectively. The organochlorine levels in blood samples seemed to decrease with increasing distance from the old irrigated cotton schemes (Wad Medani, Hasaheesa, and Elmanagil) where the heavy application of these pesticides took place historically.

Association between lung function in adults and plasma DDT and DDE levels: results from the Canadian Health Measures Survey.

BackgroundAlthough DDT [1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane] has been banned in many countries since the 1970s, it may still pose a risk to human respiratory health. In agriculture, DDT exposures have been associated with asthma and chronic bronchitis. However, little is known about the effect of DDT on lung function.MethodsWe used data on 1,696 participants 20–79 years of age from the Canadian Health Measures Survey (CHMS) and conducted multiple regression analysis to estimate associations between plasma p,p´-DDT/DDE and lung function.ResultsAlmost all participants (> 99.0%) had detectable concentrations of plasma p,p´-DDE, but only 10.0% had detectable p,p´-DDT. Participants with detectable p,p´-DDT had significantly lower mean FVC (difference = 311 mL; 95% CI: –492, –130; p = 0.003) and FEV1 (difference = 232 mL; 95% CI: –408, –55; p = 0.015) than those without. A 100-ng/g lipid increase in plasma p,p´-DDE was associated with an 18.8-mL decrease in mean FVC (95% CI: –29, –9) and an 11.8-mL decrease in mean FEV1 (95% CI: –21, –3). Neither exposure was associated with FEV1/FVC ratio or FEF25%–75%.ConclusionsDDT exposures, which may have occurred decades ago, were still detectable among Canadians. Plasma DDT and DDE were negatively associated with lung function parameters. Additional research on the potential effects of DDT use on lung function is warranted.CitationYe M, Beach J, Martin JW, Senthilselvan A. 2015. Association between lung function in adults and plasma DDT and DDE levels: results from the Canadian Health Measures Survey. Environ Health Perspect 123:422–427; http://dx.doi.org/10.1289/ehp.1408217

Walrus &lt;i&gt;Odobenus rosmarus&lt;/i&gt; research in Svalbard, Norway, 2000-2010

Herein we report results from studies on walruses in Svalbard conducted in 2000-2010. Data from newly developed satellite relay data loggers (SRDLs) revealed seasonal differences in habitat use of adult male walruses. During winter, they moved into areas of &gt;90% ice concentration, traveling as far as 600 km from ice-free water. Breeding areas deep into the pack ice were identified based on timing of the occupancy and diving behaviour. When the breeding season was over, walruses with SRDLs that were still transmitting locations returned to the coast, showing high site fidelity to the previous year’s summering area. Haul-out data from the SRDLs provided correction factors for an aerial survey of walruses that covered all known haul-out sites within the Svalbard Archipelago. This survey estimated 2,629 (95 % CI; 2,318 – 2,998) walruses to be in Svalbard during August 2006. Blubber biopsies from adult male walruses analyzed for fatty acids (FAs) showed vertical stratification similar to that observed in many other marine mammals. However, differences between layers were less pronounced, possibly because the thick dermis of walruses provides an insulating shield, affecting the FA composition of the outer blubber. The FA composition of the inner blubber most closely resembled the lipids in Mya truncata and Buccinum spp., which are considered the most important walrus prey in Svalbard. A study investigating the use of skin biopsies for assessing levels of organochlorines (OCs) in walruses found a significant relationship between OC levels in skin and blubber. Another contaminant study found a significant decrease in levels of PCBs and DDE in walruses in Svalbard from 1993 to 2002-04. Large inter-individual variation in OC levels was found, although all of the study animals were adult males from roughly the same location. In FA analyses of the inner blubber this variation appeared to be diet-related, with high OC levels having FA compositions in the inner blubber that closely matched seal tissues, while those with low levels matched typical invertebrate prey. Various enzymes, proteins, metabolites, minerals, and hormones were measured in blood samples to serve as baseline data for future health-related studies of both wild and captive walruses. Historical sex-distribution of walruses in southern Svalbard was investigated based on mandible measurements of individuals hunted during the 19th century.The analyses showed that female walruses were once more common in south-eastern Svalbard than they are today.

Derivation of exposure factors for infant lactational exposure to persistent organic pollutants (POPs)

Quantifying the influence of breastfeeding on infant’s dose and biological levels is critical for the risk assessment of persistent organic pollutant (POP) early exposures. We aimed to quantify infants’ exposure relative to the mother for POPs. Using a validated pharmacokinetic model, Monte-Carlo simulations of infants’ exposure during the first 2years of life for POPs of different half-lives (i.e., 1–20years) were performed. Infant:mother (I:M) ratios for dose and biological levels throughout infancy were derived. To evaluate model accuracy, simulated I:M biological level ratios were compared to ratios calculated from Inuit mothers’ and infants’ measured plasma levels of 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB-153), p,p′-dichlorodiphenyldichloroethylene (p,p′-DDE) and hexachlorobenzene (HCB). Practically all measured I:M biological level ratios from the Inuit cohort fell below the 95th percentile of the distributions of simulated PCB-153, p,p′-DDE and HCB levels. Peak I:M dose ratios were observed at the beginning of lactation with 95th percentile values of 13, 53, 84, 102 and 113 for half-lives of 1, 5, 10, 15 and 20years, respectively. In contrast, peak I:M biological level ratios occurred after approximately 1year of breastfeeding and plateaued at approximately 10.5 (95th percentile) for chemicals of half-lives >5years. Simulated I:M dose and biological level ratios could be employed in risk assessment of early POP exposures through breastfeeding.

Concentrations of persistent organic pollutants (POPs) and heavy metals in soil from San Luis Potosí, México.

The aim of this study was to assess the levels of polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs), p,p'-dichlorodiphenyltrichloroethane (DDT), p,p'-dichlorodiphenyldichloroethylene (DDE), and four heavy metals (arsenic, cadmium, lead, and mercury) in soil from the city of San Luis Potosí in Mexico. In order to confirm the presence of the previously mentioned compounds, outdoor surface soil samples were collected and analyzed by gas chromatography/mass spectrometer for PBDEs, PCBs, DDT, and DDE. Meanwhile, heavy metals were quantified using the atomic absorption spectrophotometry technique. The total PBDEs levels ranged from 5.0 to 134 μg/kg dry weight (dw), with a total mean PBDEs level of 22.0 ± 32.5 μg/kg dw (geometric mean ± standard deviation). For PCBs, the total mean level in the studied soil was 21.6 ± 24.7 μg/kg dw (range, <LOD to 80.5). An important finding in our study was that all soil samples (100 %) had detectable levels of the metabolite DDE. Moreover, the total mean DDT level (∑ DDT and DDE) was approximately 5.50 ± 4.50 μg/kg dw. The mean levels for arsenic, mercury, cadmium, and lead in soil samples were 7.20 ± 10.7 (range, 15.0 to 265 mg/kg dw), 0.45 ± 0.48 (range, <LOD to 2.50 mg/kg dw), 3.00 ± 3.00 (range, 1.00-13.0 mg/kg dw), and 108 ± 105 (range, 25.0 to 435 mg/kg dw), respectively. This screening study provides us with concentration data for the occurrence of persistent organic pollutants (POPs) and four heavy metals in soil samples from the city of San Luis Potosí, Mexico, and considering that soil is an important pathway of exposure for people, a biomonitoring program for the surveillance of the general population in the city of San Luis Potosi is necessary.