Persistent organic pollutants (POPs) and metals in primiparous women: a comparison from Canada and Mexico.

Under the North American Commission for Environmental Cooperation (CEC) and its Sound Management of Chemicals (SMOC) program, a tri-national human contaminant monitoring initiative was completed to provide baseline exposure information for several environmental contaminants in Canada, Mexico and the United States (U.S). Blood samples were collected from primiparous women in Canada and Mexico, and were analysed for a suite of environmental contaminants including polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene(p,p'-DDE),beta-hexachlorocyclohexane (ß-HCH), mercury and lead. A multiple stepwise linear regression analysis was conducted using data from Canadian and Mexican primiparous mothers, adjusting for ethnicity group, age, pre-pregnancy BMI, years at current city and ever-smoking status. Concentrations of p,p'-DDE, ß-HCH, and lead were found to be higher among Mexican participants; however, concentrations of most PCBs among Mexican participants were similar to Canadian primiparous women after adjusting for covariates. Concentrations of total mercury were generally higher among Mexican primiparous women although this difference was smaller as age increased. This initial dataset can be used to determine priorities for future activities and to track progress in the management of the selected chemicals, both domestically and on a broader cooperative basis within North America.

Sampling criteria for identifying human biomonitoring chemical differences in the Canadian Arctic.

Human biomonitoring studies in the Canadian Arctic have measured a wide range of metals and persistent organic pollutants in Aboriginal and non-Aboriginal mothers during two time periods in the Northwest Territories and Nunavut. This analysis provides preliminary estimates on sample sizes and sampling frequencies required to measure significant changes in maternal blood concentrations for PCB 153 and total mercury. For example, sample sizes of 35-40 mothers permit the detection of a 40% decrease in these chemical concentrations between two groups (e.g. communities or regions). Improvements in method sensitivity can be achieved by on-going sampling over multiple time periods (e.g. 4 or 5) in these regions, or increasing sample sizes.

Comparing plasma concentrations of persistent organic pollutants and metals in primiparous women from northern and southern Canada.

The exposure of Aboriginal peoples in the Canadian Arctic to persistent organic pollutants (POPs) and metals through the consumption of traditional food items is well recognized; however, less information is available for Canadian immigrants. The direct comparison of blood chemical concentrations for expectant primiparous women sampled in the Inuvik and Baffin regions of the Canadian Arctic, as well as Canadian- and foreign-born women from five southern Canadian centers (Halifax, Vancouver, Hamilton, Ottawa, and Calgary), provides relative exposure information for samples of northern and southern mothers in Canada. Based on our analyses, Canadian mothers are exposed to a similar suite of contaminants; however, Inuit first birth mothers residing in the Canadian Arctic had higher age-adjusted geometric mean concentrations for several legacy POPs regulated under the Stockholm Convention, along with lead and total mercury. Significant differences in exposure were observed for Inuit mothers from Baffin who tended to demonstrate higher blood concentrations of POPs and total mercury compared with Inuit mothers from Inuvik. Conversely, northern mothers showed a significantly lower age-adjusted geometric mean concentration for a polybrominated diphenyl ether (PBDE-153) compared to southern mothers. Furthermore, southern Canadian mothers born outside of Canada showed the highest individual concentrations measured in the study: 1700 µg/kg lipids for p,p'-dichlorodiphenyldichloroethylene (p,p'-DDE) and 990 µg/kg lipids for ß-hexachlorocyclohexane (ß-HCH). Data from Cycle 1 (2007-2009) of the nationally-representative Canadian Health Measures Survey (CHMS) places these results in a national biomonitoring context and affirms that foreign-born women of child-bearing age experience higher exposures to many POPs and metals than their Canadian-born counterparts in the general population.

Brominated flame retardant concentrations in sera from the Canadian Health Measures Survey (CHMS) from 2007 to 2009.

Pooling of surplus serum from individual samples, collected between 2007 and 2009 during Cycle 1 of the Canadian Health Measures Survey (CHMS), was performed to develop a national baseline estimate of brominated flame retardants in Canadians. Serum samples were categorized by sex and distributed by five age groups ranging from 6 to 79years. Nearly 5000 (4583) serum samples were used to form 59 composite pools. Serum pools were created to ensure a high detection frequency of these analytes in serum because low volume samples had previously resulted in non-detectable concentrations. The analytes of interest in these serum pools included 23 polybrominated diphenyl ethers (PBDEs) and three hexabromocyclododecane (HBCD) isomers (α-, ß- and γ-HBCD). PBDEs were observed in all samples tested and total PBDE concentrations ranged from 27ngg(-1) lipid to 130ngg(-1) lipid (geometric mean [GM] 46ngg(-1) lipid). ∑PBDE concentrations were significantly elevated in samples representing the 6-11year old age group (GM 65ngg(-1) lipid) relative to ages above 40years, although no difference in concentration was observed between the sexes. PBDE concentrations in Canadian sera from the general population were higher than reported in Europe and Asia, but a little lower than observed in the US. PBDE 47 was the greatest contributor to ∑PBDE concentrations and the GM concentration for this congener was 22ngg(-1) lipid. The other dominant contributors to ∑PBDE concentrations were in descending order: 153 [GM 9.4ngg(-1) lipid]>99 [GM 4.6ngg(-1) lipid]≅100 [GM 4.1ngg(-1) lipid]>209 [GM 1.1ngg(-1) lipid] and 183 [GM 0.42ngg(-1) lipid]. ∑HBCD was detected in all samples analysed, although most samples were observed at concentrations <1ngg(-1) lipid, similar to global concentrations. α-HBCD was the dominant contributor to ∑HBCD concentrations in Canadians although ß- and γ-HBCD were detected in 23% and 35% of the samples, respectively. No differences in ∑HBCD concentration were associated with age or sex. This dataset represents the first national data describing HBCD isomers and some PBDEs (e.g., 183, 209) in Canadians.

Circulating metals and persistent organic pollutant concentrations in Canadian and non-Canadian born primiparous women from five Canadian centres: results of a pilot biomonitoring study.

The developing foetus is thought to be at increased risk from exposure to environmental contaminants; however, developmental exposure data is notably lacking for many contaminants. Moreover, potential regional differences or effect of place of birth on residue levels measured in pregnant women is also unknown. Therefore, as part of a multinational biomonitoring study, 125 primiparous pregnant Canadian women were recruited from five Canadian centres (Vancouver, Calgary, Hamilton, Ottawa, and Halifax). Metals in whole blood and persistent organic pollutants (POPs) in plasma were measured by inductively coupled plasma mass spectrometry (ICPMS) and gas chromatography-mass spectrometry (GCMS), respectively. Of the 125 women recruited to this study, complete data sets were available for 123 of which 103 were Canadian born. Data were analysed by analysis of covariance and linear mixed models using age and body mass index as covariates. The metals cadmium (Cd), cobalt (Co), lead (Pb), nickel (Ni), selenium (Se), and total mercury (Hg) were detected in more than 93% of the samples tested. ß-Hexachlorohexane (ß-HCH), oxychlordane, trans-nonachlor, 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE), polybrominated diphenyl ether (PBDE) congeners (PBDE-153, PBDE-47), polychlorinated biphenyl (PCB) congeners (PCB-138, -153, and -180), and the dioxin-like PCB congener PCB-118 were quantified in greater than 70% of the samples tested. Significant differences in the concentrations of Cd, Ni, PCB-153, and p,p'-DDE were found between the centres studied. Furthermore, foreign-born pregnant women had significantly higher concentrations of Cd, ß-HCH, PBDE-47, PCB-138, -153, -180, and p,p'-DDE compared to Canadian born pregnant women. Taken together, the data suggest that there are potential regional differences in contaminant body burden and place of birth may also contribute to differences in maternal residue concentrations.

PCDD/F and PCB concentrations in sera from the Canadian Health Measures Survey (CHMS) from 2007 to 2009.

In order to establish a national baseline estimate of the concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in Canadians, pooling of individual human sera was performed to ensure that a high frequency of detectable concentrations of analytes would be achieved. Nearly 5000 (4583) sera samples from Cycle 1 of the Canadian Health Measures Survey (CHMS) collected between 2007 and 2009 were used to form 59 composite pools of approximately 25 mL each. Pools were categorized by sex and age with participants ranging from 6 to 79 years. The pooled samples were analysed for 17 PCDD/Fs and 36 PCB congeners, and from these data, total toxic equivalent concentrations (TEQ(2005 PCDD/F+Dioxin-like [DL]-PCB)) were estimated. The average 2,3,7,8 tetrachlorodibenzodioxin (TCDD) concentration was <1 pg g⁻¹ on a lipid extractable basis. The average total TEQ(2005 PCDD/F+DL-PCB) was 11 pg TEQ g⁻¹ lipid and average ΣPCB concentrations were about 100 ng g⁻¹ lipid. Sex did not affect the concentrations, while PCB and PCDD/F concentrations were positively correlated with age (p<0.001). It appeared in some cases that the age group 6-11 years had higher concentrations of these persistent organic pollutants (POPs) than the concentrations observed in 12-19 year olds, however, the results were not statistically significant based on pair-wise comparisons. Concentration levels and patterns observed in this study of Canadians were similar to those reported in the US and European populations.

Persistent organic pollutant concentrations in first birth mothers across Mexico.

This project was initiated by the North America Commission for Environmental Cooperation (CEC). Its main purpose was to obtain an initial profile on pregnant woman's exposure to persistent organic pollutants (POPs) in North America (Canada, the United States and Mexico). Persistent organic pollutants are transferred to the fetus via the placenta during the pregnancy or to the infant via maternal milk; therefore, the pregnant woman's body burden is important because of the higher exposures and potential health effects in the fetus and infant. This paper presents the results from 240 pregnant women in 10 Mexican cities, and includes the concentrations of various POPs such as polychlorinated biphenyls (PCBs), organochlorine pesticides and polychlorinated dibenzo dioxins and furans (PCDDs and PCDFs) in maternal plasma. We found concentrations of p,p'-DDE in maternal samples from Coatzacoalcos to be ∼60% higher than those found in Ciudad Obregon, which had the second highest concentration. Pregnant women from Merida had higher mean concentrations of PCBs than all women in other regions. Results for PCDDs and PCDFs plus dioxin-like PCBs data were only available on the basis of composite samples, and their concentrations are similar in most cities except for Coatzacoalcos, which had more than double the concentration found in other cities. Although this study provides useful information on the variability of POPs in specific populations and possible regional/local differences, these results cannot be generalized to the entire Mexican population because of differences in age, gender, sources of exposure and nonrandom nature of the sample.

Lead and bisphenol A concentrations in the Canadian population.

BACKGROUND: Lead is a known toxicant that occurs naturally in the environment. Bisphenol A (BPA) is an industrial chemical used primarily in polycarbonate plastic and epoxy resins. It has been 30 years since lead exposure was measured at a national level, and it is the first time for a national assessment of BPA exposure. DATA AND METHODS: Data are from the 2007-2009 Canadian Health Measure Survey. Lead in whole blood (PbB) and urinary BPA were measured in 5319 and 5476 respondents aged 6 to 79, respectively. Geometric means (GMs) are presented by age group and sex for PbB (pg/dL), volume-based BPA (microg/L), and creatinine-standardized BPA (microg/g creatinine). Adjusted least squares geometric means (LSGMs) for PbB and BPA are presented by selected covariates. RESULTS: PbB was detected in 100% of the population, with a GM concentration of 1.34 microg/dL. Adults aged 60 to 79 and males had significantly higher GM PbB concentrations. Lower household income, being born outside Canada, living in a dwelling at least 50 years old, current or former smoking, and drinking alcohol at least once a week were associated with higher PbB concentrations. Urinary BPA was detected in 91% of the population, with a GM concentration of 1.16 microg/L (1.40 microg/g creatinine). Children aged 6 to 11 had significantly higher GM creatinine-standardized BPA concentrations than did other age groups. INTERPRETATION: Although PbB concentrations have declined dramatically since the 1970s, socio-demographic characteristics, the age of dwellings, and certain lifestyle behaviours are associated with higher levels. Given the short half-life of orally ingested BPA and the high frequency of detection, the CHMS data suggest continual widespread exposure in the Canadian population.

Maternal and umbilical cord blood levels of mercury, lead, cadmium, and essential trace elements in Arctic Canada.

Maternal and umbilical cord blood levels of mercury (Hg), lead (Pb), cadmium (Cd), and the trace elements copper (Cu), zinc (Zn), and selenium (Se) are reported for Inuit, Dene/Métis, Caucasian, and Other nonaboriginal participants from Arctic Canada. This is the first human tissue monitoring program covering the entire Northwest Territories and Nunavut for multiple contaminants and establishes a baseline upon which future comparisons can be made. Results for chlorinated organic pesticides and PCBs for these participants have been reported elsewhere. Between May 1994 and June 1999, 523 women volunteered to participate by giving their written informed consent, resulting in the collection of 386 maternal blood samples, 407 cord samples, and 351 cord:maternal paired samples. Geometric mean (GM) maternal total mercury (THg) concentrations ranged from 0.87 microg/L (SD = 1.95) in the Caucasian group of participants (n = 134) to 3.51 microg/L (SD = 8.30) in the Inuit group (n = 146). The GM of the Inuit group was 2.6-fold higher than that of the Dene/Métis group (1.35 microg/L, SD = 1.60, n = 92) and significantly higher than those of all other groups (P<0.0001). Of Inuit women participants, 3% (n = 4) were within Health Canada's level of concern range (20-99 microg/L) for methylmercury (MeHg) exposure. Of Inuit and Dene/Métis cord samples, 56% (n = 95) and 5% (n = 4), respectively, exceeded 5.8 microg/L MeHg, the revised US Environmental Protection Agency lower benchmark dose. GM maternal Pb was significantly higher in Dene/Métis (30.9 microg/L or 3.1 microg/dL; SD = 29.1 microg/L) and Inuit (31.6 microg/L, SD = 38.3) participants compared with the Caucasian group (20.6 microg/L, SD = 17.9) (P < 0.0001). Half of all participants were smokers. GM blood Cd in moderate smokers (1-8 cigarettes/day) and in heavy smokers (> 8 cigarettes/day) was 7.4-fold higher and 12.5-fold higher, respectively, than in nonsmokers. The high percentage of smokers among Inuit (77%) and Dene/Métis (48%) participants highlights the need for ongoing public health action directed at tobacco prevention, reduction, and cessation for women of reproductive age. Pb and THg were detected in more than 95% of all cord blood samples, with GMs of 21 microg/L and 2.7 microg/L, respectively, and Cd was detected in 26% of all cord samples, with a GM of 0.08 microg/L. Cord:maternal ratios from paired samples ranged from 0.44 to 4.5 for THg, from 0.5 to 10.3 for MeHg, and 0.1 to 9.0 for Pb. On average, levels of THg, MeHg, and Zn were significantly higher in cord blood than in maternal blood (P < 0.0001), whereas maternal Cd, Pb, Se, and Cu levels were significantly higher than those in cord blood (P < 0.0001). There was no significant relationship between methylmercury and selenium for the range of MeHg exposures in this study. Ongoing monitoring of populations at risk and traditional food species, as well as continued international efforts to reduce anthropogenic sources of mercury, are recommended.

Contaminants in Canadian arctic biota and implications for human health: conclusions and knowledge gaps.

This paper summarizes the major findings of the special issue entitled "Contaminants in Canadian Arctic Biota and Implications for Human Health." The individual papers and reviews in this special issue present a large amount of new information on contaminants in biota primarily from the Canadian arctic as well as from Alaska, Greenland and the European Arctic. Temporal and spatial trends are examined and potential biological effects on wildlife are assessed. The special issue also presents new and updated data on human exposure to and possible health effects of current levels of environmental contaminants in the Canadian Arctic. As part of the assessment of the human health implications, the unique structures and processes that have developed in the Canadian Arctic under the Northern Contaminants Program (NCP) of Indian and Northern Affairs Canada to build partnerships and manage and communicate the benefits and risks associated with contaminant exposure are discussed. Application of this information in international forums to reduce anthropogenic emissions of contaminants to the environment is also discussed.

Organochlorine levels in maternal and umbilical cord blood plasma in Arctic Canada.

A baseline for exposure to organochlorine and metal contaminants has been established for mothers and newborns in the Northwest Territories and Nunavut areas of Arctic Canada. Maternal and umbilical cord blood plasma organochlorine levels are described for Inuit, Dene, Métis, Caucasian and Other non-Aboriginal participants. Overall, 523 women volunteered to participate by giving their written informed consent between May 1994 and June 1999, resulting in the collection of 386 maternal blood samples, 407 cord blood samples and 351 maternal/cord pairs. Nearly half of all the participants regularly smoked cigarettes, including 77% of the Inuit participants. Maternal and cord results are presented for PCBs (as Aroclor 1260 and 14 congeners) and organochlorine pesticides, including p,p'-DDT, p,p'-DDE, beta-hexachlorocyclohexane (beta-HCH), hexachlorobenzene (HCB), cis and trans nonachlor, heptachlor epoxide, oxychlordane, mirex, dieldrin and toxaphene. Maternal PCB levels (as Aroclor 1260) averaged 4.42 (+/-9.03) microg/l in Inuit, which was 3.3 times higher than those found in Dene/Métis, and 3.4 times higher than levels in Caucasians. Mean DDE levels were 2.8 times higher in the Other non-Aboriginal group (Chinese, Filipino, East Indian and multiple ethnicity) than in the Inuit group, at 3.99 microg/l and 1.42 microg/l, respectively. Cord blood PCB levels (as Aroclor 1260) averaged 1.16 (+/-2.42) microg/l for Inuit participants, which was 3.3-4 fold higher than the other ethnic groups. PCBs, p,p'-DDE and hexachlorobenzene were detected in all maternal samples, and p,p'-DDE was detected in all cord samples. Regression coefficients for maternal/cord pairs are presented for selected organochlorines. Other results from this study, including maternal and cord metals data, will be presented elsewhere.