Charlotte Bergkvist

Exposure to dioxin-like pollutants via different food commodities in Swedish children and young adults

The dietary intake of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) in terms of toxic equivalents (TEQs) was investigated in Swedish children and young adults. Exposure was estimated from concentration data of six groups of individual food commodities (meat, fish, dairy products, egg, edible fats and other foodstuff) combined with food intake data from a 7-day record book obtained from 670 individuals aged 1-24 years. The results showed that Swedish boys and girls, up to the age of ten, had a median TEQ intake that exceeded the tolerable daily intake (TDI) of 2 pg TEQ/kg body weight. Children exceeding the TDI varied from almost all individuals among the youngest children to about 20% among young men and women. Dairy and fish products were the main sources of exposure for the average child, accounting for 59% of the total TEQ intake. The individuals most highly exposed were, on the other hand, characterized by a high consumption of fish. Since children constitute a vulnerable group, results obtained from the present study show that it is essential to perform age specific dietary intake assessments of pollutants and more carefully consider sensitive and/or highly exposed groups in the population in the risk management processes.

Assessment of early-life lead exposure in rural Bangladesh.

Lead is a well-known neurotoxic metal and one of the most toxic chemicals in a childs environment. The aim of this study was to assess early-life lead exposure in a pristine rural area of Bangladesh. The exposure was expected to be very low because of the absence of vehicle traffic and polluting industries. Lead was measured in erythrocytes, urine, and breast milk of 500 randomly selected pregnant women, participating in a randomized food and micronutrient supplementation trial in Matlab (MINIMat). Lead was also measured in urine of their children at 1.5 and 5 years of age, and in rice, well water, cooking pots, and materials used for walls and roof. All measurements were performed using ICPMS. We found that the women had relatively high median erythrocyte lead levels, which increased considerably from early pregnancy to late lactation (81-136microg/kg), probably due to release from bone. Urinary lead concentrations were unchanged during pregnancy (median approximately 3.5microg/L) and non-linearly associated with maternal blood lead levels. Children, at 1.5 and 5 years of age, had a median urinary lead concentration of 4microg/L, i.e., similar to that in their mothers. Rice, the staple food in Matlab, collected from 63 homes of the study sample, contained 1-89microg/kg (median 13microg/kg) dry weight and seems to be an important source of lead exposure. Other sources of exposure may be cooking pots and metal sheet roof material, which were found to release up to 380 and 4200microg/L, respectively, into acidic solutions. Based on breast milk lead concentrations (median 1.3microg/L) a median daily intake of 1.2microg was estimated for 3 months old infants. However, alternatives to breast-feeding are likely to contain more lead, especially rice-based formula. To conclude, lead exposure in women and their children in a remote unpolluted area was found to be surprisingly high, which may be due to their living conditions.

Dietary exposure to polychlorinated biphenyls and risk of myocardial infarction — A population-based prospective cohort study

BACKGROUND Fish consumption may promote cardiovascular health. The role of major food contaminants, such as polychlorinated biphenyls (PCBs) common in fatty fish, is unclear. We assessed the association between dietary PCB exposure and risk of myocardial infarction taking into account the intake of long-chain omega-3 fish fatty acids. METHODS In the prospective population-based Swedish Mammography Cohort, 33,446 middle-aged and elderly women, free from cardiovascular disease, cancer and diabetes at baseline (1997) were followed-up for 12 years. Validated estimates of dietary PCB exposure and intake of fish fatty acids (eicosapentaenoic acid and docosahexaenoic acid; EPA-DHA) were obtained via a food frequency questionnaire at baseline. RESULTS During follow-up 1386 incident cases of myocardial infarction were ascertained through register-linkage. Women in the highest quartile of dietary PCB exposure (median 286 ng/day) had a multivariable-adjusted RR of myocardial infarction of 1.21 (95% confidence interval [CI], 1.01-1.45) compared to the lowest quartile (median 101 ng/day) before, and 1.58 (95% CI, 1.10-2.25) after adjusting for EPA-DHA. Stratification by low and high EPA-DHA intake, resulted in RRs 2.20 (95% CI, 1.18-4.12) and 1.73 (95% CI, 0.81-3.69), respectively comparing highest PCB tertile with lowest. The intake of dietary EPA-DHA was inversely associated with risk of myocardial infarction after but not before adjusting for dietary PCB. CONCLUSION Exposure to PCBs was associated with increased risk of myocardial infarction, while some beneficial effect was associated with increasing EPA and DHA intake. To increase the net benefits of fish consumption, PCB contamination should be reduced to a minimum.

Dietary exposure to polychlorinated biphenyls is associated with increased risk of stroke in women

The potentially beneficial effects of fish consumption on stroke may be modified by major food contaminants in fish. Polychlorinated biphenyls (PCBs) in particular are proposed to play a role in the aetiology of stroke. The aim of this study was to assess the association between dietary PCB exposure and stroke risk with the intake of long‐chain omega‐3 fish fatty acids and fish consumption.

Validation of questionnaire-based long-term dietary exposure to polychlorinated biphenyls using biomarkers

SCOPE The health consequences of lifelong low-level exposure to polychlorinated biphenyls (PCBs) via food are largely unknown, mainly due to the lack of large population-based prospective studies addressing this issue. We validated long-term food frequency questionnaire (FFQ)-based dietary PCB exposure against concentrations of six PCB congeners in serum. METHODS AND RESULTS Dietary PCB exposure was estimated in the Swedish Mammography Cohort by constructing a recipe-based database of CB-153, an indicator for total PCBs in food. The Spearman rank correlation (adjusted for within-person variability) was assessed between concurrent (2004-2006), past (1997), and long-term (mean of 1997 and 2004-2006) FFQ-based dietary PCB exposure, respectively, and the following serum PCB congeners, CB-118, CB-138, CB-153, CB-156, CB-170, and CB-180, in women (56-85 years of age, n = 201). The correlation between FFQ-based dietary PCB exposure and serum CB-153 was 0.41 (p < 0.001) for the concurrent (median 1.6 ng/kg body weight) and 0.34 (p < 0.05) for the past (median 2.6 ng/kg body weight) exposure assessment. Long-term validity of FFQ-based PCB estimates and the six serum PCB congeners ranged from 0.30 to 0.58 (p < 0.05). CONCLUSION FFQ-based PCB exposure estimates show acceptable validity in relation to PCB concentrations in serum, justifying their use in large-scale epidemiological studies.

Cadmium in diet and risk of cardiovascular disease in women.

Background: The toxic metal cadmium is suggested to increase the risk of cardiovascular disease, but only one incidence study has explored this association. We evaluated the association between quartiles of food frequency questionnaire–based estimates of cadmium exposure from food (the predominant source of exposure to the metal) and incident cardiovascular disease and its subtypes. Methods: From the population-based Swedish Mammography cohort, 33,333 women were followed prospectively from baseline (1997) through 2010. We estimated relative risks (RRs) with 95% confidence intervals (CIs) using Cox proportional hazard models. Results: During 12 years of follow-up, we identified 3155 incident cases of total cardiovascular disease (1322 cases of myocardial infarction and 1833 cases of total stroke [1485 ischemic and 208 hemorrhagic stroke]). Dietary cadmium exposure was not associated with risk of total cardiovascular disease, myocardial infarction, or total stroke or its subtypes. For total cardiovascular disease, the multivariable-adjusted RR comparing the highest quartile of cadmium exposure with the lowest was 0.96 (95% CI = 0.85–1.09). The corresponding RRs were 1.07 (0.88–1.29) for myocardial infarction, 0.90 (0.76–1.05) for total stroke, 0.89 (0.74–1.06) for ischemic stroke, and 1.11 (0.68–1.80) for hemorrhagic stroke. Conclusions: Our study lends no support to an overall association between low-level exposure to cadmium via food and incident cardiovascular disease.

Dietary exposure to polychlorinated biphenyls and risk of myocardial infarction in men - A population-based prospective cohort study.

BACKGROUND Major food contaminants such as polychlorinated biphenyls (PCBs) are proposed to play a role in the etiology of cardiovascular disease (CVD), but to date the impact of PCBs on cardiovascular health need to be explored. METHODS AND RESULTS We assessed the association between validated food frequency questionnaire-based estimates of dietary PCB exposure and risk of myocardial infarction, ascertained through register-linkage, among 36,759 men from the population-based Swedish Cohort of Men, free of cardiovascular disease, diabetes and cancer at baseline (1997). Relative risks were adjusted for known cardiovascular risk factors, long-chain omega-3 fatty acids (eicosapentaenoic and docosahexaenoic acids) and methyl mercury exposure. During 12years of follow-up (433,243 person-years), we ascertained 3005 incident cases of myocardial infarction (654 fatal). Compared with the lowest quintile of dietary PCB exposure (median 113ng/day), men in the highest quintile (median 436ng/day) had multivariable-adjusted relative risks of 1.74 (95% confidence interval [CI], 1.30-2.33; p-trend<0.001) for total and 1.97 (95% CI 1.42-2.75; p-trend<0.001) for non-fatal myocardial infarction. In mutually adjusted models, dietary PCB exposure was associated with an increased risk of myocardial infarction, while the intake of long-chain omega-3 fish fatty acids was associated with a decreased risk. We also observed an effect modification by adiposity on the association between of dietary PCB exposure and myocardial infarction, with higher risk among lean men (p value for interaction =0.03). CONCLUSIONS Exposure to PCBs via diet was associated with increased risk of myocardial infarction in men.

A probabilistic approach for estimating infant exposure to environmental pollutants in human breast milk.

Effective risk assessment and management are often hampered by a lack of reliable exposure data. The probabilistic exposure assessment approach takes into account individual variations in exposure, and thus, overly conservative estimates based on worst case scenarios can be avoided. The aim was to provide reliable information on the intake of non-dioxinlike (NDL) and dioxinlike PCBs, PCDDs and PCDFs in breastfed infants and their mothers during 2000-2006. Hence, a probabilistic model was developed to estimate the exposure and compare it with a deterministic exposure assessment approach. The estimated probabilistic mean intake in 1, 3 and 6 months old infants was 44, 31 and 17 pg total-TEQ/kg bw per day, and 418, 294 and 165 ng NDL-PCBs/kg bw per day, respectively. Intakes differed up to 41% between the upper-bound percentiles of the probabilistic approach and the deterministic worst case scenario approach, whereas no difference in mean values was observed between the two approaches. The median cumulative intake increased during 6 months of breastfeeding to 20 ng total-TEQ and 352 μg NDL-PCBs. There was a significant temporal decrease in infant exposure during 2000-2006 (30%). Less than 4% of the mothers had an intake exceeding the TDI of 2 pg TEQ/kg bw per day (median: 1.2 pg total-TEQ/kg bw). To conclude, by use of a probabilistic approach and biomonitoring data we were able to calculate reliable estimates of infant exposure to environmental pollutants and the daily intakes of the nursing mothers using the same data.