Halina B. Rollin

The placenta as a barrier for toxic and essential elements in paired maternal and cord blood samples of South African delivering women

Environmental toxicants such as metals may be detrimental to foetus and infant development and health because of their physiological immaturity, opportunistic and differential exposures, and a longer lifetime over which disease, initiated during pregnancy and in early life, can develop. The placental mechanisms responsible for regulation of absorption and excretion of elements during pregnancy are not fully understood. The aim of this paper is to assess the correlation for selected toxic and essential elements in paired whole blood samples of delivering women and cord blood, as well as to evaluate the placental permeability for selected elements. Regression analyses used to assess this correlation in 62-paired samples of maternal and cord whole blood of delivering women show that the concentrations of mercury, lead, cobalt, arsenic and selenium in maternal and cord blood differed statistically. Lead, cobalt, arsenic and selenium appear to pass the placental barrier by a diffusion mechanism. It was also found that the mercury levels in cord blood were almost double those of the mother, suggesting that the foetus may act as a filter for the maternal mercury levels during pregnancy. Transplacental transfer for arsenic and cobalt was 80% and 45%, respectively, suggesting that the placenta modulates the rate of transfer for these elements. Cadmium, manganese, copper and zinc levels did not show statistically significant correlations between two compartments (maternal versus cord whole blood). The study confirms that most of the toxic metals measured have an ability to cross the placental barrier.

Perfluorinated compounds in maternal serum and cord blood from selected areas of South Africa: results of a pilot study.

There is limited information about both environmental and human perfluorinated compounds (PFCs) concentrations in the southern hemisphere, and for the first time, concentrations of these compounds are reported in maternal serum and cord blood of South African women. The majority of the participants were of African Black ethnicity, with a similar socioeconomic status. In maternal serum perfluorooctane sulfonate (PFOS) was found to be the most abundant PFC (1.6 ng mL(-1)), followed by perfluorooctanoate (PFOA: 1.3 ng mL(-1)) and perfluorohexane sulfonate (PFHxS: 0.5 ng mL(-1)); however, in cord blood PFOA was the most abundant compound (1.3 ng mL(-1)) followed by PFOS (0.7 ng mL(-1)) and PFHxS (0.3 ng mL(-1)). Linear PFOS constituted 58% of the sum of PFOS, comparable with a reported percentage from Australia. Differences in PFC concentrations between communities were found, with the highest concentrations in urban and semi-urban areas. The median maternal PFOS concentration was lower than has been reported in other studies, whereas the PFOA concentration was the same. This clearly indicates that the exposure pathway is different from the western world. Significant differences in housing quality were observed and the urban and sub-urban community had the highest living and housing standards. Possible exposure pathways could be different from those elucidated in the western world with the exception of the urban community in our study that showed higher living standards in general and easier access to modern consumer products.

Concentration of selected persistent organic pollutants in blood from delivering women in South Africa

Environmental exposure to persistent organic pollutants (POPs) may cause detrimental health effects in the population with the developing foetus and infants being at highest risk. This paper reports on the findings of the pilot study that took place in seven geographical regions of South Africa, 96 pregnant women admitted for delivery participated in the study. The following selected POPs were analysed in maternal plasma: 15 polychlorinated biphenyls (PCBs) congeners (IUPAC No. 28, 52, 99, 101, 105, 118, 138, 149, 153, 156, 170, 180, 183, 187, 194); six DDT metabolites (dichlordiphenyltrichloroethane p,p-DDT and o,p-DDT; diphenyldichloroethylene p,p-DDE and o,p-DDE, dichlorophenylethane p,p-DDD o,p-DDD) and other pesticides such as hexachlorocyclohexanes (alpha-HCH, beta-HCH, gamma-HCH), hexachlorobenzene (HCB), heptachlor, chlordanes (t-CD and c-CD), nanochlors (t-NC and c-NC) and mirex. The overall results showed large regional differences with the rural site having the lowest levels for all measured contaminants. The levels of PCB congeners were found to be low in all samples and across all sites. DDT metabolites were detected in most participants of this study and large regional differences were evident. Two malaria endemic sites, where indoor residual spraying (IRS) with DDT takes place to control malaria vector, were included in the study. The highest levels of DDTs were measured in the coastal malaria site (Indian Ocean) with geometric means of 5177 ng/g lipid and 1797 ng/g lipid for p,p-DDE and p,p-DDT, and 1966 ng/g lipid and 726 ng/g lipid for p,p-DDE and p,p-DDT in inland malaria site. gamma-HCH was found to be elevated overall, except for the urban community; the highest levels were measured in the inland and coastal malaria sites. p,p-DDT and gamma-HCH were however not correlated, indicating different sources. The high DDT levels in the malaria spraying regions as well as the elevated gamma-HCH levels are of concern and call for extended monitoring of women and children in selected regions.

Levels of toxic and essential metals in maternal and umbilical cord blood from selected areas of South Africa—results of a pilot study

This pilot study uses concentrations of metals in maternal and cord blood at delivery, in seven selected geographical areas of South Africa, to determine prenatal environmental exposure to toxic metals. Samples of maternal and cord whole blood were analysed for levels of cadmium, mercury, lead, manganese, cobalt, copper, zinc, arsenic and selenium. Levels of some measured metals differed by site, indicating different environmental pollution levels in the regions selected for the study. Mercury levels were elevated in two coastal populations studied (Atlantic and Indian Ocean sites) with mothers from the Atlantic site having the highest median concentration of 1.78 microg/L ranging from 0.44 to 8.82 microg/L, which was found to be highly significant (p < 0.001) when compared to other sites, except the Indian Ocean site. The highest concentration of cadmium was measured in maternal blood from the Atlantic site with a median value of 0.25 microg/L (range 0.05-0.89 microg/L), and statistical significance of p < 0.032, when compared to all other sites studied, and p < 0.001 and p < 0.004 when compared to rural and industrial sites respectively, confounding factor for elevated cadmium levels was found to be cigarette smoking. Levels of lead were highest in the urban site, with a median value of 32.9 microg/L (range 16-81.5 microg/L), and statistically significant when compared with other sites (p < 0.003). Levels of selenium were highest in the Atlantic site reaching statistical significance (p < 0.001). All analysed metals were detected in umbilical cord blood samples and differed between sites, with mercury being highest in the Atlantic site (p < 0.001), lead being highest in the urban site (p < 0.004) and selenium in the Atlantic site (p < 0.001). To the best of our knowledge this pilot investigation is the first study performed in South Africa that measured multiple metals in delivering mothers and umbilical cord blood samples. These results will inform the selection of the geographical sites requiring further investigation in the main study.

Prenatal exposure to DDT in malaria endemic region following indoor residual spraying and in non-malaria coastal regions of South Africa☆

Exemption was granted by the Stockholm Convention in 2004 for use of DDT by indoor residual spraying (IRS) as a malaria vector control. South Africa endorsed the use of DDT in its Malaria Control Programmes in malaria endemic regions and IRS remains a primary method of controlling malaria transmitting mosquitoes in this country. This study examines the impact of IRS on the levels of DDT and its metabolites in maternal blood of delivering women as a measure of prenatal exposure. We report on the concentrations of DDT and its metabolites (p,p- DDE, p,p-DDT, o,p-DDE, o,p-DDD, p,p-DDD, and o,p-DDT) in maternal plasma of 255 delivering women residing in three sites along Indian Ocean, namely in malaria endemic where IRS takes place, low risk and non-malaria sites. Concentrations of measured compounds were found to be significantly higher in the malaria endemic site (p=0.0001): the geometric mean concentration (95% confidence intervals; n=91) for o,p-DDE was 9 ng/g lipids (7-10); for p,p-DDE, 3840 ng/g lipids (3008-4902); for o,p-DDD, 8 ng/g lipids (6-9); for p,p-DDD, 26 ng/g lipids (20-32); for o,p-DDT, 168 ng/g lipids (127-221) and for p,p-DDT, 2194 ng/g lipids (1706-2823). These compounds were also detected in women residing in other sites but in lower concentrations. The maternal characteristics, age, IRS, number of children and breastfeeding were significantly associated for both p,p-DDE and p,p-DDT levels in the malaria area where exposure through IRS is predominant. There was no association between maternal characteristics and DDT levels in the low risk and non-malaria area. Results presented are of particular value to the policy decision makers and regulatory toxicology organizations as they characterise the extent of controlled exposure to DDT used exclusively for IRS purposes. Furthermore, findings of this study will form a base for further investigation of foetal exposure to pollutants.

Levels of selected persistent organic pollutants in blood from delivering women in seven selected areas of São Paulo State, Brazil

Persistent organic pollutants (POPs) present in the living environment are thought to have detrimental health effects on the population, with pregnant women and the developing foetus being at highest risk. We report on the levels of selected POPs in maternal blood of 155 delivering women residing in seven regions within the São Paulo State, Brazil. The following selected POPs were measured in the maternal whole blood: 12 polychlorinated biphenyls (PCBs) congeners (IUPAC Nos. 99, 101, 118, 138, 153, 156, 163, 170, 180, 183, 187, 194); dichlordiphenyltrichloroethane p,p-DDT, diphenyldichloroethylene p,p-DDE and other pesticides such as hexachlorocyclohexanes (α-HCH, β-HCH, γ-HCH), hexachlorobenzene (HCB), chlordane derivatives cis-chlordane, trans-chlordane, oxy-chlordane, cis-nonachlor and trans-nonachlor. Statistical comparisons between regions were performed only on compounds having concentrations above LOD in 70% of the samples. PCB118 congener was found to be highest in the industrial site (mean 4.97 ng/g lipids); PCB138 congener concentration was highest in the Urban 3 site (mean 4.27 ng/g lipids) and congener PCB153 was highest in the industrial and Urban 3 sites with mean concentration of 7.2 ng/g lipids and 5.89ng/g lipids respectively. Large differences in levels of p,p-DDE between regions were observed with the Urban 3 and industrial sites having the highest concentrations of 645 ng/g lipids and 417 ng/g lipids, respectively; β-HCH was found to be highest in the Rural 1 site; the γ-HCH in Rural 1 and industrial; the HCB in the Rural 1 and industrial sites and oxy-chlordane and t-NC in the Rural 2 sites. An association between levels of some contaminants and maternal age and parity was also found.

Prenatal Exposure to Cadmium, Placental Permeability and Birth Outcomes in Coastal Populations of South Africa.

Background The impact of prenatal exposure to cadmium (Cd) on birth outcomes is an area of concern. This study aimed to assess an impact of prenatal Cd exposure on birth outcomes in distinct coastal populations of South Africa. Methods Cadmium was measured in maternal blood (CdB) (n = 641), cord blood and in maternal urine (n = 317). This investigation assessed the associations between CdB (non-transformed) and birth outcomes across the 25th, 50th, and 75th percentile for birth weight, birth length and head circumference, to test for a linear trend. Associations between natural log-transformed maternal CdB, size at birth and other factors were further evaluated using linear mixed-effects modelling with random intercepts. Results The average gestational age in the total sample was 38 weeks; 47% of neonates were female, average birth weight was 3065 g and 11% were of low birth weight (< 2500 g). The geometric mean (GM) of the maternal CdB level was 0.25 μg/L (n = 641; 95% CI, 0.23–0.27). The cord blood Cd level was 0.27 μg/L (n = 317; 95% CI, 0.26–0.29) and urine (creatinine-corrected) Cd level was 0.27 μg/L (n = 318; 95% CI, 0.24–0.29). The CdB cord:maternal ratio in the sub-cohort was 1, suggesting that the placenta offers no protective mechanism to the foetus. An inverse association was found between CdB and the lower birth weight percentile in female neonates only (β = - 0.13, p = 0.047). Mothers who reported eating vine vegetables daily had lower levels of CdB (β = - 0.55, p = 0.025). Maternal smoking was associated with an elevation in natural log-transformed CdB levels in both male and female cohorts. Discussion Significant inverse associations between prenatal Cd exposure and birth anthropometry were found in female neonates but not in male neonates, suggesting potential sex differences in the toxico-kinetics and toxico-dynamics of Cd.

Elevated mercury exposure in communities living alongside the Inanda Dam, South Africa

Mercury is a persistent heavy metal that has been associated with damage to the central nervous system, including hearing and speech impairment, visual constriction and loss of muscle control. In aquatic environments mercury may be methylated to its most toxic form, methyl-mercury. In 1990 concerns were raised over mercury contamination in the vicinity of a mercury processing plant in KwaZulu-Natal, South Africa. Mercury waste was reported to have been discharged into the Mngceweni River, situated in close proximity to the plant. The Mngceweni River joins the uMgeni River, which in turn flows into the Inanda Dam, along the banks of which several villages are located. This study evaluated the mercury levels in river and dam sediments, fish from the Inanda Dam and hair samples collected from residents of three villages along the banks of the Inanda Dam. The study results showed that 50% of the fish samples and 17% of hair samples collected from villagers had mercury concentrations that exceeded guideline levels of the World Health Organization. Mercury concentrations in 62% of the river sediment samples collected in close proximity to the former mercury processing plant exceeded the level at which remedial action is required according to legislation in the Netherlands. These preliminary findings give reasons for concern and should be used as a baseline for further investigations.

Regional variation in pesticide concentrations in plasma of delivering women residing in rural Indian Ocean coastal regions of South Africa.

Exposure to pesticides places pregnant women and the developing foetus at the highest risk. The objective of this study is to obtain an exposure assessment by investigating levels of pesticides in blood plasma of delivering women. We report on the concentrations of α, β, γ HCH, endosulfan, HCB and the pyrethroids: cis-permethrin, cyfluthrin, cypermethrin and deltamethrin found in the maternal blood plasma of delivering women (n = 241) in three coastal sites of KwaZulu Natal. γ-HCH and endosulfan 1 and 2 were the most dominant pesticides in all three sites. Significantly, higher levels of γ-HCH and endosulfan were found in site 3 (vicinity of Empangeni) compared to the other two sites (p < 0.05). The GM levels for γ-HCH, endosulfan 1 and 2 were 956, 141 and 21 ng g(-1) lipids in site 3, respectively. The pyrethroid pesticides, HCB, α-HCH and β-HCH were detected in less than 31% of the samples in all sites. γ-HCH correlated positively and strongly to both endosulfan 1 and 2 (r > 0.47), indicating a common source of exposure. The high levels of γ-HCH and endosulfan in maternal plasma samples in site 3 indicate the current and on-going exposure, which is of great concern for reproductive health and prenatal exposure.

Toxic and essential elements in blood from delivering women in selected areas of São Paulo State, Brazil

This study was designed to evaluate the degree of environmental contamination and possible exposure of pregnant women to toxic elements in seven selected areas of São Paulo State, Brazil. The overall median concentration of Mo in maternal blood was 0.53 μg L⁻¹, highly significant differences found between sites (p < 0.0001). Cd was found to be low overall - 0.09 μg L⁻¹ (0.01-0.58 μg L⁻¹) - with mothers from the Coastal and Rural 1 sites having the highest levels (p < 0.016).Median Hg concentration was 0.60 μg L⁻¹ (0.06 μg L⁻¹-4.35 μg L⁻¹); median Pb level was 16.2 μg L⁻¹ (3.5-57.7 μg L⁻¹) and no differences between sites were observed for both metals. Median Mn level was 16.7 μg L⁻¹ (7.0-39.7 μg L⁻¹), being highest in Urban 2 site (p < 0.016). Concentrations of maternal Co were found to range between 0.06 μg L⁻¹ and 1.1 μg L⁻¹ (median 0.25 μg L⁻¹) and As level was 0.60 μg L⁻¹ (0.10-3.8 μg L⁻¹) overall, with no statistical significance between sites for Co and As. Median Se concentrations were found to be 64 μg L⁻¹ (36-233 μg L⁻¹), with the highest median levels found in Urban 3 site; site differences were statistically significant (p < 0.0001). Correlation for each element (between paired maternal and cord blood) was measured only in Rural site 1; significant correlation was shown for Hg, Pb, Mn and Co (p < 0.05). These findings may be interpreted as indicating low environmental contamination in São Paulo State, Brazil. These findings could also indicate that pregnant women have little or no contact with pollutants, possibly due to awareness campaigns carried out by public health practitioners.