Mercury levels in parturient and newborns from Aveiro region, Portugal

ABSTRACT

Since the outbreak of methylmercury (MeHg) poisoning in Japan and Iraq, mercury (Hg) is classified as well-established teratogen. The Portuguese region of Aveiro faced some decades ago an environmental Hg contamination due to activities from a chlor-alkali plant. Until now, no apparent evaluation was conducted regarding prenatal exposure to Hg in this area. The main objectives of this study were to: i) assess maternal and fetal exposure to Hg in the Aveiro region using noninvasive biological matrices; ii) examine the influence of variables that may contribute to Hg exposure during pregnancy; and iii) improve knowledge regarding metal accumulation and distribution over the maternal–fetal–placental unit. This study was performed in 50 mother–newborn pairs from the Aveiro district. Total Hg (THg) was quantified in maternal scalp hair, placenta, amniotic membrane, and umbilical cord. Maternal hair presented THg levels with a mean value of 900 ng/g, which is lower than the USEPA and WHO acceptable threshold. Regarding THg levels in placenta and umbilical cord, mean values were similar (decidua basalis: 32.84 ng/g; chorionic plate: 30.18 ng/g; umbilical cord: 30.67 ng/g). The amniotic membrane presented the highest THg levels with a mean concentration of 42.35 ng/g, reaching a maximum of 134.1 ng/g. Further, a significant positive correlation was noted between THg levels found in hair, and all matrices analyzed reinforcing the use of hair in biomonitoring studies with respect to maternal exposure to Hg. In general, levels of THg found in our study were lower than those in previous studies performed in Europe. Consumption of fish rich in selenium and bottled water was negatively correlated with THg levels. Finally, data demonstrated that Hg is capable of crossing the placental barrier and accumulate in placental tissues. Amniotic membrane seemed to play a role in metal detoxification, but further investigations are necessary to examine whether this catabolic process affects Hg accumulation.

Acknowledgements

We thank all the participants in the study, the Centro Hospitalar do Baixo Vouga and Delivery Nursing Staff for their support and help with the study. We thank also Prof. M.J. Bebiano and Dr. Ângela Serafim for the availability of a sample questionnaire applied in a similar study.

Funding

This study is supported by CNRS/INEE—National Center for Scientific Research/Institute of Ecology and Environment, via LabEx DRIIHM—Dispositif de Recherche Interdisciplinaire sur les Interactions Hommes-Milieux, and OHMI—International Observatory Hommes-Milieux through the project (OHM-E/2015/Proj.2) “Maternal–fetal transfer of mercury in women from Aveiro district: influence of lifestyle and environmental factors.” We acknowledge the financial support to FCT (Portuguese Science Foundation) for the postdoc fellowship of M.S. Monteiro (SFRH/BPD/100448/2014); to CESAM (UID/AMB/50017); to FCT/MEC through national funds, and the co-funding by the FEDER (POCI-01-0145-FEDER-00763), within the PT2020 Partnership Agreement and Compete 2020.

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Additional information

Funding

This study is supported by CNRS/INEE—National Center for Scientific Research/Institute of Ecology and Environment, via LabEx DRIIHM—Dispositif de Recherche Interdisciplinaire sur les Interactions Hommes-Milieux, and OHMI—International Observatory Hommes-Milieux through the project (OHM-E/2015/Proj.2) “Maternal–fetal transfer of mercury in women from Aveiro district: influence of lifestyle and environmental factors.” We acknowledge the financial support to FCT (Portuguese Science Foundation) for the postdoc fellowship of M.S. Monteiro (SFRH/BPD/100448/2014); to CESAM (UID/AMB/50017); to FCT/MEC through national funds, and the co-funding by the FEDER (POCI-01-0145-FEDER-00763), within the PT2020 Partnership Agreement and Compete 2020.