Dramatic reduction in mercury levels in Bermuda’s pregnant women

A paper published last year in the scientific journal PLoS ONE has detailed a dramatic reduction in blood concentrations of methyl mercury in pregnant women in Bermuda.

The paper (which can be found at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0047388) compared results from two studies conducted almost a decade apart. The first, conducted under the auspices of the Atlantis Mobile Laboratories, the Bermuda Institute of Ocean Sciences and the Bermuda Government, was a fetal cord blood study with the Maternity Ward at the King Edward memorial hospital in 2003. The second was part of the Caribbean Eco Health Programme (CEHP) study of maternal health in 2011.

The 2003 maternal cord blood study – the first of its kind in Bermuda – revealed higher than expected levels of mercury in Bermuda fetal cord blood. In fact it was in the region of seven times higher than average levels in the US and Canada.

Although the results were not out of range of levels found in specific communities with high fish consumption, the results came as a surprise to this remote island community in the mid Atlantic.

The mercury in the 2003 study was identified as organic or ‘methyl mercury’ – the source of which was most likely from the consumption of larger predator fish.

Bermuda is not the first remote maritime community to display higher than expected levels of mercury.  The phenomenon was first described in the 1960’s in remote Inuit communities in the Arctic, as specific public health research uncovered negative impacts on humans consuming seafood containing high levels of mercury. In particular exposure to higher levels of mercury during pregnancy has been linked to neurodevelopmental issues in the newborn.

In 2003 none of the mercury levels in fetal cord blood in Bermuda exceeded the World Health Organisation guidelines. However, because of the relatively higher levels measured in Bermuda, the researchers all agreed to apply the precautionary principle and find ways to reduce exposure to the fetus and newborn.

Pregnant women in Bermuda, like those around the world, are given advisories on certain foods that should be avoided or limited during pregnancy. Fish consumption advisories are a regular part of these recommendations and refer to commercial fish sold on the international market. These generally refer to higher trophic level fish (I.e. those that are at the top of the food chain) and, in particular, larger/older fish in these categories, i.e. fish above a certain size. Prior to 2003 pregnant women were given guidelines and recommendations on the best imported fish to consume but no such data existed for local fish.

The 2003 results prompted the scientists associated with the study to put together a research programme to better understand the risk benefit balance for pregnant women from consuming local commercial fish species. 

Fish are a uniquely rich source of nutrients that are essential during pregnancy. The study conducted in 2003/4 therefore measured not only levels of mercury in local fish but also two key nutrients; selenium and omega three fatty acids. The results of this research were published in 2004 and a Bermuda-specific fish advisory was generated that contrasted mercury, selenium and omega three fatty acids so that pregnant women could select those fish that were highest in beneficial nutrients and lowest in methyl mercury.  This information was made available to local obstetricians.

http://www.conservation.bm/storage/projects-pages/Food additives and contaminants.pdf

In 2011 a new study looking at levels of a range of contaminants in pregnant women’s blood throughout the Caribbean was extended to Bermuda and carried out through the Department of Health at the public clinic. This study gave the researchers an opportunity to test for methyl mercury once again in the pregnant women of Bermuda.

The results showed a significant 5-fold decrease in methyl mercury in Bermuda mothers between the 2003 and 2011 studies.  The paper just released suggests that Bermuda’s coordinated approach in terms of advisories for pregnant women, relating to both imported and local fish consumption, has likely played a part in reducing the levels of mercury found in mothers’ blood.

In the decade between the studies the international press has given regular attention to this issue and it is felt that this heightened international awareness as well as the production of local fish recommendations has been especially significant in changing local women’s behavior and reducing overall exposure.

Further studies have recently been completed which test whether this result reflects a reorientation by pregnant women to less contaminated fish or a reduction in fish consumption overall.

The benefits of fish consumption during pregnancy are extremely significant, both to the developing fetus and the mother, and include health benefits such as longer duration of pregnancy and better visual acuity and brain development for the baby.  The survey also looked at questions related to food security during pregnancy. The full results will be released later this year.

The research in 2003 was carried out by the Atlantis Mobile Labs working with BIOS and the Maternity Ward of the King Edward Memorial Hospital and funded by the XL foundation with the support of Bermuda Container Lines.

The fish studies done in 2003/4 were supported by the Lepercq Foundation. The recent blood study conducted in 2011 was funded by the International Development Research Center of Canada and the Lepercq Foundation. The pregnancy questionnaire and survey conducted in 2013 was under the auspices of the most recent Atlantis Mobile Laboratories visit to Bermuda by a Graduate Student from University of Laval. All four studies were done in collaboration with the Bermuda Government’s Department of Health and Department of Conservation Services. Research with the Atlantis Labs was coordinated locally by Dr Philippe Max Rouja, Principal Scientist at the Department of Conservation Services.

Dr. Rouja said: "This longstanding relationship between Bermuda and Laval University through Dr. Eric Dewailly and his Atlantis Labs has produced a number of high level peer reviewed journal articles, chapters in text books and ‘op ed’ pieces. This latest publication is a testament to the unique position of Bermuda in that we are able to carry out scientific research that is of interest and importance both locally and internationally. Bermuda benefits greatly from these collaborative relationships and we, in the Government, are very cognizant of their contributions."

One of the primary missions of Atlantis has been to underline the interconnectedness of ocean health and human health helping to move communities to a better appreciation of the direct benefits of preserving and maintaining healthy environments.

The Atlantis Mobile labs were hosted at BIOS in 2003 and again in 2013.

 “The partnership between BIOS and the Atlantis Mobile Laboratory provides an excellent example of how research collaborations can produce meaningful results for the community,” said BIOS President and Director, Dr. Bill Curry. “This project—the first of its kind in Bermuda—was a significant milestone in ongoing efforts to provide government officials and health care providers with the high-quality scientific data required to make informed decisions. As a direct result of this collaboration, methyl mercury levels in Bermuda mothers between the 2003 and 2011 have decreased.”