Is exposure to metals during pregnancy dangerous?


New research investigates whether exposure to metals during pregnancy, particularly heavy metals such as lead, arsenic, and nickel, can have negative effects on the developing fetus.

Heavy metals are essentially a general term for metals that could potentially harm humans or the environment in excessive amounts.  Some common heavy metals include lead, mercury, arsenic, nickel, and many more. 

Since the 1980s, many regulatory bodies have established laws to limit the extent to which people are exposed to heavy metals.  For example, leaded gasoline is much less common, and the production and disposal of products containing mercury are highly controlled.  Some communities, however, have a disproportionately increased presence of heavy metals in the environment.  This can be from previous hazardous waste dumping sites, old pipes and plumbing systems, and other sources.  

One of these communities is Puerto Rico; for example, one study found that two of their rivers in urbanized parts of the island contained a concentration of manganese four times greater than the safe limit established by the United States Environmental Protection Agency (EPA).  However, the prevalence of heavy metal exposure to Puerto Rican citizens is still largely unknown and more research needs to be done to determine and mitigate any potential health risks.

There is some evidence that suggests that exposure to metals during pregnancy could be associated with fetal complications.  These may include premature birth and low birth weight, as well as preeclampsia, which is characterized by high blood pressure and possible proteinuria in the mother.

The exact mechanism of how this occurs is unknown, so a Rutgers University of pregnant women in Puerto Rico was conducted to determine any potential hormonal impacts of heavy metal exposure.  The findings were posted in Environment International, and it is the first population-level study to assess this exact correlation.

The study group consisted of 815 pregnant women in Puerto Rico, and all participants were enrolled in the Puerto Rico Test site for Exploring Contamination Threats (PROTECT) study.  All participants received blood tests and urinalysis tests for sixteen different metals and nine different hormones that are important in pregnancy.  These results were recorded and analyzed for further discussion.

The study found that higher concentrations of arsenic in the blood were associated with an increased level of corticotropin-releasing hormone (CRH) and a decreased level of testosterone.  Higher blood concentrations of nickel were also associated with a decreased level of testosterone.  Finally, increased levels of cobalt, lead, and manganese in the blood had a slight correlation with increased levels of sex-hormone binding globulin (SEBG) and progesterone. 

Although the implications of these hormonal changes are unknown, these results suggest that exposure to heavy metals could potentially be associated with endocrine disruption.  This endocrine disruption could potentially be related to negative fetal health outcomes; however, more research is needed to determine whether this is valid.

References List

EurekAlert! (2020 December 21). American Association for the Advancement of Science.

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Herndon, H., Ernst, H. (2018 September 4). Healthline media. Retrieved 2020 December 25,


Ortiz-Colon, A.I., Pinero-Santiago, L.E., Rivera, N.M., Sosa, M.A. (2016). Assessment of

            Concentrations of Heavy Metals and Phthalates in Two Urban Rivers of the Northeast of

            Puerto Rico. J Environ Anal Toxicol 6(2): 1000353. Doi: 10.4172/2161-0525.1000353

Physiopedia (n.d.). United Kingdom: Physiopedia. Retrieved 2020 December 25, from

Rivera-Nunez, Z., Ashrap, P., Barrett, E.S., et al (2020). Association of biomarkers of exposure

            to metals and metalloids with maternal hormones in pregnant women from Puerto Rico.

            Environment International 147. Doi: 10.1016/j.envint.2020.106310.

Environment Policy (n.d.). United Nations Economic Commission for Europe. Retrieved 2020

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Image by fezailc from Pixabay 

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