October 2019, Volume XXXIII, No 7

Public Health

The MN FEET program

Birth disparities and prenatal mercury exposure

he jar of skin lightening cream looked innocuous enough, but investigators found that merely opening its lid released enough mercury vapor to create unsafe living conditions in the home. Using a Lumex portable mercury detector, partners with the MN FEET program (Minnesota Family Environmental Exposure Tracking) found a reading of 800 nanograms per cubic meter of mercury in the air—more than twice the chronic exposure limit set by the Environmental Protection Agency. Fortunately, a few days of fans and open windows were enough to bring the readings down to safer levels.

The home visit was part of a voluntary follow-up investigation with a study participant found to have high levels of mercury in her urine. Environmental epidemiologists with the Biomonitoring Program at the Minnesota Department of Health (MDH) hypothesized that the exposure had come from an imported skin lightening product, and the Lumex readings supported their hunch.

Residents at the house had been at risk from mercury, which can damage the central nervous system, kidneys, and liver. While health consequences vary on the amount and duration of exposure, fetuses and young children are particularly sensitive to mercury, too much of which can cause lasting problems with understanding and learning.

While the MN FEET study wrapped up last year, surveillance and prevention efforts are far from over. Findings from the study reveal important information for health care providers to be aware of and discuss with the patients they serve. Here, we share key findings from the MN FEET study and discuss how we are piloting a mercury screening program for pregnant women with two St. Paul clinics.

The MN FEET study

Investigators with MN FEET measured mercury, lead, and cadmium in pregnant Twin Cities women and their newborn babies in hopes of learning more about preventing chemical exposures that could impact fetal brain development. Prior to the study’s inception, community concerns and outcomes from other biomonitoring studies suggested that some populations were experiencing marked disparities in exposure to certain chemicals, but more investigation was needed. With oversight from the Environmental Health Tracking and Biomonitoring (EHTB) Scientific Advisory Panel, researchers from the Minnesota Biomonitoring program at MDH designed and implemented the study with an eye on advancing health equity.

Many women who use [skin lightening] creams are unaware of how hazardous they can be.

Collaboration with health care and community stakeholders proved essential to the study. The HealthPartners Institute and Health for Somali, Latinos, and Hmong (SaLaHmo) Partnership for Health & Wellness at Minnesota Community Care (then known as West Side Community Services) recruited pregnant women who were patients at select local clinics and who planned to give birth at Regions or Abbott Northwestern Hospitals. In accordance with community and advisory panel recommendations, recruitment focused on women who identified as Asian, East African, Latina, or White. “This is part of our effort to ensure that every baby has a healthy start,” said Kathleen A. Culhane-Pera, MD, medical director of quality and co-director of community-based research at Minnesota Community Care. “What we learn from MN FEET will be important to the communities, families and patients served at our clinics.”

Recruits who consented to being part of the study answered a phone questionnaire about their living conditions, eating habits, use of skin lightening creams, and other factors that could influence exposure levels. When the participants’ babies were born, hospital staff collected urine samples from the women and a small amount of umbilical cord blood, which were then analyzed by the MDH Public Health Laboratory. Some ethnic groups had more women in the study than others: the largest groups were Latina and White women, followed by Asian women, with East African women representing the smallest group. Participation by East African women was unintentionally hindered by different aspects of the study design, including non-face-to-face recruitment methods and sample collection at two partner hospitals where these women were less likely to deliver.

Exposures to lead and cadmium were measured in cord blood samples, and were generally low and not of great concern for women in MN FEET. Cadmium exposure occurs primarily through smoking cigarettes. Lead exposure typically comes from contact with lead-based paints, along with some jobs, hobbies, and products like glazed ceramics with lead.

Mercury, on the other hand, showed more troubling and complicated results. The type of mercury detected in cord blood is most often organic mercury, found in fish. The type of mercury detected in urine is usually inorganic mercury, which can come from skin lightening products, light bulbs, and old thermometers. Researchers found elevated levels for both forms of mercury and identified specific populations at higher risk.

Mercury from skin lightening products

MN FEET measured mercury in the urine of 396 participants. Women in the study who said they had used a skin lightening cream in the past had more mercury in their urine than those who did not. Such products often do not list mercury on the label, and it cannot be seen, felt, smelled, or tasted by the consumer. In the United States, it is illegal to sell skin lightening products that contain mercury, but they can be ordered from the internet or carried across borders and are available at some ethnic markets.

Many women who use the creams are unaware of how hazardous they can be, but it’s a complicated and painful issue with roots in colorism and colonialism. Amira Adawe, founder of the Beautywell Project and key community partner for the study, says that removing the products from markets is not enough—consumer education and a cultural shift around beauty standards are needed. “Skin lightening practice is an issue that is impacting immigrant and communities of color,” says Adawe. “Lighter skin is considered beautiful compared to other skin tones; because of this, many dark-skinned women believe having lighter skin will increase their chances of being accepted in society and in their communities.” Globally, the skin lightening product market exceeds $10 billion annually and is expected to double by 2030.

For MN FEET, six of the nine women with elevated urine mercury levels agreed to take part in further investigation via home visits. With help from St. Paul–Ramsey County Public Health and the Minnesota Pollution Control Agency, the participants’ homes were tested for mercury contamination. The Lumex analysis revealed that airborne mercury was putting everyone in the home at risk, and not just the women using the creams. Additionally, their washing machines could become contaminated from laundering towels that contained traces of the creams, potentially spreading the mercury to other clothing and linens.

All nine women with higher mercury in their urine chose to speak Hmong or Spanish in their surveys, and all were born outside of the United States. The group of East African women tested was too small to draw statistical conclusions from their results, but they had the second-highest mercury levels in their urine after Hmong women.

Mercury from eating certain fish

The benefits of fish consumption outweigh the risks when people choose fish that are low in mercury and other chemicals. MDH provides guidelines in a number of languages and formats to help people choose which fish to eat and how often in order to keep mercury exposures low.

Health care providers can help patients understand  potential sources of these harmful chemicals.

MN FEET measured mercury in the cord blood of 395 participants and found that women who ate particular species of fish—Walleye, Northern Pike, Bass, White Bass, or King Fish—more than once per month had more mercury in their babies’ cord blood than women who ate fish less often. MDH guidelines advise pregnant women and children to eat these types of fish once a month or less.

Nine women had high levels of mercury in their babies’ cord blood. Phone follow-up revealed that most of them ate species of fish with higher mercury more than once per month. All nine of them were Hmong women, though Asian groups in general had higher cord blood mercury than other groups.

Exposures higher in some women

Asian women in MN FEET, and especially Hmong women, had the highest levels of mercury. This was true for mercury in urine and cord blood, suggesting that some Hmong women in Minnesota may have high mercury exposures from using skin lightening products with mercury and from eating fish higher in mercury.

“The evidence from MN FEET that some groups in Minnesota may be having higher mercury exposures, especially Hmong women and women from other ethnic/immigrant communities, is concerning,” said Mao Thao, Hmong Health Coordinator with St. Paul–Ramsey County Public Health. “It is critical that we work with these communities to find the best ways to share the information and reduce exposures in women and babies.”

Although relatively few women overall had elevated levels, the seriousness of potential effects from mercury exposure, widespread use of products containing mercury, and increased burden in some vulnerable subgroups garner significant public health concern.

Call to action: from research to practice

MN FEET reveals an important opportunity to halt or prevent mercury exposures in pregnant women, their babies, and their households. Health care providers can help patients understand potential sources of these harmful chemicals that may otherwise go unnoticed. Dr. Culhane-Pera agreed: “The MN FEET results shed light on some really important exposure prevention information that we as health care providers need to share with the patients, families and communities we serve.” MDH has information sheets available in Spanish, Somali, Hmong, and English about both skin lightening product use and choosing fish wisely, as well as a fact sheet for health care providers (https://tinyurl.com/mp-mdh-mercury) that lists symptoms and provides recommendations for doctors about discussing skin lightening products and mercury exposure with patients.

After sharing the study results with participants, the biomonitoring team disseminated the findings to partners and stakeholders before rolling out a community report and press release. Outreach is ongoing in the communities most impacted by the results. More multi-faceted, targeted messages and messengers are still needed—especially for women who speak languages other than English and/or were not born in the United States. Community-led programs continue to be instrumental as well, and a bill passed earlier this year will help fund local outreach and awareness campaigns to reduce the use of skin lightening products. Communications with patients in clinic can bolster these efforts.

And while prevention begins with awareness, an offshoot clinic-based project is conducting routine urine mercury screening of all prenatal patients at two St. Paul community clinics and offering exposure reduction assistance to any women found to have elevated exposures. An additional project with a clinic that serves a large East African population is in the planning stages. These projects will help determine the effectiveness and feasibility of this type of screening, and will move toward integrating the issue into clinical practice, where exposure reduction will be most effective.

“Mercury exposure can be a significant health concern, but in this case the good news is that those groups we found to be at elevated risk have the power to reduce that risk,” Minnesota Commissioner of Health Jan Malcolm said. “This study shows that we have an opportunity to help people better understand the potential dangers of using skin lightening products and frequently eating fish higher in mercury.”

Get more information about the study and resources for patients at www.health.mn.gov/MNFEET.

MDH would like to thank the following partners: MN FEET participants, SoLaHmo/Minnesota Community Care, HealthPartners Institute, Regions Hospital, Abbott Northwestern Hospital, St. Paul–Ramsey County Public Health, Minnesota Pollution Control Agency, EHTB Advisory Panel, East Africa Health Project, and Amira Adawe. All funding provided by the State of Minnesota.

Kate Murray, MPH, is a communications planner for the environmental epidemiology unit at MDH. Her breadth of experience includes creative and technical writing, multimedia production, and community engagement. She holds a Master of Public Health degree in Administration & Policy from the University of Minnesota.

Jessica Nelson, PhD, MPH, is Program Director and Epidemiologist with the Minnesota Biomonitoring Program at the Minnesota Department of Health. She was a Principal Investigator for MN FEET, the MDH biomonitoring study that measured mercury, lead, and cadmium in pregnant women and babies.

Courtney Jordan Baechler, MD, MS, is a board-certified internist and cardiologist who focuses on the prevention of heart disease and change that supports overall well-being. Her interest is on prevention from the bedside to the community. She is passionate about helping individuals, families, and communities to find their highest state of well-being—body, mind and spirit. 


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© Minnesota Physician Publishing · All Rights Reserved. 2019


Courtney Jordan Baechler, MD, MS, is a board-certified internist and cardiologist who focuses on the prevention of heart disease and change that supports overall well-being. Her interest is on prevention from the bedside to the community. She is passionate about helping individuals, families, and communities to find their highest state of well-being—body, mind and spirit.