The new NIEHS Early-Stage Investigator Spotlight Webinar series continued on May 11, featuring a presentation by Marissa Baker, Ph.D., on the mental health of mariners during the COVID-19 pandemic, and a talk by Michael Petriello, Ph.D., on how chemicals such as per- and polyfluoroalkyl substances (PFAS) can affect the gut microbiome.

Baker, an assistant professor at the University of Washington, is affiliated with the school’s Interdisciplinary Center for Exposures, Diseases, Genomics and Environment. Petriello, a pharmacology student at Wayne State University, is affiliated with the school’s Center for Urban Responses to Environmental Stressors. Both entities are supported through the NIEHS Environmental Health Sciences Core Centers Program.

The webinar series is hosted by Maria José Rosa, Dr.P.H., and Douglas Walker, Ph.D., members of the Mount Sinai Transdisciplinary Center on Early Environmental Exposures.

COVID-19 and mariners’ mental health

Baker characterizes workplace exposures experienced by vulnerable or underrepresented populations. She explores workplace determinants of understudied occupational health outcomes, such as mental health, stress, and fatigue.

Baker uses personal monitoring, surveys, modeling, interviews, and biomarkers in her research on occupational and environmental health. (Photo courtesy of Marissa Baker)

Her talk was titled “Mariner Mental Health and Well-being During COVID-19 and Beyond.” She noted that before the pandemic, data on mariner mental health had been limited.

“It really hadn't been assessed in this population at all,” said Baker. “It was assumed that it was good. There had been one study that looked at seafarers across the world, so it was really the pandemic that was the trigger that helped them realize we need to do something about this.”

She noted that more than 75% of U.S. trade involves marine transportation. In 2020, approximately 200,000 mariners from the country were on 3,650 registered merchant marine vessels. Typically, mariners may encounter extreme weather conditions, long hours, lack of internet access, and few people on board, which can lead to feelings of isolation.

Those issues continued when COVID-19 hit, and they were compounded by lack of access to shore leave, Baker told attendees.

Mariners could not go home, voyages became longer, and work protocols changed. Baker conducted a survey to assess mental health outcomes and barriers to accessing care, seeking to prioritize interventions to improve mariners’ well-being during and after the pandemic.

She assessed the likelihood of five mental health outcomes based on 1,589 answers she received. Baker observed high rates of depression, anxiety, suicidal ideation, perceived stress, and PTSD. Female and younger mariners had higher rates than their male and older counterparts.

Although mariners had high job satisfaction, the rate of adverse mental health outcomes warrants intervention and ongoing assessment, according to Baker. She recommends appropriate training and communication; increasing privacy for mariners to access mental telehealth; increasing social support onboard; focusing on the needs of women and younger, underrepresented mariners; and firm reporting policies.

Pollution and the gut microbiome

Petriello studies links between nutrition, exposures, and metabolic disorders. (Photo courtesy of Michael Petriello)

Petriello studies how chemicals such as PFAS and polychlorinated biphenyls (PCBs) can change the gut microbiome and potentially influence atherosclerosis. That condition is marked by a buildup of plaque on artery walls, and it contributes to cardiovascular disease.

Cardiovascular disease is influenced by interactions between unmodifiable factors such as genes and family history, and modifiable factors such as the environment, diet, and lifestyle. To study the progression of atherosclerosis, Petriello looked at lipid markers, cholesterol, and inflammation in mice predisposed to high cholesterol.

“We can expose the mice to our pollutant of interest and check whether atherosclerosis accelerated,” he said.

In his work, mice exposed to PCBs developed lesions and markers of inflammation. They were also more likely to absorb compounds that resemble cholesterol, which could predispose them to atherosclerosis. In addition, PCBs depleted gut microbiota that metabolize cholesterol.

“For toxicology, it's interesting to think that microbiota metabolize pollutants, but also that pollutants can directly impact bacterial health,” said Petriello.

He exposed mice to a PFAS mixture and found that the chemicals increased circulating cholesterol and inflammation in female mouse livers. In another study, PFAS increased circulating cholesterol levels in some mice and decreased bile acid excretion, a mechanism that may increase cholesterol levels and warrants further study, according to Petriello.

(Susan Cosier is a contract writer for the NIEHS Office of Communications and Public Liaison.)