New studies link air pollution to both breast cancer and suicide

Two new pieces of  research have made connections between particulate air pollution and increased breast cancer incidence, and wildfire smoke and suicide risk in rural areas.

The first mentioned research was conducted by the National Institute of Environmental Health Sciences, who examined the PM exposure of a cohort of women, numbering around 250,000, who had enrolled on a diet and health study  between 1995-96. The women in the cohort were on average about 62 years of age and were followed for approximately 20 years, during which 15,870 breast cancer cases were identified.

Women who lived in areas with higher PM levels prior to enrolling in the study were found to have a higher incidence of breast cancer.

Alexandra White, Ph.D., lead author and head of the Environment and Cancer Epidemiology Group at NIEHS said: ‘We observed an 8% increase in breast cancer incidence for living in areas with higher PM_2.5 exposure. Although this is a relatively modest increase, these findings are significant given that air pollution is a ubiquitous exposure that impacts almost everyone. These findings add to a growing body of literature suggesting that air pollution is related to breast cancer.’

Rena Jones, Ph.D., senior author and principal investigator of the study said: ‘The ability to consider historic air pollution levels is an important strength of this research. It can take many years for breast cancer to develop and, in the past, air pollution levels tended to be higher, which may make previous exposure levels particularly relevant for cancer development.’

Meanwhile, research undertaken by the University of Massachusetts, Monash University in Australia and the IZA Institute of Labor Economics in Germany examined the impact of PMs on mental health. 

The team used data on all suicide deaths along with satellite-based measures of wildfire smoke and ambient PM2.5 concentrations in the U.S. from 2007-2019, to compare year-on-year fluctuations in county-level monthly smoke exposure to changes in suicide rates and analysed the effects across local areas and demographic groups.

They found that while worse air quality did lead to higher rate of suicide this was only in evidence in rural areas and primarily confined to white males of working age, and rural adults with no college education.

David Molitor, a co-author of the study who has been appointed as a 2023-24 Center for Advanced Study associate to study climate-related environmental hazards said: ‘We don’t detect any relationship between air quality and suicide in urban areas. Suicide rates were about 36% higher in rural versus urban counties during our sample period. All of the effects seem to be concentrated in the rural populations.

‘Suicide rates have increased by approximately 30% over the past two decades, positioning it as the fourth leading cause of years of potential life lost before age 65 in 2020. It’s far too prevalent, and highly unequal across demographic groups. It’s systematically higher in rural counties than in urban ones, and the urban-rural gap in suicide rates has been widening.

‘Understanding the overall and disparate impacts of air pollution on mental health is crucial for developing effective strategies to protect vulnerable groups and increase population resilience to poor air quality.’