Exposure to a widespread, toxic chemical called PFOS may interfere with bone development in children and young adults, potentially putting them at higher risk for osteoporosis and other bone problems later in life, according to a new study that focused mainly on Hispanic individuals from southern California.
Perfluorooctane sulfonic acid (PFOS), a widespread type of per- and polyfluoroalkyl substances (PFAS), was associated with lower bone mineral density in a group of 328 overweight Hispanic children and in a group of 158 young adults of mixed ethnicity. The study, published Dec. 6 in the journal Environmental Research, was unique in that it tracked associations between bone density and PFAS blood serum levels over time.
“Existing research had established associations between PFAS and bone health, but previous studies, most of them only collected information at one time point from participants,” said Emily Beglarian, a PhD student at the University of Southern California’s Keck School of Medicine and the lead author of the study. “Additionally, many existing studies were focused on non-Hispanic, white participants and many focused on older adults.”
Although Hispanic people are at high risk for developing osteoporosis as adults, they are often not included in research on bone health, said Beglarian.
There are over 12,000 PFAS chemicals, which do not break down naturally and have been found in at least 45% of US tap water, according to the US Geological Survey, and in the blood of about 97% of Americans, according to the US Centers for Disease Control and Prevention (CDC). Exposure to PFAS has previously been linked to numerous health problems, including kidney cancer, testicular cancer, thyroid disease, thyroid cancer, and ulcerative colitis.
Last week, the International Agency for Research on Cancer (IARC), an arm of the World Health Organization (WHO), classified PFOS as possibly carcinogenic to humans. Separately, the global scientific cancer experts classified perfluorooctanoic acid (PFOA), another widely used PFAS chemical, as carcinogenic to humans.
Previous studies have found that PFAS may disrupt the formation of cells that build new bone material and have linked exposure to PFAS with worse bone health in both children and adults, although the effects of these so-called “forever chemicals” on bone development are “a pretty new area of study,” said Beglarian.
To further understand how PFAS might impact bone development, Beglarian and colleagues analyzed data from a cohort of children ages 8 to 13 who were recruited between 2001 and 2012 and received follow-up appointments for about a year and a half. They also looked at data from a cohort of young adults ages 17 to 22 who were recruited between 2014 and 2018 and received follow-up appointments for about four years. For each group, the researchers estimated associations over time between the participants’ bone density and measurements of five PFAS chemicals in their blood serum.
The young adult group, which was recruited a few years later than the adolescent group, after more PFAS regulations had been put in place, had lower levels of PFAS than the adolescent group. But even with less of the chemicals in their blood, the young adult group still showed signs of concerning bone health issues associated with PFAS exposure, said Jesse Goodrich, an assistant professor of population and public health sciences at the Keck School of Medicine and an author of the study.
“Even though we saw lower levels in the young adults that were measured more recently, we still saw very similar results, very consistent results between the two cohorts,” said Goodrich. “Even though there are some regulations that are lowering [PFAS] levels, we really need larger policies to fully eradicate these, if possible.”
Next, the researchers plan to investigate whether the associations they have observed are consistent over the course of a lifetime and to study how PFAS work at a cellular level to reduce bone mineral density. They also want to research the effects of newer types of PFAS, said Beglarian.
“Some of the PFAS that we were exposed to then are different than what we’re exposed to now because there are emerging PFAS that are becoming more common,” she said. “In our newer studies, we want to see if we can look at the newer, unregulated PFAS to see if and how those affect bone health to understand what regulations we might need moving forward.”