A new study documents how Southern Californians are chronically exposed to toxic airborne chemicals called plasticizers, including one that has been banned in children’s items and beauty products.
Plasticizers are chemical compounds that make materials more flexible. They are used in a wide variety of products, from lunch boxes and shower curtains to garden hoses and upholstery.
“It’s not just for straws and grocery bags,” said David Volz, a professor of environmental sciences at UC Riverside and corresponding author of a paper about the study published in the journal Environmental Research.
California’s previous monitoring programs focused on plasticizers called orthophthalates, some of which were phased out of manufacturing processes due to health and environmental concerns. Less research has focused on the health effects of its substitutes, called non-orthophthalates.
This study revealed the presence of both types of plasticizers in the air throughout Southern California.
“The levels of these compounds are through the roof,” Volz said. “We weren’t expecting that. As a result, we felt it was important for people to know about this study.”
The National Institute of Environmental Health Sciences also wants to increase the visibility of this study, one of the few that documents the presence of phthalates in the air of urban environments. The institute’s monthly newsletter, Environmental Factor, highlights the study in its October 2024 issue.
Investigators tracked two groups of UCR undergraduates traveling from different parts of Southern California. Both groups wore silicone bracelets designed to collect data on exposure to airborne chemicals.
The first group wore their bracelets for five days in 2019, and the second group wore two different bracelets for five days each in 2020. Both groups wore the bracelets continuously, all day, while doing their activities. At the end of the data collection period, the researchers cut the bracelets into pieces and then analyzed the chemicals they contained.
In a previous article, the team focused on TDCIPP, a known flame retardant and carcinogen, detected in the bracelets. They saw that the longer a student’s trip, the greater their exposure to TDCIPP.
Unlike TDCIPP, which likely turns to dust from travelers’ car seats, the team cannot precisely determine the origin of the plasticizers. Because they are airborne, rather than bound to dust, the bracelets could have picked them up anywhere, including outside students’ cars.
For every gram of bracelet cut, the team found between 100,000 and 1 million nanograms of three phthalates: DiNP, DEHP and DEHT. Ten plasticizers were measured in total, but the levels of these three stood out.
Both DiNP and DEHP are included on California’s Proposition 65 list, which contains chemicals known to cause cancer, birth defects, or other reproductive harm. DEHT was introduced as an alternative, but its effects on human health have not been well studied.
This study suggests that the introduction of DEHT has also not done much to reduce the level of public exposure to DiNP or DEHP. The levels of the three chemicals found by Volz and his team were similar to those found by researchers in unrelated studies conducted on the East Coast.
Despite climate differences, the air on both coasts likely contains similar levels of phthalates.
“No matter who you are or where you are, your daily level of exposure to these plasticizing chemicals is high and persistent,” Volz said. “They are omnipresent.”
For Volz, studies like this amplify the need to find alternatives to plastic. As plastics degrade, these compounds and others like them leach into the environment and the body.
“The only way to decrease the concentration of plasticizers in the air is to decrease our production and consumption of materials that contain plasticizers,” he said.