The more you dine out, the more you're getting exposed to potentially hazardous chemicals known as phthalates, suggests a new study published Wednesday in the journal Environment International.
Whether it's cafeteria food, take-out pizza, or a fancy restaurant, a new study suggests that dining out exposes us to more potentially hormone-disrupting phthalates. Photo: Peter Macdiarmid (Getty Images)
Phthalates are a group of chemicals used to help make plastics more flexible and durable. They can be found in everything from cosmetics to children's toys to medical devices. Most of us, though, are exposed to low doses of phthalates through contamination of our food.
Research, mostly in animals, has suggested that certain phthalates can muck with the organs and glands responsible for making hormones, particularly androgens like testosterone.
In the current study, researchers looked at more than 10,000 people in the US over the age of six who had taken the National Health and Nutrition Examination Survey (NHANES), an annual study that combines comprehensive interviews and physical check-ups, from 2005 to 2014. As part of the NHANES, these volunteers provided urine samples and a food diary of everything they had eaten the day before.
Because phthalates only stay in our system for about a day, the researchers used the volunteers' urine to estimate their level of total phthalate exposure from food.
"We found that people who eat out more -- at full service restaurants, cafeterias, and fast food restaurants -- have nearly 35 per cent higher phthalate levels than people who eat at home more often," senior author Ami Zota*, an assistant professor of environmental and occupational health at George Washington University's Milken Institute School of Public Health, told Gizmodo via email.
The team's earlier research had already suggested that fast food contains higher levels of phthalates, but the latest study is the first to take a deep look at all kinds of food prepared outside the home and across different age groups, Zota said.
The findings are relevant for everyone, since two-thirds of the study sample had dined out recently. But they're especially relevant for children, according to Pam Factor-Litvak, an epidemiologist at Columbia University who has studied phthalate exposure in expecting mothers and young children.
"They're developing, and hormone balance is really important for them," said Factor-Litvak, who is unaffiliated with the new study. "So anything that interferes with that is potentially quite important."
Two phthalates in particular accounted for 75 per cent of the total phthalate exposure found in the study, known as di(2-ethylhexyl) phthalate (DEHP) and di-isononyl phthalate (DiNP), respectively. Studies have specifically found an association between DEHP with conditions like childhood asthma, while other research has linked DiNP, intended as a replacement for older phthalates, to lower cognition or behavioural problems in children. Both these phthalates are abundant in food packaging, notes Factor-Litvak.
"It's very likely that the exposure for children comes mostly from packaging," she said, "and especially from these two phthalates."
Children overall had the highest levels of phthalates in their system, while the greatest difference in phthalate exposure between diners and non-diners was seen in teens.
In recent years, agencies like the World Health Organisation have looked at the research behind phthalate exposure. Their 2012 report concluded that while there's still a lot of work needed to untangle the connection between phthalates and human health, there's enough evidence that exposure during fetal development and puberty can help cause an array of complications like genital birth defects, infertility, asthma and lower IQ.
In adults, it might be raising the risk of certain cancers, obesity and even Alzheimer's.
US agencies have similarly expressed concern about phthalates. A 2014 report by the Consumer Product Safety Commission concluded that up to 10 per cent of mothers in the US might be getting exposed to unsafe levels of phthalates, Zota points out. That same year, the Environmental Protection Agency instituted a new rule that would require companies to tell them if they planned to use phthalates in a new product or application, an action that would then be reviewed and possibly rejected by the agency.
Both the EPA and agencies like the Food and Drug Administration are in the middle of conducting their own reviews of the evidence (given the EPA's recent track record, though, that's probably more discouraging than it should be).
The US and countries in the European Union have also banned certain phthalates from being used in children's toys, while states like California are planning to mandate that companies include phthalates and other potentially dangerous chemicals on their product labels.
But there might not be any such thing as a safe phthalate, Factor-Litvak said. Unlike other toxic chemicals that need a high enough dose to hurt us, the best evidence suggests there's no threshold effect for phthalates.
"That's troubling because it means even very low levels of exposure to some of these chemicals is going to be harmful," she said.
Zota and her team believe there needs to be a lot more done to keep phthalates away from people, including removing them from the food supply entirely.
"There are some things that individuals can do to reduce their exposure to harmful phthalates. For example, they can dine out less and prepare more of their meals at home. They can also increase their intake of fresh foods and decrease their consumption of processed or packaged foods," Zota said. "However, since these chemicals are ubiquitous in our environment, we also need changes in policy and in the marketplace to ensure that everyone has greater access to healthy food."
Zota's team next plans to conduct research looking into how exactly phthalates contaminate our food.