A new study suggested that there’s another reason to favor home-cooked meals over eating out at fast food outlets or restaurants — possible exposure to chemical agents known as phthalates.

As explained by the Guardian, phthalates are hormone-disrupting chemicals that are used in food packaging, shampoos, adhesives, and soaps for binding purposes. Researchers had previously found that phthalate exposure could lead to conditions such as asthma, type 2 diabetes, breast cancer, and fertility problems. Separately, CNN wrote that consuming these chemicals had previously been associated with medical issues in children and adults alike, such as birth defects, behavioral problems, and obesity. As such, U.S. officials have banned certain types of phthalates from children’s products.

In a study published this week in the journal Environment International, the researchers analyzed data taken via the U.S. National Health and Nutrition Examination Survey from 2005 to 2014. During this span of time, more than 10,000 people were given questionnaires on the food they had consumed over the last 24 hours, as participants provided information on what they ate and where they ate it. The participants’ urine was then tested to determine phthalate metabolite content.

Out of all the people who took the survey, 61 percent said they had eaten out at some point in the previous day. These individuals were shown to have 35 percent more phthalates in their system than those who ate at home, with a “significant” link present regardless of age group, gender, or ethnicity. The association between phthalate exposure and dining out was particularly evident in teenagers who usually ate their meals at fast food chains, who had 55 percent higher phthalate levels than those who ate at home.

Regarding the types of food with the highest levels of the chemicals, the researchers found that burgers and other sandwiches were associated with especially high phthalate levels if they were ordered at “dining-out establishments” such as restaurants, cafes, or fast food joints.

In a statement, George Washington University researcher Ami Zota, an assistant professor of environmental and occupational health, said that plastic packaging appeared to be the leading cause of phthalate exposure in the participants. She noted that these chemicals are usually added to food packaging, or found in plastic gloves used to handle food.

“The main idea is that food that is made in restaurants and cafeterias may be coming into contact with materials containing phthalates in part because some portion of the food is made in decentralized locations.”

According to CNN, this wasn’t the first time that researchers found a possible association between phthalate exposure and fast food, as Zota had discovered such a link while leading a separate study in 2016. The new research, however, differs because Zota and her colleagues were able to find evidence that the association is still present when people eat at cafes, restaurants, or other similar “sit-down” establishments.

Additionally, an advocacy group published a report in 2017 that suggested macaroni and cheese products were rich in phthalates, while lobbying for stricter government regulations of chemical agents used in food.

Although phthalates only stay in the human body for a day or so, the researchers stressed that it is still best to refrain from eating out and to nourish oneself with home-cooked meals in order to avoid the potentially harmful effects of phthalate exposure. Zota also mentioned that officials might need to change their policies in such a way that phthalate exposure is reduced, or completely eliminated in the packaging and manufacture of food products.

“Home-cooked meals can be a good way to reduce sugar, unhealthy fats and salt, and this study suggests that they may not have as many harmful phthalates as restaurant meals,” Zota concluded.