There is more to worry about in fast food than the fat, sodium and calories. People who eat a lot of fast food have higher levels of chemicals in their body called phthalates. These potentially harmful chemicals are found in the plastic packaging fast food comes in, and there is concern that they may leach out and contaminate food. The food itself is also a source.

To conclusively link phthalates in fast food to health issues will require studies that could take years to complete. In the meantime, you can take steps to protect yourself.

Researchers at the George Washington University Milken Institute School of Public Health looked at data collected from nearly 9,000 people who reported detailed information about their diet during a 24-hour period. Each person also provided a urine sample which was tested for the breakdown products of two phthalates — DEHP and DiNP.

The more fast food the people in the study ate, the higher their exposure to phthalates. Those who ate the most fast food had 24 percent higher levels of DEHP in their urine and 40 percent higher levels of DiNP compared to people who ate no fast food. Meat and grain products, including bread, pizza, burritos, cakes, rice dishes and noodles, and were responsible for the most phthalate exposure.

Another part of the study looked at exposure to the endocrine disruptor bisphenol A (BPA), a chemical also used in plastic food packaging. BPA is believed to cause health and behavior problems, particularly in young children. The study found no link between total fast food intake and BPA, though people who consumed meat from fast food outlets had higher levels of BPA than those who ate no fast food.

Those who ate the most fast food had 24 percent higher levels of DEHP in their urine and 40 percent higher levels of DiNP compared to people who ate no fast food.

Phthalates are found in a wide variety of personal products, perfumes, toys and food. They were banned for use in toys by Congress in 2008 due to concerns about their health impact on children.

Despite the ban, DEHP and DiNP continue to be used in other products even though there are worries that they can leach out of products and enter the body. Research has suggested that these chemicals can damage the reproductive system and possibly lead to infertility.

To conclusively link phthalates in fast food to health issues will require studies that could take years to complete. In the meantime, you can take steps to protect yourself.

For starters, quit your fast food habit, or at least limit yourself. The amount of fat, salt and calories is reason enough, but the boost to your brain and exposure to phthalates are two more reasons to do so. Eat at home more often.

Limit the amount of packaged foods you eat. Concentrate on eating more fruits and vegetables, whole grains and fresh meat or seafood. Not only will these steps improve your diet, they'll cut your exposure to potentially harmful chemicals.

The study is published in Environmental Health Perspectives.