Most of us have known for a long time that fast foods are not a good source of nutrition. However, what a lot of people don’t know is that they are a very good source of toxins, which is another reason not to eat them.

A new study from George Washington University’s Milken Institute School of Public Health, in Washington, D.C. has found harmful chemicals known as phthalates in the urine of people who consumed lots of fast food. Phthalates are used in the manufacture of plastics to make them flexible. The more fast food you eat; the more phthalates you get.

Phthalates are found in a wide array of food packaging materials and food-processing machinery. They can leach from the food packaging plastics, and they can even come from the vinyl gloves that restaurant workers wear to prevent bacterial contamination of the food. Phthalates mimic hormones in the body. They are endocrine disrupters that can affect the development of the male reproductive system, and they also have been implicated in birth defects, childhood behavioral problems and childhood chronic illnesses, such as asthma. They can even cause cancer. With continued exposure, they accumulate in the body’s tissues, causing chronic problems. Even very low levels of endocrine disrupters can cause serious problems.

Most of our fast food is one big chemistry experiment, and one result of this experiment is our sky high rate of premature aging and chronic disease. A typical thick shake contains corn syrup, artificial colors and flavors, and various chemical thickening agents—none of which are good for you. Among other chemicals, McDonald’s Chicken McNuggets contain dimethylpolysiloxane, a silicone compound that is added as an anti-foaming agent to the nuggets, with questionable safety. They also contain autolyzed yeast extract, which is chemically similar to the excitotoxin MSG that is known to damage the brain and has been linked to obesity and other health problems. Even McDonald’s “healthy” salads, contain cilantro lime glaze and orange glaze, which contain propylene glycol—a chemical that is not even allowed for use in cat food because of questionable safety.

On the bottom line, fast foods are a very poor choice from either a nutritional or a toxicological standpoint. Remember that because of our compromised food supply, nutritional supplements are a necessity if you want to be healthy. The challenge is to find supplements you can trust to deliver what your body needs.