Styrene has been added to the list of possible human carcinogens, according to a report by the government. The 12th Report on Carcinogens was put together by the National Toxicology Program of the National Institutes of Health. 

Styrene is found in foam coffee cups and food containers, primarily used in the manufacture of plastic packaging, thermal insulation in buildings, and coffee cups and food containers. It is also found in building materials as an important component of fiberglass found in boats, shower stalls and carpet backing.

Plants that use styrene can expose workers to high levels of the chemical, and studies have suggested that they suffer high levels of cancer. However, only a small amount of styrene can be found in a coffee cup.

Other substances such as formaldehyde, was also included in the report, noted that it was known to cause some kinds of leukemia. The substance is found in plywood, pressboard and some hair treatments. The research focused on workers in plants where they are exposed to large amounts of the substance.