Styrene and Cancer

The simple versionExplain▾

Styrene is a chemical used to make many plastics and foam products, including packaging and some disposable cups. Workers who breathe styrene, such as those making fiberglass products, have the highest exposure. It is classified as a probable carcinogen.

What styrene isExplain▾

Styrene is used to make polystyrene plastics, resins, and synthetic rubber. It is also found in tobacco smoke and vehicle exhaust, and small amounts can migrate from some food containers. IARC and the NTP classify it as a probable/anticipated carcinogen, based largely on studies of exposed workers.

How people are exposedExplain▾

Common ways people come into contact with it:

• Working in fiberglass, plastics, rubber, or resin manufacturing
• Breathing styrene vapors in industrial settings
• Tobacco smoke and, at very low levels, some food packaging

The cancer connectionExplain▾

Styrene is linked to cancers of the blood and lymphatic system (such as leukemia and lymphoma) in exposed workers. The human evidence is limited.

The International Agency for Research on Cancer (IARC), the cancer arm of the World Health Organization, places styrene in Group 2A, probably carcinogenic to humans — meaning the evidence in people is limited but there is strong support from animal or mechanistic studies (evaluated in 2019). In the United States, the National Toxicology Program's Report on Carcinogens lists it as reasonably anticipated to be a human carcinogen.

Hazard is not the same as riskExplain▾

It helps to separate two ideas that are easy to mix up: hazard and risk. When an agency lists styrene as a carcinogen, it is making a statement about hazard — whether the substance is capable of causing cancer under some conditions. It is not, by itself, a statement about your personal risk, which depends on how much you are exposed to, for how long, and other factors. Two substances in the same group can carry very different real-world risks. The label answers "can it cause cancer?" — not "how likely is it to cause cancer for me?"

How to lower your exposureExplain▾

• Use ventilation and respiratory protection in styrene industries
• Follow occupational exposure limits
• Do not smoke

If you are looking at your overall cancer risk, small, steady steps add up. See our overview of cancer prevention and what raises cancer risk to put any single exposure in context.

The bottom lineExplain▾

Styrene is a probable human carcinogen (IARC Group 2A). The most important thing you can do is understand where exposure comes from and take reasonable steps to reduce it, without losing sleep over a single label. Focus your energy on the biggest, most controllable risks in your own life.