Estrogen. Wood dust. Sunshine. Even the tasty char on grilled meat. They all show up in the latest Report on Carcinogens (ROC) from the U.S. government's National Toxicology Program. To produce the report, government and independent scientists scour international research for substances that caused cancer in humans or animals.

On first read, this who's who of 246 known and suspected bad actors is downright terrifying—as in, "I'll just move into a dark cave and eat leaves and tree bark (but not sassafras bark—it's carcinogenic, too)". ROC director Bill Jameson, PhD, says freaking out isn't necessary—a little caution and awareness on your part can go a long way. "The report identifies hazards," he explains. "I read labels all the time. If there are two products that do the same job, I'll pick the one that doesn't list something in the ROC."

Still, the information can be maddening: Estrogen and progesterone make the list for possibly raising breast cancer risk, but research shows that in birth control pills, these hormones may protect against ovarian and endometrial cancer. And at least 18 different drugs used to treat cancer can raise the risk of, well, other cancers.

The best approach is to balance the benefits and risks, says Jameson. Preventing unwanted pregnancies and treating the cancer you have versus worrying about the slim chance of one you might get are obvious choices. "The probability of developing cancer in your lifetime is about one in three for women and one in two for men," Jameson says. "Most scientists in cancer research believe that the environment may be a major contributor—and much of the risk can be avoided." Below are some of the nasties you should watch out for.

Acrylamide: Crispy, crunchy stuff such as potato chips, crackers, and fries contain the most. This suspected carcinogen was recently let off the hook as a breast cancer promoter, but it may raise the risk of other types.

Alcohol: Moderation, meaning no more than a drink (for women) or two (men) a day, is your best bet.

Bromodichloromethane: It's in the water and vapors released from chlorinated swimming pools and saunas. It has given rats kidney and intestinal cancers. More and more pools are using alternative water-purification systems; you can check with local pools to see if there is one near you.

Heterocyclic amines and polycyclic aromatic hydocarbons: The first are in very well-done meats, the second in charred grilled meats and veggies. Minimize exposure by cooking food until done, not well-done.

Reserpine: This blood pressure drug has induced adrenal and breast tumors in rats and mice. Reserpine can be an effective treatment for patients who don't respond to diuretics, but it should always be a second-line treatment. You can discuss your options with your doctor.

Safrole: Found in the pungent oil of sassafras root bark, it has caused lung and liver cancer in mice. Although safrole is banned by the FDA, sassafras root bark is still sold.

Wood dust and soot: Known human carcinogens, both can up your odds for nasal and lung cancer. This is a concern for carpenters and cabinetmakers; even hobbyists will want to take precautions like wearing a mask or respirator while working.