Parking your car in an indoor, enclosed parking deck
A concrete parking lot is not the best place for a casual, cancer-risk-free hang.
"Breathing the air in this parking garage can expose you to chemicals including carbon monoxide and gasoline or diesel engine exhaust," California says on its parking-lot warning. "Do not stay in this area longer than necessary."
The state insists that phrase is printed on signs in indoor parking decks or just about anywhere that people park inside.
The International Agency for Research on Cancer agrees with California on this one. Diesel oil has more than 30 known components that can cause cancer — though in a well-ventilated parking deck, there shouldn't be too many fumes.
California warns all residents that a cup of joe might cause cancer. A judge ruled earlier this year that the warnings were necessary as coffee contains a tiny dose of a chemical called acrylamide and therefore might be associated with an increased cancer risk. The compound can form when food is cooked at high temperatures through processes like frying, baking, and roasting.
Acrylamide has been linked to cancer in mice and rats when it's put in their drinking water, but only in very high doses.
"In animal studies, if you give animals a very high dose of acrylamide, it may cause cancer," Frank Hu, the chair of the nutrition department at the Harvard T.H. Chan School of Public Health, recently told The Seattle Times. "However, there is no evidence that acrylamide intake is related to cancer in humans."
Researchers who've for years studied coffee drinkers think those people probably aren't at any higher risk of getting cancer.
Instead, the International Agency for Research on Cancer and the American Cancer Society both point to scientific evidence suggesting that drinking coffee may lower a person's risk of developing some kinds of cancers, including oral, prostate, and liver cancers.
Acrylamide is in all kinds of cooked food we regularly eat, like french fries, potato chips, cookies, and cereal. There's no evidence yet that the amount of acrylamide in a cup of coffee has any detrimental health effects — in fact, you'd have to drink thousands of times the amount of acrylamide in that cup to get to those levels. It's much more likely that acrylamide in cigarettes could be worrisome for people.
The California Office of Environmental Health Hazard Assessment is challenging the coffee-warning ruling, arguing there's not enough evidence that coffee causes cancer.
Still, places like Starbucks in California have started pinning up signs to comply with the regulation.