Birth control
Going on birth control is a mixed bag when it comes to cancer.
While it may increase a woman's risk for developing breast and cervical cancers, studies suggest it might also lower the chances of developing endometrial, ovarian, or colorectal cancers.
Sugar
Scientists now know that eating too much sweet stuff can not only lead to diabetes, it can also actively damage your cells and up your odds of developing cancer.
But that's not all.
New research suggests that sugar may fuel tumor growth in the body, because cancer loves to use sugar as fuel.
"The hyperactive sugar consumption of cancerous cells leads to a vicious cycle of continued stimulation of cancer development and growth" Belgian molecular biologist Johan Thevelein said when his latest study was released in 2017. Scientists say the groundbreaking research gives us a better understanding of how sugar and cancer interact, and could one day help create targeted diet strategies for patients.
Some plastics
Plastics can be dangerous, especially when they leach chemicals out through scratches or cracks in a container.
BPA is a synthetic estrogen that's been used in many plastics and resins since the 1960s. And it's a known endocrine disruptor, which means it messes with the natural balance of hormones in our bodies. BPA resins can be used inside products like metal food cans as sealants, while polycarbonate BPA plastics can include water bottles and food storage containers. BPA even shows up on the shiny side of receipt paper, to stabilize the ink.
While many plastic manufacturers have started labeling their products as "BPA-free," there's still a lot of the breast and prostate cancer-causing stuff around.
Processed foods
Any food that comes in a crinkly plastic wrapper, is industrially sealed, and built to last for months without spoiling may be a quick fix for a hunger pang on-the-go, but it's also likely upping your risk for cancer.
Scientists in France recently zeroed in on a link between people who eat more processed foods, and those who develop more cancer.
They're not sure yet whether it's the shelf-stabilizing ingredients in the food that's the problem, the plastic packaging, or some combination of the two. And because their study was correlative, it's possible there's some other hidden factor at work.
Cigarettes
Even though the tobacco industry tried to cover this one up, we've known for years that tobacco smoke has at least 70 cancer-causing chemicals inside. And it's not just smokers who are affected: people who inhale secondhand smoke can develop deadly forms of cancer too.
The Centers for Disease Control and Prevention says "nonsmokers who are exposed to secondhand smoke at home or at work increase their risk of developing lung cancer by 20–30%."
People who chew their tobacco are at increased risk, too.
Grilled meat
Smoky meats from the grill may be tender and tasty, but they probably also increase your risk of cancer. That's because the muscle meats contain compounds called Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs).
According to the National Cancer Institute, when meats like beef, poultry, or fish are cooked over a hot open flame or pan fried at high temperatures, the fat and juices they release into the fire spark flames with the dangerous chemicals inside that then cook into the meat we eat.
They're not positive these cause cancer, but in lab tests, they change DNA in ways that might increase cancer risk.
Alcohol
Regular, heavy alcohol consumption can up your risk of developing several different kinds of cancer, including throat, liver, breast and colon cancer.
According to the National Cancer Institute, "the risk of developing cancer increases with the amount of alcohol a person drinks."
Salt-cured meat or fish and pickled foods
Salt-cured fish, which is popular in China, is high in nitrates and nitrites — known carcinogens in animals that may also cause cancer in humans. The chemical compounds can damage DNA, spurring head and neck cancer.
According to Cancer Research UK, "People from China, or with Chinese ancestry living in the UK, have higher rates of nasopharyngeal cancer than other ethnic groups. This might be due to their diet."
Eating lots of pickled foods can also up your risk for stomach cancer.
Processed meats like ham, bacon, and sausages
Sorry.
The World Health Organization says processed meats like hot dogs, ham, bacon, and sausage can cause cancer.
That's because the meat has been treated in some way to preserve or flavor it,using techniques like salting, curing, fermenting, or smoking.
The WHO also thinks that any kind of red meat at all may be linked to increased risk of cancers like colorectal cancer, but they can't say that for certain yet.
Acrylamide, which is produced in small amounts when some foods are cooked and browned.
Similar to the way that cooking meat over an open flame can increase cancer risk, the browning of certain foods when cooked at high temperatures produces a chemical compound called acrylamide.
This happens naturally when foods like bread, coffee beans, toasted marshmallows or cookies are baked, in a process called the Maillard reaction.
But the dose of acrylamide in a toasty cup of coffee or a chewy cookie are probably not going to kill you; it's dangerous when inhaled in large doses (and it is one of the toxic chemicals smokers suck in), but we don't have solid evidence yet that a little browning is harmful.
California just mandated that coffee sellers warn their customers about the possible cancer risks of drinking in roasty acrylamide-laden coffee, even though the bulk of available scientific evidence suggests that drinking coffee is actually pretty good for your health.
Tanning beds
According to the Skin Cancer Foundation, people who use a tanning bed before age 35 up their risk of developing melanoma by 75%.
Regular sun can hurt you too, so wearing protective clothing, sunscreen, and finding shade are all good ideas if you're going to be out in the sunshine for more than 15 minutes.