Among the buzzwords in health circles these days, chemicals—BPA, VOCs, parabens—are coming under more and more scrutiny. You may not be able to see them, but they sure can be scary, given all the headlines about how they make your hormones go haywire, may be linked to obesity or cancer, and could be lurking in your mac and cheese.

If you’ve heard people chattering about phthalates, you probably have a few questions: What are they? How big of a risk do they pose to your health? And how can you lower your exposure to them? We tapped expert Emily S. Barrett, PhD, associate professor of epidemiology at Rutgers School of Public Health, to answer these questions–and more–about phthalates.

Phthalates (the “ph” is silent) are a class of chemicals that are put into all sorts of different products, often to make plastic soft and flexible, says Barrett. (Think: a rubber ducky or your plastic shower curtain liner). They also hold onto scent and color really well, so they’re used in products “that need to smell good or be colorful,” she adds, like cosmetics and perfume.

Short answer: Just about anywhere.

The main sources are personal care products like lipstick, nail polish, shampoo, or perfume, as well as food. Barrett says the phthalate that’s most worried about is called DEHP. “Most of the DEHP we have in our bodies comes from what we eat,” she says. A 2014 study in Environmental Health pointed out that eating a diet high in meat and dairy doubled your exposure to phthalates, and a more recent report found phthalates in boxed macaroni and cheese.

Processed and fast foods are top offenders. “This food goes on conveyor belts, through tubes, and is packaged, so it may pick up phthalates that are in the processing equipment along the way,” Barrett says. “The more fast food you eat, the more likely you are to ingest phthalates.”

Phthalates in deodorants, perfumes, and cosmetics can be absorbed through your skin. You can eat them in food and ingest them when swallowing small amounts of products like lipstick and lip gloss–it happens!

You can also inhale them. “Dust is a big source of phthalates. If you were to take a dust sample from any home and send it to a lab, you’d almost certainly find phthalates,” says Barrett. Like we mentioned, these chemicals are everywhere—it’s impossible to get away from them entirely. But that may be okay—more on that in a minute.

Phthalates are ubiquitous. Almost all of us have measurable levels of the chemicals in our bodies, Barrett says. “We’re all exposed to phthalates, it’s just a matter of how much,” she says. But experts don’t know what’s a safe amount of exposure. Much of the research on phthalates is on animals, which doesn’t always translate clearly to humans.

Barrett’s research has compared phthalate levels in ordinary people with various markers of health. In kids, for instance, she’s looked at brain development or body composition. “We see that even at the ‘normal’ phthalate levels that everyone has in their bodies, there’s an association with obesity or altered development,” she explains. That said, researchers don’t yet know if there’s a certain amount you can carry around and be fine or a cut off above which you might start to worry. “We’re still trying to figure out in humans what’s safe and what’s not,” she says.

Prenatal exposure to phthalates may actually be the most worrisome. This may make any mama-to-be nervous (and you have plenty to stress about already), but the time you might want to be especially vigilant about reducing your levels is if you’re pregnant. Ingested, inhaled, and absorbed phthalates can actually cross the placenta and reach the baby, Barrett says. “We don’t know exactly how, but we have a pretty good idea that phthalates affect hormones of the baby and thus development,” she says.

Alarmingly, phthalates may interfere with reproductive development. Barrett points to data that shows that moms who have higher levels of phthalates in their body are more likely to have sons with altered reproductive development. “What this means in terms of future problems, we aren’t sure. We don’t know if those boys will have fertility issues,” she says.

In one 2014 study, which Barrett co-authored, phthalate exposure late in pregnancy was associated with behavioral problems in boys who were six to 10 years old.

For anyone hoping to become pregnant, this class of chemicals may also interfere with your own hormones, which are obviously key for conceiving and maintaining a pregnancy. Barrett points out that phthalates may also interfere with things like semen quality in adult men.

Not necessarily. Research has been laser-focused on DEHP, which is why it gets a lot of attention. “Some phthalates don’t really seem to have health effects that are obvious. So, no they’re not necessarily all bad when it comes to our health,” Barrett says. Some brands have opted to take DEHP out of their products (and advertise by including “DEHP-free” on their labels), but there is some concern about what it’s being replaced with. Often, that may be another phthalate that poses unknown dangers.