From hamburger wrappers to car seats, forever chemicals are everywhere. Here’s what parents need to know.

Although scientists are still investigating the impact of so-called "forever chemicals" in humans, it's become clear that they're nearly everywhere. Now, a new study by the U.S. Geological Survey (USGS) finds that about 45% of tap water in the U.S. contains per- and polyfluoroalkyl substances (PFAS), which have been called forever chemicals.

In the study, scientists tested water collected "directly from people’s kitchen sinks across the nation, providing the most comprehensive study to date on PFAS in tap water from both private wells and public supplies,” Kelly Smalling, the study's lead author and USGS research hydrologist, said in a statement. “The study estimates that at least one type of PFAS — of those that were monitored — could be present in nearly half of the tap water in the U.S. Furthermore, PFAS concentrations were similar between public supplies and private wells.”

But that's not the only study looking at forever chemicals in our environment. Recent research shows that 1 in 5 children have levels of forever chemicals that are above established safety limits.

The study, which was published in the International Journal of Hygiene and Environmental Health, analyzed blood samples from 1,094 children in Norway between the ages of 6 and 16 and looked for the presence of PFAS. The researchers found that four common PFAS were found in all children and that 22% had levels above safety limits set by the European Food Safety Authority.

Another recent study on the impact of forever chemicals on kids found that mothers who were exposed to higher levels of PFAS during pregnancy had children with slightly higher BMIs and a higher risk of obesity than those whose mothers had lower levels of PFAS in their blood during pregnancy.

But what are forever chemicals exactly, and why are they so concerning? Experts break it down.

What are forever chemicals?

Forever chemicals are a large group of man-made chemicals that have been used in consumer goods since the 1950s, according to the National Institute of Environmental Health Sciences (NIEHS). PFAS have a lot of uses, including making carpets stain resistant, creating firefighting foam and keeping food from sticking to packages or cookware.

"These chemicals have gotten into the environment, but they don't break down in the environment," Dr. Robert Laumbach, a researcher and occupational medicine physician at Rutgers Environmental and Occupational Health Sciences Institute, tells Yahoo Life. They end up "bioaccumulating," which means they build up over time. "They've been found all over, including in polar bears in the Arctic," Laumbach says. "Because they don't break down and bioaccumulate, we're all exposed."

"These chemicals have long half-lives and tend to accumulate within the body and environment over time," Jamie Liu, a postdoctoral research associate in epidemiology at Brown University and lead author of the recent study that linked PFAS to childhood obesity, tells Yahoo Life.

Worth noting: Thousands of PFAS have been identified.

Where are forever chemicals commonly found?

Forever chemicals are nearly everywhere. "PFAS are ubiquitous in society, in everything from hamburger wrappers and raincoats to car seats and carpets," Emily Scarr, Maryland state director of public safety advocacy organization PIRG (Public Interest Research Group), tells Yahoo Life. "And because there are no required labels, it’s hard to know everywhere they are."

In addition to firefighting foams, PFAS are usually used in waterproof and stain-resistant products, along with food packaging, rugs, makeup and outdoor apparel, Scarr says. It's also found in nonstick cookware.

How harmful are forever chemicals?

PFAS "have been linked to various health risks," Liu says, and research on their health impact is still ongoing.

These forever chemicals raise the risk of developing cancer with long-term exposure, according to the Environmental Protection Agency (EPA). Research has also linked PFAS to conditions such as obesity, infertility and thyroid disease.

Last year, the EPA issued health advisories for drinking water, noting that forever chemicals are more hazardous to human health and at lower levels than scientists previously thought.

While research into the impact of PFAS is ongoing, what's been discovered so far isn't great. "Right off the bat, we're concerned about what the potential effects of these chemicals are, given how common they are," Laumbach says.

How parents can help kids lower their exposure to forever chemicals

Experts admit that this is tricky because they're nearly everywhere. A 2015 report found that at least 97% of Americans have forever chemicals in their blood, while a 2019 study found that 98% of Americans have PFAS in their blood.

"It is not possible to completely avoid PFAS," Liu says. "These chemicals are everywhere in the environment; people can be exposed to PFAS through the ingestion of contaminated food and drinking water as well as the inhalation of indoor air and house dust."

Still, Liu says you may be able to minimize your family's exposure to these chemicals. That includes doing the following:

• Use water filters containing activated carbon or reverse osmosis membranes to remove PFAS from drinking water.

• Avoid or limit takeout and fast food — the containers and packaging often have PFAS that can leach into food.

• Frequently vacuum, using HEPA filters to remove PFAS-containing dust.

• Avoid stain-resistant rugs, which are treated with chemicals that contain PFAS.

• Try to keep babies and infants from putting objects into their mouths, which is easier said than done.

Again, it's not possible to completely prevent your family from being exposed to PFAS — but experts say you can take some steps to reduce your exposure.

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