By Liz Szabo, USA TODAY

A crawling baby learns about her world with every step, building her muscles as she discovers the difference between smooth bathroom tiles and squishy living room rugs. To her burgeoning taste buds, both taste great.

But research shows that babies pick up more than new skills as they explore their environments.

Infants may take in two to five times as much household dust as adults, even though they weigh only one-eighth as much, says Alan Greene, a pediatrician at Stanford University’s Lucile Packard Children’s Hospital. Because of that dust, babies are more likely to be exposed to pesticides and other potentially harmful chemicals inside the home than outside, he says.

Children younger than 2 are also more vulnerable to toxins than adults because they’re still developing, Greene says. On average, children that age who are exposed to a carcinogen are 10 times more likely than an adult to develop cancer, according to the Environmental Protection Agency.

“It’s a sound assumption that we should be 10 times more careful with children,” Greene says.

Pediatrician Harvey Karp, author of The Happiest Baby on the Block, suggests parents open their windows to ventilate the air once a day, if weather permits. He notes that indoor air is often more polluted than outdoor air, partly because of solvents and other chemicals found in paint, flooring, rugs, furniture and dry cleaning.

Yet toxic exposures often start long before babies can crawl. Babies today are typically born “pre-polluted,” exposed to potential carcinogens even before birth, a report by the President’s Cancer Panel said in May.

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In a study of umbilical cord blood by the Environmental Working Group, researchers found 180 carcinogens in babies and 217 chemicals that were toxic to the brain or nervous system.

The American Cancer Society estimates that about 6% of cancer deaths — nearly 34,000 a year — are caused by environmental pollutants.

Because so little research has been done on cancer and the environment, it’s possible the true number of pollution-related cancer deaths is actually much higher, the President’s Cancer Panel says.