I Study Microplastics and Chemicals. Nobody Wears Shoes in My Home.

This as-told-to essay is based on a conversation with Tracey Woodruff, the director of the Program on Reproductive Health & the Environment at the University of California, San Francisco. She studies how microplastics and toxic chemicals impact fertility and child development. The below has been edited for length and clarity.

I did not grow up removing shoes when entering the house.

My husband and I started getting into the habit when we had kids, and I got more immersed in my research and how to lower exposures to toxic chemicals.

One of the things that can help reduce exposure to microplastics and other toxic chemicals is taking your shoes off before coming into the house to avoid tracking things in from outside.

What’s on your shoes

One contributor to microplastic pollution is car tires, so that’s going to be outside, and you can track them around on your feet. Degrading plastic from garbage and vehicle runoff can also get on your shoes.

Microplastics are in the air, they’re in food, and they’re in water. You can breathe them, eat them, and chemicals on them can also absorb into your skin.

I co-authored a systematic review of studies on microplastics last year. We found they may increase the risk of reproductive health effects, particularly for effects on sperm, as well as chronic inflammation and the potential to increase the risk of lung and colon cancer.

Then there are the chemicals used in plastic — like phthalates, which can disrupt testosterone levels and affect fetal development.

It just became a habit

I would say leaving shoes at the door gradually happened over time. It wasn’t too hard. It just became a habit.

We have a closet, a bench, and a cabinet for shoes.

One of my sons is very diligent about taking off his shoes when he goes in the house now. He lived in Japan for a couple months. He’s got his house slippers.

My other kids also take their shoes off when they come in the house. It’s a part of their cultural heritage. My husband’s parents came from Japan, and they took their shoes off when they were in the house. We took the kids to Japan to visit relatives when they were small and almost everyone does it there. They identify with their Japanese heritage.

My daughter does it too in her townhouse with her roommates. They have one of those giant shelves with shoes on it.

At my home we have dogs, which I admit is a complicating factor because they’re tracking stuff in all the time. I don’t have a good solution to that at this point in time.