Buying a used mattress sounds like a great idea when you compare the price tag with that of a new one, but stop to consider why someone might have given it away in the first place. A mattress that’s already had a long life may turn out to be lumpy, which could cause you back pain  down the line. Plus, you probably don’t want to think about the dead skin cells, pet dander, dust mites, and bodily fluids that have probably seeped into it over the years. Aside from just being plain gross, they can all cause respiratory allergies. Then, of course, there are the industrial chemicals like flame-retardants, formaldehyde, and phthalates that were used to make it. If you’ve got the resources, a mattress made from organic and natural fibers is a worthwhile investment—they’re free of toxins and will last for years to come.
Related: Eco-Friendly Beds Under $1,500 
2. Vinyl Records
Who doesn’t like to listen to the oldies now and again? But did you realize those vintage albums you like to rifle through at the consignment shop are made from PVC plastic (that’s polyvinyl chloride), which is associated with all sorts of environmental evils, like dioxins, lead, and phthalates? Downloading music is the greener option, but don’t feel you need to trash your old records immediately, since they can’t be recycled anyway. What you shouldn’t do, though, is make them into decorative bowls  by melting them in the oven. The heat will release hazardous fumes and dioxins, a group of highly toxic chemicals known to cause reproductive problems, damage to the immune system, and cancer.
3. Fleece Jackets
You know shopping for clothing secondhand is easy on the Earth, but stay away from fleece. It turns out that those cuddly sweaters are made from upcycled plastic bottles, which sounds great until you realize they shed thousands of tiny plastic microfibers  every time you run them through the washing machine. These end up in water systems and do damage to marine life. Stick to secondhand wool and cotton, which have natural fibers, instead.
4. Halloween Costumes
A few years back, consumer-testing group Healthy Stuff discovered some scary chemicals  in kids’ Halloween costumes—including lead, flame-retardants, and phthalates. Plus, consider the added risk of buying these items secondhand. You don’t know what kind of bacteria could have ended up inside a Halloween mask or wig, and it’s unlikely those items could stand up to a run through the washing machine.
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5. Stoneware Pottery
You may be tempted to pick up a vintage crock for starting sourdough  or some beautiful old mugs for pennies on the dollar, but how do you know you’re not setting your family up for exposure to lead? In 1987, The Los Angeles Times reported  that the FDA recalled thousands of crockery items, mostly those made overseas in places like Spain, Italy, China, and Mexico from 1986 to 1987. There’s always a chance you could still come across some of these ceramics lining the shelves of thrift stores. Those that are highly decorated, handcrafted, or brightly colored (especially orange, red, and yellow) are more likely to contain lead . Reserve them for decorative purposes only or pick up an at-home lead-testing kit.
Related: Sustainable Table Settings 
6. Stuffed Animals
The Environmental Working Group reported in 2009  that PBDEs, a class of flame-retardant chemicals, were found in all stuffed toys manufactured in China that year. Some of these chemicals have been banned in the United States due to health concerns (especially fertility and hormone problems), but chances are that they’re lurking in that teddy bear your child begged for at the thrift store. Even if the tag doesn’t say “Made in China,” think twice. Chances are good that old stuffed animals are loaded with dust mites, which are linked to allergies and asthma in some people.
The Consumer Products Safety Commission banned drop-rail cribs back in 2011 following infant deaths and injuries caused by faulty parts, so don’t even consider buying one at a thrift store. Even if you find a crib without the dangerous sliding side rail, you should still be wary. You have no way of knowing about past or future recalls on the product, so play it safe and get a new one or borrow newer models from friends and family instead.