Halloween is on Friday, and you'll probably be done with your costume by the time the calendar flips to November. So what should you do with those old costumes? 

Simply throwing them away can create a lot of trash.

Massachusetts residents throw away an average of 230,000 tons of clothes and textiles each year, and used Halloween costumes are one of the biggest culprits.

One sustainability expert has several suggestions on what you can do instead.  

What to do with used Halloween costumes

Lexy Silverstein, a sustainable fashion advocate, spoke to WBZ-TV about how to combat this growing environmental concern without ruining one of our most enjoyable holidays.

"Americans throw away 35 million costumes every single year, which adds up to 5.4 million kilograms of textile waste, which is equal to 83 million plastic water bottles," Silverstein said. "These costumes, 63% of them are made up of polyester and plastic, which can take anywhere from 20 to 200 years to decompose."

On top of that, costume prices are at an all-time high. Between costumes and candy, Halloween can cost $114 per person on average, which Silverstein calls "not only unsustainable, but also less accessible."

Silverstein offered several alternative solutions to throwing Halloween costumes away.

Thrift stores always have an excess of items, especially this time of year. And many of them have Halloween racks. This would offer the perfect way to buy a used costume to save money and give someone else's a second life. You can also donate your costume instead of throwing it away once Halloween is over.

Sharing and reusing is another great option. Talk to friends and family about using their old costumes or trading in some of yours. There are even some apps dedicated to renting costumes locally.

Check with your town to see if they have a Halloween costume exchange program. There are a number of them in and around the Boston area.

Finally, Silverstein suggests scouring your own closet and attic to find clothes that can help you be creative for Halloween.