As fireworks from cities and individual homes streak across the sky this Fourth of July, one Indiana water utility company is warning that they could pose a threat to the state’s water systems.  Indiana Public Broadcasting’s Nick Janzen reports.

Fireworks contain a chemical called perchlorate. It’s also found in rocket fuels, explosives, and some fertilizer. At high levels, the chemical in drinking water can create problems with the human thyroid gland, according to the U.S. Geological Survey.

Indiana American Water serves a million Hoosiers. Company spokesman Joe Loughmiller says there’s a few ways Hoosiers can lessen the threat fireworks pose to the state’s water sources.

“The main thing is just to make sure you’re not setting these fireworks off near lakes and waterways, and then if there’s debris left over afterwards, make sure you clean that up.”

Loughmiller also says public firework displays usually take good care to clean up after themselves, so Hoosiers might want to skip personal firework displays all together.