A greener 4th of July.

Scientists are increasingly worried that the beautiful fireworks millions of Americans will be watching this Independence Day contain toxic chemicals that may pose a threat to the environment. A particular focus is perchlorate, which helps “create the combustion reaction needed for the explosion.” According to a 2009 article in the journal Environmental Science and Technology, “the amount of perchlorate in nearby bodies of water could increase by anywhere from 24 to 1,068 times the amount present before the fireworks, and that it takes 20 to 80 days for the chemical levels to subside.” When ingested, perchlorate can hinder the thyroid’s production of growth hormones. In response, some chemists are looking for other solutions, including cleaner-burning fireworks that use nitrate-based oxidants.