Cigarettes are the most littered item on earth. Worldwide, about 4.5 trillion cigarettes are littered each year. Cigarettes contain more than 7,000 chemicals, such as arsenic (used to kill rats) and formaldehyde (used to preserve dead animals, and humans, too). Littered cigarette butts leach toxic chemicals into the environment and can contaminate water. The toxic exposure can poison fish, as well as animals who eat cigarette butts. Cigarette filters may look like cotton, but 98 percent of cigarette filters are made of plastic fibers (cellulose acetate) that are tightly packed together, which leads to an estimated 1.69 billion pounds of cigarette butts winding up as toxic trash each year. Cigarettes don’t break down naturally, they can gradually decompose depending on environmental conditions like the rain and sun. Estimates on the time it takes vary, but a recent study found that a cigarette butt was only about 38 percent decomposed after two years.