In soil, some microorganisms break down naphthalene. When near the surface of the soil, it will evaporate into air. Healthy soil will allow the growth of microorganisms which break down most of the naphthalene in 1 to 3 months. If the soil has few microorganisms, it will take about twice as long. Microorganisms may change the chemical structure of naphthalene.
Some common bacteria grow on naphthalene, breaking it down to carbon monoxide.
Naphthalene does not accumulate in the flesh of animals and fish that you might eat. Naphthalene and the methylnaphthalenes have been found in very small amounts in some samples of fish and shellfish from polluted waters. These compounds are similar to naphthalene and should act like it in air, water, and soil. Exposure Pathways You can be exposed to naphthalene if you live in a city that has polluted air. Naphthalene is generally not found in water, but when it is present, the levels are usually lower than 0.01 ppm.