Lindane is an organic compound produced as a white solid from hexachlorocyclohexane for use as an insecticide. Also known as gamma-hexachlorocyclohexane, benzene hexachloride, and Gammallin, lindane is also used in the preparation of prescription-based shampoos and creams to treat scabies and lice.
Lindane is classified as a neurotoxin and is a suspected carcinogen and endocrine disruptor. Its mechanism of action is to block an important neurotransmitter called gamma-aminobutyric acid (GABA) at receptor sites. As a pharmaceutical, lindane products are required to be labeled with a "black box warning" in the United States. This is a cautionary statement that improper use of the product may cause harm to infants, children, the elderly, those with certain skin conditions, or weighing less than 110 pounds (50 kg). The warning also advises that lindane products must not be used at all on premature infants or those with seizure disorders.
Although lindane has not been manufactured in the U.S. since 1976, it continues to be imported for pharmaceutical use. With the exception of California and Michigan, it is permitted for this purpose in most states. On a global scale, numerous countries either restrict or require registration for the use of lindane as an agricultural insecticide, including the U.S. However, lindane has been banned altogether in at least 52 countries since 2006.
Lindane is very persistent in the environment. In fact, it accumulates in the fatty tissue of fish and adheres to soil particles as a vapor. Lindane can also be transported significant distances through a natural process known as global distillation, or the grasshopper effect. Since it survives as an airborne vapor for long periods, it will ride air currents and eventually gravitate to cooler climates where it will condense and accumulate. This is why pollutants are sometimes found in animal tissue and soil samples in elevated regions, even though the substance didn’t originate there.
Although lindane exposure does not usually cause birth defects in animals, it is not known if it does in humans. However, it should be noted that studies have shown that lindane can pass through the placenta of pregnant women and enter breast milk. If there is any concern over possible toxicity from this organic compound, testing is available. Hexachlorocyclohexane isomers can be detected and measured from samples of body fat, breast milk, semen, blood and urine.