Toxicity Profiles

RAGs A Format for Heptachlor - CAS Number 76448

Heptachlor is a manufactured chemical that does not occur naturally. Pure heptachlor is a crystalline white powder that smells like camphor (mothballs) while the less pure grade is tan. Trade names include Heptagran®, Basaklor®, Drinox®, Soleptax®, Termide®, and Velsicol 104®. Heptachlor was used extensively in the past for killing insects in homes, buildings, and on food crops. It was also used until the 1970s for the control of certain soil-inhabiting insects that attack corn and other field crops, cotton insects, grasshoppers and for treatment of seeds. Heptachlor was found to be uniquely suited for termite control. Use of Heptachlor slowed in the 1970s and stopped in 1988. As of April 1988, it can no longer be used for underground control of termites; its only permitted commercial use in the United States is fire ant control in power transformers.

Heptachlor is clearly toxic to humans and animals and can damage the nervous system. Heptachlor is absorbed from the digestive tract, lungs, and skin. There are some human data on brief exposures to high levels. A few reports showed that people who accidentally swallowed pesticides containing heptachlor, or who spilled pesticides on their clothes, became dizzy, confused, or had convulsions. Most of the knowledge about the health effects of these pesticides comes from studies on mice and rats fed heptachlor in the food or water. Very high levels for short periods produce serious liver problems. Mice had trouble walking and rats developed tremors. High levels of heptachlor in the feed for several weeks damaged the livers of rats and the livers and adrenal glands of mice.

Existing epidemiological studies on heptachlor are inadequate to establish a clear assessment of heptachlor exposure and human risk of developing cancer. Large-scale occupational cohort studies on workers engaged in the manufacture of heptachlor and pesticide applicators have not identified significantly increased cancer deaths. Several bioassays have shown that heptachlor can cause liver cancer in mice. Based on EPA guidelines, heptachlor was assigned to weight-of-evidence group B2, probable human carcinogen.

The following is a presentation of the toxicity information associated with Heptachlor.

Noncarcinogenic Health Effects
  • The Oral Chronic Reference Dose is 5.00E-04 (mg/kg-day).
  • The Oral Chronic Reference Dose has a modifying factor of 1.
  • The Oral Chronic Reference Dose has an uncertainty factor of 300.
  • The Oral Chronic Reference Dose is based on the Velsicol Chemical study from 1955.
  • The Oral Chronic Reference Dose study target organ is liver.
  • The Oral Chronic Reference Dose study critical effect is weight increases.
  • The overall confidence in the Oral Chronic Reference Dose is low.

  • The Dermal Chronic Reference Dose is 3.60E-04 (mg/kg-day).
  • The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 0.7200.

Carcinogenic Health Effects
  • The Oral Slope Factor is 4.50E+00 (mg/kg-day)-1.
  • The Oral Slope Factor study target organ is liver.
  • The Oral Slope Factor study cancer type is carcinomas.
  • The Oral Slope Factor is based on the NCI study from 1977.

  • The Inhalation Unit Risk is 1.3E+00 (mg/m3)-1.
  • The Inhalation Unit Risk study target organ is liver.
  • The Inhalation Unit Risk study cancer type is carcinomas.
  • The Inhalation Unit Risk is based on the NCI study from 1977.

  • The Dermal Slope Factor is 6.25E+00 (mg/kg-day)-1.
  • The Dermal Slope Factor is based on a gastrointestinal absorption factor of 0.7200.