Chronic studies of workers exposed to endrin via inhalation have not suggested an association between exposure and the occurrence of any type of cancer. However, these studies are limited by inadequate exposure data, including concurrent exposure to other chemicals, short followup, and small size of study cohort.
No studies were located regarding cancer risk in humans via oral or dermal exposure.
There were slight excesses of cancer of the esophagus, rectum, liver, respiratory system, bladder and urinary system, and of the lymphatic and hematopoietic systems in manufacturing workers exposed to vapours of endrin/aldrin/dieldrin in two plants. However, as already noted, these findings were not statistically significant, the elevated standard mortality ratios (SMRs) were based on small numbers of observed deaths, and workers were subject to concurrent exposure to chemicals other than endrin.
Oral exposure studies in rats and mice did not show association between exposure to endrin and increased incidence of cancer. No chronic studies are available in animals exposed to endrin via inhalation or dermal exposure. In the absence of evidence of a carcinogenic effect in two animal species, additional studies are not warranted at this time.
The Department of Health and Human Services (DHHS) has not listed endrin in the U.S. National Toxicology Program Carcinogen List. IARC has concluded that there is inadequate evidence for the carcinogenicity of endrin in humans, and there is only limited evidence in experimental animals. Endrin is therefore not classifiable as to its carcinogenicity in humans.
According to the U.S. EPA Carcinogen List the endrin carcinogenicity data are either incomplete, inadequate or ambiguous there for endrin is classified as a Category D, Not classifiable as to human carcinogenicity.