Beta hexachlorocyclohexane (BetaHCH)

Beta-HCH is one of the five stable isomers of technical HCH, an pesticide formerly used in agriculture. In general HCHs are among the most studied pesticides with respect to environmental fate and effects (Breivik et al., 1999).

Production

Beta-HCH by itself is not intentionally produced or available on the market. Instead, betaHCH is produced as a part of technical HCH which is used as an insecticide or as an intermediate chemical in the manufacturing of lindane (enriched HCH). Currently no production data on technical HCH have been reported, whereas manufacture of lindane still takes place (IHPA, 2006).

HCH is manufactured by photochemical chlorination of benzene which leads to the formation of mainly five stable HCH isomers. The yields of different isomers vary due to technical differences in the production process. The reported ranges are:

  • alpha-HCH : 55-80%,
  • beta-HCH: 5-14%,
  • gamma-HCH: 8-15%,
  • delta-HCH: 6-10%; and
  • epsilon-HCH:1-5%.

Persistence

Due to its persistence, beta-HCH can still be detected at low background levels in all environmental media except in regions with recent usage and/or high pollution. Fairly high concentrations of beta-HCH have been found in Arctic marine mammals and birds.

Beta-HCH is present in terrestrial and aquatic food chain. Beta-HCH may bioaccumulate and biomagnify in biota and Arctic food webs, especially in upper trophic levels. In humans, accumulation in fat tissue and high concentrations in blood and in breast milk may occur. Beta-HCH transfers from mothers to embryos and lactating infants.

Human Health Impacts

In humans, breathing toxic amounts of beta-HCH can result in blood disorders, dizziness, headaches, and possible changes in the levels of sex hormones in the blood. These effects have occurred in workers exposed to HCH vapors during pesticide manufacturing. People who have swallowed large amounts have had seizures; some have died. All HCH isomers can produce liver and kidney effects. HCH isomers are changed by the body into other chemical products, some of which may be responsible for the harmful effects. Long-term oral administration of technical-grade HCH to laboratory rodents has been reported to result in liver cancer.

The US Department of Health and Human Services (DHHS) has determined that HCH (all isomers) may reasonably be anticipated to cause cancer in humans. The International Agency for Research on Cancer (IARC) has classified HCH (all isomers) as possibly carcinogenic to humans. The US-EPA has classified betaHCH as possibly human carcinogenic.

More information

 

 

References:

Adapted from Stockholm Convention Draft Risk Profile (pdf) and US Agency for Toxic Substances and Disease Registry Toxicological Profile (pdf)

Hatfield Consultants The World Bank funded by the Canadian POPs Trust Fund through the      
Canadian International Development Agency
Not logged on: log on here