Hexachlorobenzene

Introduction
Effects on Humans
Effects on the Aquatic Environment
Monitoring Techniques and Standards
Safety Cards
Links

Introduction

*IARC: International Agency for Research on Cancer.

Hexachlorobenzene (HCB) has been used as both a pesticide and as industrial chemical. While intentional production has declined, HCB is also still produced as a by product during the manufacture of several chlorinated chemicals, it has been detected in the flue gas and the fly ash of municipal incinerators and other thermal processes.

HCB accumulates in human body tissues and breast milk in 1986, HCB was found in 98 out of 100 human adipose samples from people throughout the U.S. Breast-fed Australian infants were found to have HCB dietary intakes exceeding the WHO ADI* standards in 27 percent of the cases. Levels of HCB in Inuit mother's milk are five to nine times higher than levels seen in southern Canadian mothers' milk. (WFPHA, World Federation of Public Health Associations, 2000).
*Intake of 0.0006 mg/kg bw daily is considered below any dosage rate known to harmful.

Effects on Humans

Acute high dose exposure to HCB is associated with porphyria cutanea tarda due to its liver toxicity. In Turkey, people exposed to HCB contaminated flour developed this condition, and although most recovered after exposure ceased, some continued to experience porphyria through several years of follow-up.

HCB is also associated with enlarged thyroid glands, scarring, and arthritis exhibited in offspring of accidentally exposed women. Children born to mothers known to have ingested HCB-tainted food during pregnancy experienced acute illnesses and rashes. These children were additionally exposed through breast milk. Follow up studies reported porphyria cutanea tarda, reduced growth, and arthritic symptoms in children directly exposed to contaminated bread or mothers' milk. There was also a 37 percent prevalence of enlarged thyroids.(WFPHA, 2000).

Effects on The Aquatic Environment

Dietary level of 1500 micrograms/kg caused reduced embryo weights in herring gulls. Dietary level of 1000 micrograms/kg was associated with reduced birth weight and increased mortality of offspring in mink. Long-range atmospheric transport of HCB to the Arctic and other remote areas is a well-recognized phenomenon. The substance has been detected in Arctic air, snow, seawater, vegetation and biota. It had also been observed in other remote areas such as the North Pacific Ocean and in the rainfall of two remote islands on Lake Superior. HCB has been measured in freshwater and marine biota, including grass shrimps, sheephead minnows, and pinfish. Concentrations of HCB have been observed in fish-eating birds and predatory bird species. It had also been detected in the eggs of the peregrine falcon. (WFPHA, 2000).
Organisms generally accumulate HCB form water and from food, although benthic organisms may also accumulate HCB directly from sediment. The bioavailability of sediment-bound HCB is inversely correlated to sediment organic carbon content, and varies with the feeding habits of the organisms. Fields studies indicate that exposure via food is important for organisms at higher trophic levels, as significant biomagnification has been observed in several studies in natural aquatic ecosystems. (EHC, Environmental Health Criteria 195, WHO, 1997).

Monitoring Techniques and Standards

The HSDB, Hazardous Substances Data Bank: type Hexachlorobenzene

This site reports a full list of information on the substance as: Human Health Effects, Animal Toxicity Studies, Environmental Fate & Exposure, Environmental Standards & Regulations, Chemical/Physical Properties, Chemical Safety & Handling, Occupational Exposure Standards, Laboratory Methods, Synonyms and Identifiers.

Toxicology report with toxicity data from the Vermont Safety Information Resources, Inc.

This site provides a list or toxicity tests results, references for toxicity literature reviews, USA standards and regulations, occupational exposure limits in different states all over the world, and reference to NIHOSH, National Institute for Occupational Safety and Health, analytical standard methods.

Safety Cards

ICSC, International Chemical Safety Cards European Union version

The International Occupational Safety and Health Information Centre (CIS) access to
International Chemical Safety Cards: two pages data sheets on pure substances from the ILO/WHO/UNEP International Program on Chemical Safety (IPCS).

ICSC, International Chemical Safety Cards U.S. National version

The National Institute for Occupational Safety and Health (NIOSH) access to
International Chemical Safety Cards.

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