NL-Hexaclorobenzene –toxicological assessment and occupational exposure limit 07.12.2011
At request of the Minister of Social Affairs and Employment, the Dutch Expert Committee on Occupational Exposure Safety (DECOS), a Committee of the Health Council of The Netherlands, proposes health-based recommended occupational exposure limits (HBROEL) for chemical substances in the air at the workplace. These recommendations serve as a basis in setting legally binding occupational exposure limits by the minister.
In this report, the Committee discusses the consequences of occupational exposure to hexachlorobenzene and recommends a health-based occupational exposure limits. The Committee’s conclusions are based on scientific papers published prior to May 2010.
Hexachlorobenzene is a white crystalline solid, which is highly lipophilic and poorly soluble in water. It has a molar weight of 285 g/mol. Hexachlorobenzene is not produced in The Netherlands. However, it can arise as a by-product or contamination in the production of other chlorinated hydrocarbons. Therefore, occupational exposure is possible for workers involved in this type of production or in the formulation/application of plant protection products containing chlorothalonil as an active ingredient.
The International Agency for Research on Cancer (IARC) classified hexachlorobenzene previously as ‘possibly carcinogenic to humans’ (group 2B), based on inadequate evidence in humans and sufficient evidence in experimental animals for carcinogenicity (IARC 2001).
On request of the Dutch Expert Committee on Occupational Safety of the Health Council, the Subcommittee on the Classification of Carcinogenic Substances evaluated the carcinogenic properties of hexachlorobenzene. The Subcommittee states that hexachlorobenzene appears to cause cancer via a non-genotoxic mechanism, such as hepatotoxicity. It may act as a promotor of liver carcinogenesis. It recommends classifying hexachlorobenzene in category 1B *.
On request of the Dutch Expert Committee on Occupational Safety of the Health Council, the Subcommittee on the Classification of Reprotoxic Substances evaluated the reprotoxic properties of hexachlorobenzene: after weighing the evidence from animal studies, the subcommittee concluded that hexachlorobenzene does affect both fertility and development in experimental animals. Consequently, the subcommittee proposes to classify hexachlorobenzene as a ‘presumed human reproductive toxicant’ and recommends classifying the substance in category 1B *. Furthermore, it recommends classifying hexachlorobenzene as a substance that ‘may cause harm to breastfed babies’.
