Hexachlorobenzene – inhalable fraction. Documentation of proposed values of occupational exposure limits (OELs)

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Hexachlorobenzene – inhalable fraction. Documentation of proposed values of occupational exposure limits (OELs)

Journal Title: Podstawy i Metody Oceny Środowiska Pracy - Year 2016, Vol 32, Issue 3

Abstract

Hexachlorobenzene is a solid substance, insoluble in water, highly lipophilic with high melting and boiling point and high vapor density. The compound was used in war, electrotechnical, and chemical industries. Nowadays hexachlorobenzene is used for laboratory purposes. Except for destination synthesis this compound originates as a by-product during synthesis of chloroorganic solvents.In Poland, the exposure to hexachlorobenzene is increasing despite interdiction to its application. In 2005 in Poland, 28 people were exposed to hexachlorobenzene, whereas in 2014 exposed were 167 (men and women). According to Stockholm convention (2001) on persistent organic pollutions (POPs) there is prohibition of production, introduction to trade turnover and usage of hexachlorobenzene.There is no information about symptoms of acute poisoning by hexachlorobenzene in humans. Chronic intoxications by this compound were caused by uptake it with food, which happened in Turkey towards the end of 50s of last century. These poisonings had epidemic character. The chemical induced in humans, e.g., porphyria cutanea tarda, skin hyperpigmentation and hirsutism, neurological and orthopedic disorders.The median lethal dose and concentration values in animals indicate that hexachlorobenzene is outside of the classification of chemicals based on an acute toxicity. In experimental animals repeatedly exposed to this chemical, porphyrinogenic, hepatotoxic, thyreotoxic, and ototoxic effects were observed. Hexachlorobenzene as a weak ligand of AhR receptors shows dioxine-like activity. It causes functional disturbances in thyroid gland, ovaries, adrenal gland and leads to reduction of thyroid hormone concentrations, estrogens, glycocorticoids and their receptors. Hexachlorobenzene is not mutagenic and genotoxic in vitro and in vivo. The epidemiologic examinations did not proved carcinogenic effects of hexachlorobenzene in humans, however, numerous experimental studies noted its carcinogenic, promoting and cocarcinogenic activities. International and national institutions classified hexachlorobenzene to a carcinogen category 2.B (IARC), 1.B (EU, Poland) and to A.3 group (ACGIH).SCOEL did not established OEL value for hexachlorobenzene, since the compound has cumulative effect. Admissible concentration value in biological material (BLV) of 150 µg/l of serum or plasma and labeling „skin” because the compound is resorbed through the skin was recommended for assessing the exposure to hexachlorobenzene. Hexachlorobenzene is included in the register of the substances for which binding BOELV values should be established. Because of the prohibition (Stockholm convention) and cumulative effect of hexachlorobenzene BOELV value was not established.Hexachlorobenzene demonstrates reproductive and developmental toxicities. In females of different species, gonadotoxic effects were seen as result of hormonal disturbances, ovarian and egg cells injury which led to ovulation and fertilization impairment. The results of study on gonadotoxic effect of hexachlorobenzene in the female cymonolgus monkey exposed per os for 13 weeks were basis for calculating MAC value. The NOAEL value at level of 0.01 mg/kg b.w./day and joind uncertainty factor value of 24 were used to calculate MAC value at level of 0.003 mg/m3. It was recommended to label the substance with “Skin”. No STEL value has been recommended. In agreement with recommendation of SCOEL, the BLV value at level of 150 µg/l of serum or plasma has been proposed.

Authors and Affiliations

Stanisław Starek

Keywords

heksachlorobenzen toksyczność narażenie zawodowe NDS chlorophenylmethane (benzyl chloride) toxicity Occupational Exposure MAC

EP ID EP81654
DOI -
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