Hexachlorobenzene (HCB)

The substance
Pure hexachlorobenzene is a white crystalline solid with an unpleasant odour. It is virtually insoluble in water but dissolves readily in organic solvents, fats and oils. It is quite volatile.

Hexachlorobenzene has been widely employed as a fungicide on seeds, especially against the fungal disease 'bunt' that affects some cereal crops. The marketing and use of hexachlorobenzene as a plant protection product was banned in the European Union in 1988.

Major emissions
As there is no more hexachlorobenzene production in the EU, the only man-made releases of hexachlorobenzene are as unintentional by-product in the chemical and metal industries and in combustion processes. Hexachlorobenzene could also be present as a contaminant in several pesticide formulations such as Clorothalonil. Hexachlorobenzene is as unintentional by-product released from some processes manufacturing chlorinated solvents and secondary aluminium processing.

Impacts on human health and environment
Excessive exposure may cause health effects on the adrenal gland, blood, bone, brain, breastfed babies, immune system, kidney, liver, lung, parathyroid gland, peripheral nerve, reproductive system, skin, thyroid gland and the unborn child, and may cause cancer. A main concern over environmental releases of hexachlorobenzene is related to its persistence and ability to bioaccumulate/bioconcentrate up the food chain. High levels can build up in fish and marine mammals, and also certain plants. Hexachlorobenzene is ubiquitous in the environment and has been measured in different types of food. The volatility of HCB, together with its resistance to decomposition in the environment and tendency to bioaccumulate favours the long-range transport around the globe. Hexachlorobenzene has been found in air, water and organisms in the Arctic region. Hexachlorobenzene is classified as a POP ('persistent organic pollutant').As a VOC it can be involved in reactions with other air pollutants that form ground-level ozone, which can cause damage to crops and materials as well as having potential effects on human health. Hexachlorobenzene is listed as priority hazardous substance in the Water Framework Directive.

Emission to air reporting threshold: 10 kg/year

Emission to water reporting threshold: 1 kg/year

Data source: European Pollutant Emission Register