ABSTRACT
Hexachlorobenzene (HCB), a pesticide that was one of the first persistent organic pollutants (POPs) to be listed under the Stockholm Convention, has not been used for many decades. However, it is still present in all environment compartments, and consequently in tissues of humans and other animals where it is believed to be responsible for toxic effects. It is a major component of industrial wastes: some legacy sites have been remediated but others await treatment. HCB continues to be emitted to the atmosphere from soils to which it had been applied, and as a by-product from metal production and waste burning. Concentrations have declined over the last two decades and seem to be approaching a steady state, and the view has been expressed that it is the POP that is furthest along the transition to global equilibrium. There is uncertainty in reaching this conclusion because reporting of data, as required of countries under the Stockholm Convention, has been inconsistent.
