Environmental exposure to hexachlorobenzene in the USA

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Chemical Monitoring

Background:

• Hexachlorobenzene (HCB) is a persistent chlorinated hydrocarbon with industrial and agricultural applications.
• HCB's agricultural use as a fungicide is declining, but it persists as an industrial chemical and manufacturing byproduct.
• HCB is a contaminant associated with chlorinated solvents and pesticide production.

Purpose of the Study:

• To review Hexachlorobenzene (HCB) data from the National Pesticide Monitoring Program.
• To analyze trends in HCB residue levels and detection percentages in environmental samples during the 1970s and early 1980s.

Main Methods:

• Review of Hexachlorobenzene (HCB) data from ambient environmental monitoring networks.
• Analysis of HCB residue levels and detection percentages in soils, air, aquatic life, birds, and food.
• Examination of data from the National Pesticide Monitoring Program.

Main Results:

• Actual mean residue levels of Hexachlorobenzene (HCB) showed no significant upward or downward trends during the 1970s.
• The percentage of detectable Hexachlorobenzene (HCB) generally increased from the early 1970s, peaked in the late 1970s, and then declined into the early 1980s.
• Erratic or steady mean residue levels contrasted with a clear trend in detection frequency for HCB.

Conclusions:

• While mean Hexachlorobenzene (HCB) levels were stable, its detectability in the environment increased significantly during the 1970s.
• The peak and subsequent decline in detectable Hexachlorobenzene (HCB) suggest complex environmental dynamics.
• The underlying reasons for the observed increase in Hexachlorobenzene (HCB) detection rates remain undetermined.