Exposure assessment framework for antimicrobial copper use in urbanized areas

Area of Science:

• Environmental Science
• Ecotoxicology
• Urban Hydrology

Background:

• Copper compounds are utilized as antimicrobial agents in building materials, including algae-resistant roofing shingles and treated wood for outdoor structures.
• Potential environmental risks to aquatic and terrestrial organisms arise from copper releases from these materials in urbanized environments.

Purpose of the Study:

• To estimate copper exposures in surface water, sediment, and soil within a hypothetical urban setting.
• To evaluate the environmental risks associated with copper releases from algae-resistant shingles and treated wood products.

Main Methods:

• Utilized the TREX watershed model to simulate copper releases and exposures over a 10-year period in an urban landscape.
• Incorporated data on drainage, soil characteristics, housing densities, and copper use in building materials for a spatially distributed assessment.
• Defined release rates based on material surface area and rainfall, evaluating exceedances against established water, sediment, and soil benchmarks.

Main Results:

• Copper exposures from algae-resistant shingles did not exceed environmental benchmarks in any assessed medium (water, sediment, soil).
• Copper exposures from treated wood did not exceed sediment and soil benchmarks.
• Surface water benchmarks for copper were exceeded on only 2 days over the 10-year simulation period for treated wood.

Conclusions:

• Copper used as an antimicrobial agent in algae-resistant shingles is unlikely to pose significant adverse environmental risks.
• Copper used in treated wood products is not expected to pose significant risks to sediment and soil organisms, with minimal exceedances in surface water.