Home > environment, Health & Science > Misclassification of Copper: What the Scientific Studies Say (Part II)

Misclassification of Copper: What the Scientific Studies Say (Part II)

By Joe Gorsuch, Copper Development Association (CDA), Manager, Health, Environment and Sustainable Development, and Dr. Joe Meyer, ARCADIS Technical Expert

Architects and building construction professionals in recent years have been increasingly concerned about using copper as a building material and have incorrectly classified it as a “chemical of concern,” although it is not included in the official list identified by the U.S.  Environmental Protection Agency. We believe architects, developers and contractors have incorrectly moved toward a decision-making process based on potential hazards, rather than risks. We’ll explore what the scientific evidence shows in this blog.

Copper has been placed on many lists of chemicals of concern because it can cause or is suspected to cause toxicity in some forms. However, the few forms of copper that are of actual concern are not specified in the lists, leaving an uninformed reader to conclude that all forms of copper are “bad.”

Many tests to determine toxicity are conducted in lab settings and use copper in the form of salts that easily dissolve in water. In contrast, durable building materials like copper roofing do not easily dissolve. Results from toxicity tests with copper salts (copper sulfate, for example), which represent only two percent of world copper production, are used most often in hazard assessments.

An important distinction is that hazards are defined as hypothetical worst-case scenarios, whereas risks are defined as the probability of harm occurring in specific contexts. Therefore, hazard assessments based on the results of toxicity tests with copper salts can greatly overestimate the potential harm that copper building materials pose to humans and the environment.

Some “suspected,” but unconfirmed health effects of exposure of humans to copper that are cited by architectural and building construction firms include blood, liver or respiratory problems. But these would only affect human health if copper salts are swallowed or copper dust is inhaled. Neither activity occurs when copper-metal mass alloys are used in building construction so the risks are negligible.

However, ad hoc, and sometimes proprietary procedures are being used to classify copper as a chemical of concern in building materials. Those classifications are usually hazard-based instead of risk- based and are not necessarily based on current science or appropriate scientific approaches to determine the safety of the material.

A Roof Runoff Case Study

The CDA and the International Copper Association, are supporting a study that was launched in 2012 by scientists at Towson University, near Baltimore. The study is designed to determine how appropriate treatment or mitigation of rainwater could reduce copper toxicity to aquatic and terrestrial organisms. The researchers built a copper-roofed picnic shelter with stormwater control measures to assess the amount, biological availability (bioavailability) and treatability of copper in stormwater runoff generated by the structure.

The researchers have found that the planters and swales (through which roof runoff is diverted) significantly reduce the amount of copper – some 88-99%. In addition, the bioretention and biofiltration systems alter the chemistry of the runoff as it passes through. Model calculations made using stormwater data indicate that the change in runoff chemistry made copper less bioavailable and therefore less likely to cause terrestrial or aquatic toxicity.

In contrast to generalized lists compiled by various architecture and building organizations, copper is not included on the EPA list of 31 Priority Chemicals (PCs). The EPA’s National Waste Minimization program is focusing its efforts on decreasing the amount of these PCs found in U.S. products and waste by “finding ways to eliminate or substantially reduce their use in production.” It’s important to note the EPA used a risk-based instead of a hazard-based approach in compiling this list. Risks are defined as the probability of harm in a specific situation, while hazards are hypothetical worse-case scenarios.

So when it comes to determining the safety of copper as a building material, beware of generalized lists that lump all forms of copper into one category. Instead, consider the context of each individual location before determining the designated uses and provide appropriate treatment/mitigation (planters and swales for copper roof runoff) when deciding on a building’s design.

Copper as a building material is safe for use by building professionals, construction workers and homeowners. Copper is only harmful to humans if a very concentrated copper salt (such as in a laboratory setting) is ingested or inhaled.

The bottom line: Durable copper building products present little risk to humans and the environment.

For more information on copper as a building material, please contact Joe Gorsuch, CDA Manager, Health Environment and Sustainable Development, joseph.gorsuch@copperalliance.us.

 

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