Tackling Toxics: Is your roof shedding chemicals into our lakes, rivers and Puget Sound?

By Alli Kingfisher, Building Materials and Sustainability Specialist, Waste 2 Resources Program

Ecology scientists Kyle Graunke and Tom Gries collect runoff samples while Ecology Director Maia Bellon looks on.

Here at Ecology, we often talk about non-point pollution that contaminates our waterways.

This is the kind of pollution that is often invisible. It comes from lots people doing lots of things on the land, and from lots of different places. It’s oil from leaking cars, fertilizer and pesticides from our yards, and dog poop from our beloved pets.

When rainwater lands, it picks up and carries pollution into our downstream receiving waters. Essentially, this is the stormwater pollution problem.

Where your roof comes in

But could you have ever guessed that the water that falls on our roofs might carry away trace contaminants to add to the problem of toxics in our lakes, streams and Puget Sound?

This is a question Ecology’s Environmental Assessment Program sought to answer with a recent study of roofing materials. The study was funded through a grant from the National Estuary Program to help restore Puget Sound.

The basis for the project started when Ecology’s Puget Sound Toxics Assessment indicated that roofing materials appeared to be sources of chemicals we have found in the Puget Sound basin. The study identified arsenic, copper, cadmium, zinc, and possibly PAHs and phthalates. Different chemicals and metals cause different problems. Many are toxic to fish, invertebrates, and the algae that the fish eat.

Salmon are sensitive

For example, we know that even very low concentrations of copper in the water can reduce an adult salmon’s ability to find its spawning area or for juvenile salmon to detect predators. We also know that zinc can damage fish gills. And in people, other chemicals either cause cancer or mess with our hormones (endocrine distrupters).

We wanted to determine to what extent roofing materials might contribute to the overall problem. And, in an innovative partnership, we collaborated with roofing manufacturers, their associations and other environmental and industry partners to design a rigorous study.

Many types of roofing materials tested

In Roofing Materials Assessment: Investigation of Toxic Chemicals in Roof Runoff, we set up 14 types of roofing materials in a test plot behind the Ecology Lacey headquarters building. The roofing materials represented residential and commercial materials commonly used in our area. When it rained and stormed, we collected water runoff from the roof samples 20 times over a one year period.

Roof types we studied:

• Asphalt shingle
• Asphalt shingle with copper-containing granules
• Copper
• Manufacturer-painted galvanized steel
• Concrete tile
• Wood shingles
• Manufacturer-treated wood shake
• Thermoplastic polyoleifn (TPO)
• Ethylene propylene diene monomer (EPDM)
• Zincalume®
• Built-up roof (BUR) with oxidized asphalt granulated cap sheet
• Modified BUR with Styrene Butadiene Styrene (SBS) granulated cap sheet
• Modified BUR with Atactic Polypropylene (APP) granulated cap sheet

The good news was that new asphalt shingles — the most prevalent roofing in Puget Sound — release low concentrations of metals. And in general, roofing materials less than a year old generally release low concentrations of metals.

Some roofing materials released higher concentrations of toxic metals:

• Treated wood panel released copper and arsenic
• Copper panel released copper
• Zincalume® and EPDM panels released zinc

The study has ended for now and the roofing panels have been relocated to the Washington Stormwater Center. We hope in the future they can be used to evaluate the effects of aging and to study other roofing components such as gutters, downspouts, and flashing.

Visit our website and learn more.

---