Toxic heavy metals found in moss

Federal scientists studying the levels of heavy metals in tree moss found high concentrations of arsenic, lead and nickel in neighborhoods throughout Portland in 2013. The maps below were drawn from low resolution copies of U.S. Forest Service maps, and the boundaries shown are not precise. The colors reflect the volume of heavy metals in moss and cannot be translated into specific health risks for residents.

Arsenic

Micrograms per dry kilogram of moss

Lead

Micrograms per dry kilogram of moss

Nickel

Micrograms per dry kilogram of moss





The following graphics show toxic air trends in Portland and La Grande. The values are compared to the Health Benchmark, which is the level at which an individual has a 1-in-a-million chance of developing cancer when exposed over a lifetime. Until 2013, Oregon’s only two air toxics monitoring stations were in North Portland and La Grande. A third was installed in Hillsboro in 2013, and a fourth just went live on Swan Island; neither has been active long enough to collect reliable data.

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