We don’t often think about whether there are toxins in the trees around us, but researchers in Portland, Oregon recently made a very unsettling discovery. Common tree moss in the area contains dangerous heavy metals like arsenic, and it isn’t just in the trees – it’s in the air, too.

Toxic heavy metals, toxins, cadmium, arsenic, Portland, Oregon, moss studies, Portland at night

United States Forest Service researchers, including economist Geoffrey Donovan and moss and lichen expert Sarah Jovan, weren’t searching for pollution. They were working on a study to demonstrate how trees benefit cities when they began the moss experiments, which health experts say is the first type of this research. Yet their 346 samples revealed toxic heavy metals such as cadmium, and the concentrations were greatest near two glass factories, one in southeast Portland, the other in north Portland.

Related: IS IT GREEN?: Portland, Oregon

After the researchers confirmed their find, the Oregon Department of Environmental Quality began to conduct more studies. They found “high levels” of cadmium and arsenic in the air, concentrated in southeast and north Portland.

Portland prides itself on being a green city; in 2013 it was among the top 25 areas with the cleanest air in the United States. Residents recycle over half the waste they create – and these are just a few of the ways in which Portland tops other cities in the country. Locals are naturally concerned, although the department says it needs to do more testing to figure out how serious the pollution is.

A paper released by the Oregon Health Authority stated that people probably would not experience negative health effects, and that air pollution clears swiftly after wind or rain. Health officials say residents can discern whether the metals have affected them through urine testing with their doctor, and that they will pay for those who cannot pay for the test themselves.

The two factories, Bullseye Glass and Uroboros Glass Studies, are near residential neighborhoods, whose inhabitants were asked not to plant spring gardens until more information could be obtained. Both glass studios said they did not want to harm local residents and both stopped using cadmium and chromium, which are used in coloring processes.

Further research is ongoing in Oregon, but scientists think the surprising moss study could aid a better understanding of the environment in other areas of the country. Donovan and Jovan already intend to study Cincinnati this spring at the request of the Cincinnati Children’s Hospital Medical Center.

Via The New York Times

Images via Brian on Flickr and Wikimedia Commons