Tag Archives: Environmental science

More results, more questions found in toxic studies

Five years of studies and analysis have helped refine our understanding about the toxic pollution getting into the streams of Puget Sound and eventually into the open marine waters.

The latest study on toxic chemicals (PDF 3.1 mb) Click on image to download

The final report in the series was released yesterday, prompting a story I wrote for today’s Kitsap Sun.

When accounting for all the pollution, it’s not surprising to learn that the sources of toxic chemicals are so diverse that it is difficult to figure out where everything is coming from. But we do know that if chemicals are picked up in stormwater, they are likely to make their way into freshwater, where they pose short-term or long-term risks to aquatic organisms.

The solutions are common sense, if one can be assured of the sources of harmful chemicals:

  1. Remove materials from the environment if they are found to release toxic pollution. This can involve a legal ban on certain products or else educating people to select less toxic alternatives.
  2. Reduce the amount of stormwater that flows into streams by infiltrating rainwater into the ground before it leaves the site. This “low-impact development” can include permeable pavement, rain gardens and even natural forests where a thick organic carpet has been retained.
  3. Clean sediment out of storm drains and sweep up the dust on city streets and other areas where toxic chemicals are likely to reside in metallic form or be bound to soil particles. Safely dispose of these materials. When the rains arrive, there won’t be much left to wash into streams.

While all this sounds simple enough, the issue gets complicated when trying to decide which products to ban and when to recommend that people voluntarily stop using certain items. Alternative products may cost more, which tends to raise questions among users. Also, manufacturers and retailers are not likely to give up selling profitable products without a fight.

Further complicating the situation is the scientific uncertainty surrounding the alleged harm when someone declares a product not good for the environment. Such uncertainty inevitably sparks scientific, economic and policy debate about whether the proposed action is justified.

For example, the Washington Legislature approved a ban on automobile brake pads containing certain levels of copper. Brake pads are believed to release enough copper to harm salmon in some urban streams. But the metallic form of copper found in brake pads is not toxic until it is converted to an ionic form. How much gets converted in the environment is still a question. For details, see a story I wrote for the Kitsap Sun in March of 2010.

As for the latest study released yesterday, some additional focused research and debate may be needed before further actions can be taken.

For example, questions are raised about the total amount of toxic metals leached from roofing materials, including common asphalt shingles. Copper, cadmium, lead and zinc are listed as contaminants along with diethylhexyl phthalate (DEHP).

As suggested by the report, direct studies of roofs in the Puget Sound region could help determine the potential harm of various roofing materials and suggest whether bans or advisories are appropriate.

The amount of polycyclic aromatic hydrocarbons (PAHs) coming from creosote-treated wood was something of a surprise in the report. If anything, the findings tend to support the ongoing effort by the Department of Natural Resources, which has been removing creosote pilings from shorelines. Further studies might help to focus removal efforts in areas most sensitive to creosote compounds.

The latest report, which includes discussions about the uncertainties, is called “Assessment of Selected Toxic Chemicals in the Puget Sound Basin, 2007-2011.” You may also wish to review all the toxics work to date on Ecology’s webpage called “Control of Toxic Chemicals in Puget Sound.”