On September 23, at the Verso Company paper mill on the N. Branch of the Potomac River (near Luke, Maryland), just under 10,000 gallons of "latex" was released during a four-hour period as it was being unloaded from a rail car. A "Verso worker failed to close a drain line on a 26,500-gallon storage tank that was being filled from a railroad tank car at the mill,"
According to a piece in the Cumberland Times-News from September 25, the spill was "discharged through a collection system." Attempts to clarify how much of the release was retained by the collection system were deferred by Verso to the Upper Potomac River Commission. The Luke plant receives latex material via rail car to produce specialty paper that has a latex-based coating. (Latex binds the coating to the paper and imparts high-quality optical properties.)
Over the weekend, a plume of "green goo" was seen in the Potomac near Cumberland. On Monday (today), the Times-News reported that Paw Paw, WV shut its water intake system (to provide drinking water to the town from the river) to avoid "gumming up the works" literally. It is anticipated to reach the Hagerstown water intake by this Saturday (October 4).
The product that spilled was an emulsion (or mixture) of water and a "styrene-butadiene based polymer" referred to as "Latex CP 620NA" and manufactured by Trinseo LLC.
A "safety data sheet" dated 2013 was procured from the company (available upon request) and it provides the following information:
- "may cause temporary eye irritation" and "prolonged contact may cause slight skin irritation;" however, "prolonged skin contact is unlikely to result in absorption of harmful amounts"
- the substance generally poses very low toxicity via oral and dermal exposure; "practically nontoxic to aquatic organisms on an acute basis"
- coagulation of the material can occur in low temperatures and with the "addition of chemicals, such as acids or multivalent salts"
- decomposition of the material in the environment depends on the ambient temperature, the supply of oxygen from air and the presence of other materials; however "the polymeric component is not expected to degrade"
The available data on the product seems to be indicate it is fairly non-toxic on an acute basis (upon short-term exposure) to both humans and aquatic life. There appears to little to no data on effects from chronic (repeat) exposure. There is also little reason to worry about chronic exposure for us humans getting our drinking water out of the Potomac as localities have the ability to store clean water and close the water intakes for up to a few days, depending on storage capability.
There is also little information on the types of degradation products that could be expected in the Potomac River water as the slug of pollution makes its way from Allegheny County downstream to the Chesapeake Bay.
No fish kills have been noted as of yet and samples have been collected; however no results have been shared yet with the public. It has been reported that volatile organic chemicals were being sampled for; however, it should be verified that styrene , butadiene and their primary aquatic breakdown products are on that list. Some of these might be classified as semi-volatile and covered by a different testing method.
Some useful information on styrene has been previously published by the CDC: http://www.atsdr.cdc.gov/toxprofiles/tp.asp?id=421&tid=74