Almost everything made of plastic starts out as "nurdles": lentil-sized bits that sometimes get loose and end up in rivers and streams, where aquatic creatures easily mistake them for food. On the heels of a train derailment that spilled carloads of plastic pellets and crude oil into the Allegheny River in May, western PA watershed groups are working with university researchers and citizen scientists to measure the presence of nurdles in the region's waterways.