A recent US study revealed that the more than 1,000 ducks discovered perished at wastewater treatment plants in Colorado, USA likely died from exposure to polyethylene glycol, a chemical found in many household products that causes feathers to lose their water repellency.

http://www.upi.com/Science_News/2010/07/28/Household-chemicals-eyed-in-duck-deaths/UPI-75101280352447/
http://www.thedenverchannel.com/news/24412344/detail.html