Conventional chicken feather meal contains anitbiotics, acetaminophen, Benadryl, arsenic.

At least this is being picked up in the mainstream.

http://www.nytimes.com/2012/04/05/opinion/kristof-arsenic-in-our-chicken.html

Unless we grow our own (with no outside inputs), our domestic food source is broken.

Links to the two studies cited in the NYTimes article:

http://www.ncbi.nlm.nih.gov/pubmed/22244353

http://pubs.acs.org/doi/abs/10.1021/es203970e

This is merely the tip of the iceberg. Many certified organic growers routinely use feather meal as a fertilizer. ouch!