Although biosolids have been classified in 40 CFR 503 for potential environmental impacts, there has been minimal investment in understanding and quantifying microconstituents in biosolids. As used here, microconstituents is a broad, umbrella term that encompasses substances for which some information is available, such as those that can be categorized by effects or source, but which may require more study. Recent studies documented in this Technical Practice Update (TPU) indicate the presence of pharmaceuticals, polyaromatic hydrocarbons, sterols, and other microconstituents in Class B biosolids, regardless of the biosolids treatment technologies used. This TPU serves as a resource for sound and accurate information on the current state of knowledge of these microconstituents until future standard practices are fully developed. Users can draw upon this information to better understand the issue and how it may impact them, and to assist in making informed decisions as to how they might proceed to manage their own biosolids programs in such a manner as to protect the health and welfare of their employees, the public, and the environment.

Included are a literature review of pertinent references on pharmceuticals, brominated flame retardants, plastics and plasticizers, and musks and fragrances; U.S. and European Union framework for regulating microstituents in biosolids; how the issue should be addressed; methodologies for assessing microconstituents in biosolids; and a discussion of future research/directions on this issue. Published by WEF. 2007. Electronic download. 52 pages.