Occurrence of Microconstituents in Biosolids

In May 2007, the Community of Practice terminology working group recommended to the Water Environment Federation (WEF) Technical Practice Committee that the term microconstituents be used to encompass natural and manmade substances detected in water and the environment for which continued assessment of the potential impact on human health and the environment may be prudent. 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.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. The need for understanding microconstituents in biosolids has acquired greater urgency in light of technical publications on their actual and potential effects in the water environment. Recent studies indicate the presence of pharmaceuticals, polyaromatic hydrocarbons, sterols, and other microconstituents in Class B biosolids, regardless of the biosolids treatment technologies used. These studies did not assess human health and/or environmental risk levels associated with exposure to the microconstituents found. Consequently activities directed at further understanding the fate of microconstituents in biosolids in the environment are necessary by all stakeholders. This paper presents information from a focused literature review on the topic by members of a WEF Technical Practice Update Task Force.