Chicago Ecological Services Office staff are working with the City of Chicago in an effort to determine whether using biosolids as part of a  land fill cap adjacent to natural areas and in restoration of natural areas poses increased risk to wildlife populations. 

Biosolids are a by-product of sewage treatment processes essentially consisting of dried and decomposed sludge.  Testing has shown that the biosolids contain relatively low concentrations of metals such as lead and mercury, and have received an EPA rating indicating that they are of exceptional quality. 

The Service is concerned about the presence of some metals and of endocrine disrupting chemicals in the biosolids.  In addition to pharmaceuticals, certain chemicals in detergents also behave like estrogen.  Nano phenols, are a break down product of APEO, a common ingredient of detergents, and  a chemical voluntarily taken off the market in Europe. 

The biosolids, at one point in the process, contain over 800 ppm of NP’s, and the Dutch standard for land application is 10ppm.  The City will use its Calumet Ecotox team to help with the evaluation.