Biosolids are an organic amendment available to gardeners. According to the United States Environmental Protection Agency, biosolids are carefully treated and monitored residuals formed at sewage treatment facilities. They may be recycled into fertilizers to stimulate plant growth. Biosolids may help reduce the need for chemical fertilizers. Biosolids can be safe to use, but homeowners should be cautious about heavy metal content, pathogen levels and salts. Rely on only Class A biosolids, which have been treated to reduce the bacterial content and are approved for use in production agriculture. Home gardeners may want to avoid biosolids in vegetable gardens because of the potential for heavy metal content seeping into the produce.