To test the potential harmfulness of soils fertilized with sludge-based products to plant organisms, a biotest method using the physiological/biochemical reaction of the organisms to assess their toxicity was chosen. This paper presents the results of a preliminary ecotoxicological study of different products: a sludge-based fertilizer, a plant growth promoter, and a reclamation blend. The study was conducted using Sinapis alba L., a plant used in agriculture for intercropping and recommended for toxicological testing. Toxicity tests were performed in a gradient of concentrations of the indicated products (2.5%, 5%, and 10%). For comparison purposes, a trial containing a commercial fertilizer was used alongside the control soil (without additives). The fertilizer and the crop support agent were of low toxicity, but data analysis indicated toxicity of the so-called reclamation blend, which contained heavy metals among other things. The test products showed an increase in toxicity with the increasing dose used. This research represents an important step in assessing the usefulness of products created from sewage sludge and may help overcome the „psychological barrier” that prevents potential investors from investing capital that would allow production to spread.