Technical Bulletin No. 0049: Aquatic Biology Report: The Effect of Sublethal Concentrations of Kraft Pulping Wastes and Their Components on Fish Organs

Statements that constituents of kraft pulping waste waters might be deleterious to fish at concentrations less than those required to cause death suggested the studies reported in the attached technical bulletins. This question arose following previous findings by the Institute of Paper Chemistry that toxic conditions do not occur in streams receiving such wastes when the dilution ratio was one to twenty or greater. The Wisconsin Kraft Sub-Committee of the Council, under the Chairmanship of Mr. Martin L. Downs, Initiated and guided this research which was conducted under the direction of Dr. Willis M. Van Horn. Both gross and microscopic examination of the tissues of common species of fish exposed to kraft wastes and their individual constituents indicate that no pathological conditions existed after exposure for appreciable periods of time. Comparison of the photomicrographs of gill and liver tissue presented in this report of fish not exposed and those exposed bear out this conclusion.