The oxidation and weathering of sulfide-rich sediments, resulting in extensive acid sulphate soil (a.s. soil) development, occurs after artificial farmland drainage, and results in increased acidity and metal mobility. During seasonal high-flow events in autumn and spring, potentially toxic metals (Co, Mn, Ni, Zn, Al, Cd and Cu) and acidity will be extensively leached to adjacent watercourses and thus, exist in vast amounts compared to natural background concentrations in streams throughout Finland and rivers in Fennoscandia. The objective of this study was to, based on a literature review, give a comprehensive picture and a developed understanding of the importance of the serious biological effects induced by a.s. soils. Based on the limited amount of research in this particular area, it was found that crops (oat and timothy) grown on a.s. soils are enriched in Co, Mn, Ni, Al and Cr and depleted in Ca, Mg, Se, K and P, and that Zn and Al concentrations are 2 to 20 times higher in cow milk from farms on a.s. soils compared to reference samples and Finnish average values from other dairies, respectively. Fish exposed to the poor waterquality in a.s. soil affected environments have physiological responses which impact upon their respiration, -reproduction, -growth and -behaviour. These impacts are indirectly and directly linked to the numerous cases of mass fish kills that have occurred along the Finnish coast. Long-term exposure to elevated or deficient doses of metals and nutrients pose an actual threat on human health. The potential risks for Alzheimer′s and Parkinson′s disease in a.s. soil areas are discussed.