Compound Species Toxicological response Toxicological parameter established Toxicological basis Bioavailability incorporated As inorganic As-species circulatory diseases, acute toxicity both chronic and acute endpoints 25% of TDI²-value (chronic toxicity) allocated to soil exposure NOAEL³ of 0,01 mg/kg for acute exposure the MCL is based on readily absorbed As, i.e.: the water soluble As content Cd inorganic Cd-species adverse effects on kidneys, nefrotoxicity PTWI⁴ 10% of PTWI results in MCL- value of 5 mg/kg The MCL of 0,5 mg/kg is set to protect from uptake in plants for consumption the MCL specifically addres- ses bioavailability in plants Cr Cr(VI) carcinogenic by inhalation, sensitising, acute toxicity no specific NOAEL/LOAEL⁵ overall assessment of data no specific considerations Cr Cr(III + VI) - - the MCL of 500 mg/kg set on an administrative basis no specific considerations Cu inorganic Cu-species irritation of the gastro- intestinal tract, adverse effects on the liver the provisional TDI of 0,5 mg/kg bw⁶/d⁷ for chronic exposure also used for acute exposure the MCL is set to prevent acute effects from soil ingestion the MCL is to protect against water soluble Cu Ni inorganic Ni-species increased reactivity in Ni- allergic persons LOAEL with respect to worsening of allergic reactions human clinical study a RAF⁸ of 30 is used specifically for soil Pb inorganic Pb-species neurotoxic response, neurobehavioural disturbances in children, impaired IQ NOAEL with respect to increase in blood lead level epidemiological/clinical studies the overall bioavailability for lead from different sources is considered no specific factor is used for lead in soil. Zn inorganic Zn-species acute toxicity, irritation of gastrointestinal tract - comparable dose tolerated from drinkingwater the MCL is based on water soluble Zn. PAH total PAH⁹   benzo(a)pyrene carcinogenic effects cancer potency estimates epidemiological data, experimental animal data the MCL set based on an overall assessment for