Text: The concentration of the metals, Al, As, Cr, Co, Cu, Fe, Pb, Ni, and Zn, expressed as total metal, should not exceed 1 eg/L each, and Cd, Hg, and Ag, expressed as total metal, should not exceed 100 ng/L each.
Entailment: Al, As, Cr, Co, Cu, Fe, Pb, Ni and Zn are all metals.
Contradiction: Al, As, Cr, Co, Cu, Fe, Pb, Ni, and Zn, expressed as total metal, should exceed 1eg/L each.