TEQ "TEQ" means toxicity equivalents in comparison to 2, 3 , 7, 8 tetrachlorinated dibenzo-para-dioxin and which is also known as 2, 3, 7, 8 tetrachlorodibenzodioxin or 2, 3, 7, 8 TCDD. PU(A) 104/2004 - ENVIRONMENTAL QUALITY (DIOXIN AND FURAN) REGULATIONS 2004 2. Interpretation.