1,2-dihydropyridazine-3,6-dione, sodium salt is listed in PIC since it has been identified as a member of the chemical group:
Maleic hydrazide, and its salts ...
Commission Directive 2003/31/EC of 11 April 2003 amending Council Directive 91/414/EEC to include 2,4-DB, beta-cyfluthrin, cyfluthrin, iprodione, linuron, maleic hydrazide and pendimethalin as active substances (Text with EEA relevance) Official Journal L 101 , 23/04/2003 P. 0003 - 0009
Council Directive 90/533/EEC of 15 October 1990 amending the annex to Directive 79/117/EEC prohibiting the placing on the market and use of plant protection products containing certain active substances
OJ L 296, 27.10.1990, p. 63-63