Yn adran 3 o Ddeddf Cynllunio (Sylweddau Peryglus) 1990 (p. 10) (awdurdodau sylweddau peryglus heblaw cynghorau sir a chynghorau bwrdeistref sirol), ar ôl is-adran (5B) mewnosoder—
“(5C)A joint planning board constituted under section 2(1B) of the principal Act for a united district in Wales is the hazardous substances authority for land in the united district unless subsection (4) or (5) applies.”