Green’s Dictionary of Slang

(drugs) under the influence of phencyclidine.

1971		E.E. Landy Underground Dict. (1972).
1985		T.R. Houser Central Sl.
1998		Mayor’s Anti-Gang Office City of Houston, TX Street Gang Sl. / Gloss. 9 Nov. n.p.: dusted Under the influence of P.C.P.; often used to refer to a marijuana joint laced with P.C.P.
2009		J. Stahl Pain Killers 48: How’m I supposed to know Joker was so dusted he’d start shootin’ outside the cop shop?