California Code, Health and Safety Code - HSC § 25120.55

(a) Used or spent etchants, stripping solutions, and plating solutions are spent, contaminated, or used material for purposes of this chapter.

(b) Used or spent etchants, stripping solutions, and plating solutions which meet a characteristic established by or are listed by the Environmental Protection Agency or the department as a hazardous waste and are transported from the site where they are produced, and transferred to an unrelated or unaffiliated person for any purpose, are subject to the requirements of this chapter which apply to hazardous waste unless the department waives any specific provision of this chapter pursuant to Section 25143. Nothing in this section exempts any used or spent etchant, stripping solution, or plating solution from any other requirement of this chapter.