40 CFR §180.1090

1. (a)Lactic acid (2-hydroxypropanoic acid), including l-lactic acid is exempted from the requirement of a tolerance when used as a plant growth regulator or fruit and vegetable wash in or on all raw agricultural commodities.
2. (b)An exemption from the requirement of a tolerance is established for indirect or inadvertent residues of lactic acid (2-hydroxypropanoic acid), including l-lactic acid, in or on all livestock commodities, when residues are present therein as a result of animal drinking water coming into contact with hard non-porous surfaces treated with lactic acid (i.e., troughs).