WASHINGTON - Under pressure from interest groups, the FDA last week released its "interim guidance" to states for labeling milk products from cows that have not been treated with recombinant bovine somatotropin. The agency, which was sued Feb. 3 by opponents of the milk increasing growth hormone, reiterated its finding that "no significant difference has been shown between milk drived from rbST-treated and non-rbST-treated cows." The FDA also noted that under such circumstances, it did not have any authority under the Federal Food, Drug, and Cosmetic Act to require special labeling for milk from rbST-treated cows. The agency approved the product last Nov. 5, and marketing began Feb. 4 with the end of a congressional moratorium on sales of rbST. False and misleading Although labeling laws for milk products are established at the state level, the FDA's authority does permit it to prohibit "false and misleading" statements. According to the FDA, "the agency intends to rely primarily on the enforcement activities of the interested states to ensure that rbST labeling claims are truthful and not misleading."