Canada and the European Union both banned a genetically engineered dairy hormone in 1999, and the assumption that follows — banned abroad, so it must be a human health risk — is exactly backwards here. Both governments' own scientific reviews found the milk safe to drink. They banned the hormone anyway, for a completely different reason: what it does to the cow.
The hormone is recombinant bovine somatotropin, rBST, sold in the U.S. under the brand name Posilac. FDA approved it on November 5, 1993, under NADA 140-872, as an over-the-counter injection given to lactating dairy cows every 14 days starting roughly nine weeks after calving, to increase milk yield. It remains approved on that same basis today, and FDA's current position, stated on its own website, is that milk and meat from rBST-treated cows are safe, because bST is a large protein that's broken down by digestion and has no biological activity in humans regardless.
Health Canada reached the same conclusion on human safety — and banned the hormone anyway. The decision, announced January 14, 1999, followed more than nine years of review split across two independent expert panels, according to a report from the Standing Senate Committee on Agriculture and Forestry. A Royal College of Physicians and Surgeons of Canada panel examined human safety and unanimously found no significant risk. A separate animal-health panel, convened through the Canadian Veterinary Medical Association, examined what the hormone does to treated cows and found an increased risk of mastitis of up to 25 percent, of infertility of around 18 percent, and of lameness of up to 50 percent. Health Canada's public reasoning cited the animal-health findings, not the human-safety ones, as the basis for refusing to approve rBST for sale in Canada.
The European Union's decision, Council Decision 1999/879/EC, ran on the same track. The EU's Scientific Committee on Animal Health and Animal Welfare found that rBST use "increased the risk of infections and could adversely affect reproduction and induce severe reactions in cattle." That's the entirety of the EU's stated basis for prohibiting the hormone's use on dairy cows within the bloc — an animal-welfare finding, with no human-safety concern cited in the decision at all. EU production and export of rBST to non-EU markets remained legal even after the ban on its use within Europe.
So the divergence here isn't really about whether rBST is safe for people to consume — on that narrow question, U.S., Canadian, and European reviewers essentially agree. It's about how differently national regulators weigh animal-welfare findings against a permitted use. FDA's approval process, structured around human food safety and target-animal safety in a narrower sense, allowed a use that increases certain health risks in the treated animal as long as those risks don't translate to a human food-safety problem. Canada and the EU built animal-welfare judgment directly into the same approval decision, and on that basis, rejected it.
Inside the U.S., the fight that followed FDA's 1993 approval wasn't really about the hormone's safety either — it was about the words allowed on a milk carton. Some producers wanted to advertise their milk as coming from cows not given the hormone, and FDA issued formal labeling guidance in February 1994 to govern exactly how. The guidance says plainly that a "bST-free" claim is false on its face, because all milk naturally contains some bST regardless of whether a cow was ever treated. A claim like "from cows not treated with rbST," FDA said, is permitted, but only when paired with a required qualifying disclaimer: "No significant difference has been shown between milk derived from rbST-treated and non-rbST-treated cows." Vermont passed a law making that kind of disclosure mandatory rather than voluntary, and Monsanto sued the state over it — a fight that helped cement the current framework where the claim is legal but constrained, not banned outright the way some assumed.
That labeling fight turned out to matter more than the regulatory one, commercially speaking. According to USDA's own Economic Research Service, the share of U.S. dairy farms and milk production using rBST has trended steadily downward for years — a decline the agency attributes to dairy processors and retailers phasing the hormone out over marketing concerns and research questioning whether it reliably improved farm profitability, not to any new FDA restriction. The approval never moved. The market did.
On the label today, a shopper looking for this specifically should look for "rbST-free" or "produced without the use of rbST" language, which by law has to carry that FDA-mandated disclaimer nearby if it's on the package. Its absence doesn't mean a product contains rBST — a majority of the dairy supply chain has voluntarily moved away from it over the past two decades — but the label alone won't distinguish "the farm never used it" from "the processor doesn't test for it," and FDA's rule was written to prevent exactly the kind of implied-superiority claim that distinction invites.
None of this resolves into a verdict, and that's the honest shape of the story. FDA approved a hormone still legal today; Canada and the EU rejected the identical use over animal-welfare findings their own regulators reached independently, not over any human-safety disagreement with FDA; and the U.S. market has drifted away from the product anyway, for reasons that have nothing to do with any of those official positions changing. PurityIQ doesn't try to collapse that into a score. It shows you, at the shelf, whether a scanned dairy product is one where this history applies, and puts the actual regulatory record next to it — the FDA approval, the Canadian and EU animal-welfare findings, the labeling rule — cited to the source, not to an advocacy group's summary of it. You see the record. You decide.
As of September 2026, rBST remains an FDA-approved dairy hormone under NADA 140-872, remains prohibited from use on dairy cows in Canada and the European Union on animal-welfare grounds, and FDA's 1994 labeling framework for "not treated with rbST" claims remains in effect.
Sources
FDA, Bovine Somatotropin (bST) — https://www.fda.gov/animal-veterinary/product-safety-information/bovine-somatotropin-bst
FDA/Animal Drugs at FDA, Posilac (sometribove zinc) Freedom of Information Summary, NADA 140-872, approved Nov. 5, 1993 — https://animaldrugsatfda.fda.gov/adafda/app/search/public/document/downloadFoi/512
Federal Register Vol. 59, No. 28 (Feb. 10, 1994), FDA interim guidance on rbST dairy product labeling — https://www.govinfo.gov/content/pkg/FR-1994-02-10/html/94-3214.htm
Standing Senate Committee on Agriculture and Forestry (Canada, 36th Parliament), interim report on Health Canada's Jan. 14, 1999 rBST decision — https://sencanada.ca/en/content/sen/committee/361/agri/rep/repintermar99-e
Health Canada, Report of the Royal College of Physicians and Surgeons of Canada Expert Panel on the Human Safety of rBST (1999) — https://canada.ca/en/health-canada/services/drugs-health-products/veterinary-drugs/other-issues/recombinant-bovine-somatotropin-rbst/report-royal-college-physicians-surgeons-canada-expert-panel-human-safety-rbst-health-canada-1999.html
EUR-Lex, Council Decision 1999/879/EC — Bovine somatotrophin: EU rules on marketing and use (summary) — https://eur-lex.europa.eu/EN/legal-content/summary/bovine-somatotrophin-eu-rules-on-marketing-and-use.html
USDA Economic Research Service, Structure, Costs, and Technology Used on U.S. Dairy Farms (ERR-334), rBST adoption trend — https://www.ers.usda.gov/media/9104/err-334.pdf