After two years of pressure, Starbucks has agreed to stop using milk from cows given artificial growth hormones by December 31, according to Food & Water Watch, a consumer rights group.

"All of our fluid milk, half and half, whipping cream and eggnog used in U.S. company-operated stores will be produced without the use of rBGH (recombinant bovine growth hormone)," Starbucks Vice President of Sustainable Procurement Sue Mecklenburg said in a letter addressed to Wenonah Hauter, Food & Water Watch's Executive Director, according to a FWW press release.

Starbucks currently sources 72 percent of their total dairy supply from  milk suppliers that do not use rBGH in their milk, Food and Water Watch said.

RBGH, which received approval from the Food and Drug Adminstration in 1993, is an artificial hormone that is often injected into dairy cows to increase their milk production by about 10 percent. It’s both safe and virtually undetectable in milk products, according to the FDA.

But no long-term studies have been done, and some experts contend that high levels of insulin-like growth factor (IGF) found in rBGH raise the risk of breast, colon and prostate cancers.