The New York Times

Alexis Gersten, a Long Island dentist, never thought about what she poured over her cereal until her son turned 1.

“Having a new milk drinker, I sort of wanted to start him off on the right foot,” she said.

Ms. Gersten worried about what synthetic growth hormones, pesticides and antibiotics might do to her child and to the environment. She was concerned about the health of the cows and the survival of local farmers. So she became one of the new mothers who are making milk the fastest growing slice of the organic market. “Some of my friends who don’t really think about feeding their children organic food will feed them organic milk,” she said.

Milk represents all that is wholesome. Add the word organic, and the purity of milk’s image only increases. But a carton of organic milk does not come without complications. It is expensive. Some brands are processed so that an unopened carton can last for months. And an organic seal does not necessarily mean the cows are grazing on pasture or that the milk is local.

Organic milk accounts for more than 3 percent of all milk sold in the United States. But with an annual growth rate of 23 percent in an era when overall milk consumption is dropping by 8 percent a year, organic milk has made the nation’s $10.2 billion-a-year dairy industry take notice.

Horizon Organic, which controls 55 percent of the market, is selling $16 million worth of organic milk a month. It is owned by Dean Foods, the nation’s largest dairy producer. Groupe Danone, the French dairy giant, owns Stonyfield Farm. Large grocers, including Whole Foods Market and Safeway, have organic house brands. Wal-Mart even sells it.

“It’s being held back only by supply now,” said George Siemon, chief executive of Organic Valley. A Wisconsin dairy cooperative that Mr. Siemon began in 1988, it is the second-largest seller of organic milk in the country.

Milk is considered a gateway to organic food. Along with produce it is one of the first organic products a consumer will buy, according to the Hartman Group, a research firm in Bellevue, Wash.

The ethos of organic milk – one that its cartons reinforce – conjures lush pastures dotted with grazing animals, their milk production driven by nothing more than nature’s hand and a helpful family farmer.

But choosing organic milk doesn’t guarantee much beyond this: It comes from a cow whose milk production was not prompted by an artificial growth hormone, whose feed was not grown with pesticides and which had “access to pasture,” a term so vague it could mean that a cow might spend most of its milk-producing life confined to a feed lot eating grain and not grass.

Exactly how much time cows should spend grazing before their milk can carry the government’s organic label is under scrutiny. Several hundred farmers and organic advocates want organic dairy rules tightened so that cows have more than what they call token access to pasture.

The issue may be ultimately decided in court, said Mark Kastel of the Cornucopia Institute in Wisconsin. His organization is fighting the rise of confinement organic dairies, which, by his estimate, account for about 30 percent of the organic milk sold.

So, what’s a well-intentioned milk drinker to do? Decide what matters to you most.

First, weigh the importance of the organic label. Milk from the Ronnybrook Farm Dairy in the Hudson Valley, which is sold in bottles at Manhattan’s Greenmarkets, is not certified organic. The dairy uses no artificial growth hormones, but it treats sick animals with antibiotics. In the summer the animals eat mostly pasture; in the winter they eat hay with grain mixed in.

It is a sustainable operation whose owners decided that the term “organic” was becoming co-opted by large corporations, and that the extra cost of the federal organic label was not worth it. For some, milk that has not traveled far and that comes from cows in small pasture-based operations is more important than an official stamp.

Many connoisseurs say the best milk comes from cows who eat mostly grass. The flavor is more complex, and varies with the seasons. In addition, a grass diet leads to milk with as much as five times the amount of conjugated linoleic acid, which some studies using animal models show can help fight cancer. And grazing is better for the cows’ health than a diet of grain.

“We believe in the benefits of grass,” Mr. Siemon of Organic Valley said, not that all of the 534 farmers who sell the cooperative milk can meet its pasture standards. Weather and other factors can mean cows’ diets must be supplemented with grain.

For Horizon, the issue is supply and demand, said Caragh McLaughlin, brand manager for the company. The diet of Horizon cows can be as much as 40 percent grain, whether the animals are at one of the 300 family-run dairies that sell milk to Horizon or its two large company-owned operations. One is a 4,500-head dairy in Idaho, the other a 600-head facility in Maryland. All Horizon cows have access to pasture.

There is also the issue of pasteurized and ultrapasteurized, a question that weighs shelf life against taste and geography.

Dairies pasteurize milk to kill bacteria and other pathogens that can make people sick and to keep it fresher longer. In pasteurization milk is heated to about 162 degrees for at least 15 seconds. Dairies then stamp cartons with a sell-by date generally from 10 to 16 days after processing. In ultrapasteurization the milk temperature is raised to 280 degrees for about two seconds, then quickly chilled. The sell-by date can be several weeks in the future. For example, a brand of ultrapasteurized milk purchased at a New York store on Nov. 2 had a sell-by date of Jan. 2.

Ultrapasteurized milk can taste creamier than traditionally pasteurized milk, but it can also take on a cooked or burnt flavor. Research is still being done on how much the process compromises the milk’s nutritional profile. Because the nature of the milk protein is changed at such high temperatures, ultrapasteurized cream can take longer to whip and never quite achieves the same light, fluffy texture. With either method, an opened carton will stay fresh for only about a week.

For the nation’s top organic milk producers, ultrapasteurizing has been a godsend. “The availability of ultrapasteurization has allowed organic milk to enter markets it might not otherwise,” Ms. McLaughlin of Horizon said.

At Organic Valley, where almost two-thirds of the milk is ultrapasteurized, its panels of tasters prefer it, Mr. Siemon said.

But for purists, unpasteurized, or raw milk, is the only way to go. It can be delicious and more nutritious, but finding raw milk takes a lot of work. In most states it can be sold legally only on the farm or through clubs in which people buy shares of a cow and divide the milk. And raw milk can pose a health hazard, especially for people with weakened immune systems.

In some parts of the country, finding organic milk is more work than some people are willing to put in. René Nuñez, a Los Angeles lawyer who does much of the shopping and cooking for his wife and two young children, has seen organic milk at Trader Joe’s. But that store is a long drive from his house in Pasadena. “We just shop at your regular supermarket down the street and it’s not there,” he said.

Other milk shoppers care only about price. At Pathmark, a half-gallon of regular milk was $1.70. The same size of Horizon Organic milk was $4.29. Organic milk is so expensive that most state governments consider it a luxury item and will not pay for it under low-income food programs like the Special Supplemental Nutrition Program for Women, Infants and Children.

Ann Lickteig, a mother of four in Burlington, Vt., stopped buying organic milk when it reached nearly $5 a gallon. Now she goes to a local store on Mondays, when milk from a local dairy is on sale for $2.99 a gallon.

“I buy the milk that says no growth hormones, but I don’t know that that’s the only thing to worry about,” she said. “I don’t want my kids exposed to potentially harmful chemicals, but I haven’t done the research myself.”

For some parents, cost does not matter. Nor do the intricacies of the organic pasture rules. They search for the organic label and buy it, no matter what.

“I look at what I pay for everything else, but I don’t for the milk,” said Ms. Gersten, the Long Island dentist. “Buying any other milk for him is just not an option.”

Kim Severson

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