Mother’s milk—it has been humankind’s first food for as long as the human race has existed. For perhaps 2 million years, human milk has served to nurture life in its infancy. Yet only within the past 50 years has a mother, who is faced with loss of milk and lacking a wet nurse, had a reasonable substitute on which to rely. Although infant formula has not been used very long, much has happened during that period of time. Most importantly, the human population doubled, adding 2 billion persons to the planet. As a consequence, the need for weaning foods doubled, and the need for a human milk substitute for those mothers who either chose not to or were unable to breast-feed expanded to an unprecedented level. In addition to rapid population growth, a scientific-industrial complex came into its own, creating a new world. Science discovered chemicals for controlling insects, weeds, or other pests; industry found ways of producing these chemicals in amounts needed to serve the entire farm community. Pesticides thus became a part of the environment, permitting the cultivation of ever-increasing quantities of food. Unfortunately, some of these same chemicals began to show up in the blood, fat, and tissues of the human and livestock population; some also began to appear in the milk of both animals and humans. You could consider these chemicals intentional contaminants of the environment. But literally thousands of other contaminants were being found at the same time, including pollutants like methyl mercury, lead, cadmium, poly chlorinated biphenyls (PCB’s), and radioactive (nuclear) isotopes (e.g., strontium-90 and iodine-131). Those pollutants that found their way to milk supplies were often in such minute amounts as to require other scientific breakthroughs in detection methods sensitive enough to measure them. Contaminants of milk and food were soon to become measureable in parts per million, parts per billion, and even parts per trillion. This exquisite ability to detect and quantify results was used to measure the presence of tens of thousands of chemical compounds unknown or nonexistent less than 50 years ago. Among these compounds are not only the pollutants and contaminants already mentioned but also certain vitamins and minerals. To know needs, you must first be able to detect and measure amounts. Thus, the new measuring tools allowed scientists to determine the precise level of need for most nutrients. Scientists were also able to detect and measure poisons the world had not recognized before. For instance, aflatoxins, poisons produced by certain molds, were discovered and were found to be among the most potent cancer-causing compounds known to humankind. Some have been found in food and feed, and some small amounts, mostly of less toxic cousins, have shown up in the milk of humans and animals. The scientific-industrial complex also combined in another area of great importance. The end result, as is usually the case, bore fruit and, at the same time, posed problems never before encountered. The following example illustrates this dilemma. In 1929, Sir Alexander Fleming first described the antibiotic penicillin. The drug had been discovered quite by chance when a culture of bacteria, of a type called staphylococci, was accidentally contaminated with a penicillin-producing mold. Within 50 years, penicillin and other antibiotics were administered to dairy cows at a rate of some 350 tons annually in the United States. It was the greatest boon to disease treatment ever. In the face of that benefit, a germ of cow’s udders, staphylococci, replaced other germs as the most common infective agent of these milk-producing animals. Partly for the same reason, it became a common infective agent of the human breast. It is destructive of milk-making tissue, and certain strains produce toxins so potent that as little as 1 fig causes illness. We learned that infants could become ill on such small amounts, and on milk produced and fed directly from the mother’s breast. But that was only one problem. Some infants have been found to react to antibiotics. The mother who has taken penicillin for some illness, as in the treatment of other milkproducing species, may find her milk contaminated with the drug. If not told otherwise, she feeds it unknowingly to her infant. This may only rarely be a serious problem. Nonetheless, the same industries that produce antibiotics by the tons have also come up with untold amounts of other drugs. In 50 years the developed world has become the largest user of drugs in history. Some of these chemicals have been taken for purely medical reasons. Still other drugs have been taken for “kicks.” Today infants are born with the drug habits of the mother. Others are born deformed or otherwise mentally or physically afflicted. No matter what the drug or what the reason for taking (or giving) it, chances are that mother’s milk is in some way tainted. There has been another development, after 2 million years, that has finally come into widespread practice—pasteurization, a heat treatment of milk.