Modern life may be harmful to babies' health, reports CBS News Senior European Correspondent Tom Fenton. The World Wide Fund for Nature wants the oldest source of nutrition - mother's milk - to be further studied for harmful chemicals.
In a report, the WWF said some 350 contaminants had been found in breast milk, including some 87 dioxin and dioxin-like substances.
Dioxin is a highly toxic chemical which hit the headlines most recently in Belgium, where the cancer-causing substance was found in animal feed and then entered the food chain.
Pointing an accusatory finger at contaminants in cosmetics, perfumes and pesticides, the Fund's study claims two-month old British babies may have been exposed to 43 times the daily safe level of chemicals.
"Some of these substances - at high levels - we know can cause cancer," says report author Gwyne Lyons. "They can cause effects on the immune system and they can cause effects on reproduction."
But the British government - and indeed the Fund itself - stress that any harm from bad substances pales in comparison to the benefits of breast-feeding.
"The immunological benefits, the nutrient benefits and the mother-baby bonding...definitely outweigh the negative impact of the toxic chemicals," says Elizabeth Salter, head of WWF-UK's Toxic Program. "But the bottom line is that those toxic chemicals should not be there in the first place."
Salter and her colleagues hope the government will enforce stricter controls on pesticides and other chemicals.
"WWF believes governments and industry must take urgent action now to address the toxic legacy being passed on to future generations," the group said in a statement.
The British government is setting up a research project in the northern English city of Leeds, recruiting about 1,000 mothers to help form an "archive" of breast milk samples in a trial study that might then be extended.