Decades after DuPont and 3M first discovered that the perfluorinated chemicals making them fortunes could be transmitted from mothers to babies, millions of women around the world are passing dangerous amounts of these toxic compounds to their children, according to a report published on Monday.

Women’s breast milk in many countries now contains chemicals belonging to a class of compounds known as PFAS at levels well above the safety thresholds set by governments, says the report from international environmental group IPEN. In Jordan, for instance, researchers found breast milk contained, on average, 144 parts per trillion of PFOA, according to a 2015 study. That’s more than double the 70 ppt health advisory level the U.S. Environmental Protection Agency set for that chemical in drinking water; more than seven times the 20 ppt drinking water safety level recently set by the state of Vermont; and more than 10 times the 14 ppt drinking water threshold the state of New Jersey proposed for PFOA earlier this month.

One woman’s milk contained 1,120 ppt of PFOA, according to the Jordanian study, which also found that 96 percent of cow’s milk samples also contained PFOS and PFOA. Dairy farmers in the U.S. have recently run into a similar contamination problem.

PFAS chemicals — used in nonstick pans, firefighting foam, and hundreds of other products — have also been found in breast milk in at least 19 countries in Europe, Asia, and North America, according to a study published in November in Environmental Science and Pollution Research. That article, which noted that scientists have yet to look for the chemicals in breast milk in Africa, Antartica, Australia, and South America, cited research documenting PFAS levels above 100 ppt in breast milk in Hungary, Spain, German, China, Malaysia, and Canada. The highest average level was found in the Ehime region of Japan, where human breast milk contained PFOS at an average level of 232 ppt in 2008.

In the United States, a 2004 study found nine PFAS chemicals in breast milk in Massachusetts, with PFOS being the highest at 131 ppt. But later studies suggest that levels of some of those chemicals may have dropped.

Early exposure to the chemicals can cause permanent harm. PFAS compounds reach fetuses through the placenta and are present at all stages of pregnancy, according to a study published last month. After birth, they can accumulate in breastfeeding babies. Prenatal exposure can affect immunity, the development of the nervous system, and hormonal function, according to a 2018 Japanese study. Other research has shown that the compounds can affect vaccine response, asthma, kidney function, obesity, and the age at which girls first get their periods.

DuPont, which started using PFOA to make Teflon in the 1940s, has known that women pass the chemical onto their newborns since at least 1981, when it was monitoring a small group of pregnant workers in one of its West Virginia factories and found measurable amounts of PFOA in their babies. At the time, both DuPont and 3M, which created PFOA and sold it to DuPont for decades, already knew from their own research that pregnant rats exposed to PFOA could pass the chemical onto their pups. And in 1993, 3M scientists confirmed in an unpublished study that mother goats also transmitted the chemicals to their young through their breast milk.