In the journal Pediatrics (vol. 89, no. 4, April 1992), there appeared an article titled, "Effects of Microwave Radiation on Anti-infective Factors in Human Milk".
Richard Quan, M.D. from Dallas, Texas, was the lead name of the study team. John A. Kerner, M.D., from Stanford University, was also on the research team, and he was quoted in a summary article on the research that appeared in the 25 April 1992 issue of Science News.
To get the full flavour of what may lie ahead for microwaving, here is that summary article:
"Women who work outside the home can express and store breast milk for feedings when they are away. But parents and caregivers should be careful how they warm this milk. A new study shows that microwaving human milk-even at a low setting-can destroy some of its important disease-fighting capabilities.
"Breast milk can be refrigerated safely for a few days or frozen for up to a month; however, studies have shown that heating the milk well above body temperature-37°ree;C-can break down not only its antibodies to infectious agents, but also its lysozymes or bacteria-digesting enzymes. So, when paediatrician
John A. Kerner, Jr, witnessed neonatal nurses routinely thawing or reheating breast milk with the microwave oven in their lounge, he became concerned.
"In the April 1992 issue of Pediatrics (Part I), he and his Stanford University co-workers reported finding that unheated breast milk that was microwaved lost lysozyme activity, antibodies and fostered the growth of more potentially pathogenic bacteria. Milk heated at a high setting (72 degrees Celsius to 98 degrees C) lost
96 per cent of its immunoglobulin-A antibodies, agents that fend off invading microbes.
"What really surprised him, Kerner said, was finding some loss of anti-infective properties in the milk microwaved at a low setting-and to a mean of just 33.5 degrees C. Adverse changes at such low temperatures suggest 'microwaving itself may in fact cause some injury to the milk above and beyond the heating'.
"But Randall M. Goldblum of the University of Texas Medical Branch in Galveston disagrees, saying: 'I don't see any compelling evidence that the microwaves did any harm. It was the heating.' Lysozyme and antibody degradation in the coolest samples may simply reflect the development of small hot spots-potentially 60 degrees C or above-during microwaving, noted Madeleine Sigman-Grant of Pennsylvania State University, University Park. And that's to be expected, she said, because microwave heating is inherently uneven-and quite unpredictable when volumes less than four millilitres are involved, as was the case in the Kerner's study.
"Goldblum considers use of a microwave to thaw milk an especially bad idea, since it is likely to boil some of the milk before all has even liquefied. Stanford University Medical Center no longer microwaves breast milk, Kerner notes. And that's appropriate, Sigman-Grant believes, because of the small volumes of milk that hospitals typically serve newborns-especially premature infants."