Allergys from being too antiseptic? Technology Review: The New Hygiene Hypothesis

http://www.technologyreview.com/Biotech/19997/ --- A host of explanations have been put forth to account for rising rates of allergy and asthma, including reduced rates of breast feeding, parents who smoke, and worsening pollution. But as most of these factors have been ruled out--poorer cities with high levels of pollution often have lower allergy levels, for example--an alternative explanation has taken the lead. Scientists suggest that now that many of the most harmful bugs in our environment have been eradicated with modern sanitation and medicine, our immune systems turn their attack on usually harmless molecules, such as those in cat dander or dust mites.