t o'brien: virginia rauh is an epidemiologist columbia university mailman school of public health.for 20 years now, she has followed 750 mothers and their children in the washington heights section of manhattan. pregnant mothers in her study wore a backpack withp designed to gather air samples as they went about the daily routin rauh's team found organophosphates in 99% of the air samples she gathered, and 70% of the blood samples of the children. rauh concludes that higher levels of organophosphates found in the blood of her subjects lead to lower birth weight, reduced i.q., a.d.h.d. symptoms, and tremors. m.r.i.s of the brains of exposed nobjects reveal enlargement in some areas, and ally thin cortices-- the outermost layer n-of nerve cells in the br crucial for cognitive functions suchs perception, language, memory andonsciousness. >> i think in reality, there is no safe level. it depends upon the level of risk that we tolerate as a society. but to damage even to the extent of several i.q. points or some t vey attentional issues, int my mind, is ceptable if we know that it is as