<P> A September 2003 review by the Agency for Toxic Substances and Disease Registry (ATSDR) stated that atrazine is "currently under review for pesticide re-registration by the EPA because of concerns that atrazine may cause cancer", but not enough information was available to "definitely state whether it causes cancer in humans ." According to the ATSDR, one of the primary ways that atrazine can affect a person's health is "by altering the way that the reproductive system works . Studies of couples living on farms that use atrazine for weed control found an increase in the risk of preterm delivery, but these studies are difficult to interpret because most of the farmers were men who may have been exposed to several types of pesticides . Little information is available regarding the risks to children, however "(m) aternal exposure to atrazine in drinking water has been associated with low fetal weight and heart, urinary, and limb defects in humans". Incidence of a birth defect known as gastroschisis appears to be higher in areas where surface water atrazine levels are elevated especially when conception occurs in the spring, the time when atrazine is commonly applied . </P> <P> The EPA determined in 2003 "that atrazine is not likely to cause cancer in humans". </P> <P> In 2006, the EPA stated, "the risks associated with the pesticide residues pose a reasonable certainty of no harm". </P> <P> In 2007, the EPA said, "studies thus far suggest that atrazine is an endocrine disruptor". The implications for children's health are related to effects during pregnancy and during sexual development, though few studies are available . In people, risks for preterm delivery and intrauterine growth retardation have been associated with exposure . Atrazine exposure has been shown to result in delays or changes in pubertal development in female rats; conflicting results have been observed in males . Male rats exposed via milk from orally exposed mothers exhibited higher levels of prostate inflammation as adults; immune effects have also been seen in male rats exposed in utero or while nursing . EPA opened a new review in 2009 that concluded that "the agency's scientific bases for its regulation of atrazine are robust and ensure prevention of exposure levels that could lead to reproductive effects in humans ." Deborah A. Cory - Slechta, a professor at the University of Rochester in New York has said in 2014, "The way the E.P.A. tests chemicals can vastly underestimate risks ." She has studied atrazine's effects on the brain and serves on the E.P.A.'s science advisory board . She further stated, "There's still a huge amount we don't know about atrazine ." </P>

Without atrazine how much would the national corn yield fall based on the epa study