repetitively, resulting in more rapid biodegradation. Like the herbicides trifluralin and alachlor, atrazine is susceptible to rapid transformation in the presence of reduced iron-bearing soil clays, such as ferruginous smectites. In natural environments, some iron-bearing minerals are reduced by specific bacteria in the absence of oxygen, thus the abiotic transformation of herbicides by reduced minerals is viewed as "microbially induced". Photolysis In 2016, photolytic degradation with 254 nm ultraviolet was seen by the authors of a particular study as an efficient process, which could be used in pilot plants to reduce or eliminate compounds of the atrazine class or similar emerging contaminants, in effluents. Health effects According to Extension Toxicology Network in the U.S., "The oral median Lethal Dose or for atrazine is 3090 mg/kg in rats, 1750 mg/kg in mice, 750 mg/kg in rabbits, and 1000 mg/kg in hamsters. The dermal LD50 in rabbits is 7500 mg/kg and greater than 3000 mg/kg in rats. The 1-hour inhalation LC50 is greater than 0.7 mg/L in rats. The 4-hour inhalation LC50 is 5.2 mg/L in rats." The maximum contaminant level is 0.003 mg/L and the reference dose is 0.035 mg/kg/day. Mammals 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. The World Health Organization's International Agency for Research on Cancer has classified atrazine as "not classifiable as to its carcinogenicity to humans"