The weight of evidence of more than 160 epidemiology studies shows only trace levels of 2,4-D in urine of the general population, even though 2,4-D is one of the most commonly used herbicides in both the home and garden market and the commercial market (CDC, 2005; Health Canada, 2013). Evaluations of these and other exposure studies have concluded that actual exposures are well below the conservative assumptions made by policy makers for the registration process (Hays 2012; Burns and Swaen 2012; Aylward and Hays 2015).
The 2,4-D toxicology research studies required by United States Environmental Protection Agency (US EPA) and Health Canada’s Pest Management Regulatory Agency (PMRA) have incorporated state-of-the-art technologies. These methods of analysis are increasingly more sophisticated than earlier testing techniques, and thus permit development of an improved understanding of 2,4-D toxicology. The extensive data package of more than 121 new toxicology studies on 2,4-D provide valuable new perspectives affirming the minimal potential for the use of 2,4-D to adversely affect the environment, animal or human health.
Exposures of wildlife to 2,4-D, whether from direct spraying or consumption of treated vegetation, is of low toxicological significance. 2,4-D has a relatively short half-life and is rather immobile in the soil, with low potential for bioaccumulation or bioconcentration. Moreover, animal metabolism studies demonstrate that the herbicides are rapidly eliminated. As documented in the Bramble and Burns 1974 long-term study, many common game many common game species occupied the wildlife habitat created by a sprayed utility right-of-way out of an apparent preference and prospered there for many decades.