The limitations [on existing studies] include the lack of quantified exposures, the potential for residual confounding, inconsistencies in design and results across studies, and the limited number of studies for any one outcome,” the HEI Energy study notes The Committee noted, however, that given the range of activities and chemicals to which populations surrounding UOGD activities may be exposed, it is critical that additional high-quality research be undertaken to better understand the potential for human exposure and health effects from UOGD.” (Emphasis added)