Population allocation at the housing unit level: estimates around underground natural gas storage wells in PA, OH, NY, WV, MI, and CA.

BACKGROUND: Spatially accurate population data are critical for determining health impacts from many known risk factors. However, the utility of the increasing spatial resolution of disease mapping and environmental exposures is limited by the lack of receptor population data at similar sub-census block spatial scales. METHODS: Here we apply an innovative method (Population Allocation by Occupied Domicile Estimation - ABODE) to disaggregate U.S. Census populations by allocating an average person per household to geospatially-identified residential housing units (RHU). We considered two possible sources of RHU location data: address point locations and building footprint centroids. We compared the performance of ABODE with the common proportional population allocation (PPA) method for estimating the nighttime residential populations within 200 m radii and setback areas (100 - 300 ft) around active underground natural gas storage (UGS) wells (n = 9834) in six U.S. states. RESULTS: Address location data generally outperformed building footprint data in predicting total counts of census residential housing units, with correlations ranging from 0.67 to 0.81 at the census block level. Using residentially-sited addresses only, ABODE estimated upwards of 20,000 physical households with between 48,126 and 53,250 people living within 200 m of active UGS wells - likely encompassing the size of a proposed UGS Wellhead Safety Zone. Across the 9834 active wells assessed, ABODE estimated between 5074 and 10,198 more people living in these areas compare to PPA, and the difference was significant at the individual well level (p = < 0.0001). By either population estimation method, OH exhibits a substantial degree of hyperlocal land use conflict between populations and UGS wells - more so than other states assessed. In some rare cases, population estimates differed by more than 100 people for the small 200 m2 well-areas. ABODE's explicit accounting of physical households confirmed over 50% of PPA predictions as false positives indicated by non-zero predictions in areas absent physical RHUs. CONCLUSIONS: Compared to PPA - in allocating identical population data at sub-census block spatial scales -ABODE provides a more precise population at risk (PAR) estimate with higher confidence estimates of populations at greatest risk. 65% of UGS wells occupy residential urban and suburban areas indicating the unique land use conflicts presented by UGS systems that likely continue to experience population encroachment. Overall, ABODE confirms tens of thousands of homes and residents are likely located within the proposed UGS Wellhead Safety Zone - and in some cases within state's oil and gas well surface setback distances - of active UGS wells.

The Legal Implications of Report Back in Household Exposure Studies.

BACKGROUND: Scientists conducting research into household air or dust pollution must decide whether, when, and how to disclose to study participants their individual results. A variety of considerations factor into this decision, but one factor that has not received attention until now is the possibility that study participants' receipt of their results might create legal duties under environmental, property, landlord-tenant, or other laws. OBJECTIVES: This article examines relevant laws and regulations and explores the scope of participants' legal duties and the resulting legal and ethical consequences for researchers. Participants could be required in some situations to disclose the presence of certain chemicals when selling or renting their homes or to frequent visitors. The article discusses hypothetical case studies involving the reporting back of results regarding lead, polychlorinated biphenyls, and phthalates. DISCUSSION: The potential legal duties of study participants have both ethical and legal implications for researchers. Issues include whether the legal consequences for participants should affect the decision whether to report back individual results, how researchers should disclose the legal risks to participants during the informed consent process, and whether researchers would be liable to study participants for legal or economic harm arising from reporting study results to them. The review provides recommendations for language that researchers could use in the informed consent process to disclose the legal risks. CONCLUSIONS: Researchers should still report back to participants who want to see their results, but they should disclose the risks of obtaining the information as part of the informed consent process. Citation: Goho SA. 2016. The legal implications of report back in household exposure studies. Environ Health Perspect 124:1662-1670; http://dx.doi.org/10.1289/EHP187.