Post Publication Peer Reviews of USGS Volatilization Studies

The USGS has been seeking to conduct “policy relevant science” (for example, here), and must have thought they’d hit the jackpot by manipulating the data of their Austin study to support the City of Austin’s long-standing desire to, for reasons known only to City personnel, ban RTS (see here). The USGS seems to have quickly adopted Austin’s quest as their own, and, for the past decade, has engaged in a program of advocacy research (a type of confirmation bias) targeted at RTS. One of the research projects undertaken by the USGS was a study of volatilization of PAHs from RTS-coated parking lots. This study resulted in two publications: Van Metre et al. (2012a) and Van Metre et al. (2012b). PCTC commissioned two post publication peer reviews of these papers, the first by ENVIRON of the two USGS papers in their entirety and the second by ARCADIS focused on a specific claim made by the USGS in one of their two papers.

R. DeMott, T. Gauthier and M. Masonjones of ENVIRON conducted complete post-publication peer reviews of the two volatilization papers. As has been found in other work by the same USGS authors, reported effects have been exaggerated and uncertainties have been minimized to make it falsely appear that lots sealed with refined tar-based sealant are the dominant source of PAHs released to the atmosphere. DeMott and colleagues conclude

Based on our analysis, we find that the two papers recently published by Van Metre and coworkers (2012) overstate the volatilization of PAHs from coal tar sealers. These papers employ a set of modeling assumptions and experimental study design approaches that consistently bias their findings to overestimate PAH volatilization from sealed parking lots.

Read the entire review here.

Citation: DeMott, R., Gauthier, T., and Masonjones, M. (2013). Volatilization of PAHs from Coal-Tar-Sealed Parking Lots. Report prepared by ENVIRON for the Pavement Coatings Technology Council. 46 p.

In one of the USGS papers (Van Metre et al. (2012b)), the authors make this statement:

Combining the estimated mass of ∑PAH8 released to the atmosphere with a national-use estimate of coal-tar-based sealant suggests that PAH emissions from new coal-tar-based sealcoat applications each year (˜1000 Mg) are larger than annual vehicle emissions of PAHs for the United States.

B. Magee of ARCADIS evaluated this statement. Dr. Magee found that the USGS used a Chinese estimate of PAHs in U.S. air rather than actual data available from EPA’s National Emissions Inventory. It appears the authors used the Chinese estimate to calculate that US motor vehicle emissions for 2010 were 46 Mg for six selected PAHs (it is conjecture that the USGS calculated the 46 Mg value using the Chinese estimate; the USGS did not clearly explain how they arrived at 46 Mg). Using the US National Emissions Inventory, the value for these six in 2011 is 888 Mg (excluding California) or 1,278 Mg (including an estimate for the six PAHs for California). Use of the Chinese estimate for US motor vehicle emissions rather than EPA’s actual data led the authors to posit that application of sealcoat is responsible for more PAH emissions than motor vehicles in the US. Read the entire evaluation of the USGS’ claim here.

Citation: Magee, B. (2014). PAH Vapor Emissions from Coal Tar Pavement Sealers. Report prepared by ARCADIS for the Pavement Coatings Technology Council. 5p.

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