On 2016 Aug 17, Kirk O'Reilly commented:

McIntyre et al. have published a series of papers evaluating the use of soil bioretention systems to reduce the toxicity of stormwater and highway runoff (McIntyre et al. 2014, 2016, 2016b). Their recent paper (McIntyre et al. 2016) investigates the use of soil bioretention to treat artificial runoff from a test plot treated with a refined tar sealant (RTS). What readers may not know is that there is an on-going controversy concerning the environmental implications of RTS use (LeHuray 2015; USGS 2016). According to McIntyre’s acknowledgement, U.S. Geological Survey personnel responsible for the agency’s effort to ban RTS assisted in project planning. The goal of this comment is not to criticize McIntyre’s research on the use of soil bioretention systems but to discuss the results in the context of other studies so that the paper is not misused by those advocating for RTS product bans. The technical basis for these comments are summarized in Exponent (2016).

Key Points:

The title overstates the toxicity of RTS runoff.

The title suggests that sealant runoff causes “severe” toxicity. But severe is neither defined nor used in the text of the article. Severe toxicity is not a commonly used term in aquatic toxicology. Use of “acute toxicity” or just “toxicity” in the title would be less inflammatory and more consistent with the study results.

As noted by the authors in a prior publication (McIntyre et al. 2014), “Developing fish embryos are particularly vulnerable to the harmful effects of chemical contaminants and have long been a focus for toxicity screening. More recently, model species such as the zebrafish have provided an increasingly sophisticated experimental context for evaluating the developmental toxicity of individual chemical constituents in stormwater.” McIntyre et al. (2016b) says that their tests measure subtle biological effects. A positive bioassay result with a particularly vulnerable fish embryo test system is insufficient to support the suggestion of severe toxicity.

While the survival of another test species, juvenile Coho salmon, was less in runoff from a sealant test plot than the control, only the runoff collected within a few hours of sealant application killed all the organisms. Mortality decreased substantially for subsequent samples and remained significantly different from controls with runoff collected two weeks but not three weeks after application.

The toxicity of sealant runoff is consistent with the toxicity of runoff from unsealed surfaces.

McIntyre et al. (2014, 2016b) describe tests conducted on highway runoff collected during six storm events. Two of the six stormwater samples killed all Zebrafish embryos, and a third sample resulted in a significant reduction in survival. All six of the stormwater samples caused sublethal effects similar to those discussed in the RTS paper.

Greenstein et al (2004) tested the toxicity of artificial runoff from an operating asphalt parking lot in Southern California. There was no evidence that RTS was ever applied on the lot. Using a sensitive marine aquatic bioassay, sea urchin egg fertilization, toxicity was noted in all runoff samples.

Soil Bioretention treatment of RTS and highway runoff can eliminate toxicity and significantly reduced the response of sensitive molecular indicators.

Soil bioretention is a sustainable approach in which runoff is filtered by soil. It mimics natural processes that can reduce the toxicity of runoff from urban surfaces including sealed parking lots.

Acknowledgment

The author of this comment has conducted research funded by the Pavement Coating Technology Council.

References

McIntyre JK, Edmunds RC, Anulacion BF, Davis JW, Incardona JP, Stark JD, Scholz NL. 2016. Severe coal tar sealcoat runoff toxicity to fish and reversal by bioretention filtration. Environmental Science & Technology 50(3): 1570–1578.

LeHuray, A. 2015. In response to Bales (2014). Integrated Environmental Assessment and Management, 11(2), 185–187.

USGS. 2016. Information Quality - Information Correction Request. At: https://www2.usgs.gov/info_qual/archives/coal_tar_sealants.html

Exponent 2016. Summary of McIntyre et al. 2016. “Severe Coal Tar Sealcoat Runoff Toxicity to Fish Is Prevented by Bioretention Filtration” Environ. Sci. Technol. 50:1570−1578. Pavement Coatings Technology Council. 2016-08-14. URL:http://www.pavementcouncil.org/wp-content/uploads/2016/08/Tech-Memo-McIntyre-2016-review-Final.pdf. Accessed: 2016-08-14. (Archived by WebCite® at http://www.webcitation.org/6jlOpIS8t)

McIntyre JK, Davis J, Incardona J, Stark J, Anulacion B, Scholz N. 2014. Zebrafish and clean water technology: Assessing soil bioretention as a protective treatment for toxic urban runoff. Science of the Total Environment 500:173–178. Open Access: http://www.sciencedirect.com/science/article/pii/S0048969714012455

McIntyre JK, Edmunds RC, Redig MG, Mudrock EM, Davis JW, Incardona JP, Stark JD, Scholz NL. 2016b. Confirmation of stormwater bioretention treatment effectiveness using molecular indicators of cardiovascular toxicity in developing fish. Environmental Science & Technology 50(3): 1561–1569.

Greenstein D, Tiefenthaler L, and Bay S. 2004. Toxicity of parking lot runoff after simulated rainfall Arch Environ Contam Toxicol. 47:199–206.

On 2016 Aug 17, Kirk O'Reilly commented:

McIntyre et al. have published a series of papers evaluating the use of soil bioretention systems to reduce the toxicity of stormwater and highway runoff (McIntyre et al. 2014, 2016, 2016b). Their recent paper (McIntyre et al. 2016) investigates the use of soil bioretention to treat artificial runoff from a test plot treated with a refined tar sealant (RTS). What readers may not know is that there is an on-going controversy concerning the environmental implications of RTS use (LeHuray 2015; USGS 2016). According to McIntyre’s acknowledgement, U.S. Geological Survey personnel responsible for the agency’s effort to ban RTS assisted in project planning. The goal of this comment is not to criticize McIntyre’s research on the use of soil bioretention systems but to discuss the results in the context of other studies so that the paper is not misused by those advocating for RTS product bans. The technical basis for these comments are summarized in Exponent (2016).

Key Points:

The title overstates the toxicity of RTS runoff.

The title suggests that sealant runoff causes “severe” toxicity. But severe is neither defined nor used in the text of the article. Severe toxicity is not a commonly used term in aquatic toxicology. Use of “acute toxicity” or just “toxicity” in the title would be less inflammatory and more consistent with the study results.

As noted by the authors in a prior publication (McIntyre et al. 2014), “Developing fish embryos are particularly vulnerable to the harmful effects of chemical contaminants and have long been a focus for toxicity screening. More recently, model species such as the zebrafish have provided an increasingly sophisticated experimental context for evaluating the developmental toxicity of individual chemical constituents in stormwater.” McIntyre et al. (2016b) says that their tests measure subtle biological effects. A positive bioassay result with a particularly vulnerable fish embryo test system is insufficient to support the suggestion of severe toxicity.

While the survival of another test species, juvenile Coho salmon, was less in runoff from a sealant test plot than the control, only the runoff collected within a few hours of sealant application killed all the organisms. Mortality decreased substantially for subsequent samples and remained significantly different from controls with runoff collected two weeks but not three weeks after application.

The toxicity of sealant runoff is consistent with the toxicity of runoff from unsealed surfaces.

McIntyre et al. (2014, 2016b) describe tests conducted on highway runoff collected during six storm events. Two of the six stormwater samples killed all Zebrafish embryos, and a third sample resulted in a significant reduction in survival. All six of the stormwater samples caused sublethal effects similar to those discussed in the RTS paper.

Greenstein et al (2004) tested the toxicity of artificial runoff from an operating asphalt parking lot in Southern California. There was no evidence that RTS was ever applied on the lot. Using a sensitive marine aquatic bioassay, sea urchin egg fertilization, toxicity was noted in all runoff samples.

Soil Bioretention treatment of RTS and highway runoff can eliminate toxicity and significantly reduced the response of sensitive molecular indicators.

Soil bioretention is a sustainable approach in which runoff is filtered by soil. It mimics natural processes that can reduce the toxicity of runoff from urban surfaces including sealed parking lots.

Acknowledgment

The author of this comment has conducted research funded by the Pavement Coating Technology Council.

References

McIntyre JK, Edmunds RC, Anulacion BF, Davis JW, Incardona JP, Stark JD, Scholz NL. 2016. Severe coal tar sealcoat runoff toxicity to fish and reversal by bioretention filtration. Environmental Science & Technology 50(3): 1570–1578.

LeHuray, A. 2015. In response to Bales (2014). Integrated Environmental Assessment and Management, 11(2), 185–187.

USGS. 2016. Information Quality - Information Correction Request. At: https://www2.usgs.gov/info_qual/archives/coal_tar_sealants.html

Exponent 2016. Summary of McIntyre et al. 2016. “Severe Coal Tar Sealcoat Runoff Toxicity to Fish Is Prevented by Bioretention Filtration” Environ. Sci. Technol. 50:1570−1578. Pavement Coatings Technology Council. 2016-08-14. URL:http://www.pavementcouncil.org/wp-content/uploads/2016/08/Tech-Memo-McIntyre-2016-review-Final.pdf. Accessed: 2016-08-14. (Archived by WebCite® at http://www.webcitation.org/6jlOpIS8t)

McIntyre JK, Davis J, Incardona J, Stark J, Anulacion B, Scholz N. 2014. Zebrafish and clean water technology: Assessing soil bioretention as a protective treatment for toxic urban runoff. Science of the Total Environment 500:173–178. Open Access: http://www.sciencedirect.com/science/article/pii/S0048969714012455

McIntyre JK, Edmunds RC, Redig MG, Mudrock EM, Davis JW, Incardona JP, Stark JD, Scholz NL. 2016b. Confirmation of stormwater bioretention treatment effectiveness using molecular indicators of cardiovascular toxicity in developing fish. Environmental Science & Technology 50(3): 1561–1569.

Greenstein D, Tiefenthaler L, and Bay S. 2004. Toxicity of parking lot runoff after simulated rainfall Arch Environ Contam Toxicol. 47:199–206.