- Email: [email protected]
Response to Harper and Key-Schwartz
Regulatory Toxicology and Pharmacology 83 (2017) 103
Contents lists available at ScienceDirect
Regulatory Toxicology and Pharmacology journal homepage: www.elsevier.com/locate/yrtph
Response to Harper and Key-Schwartz*
Dear Editor, We appreciate the call by Harper and Key-Schwartz (2016) for further careful review of preparation of respirable crystalline silica samples for subsequent analysis and believe that their comments help to illustrate the need for the Occupational Safety and Health Administration (OSHA) to conduct a much larger-scale blind study, as previously recommended by Cox, et al. (Cox et al., 2015; Lee et al., 2016). OSHA's criticism (OSHA, 2014) of the Cox paper was not data driven, but instead emphasized the fact that RJ Lee Group (RJLG) was not a certified laboratory for standards work. We therefore conducted the follow-up study specifically to reproduce the basic elements of the original study using samples prepared by the National Institute of Standards and Technology (NIST), certainly a “certified” laboratory. The results of this study demonstrate conclusively that the poor non-uniform results found in the original study were not caused by the fact that RJLG is not a certified laboratory, nor could they be attributed to the major alternative source of error we could identify e the effect of shipping. Thus, the follow-up study confirmed the results of the original. We believe that Harper et al.’s comparison of our results with prior PAT rounds reinforces our previous conclusions. They point out that prior PAT rounds found no statistical difference between muffle furnace (MF) and plasma asher (PA) results. This happens for one of two reasons: either there was no difference between the two preparation methods or the internal variability for each method was so large that such differences could not be statistically detected. Neither explanation answers a key question motivating our study: Do laboratories perform in the same manner in a blind study as when they knew they are being tested? As is well known in the industry, laboratories tend to perform better when they know they are being evaluated. If the past results are indeed valid, Cox's data clearly shows the presence of such an effect. Under blind conditions, laboratories performed poorly and there is no doubt as to the statistical significance of the results. Clearly the laboratories underestimate the silica content of filters more when using the MF preparation under blind conditions than in the former PAT rounds. Finally, Harper et al. perform a statistical analysis of our data in which they do not replicate our finding, using different methods, of a statistically significance difference. We welcome further discussion and evaluation of alternative statistical methods, but note that our results are supported by an independent test: the * RE: In response to Harper and Key-Schwartz Letter to the Editor: Preparation of respirable crystalline silica samples for subsequent analysis.
http://dx.doi.org/10.1016/j.yrtph.2016.10.019 0273-2300/© 2016 Elsevier Inc. All rights reserved.
reanalysis of the crucibles prepared by the MF methods found significant levels of silica (see Table 4 of the paper). In summary, we believe that the Harper, et al. letter does nothing to change the fact that two studies confirm that MF filter preparation is unreliable and undermines the reliability of the standards used to determine whether workers are at risk from exposure to silica. We join Harper et al. in calling for more careful scrutiny of methods, and we again urge careful review and further critical evaluation and testing of methods before approving their use in supporting the new standard (OSHA, 2016).
Transparency document Transparency document related to this article can be found online at http://dx.doi.org/10.1016/j.yrtph.2016.10.019.
References Cox Jr., L.A., Van Orden, D.R., Lee, R.J., Arlauckas, S., Kautz, R.J., Warzel, A.L., Bailey, K.F., Ranpuria, A.K., 2015. How reliable are crystalline silica dust concentration measurements? Regul. Toxicol. Pharmacol. 73, 126e136. Harper, M., Key-Schwartz, R.J., 2016. Letter to the Editor: preparation of respirable crystalline silica samples for subsequent analysis. Regul. Toxicol. Pharmacol. 83, 100e102. Lee, R.L., Van Orden, D.R., Cox, L.A., Arlauckas, S., Kautz, R.J., 2016. Impact of muffle furnace preparation on the results of crystalline silica analysis. Regul. Toxicol. Pharmacol. 80, 164e172. Occupational Safety and Health Administration (OSHA), 2016. Occupational exposure to respirable crystalline silica; final rule. Fed. Regist. 81, 16286e16890. Occupational Safety and Health Administration (OSHA), March 26, 2014. Informal Public Hearings for the Proposed Rule on Occupational Exposure to Respirable Crystalline Silica.
R.J. Lee, D.R. Van Orden* RJ Lee Group, Inc., 350 Hochberg Road, Monroeville, PA 15146, USA L.A. Cox Cox Associates Inc, 503 Franklin Street, Denver, CO 80218, USA S. Arlauckas, R.J. Kautz RJ Lee Group, Inc., 350 Hochberg Road, Monroeville, PA 15146, USA * Corresponding author. E-mail address: [email protected] (D.R. Van Orden).
4 October 2016 Available online 10 November 2016
Contents lists available at ScienceDirect
Regulatory Toxicology and Pharmacology journal homepage: www.elsevier.com/locate/yrtph
Response to Harper and Key-Schwartz*
Dear Editor, We appreciate the call by Harper and Key-Schwartz (2016) for further careful review of preparation of respirable crystalline silica samples for subsequent analysis and believe that their comments help to illustrate the need for the Occupational Safety and Health Administration (OSHA) to conduct a much larger-scale blind study, as previously recommended by Cox, et al. (Cox et al., 2015; Lee et al., 2016). OSHA's criticism (OSHA, 2014) of the Cox paper was not data driven, but instead emphasized the fact that RJ Lee Group (RJLG) was not a certified laboratory for standards work. We therefore conducted the follow-up study specifically to reproduce the basic elements of the original study using samples prepared by the National Institute of Standards and Technology (NIST), certainly a “certified” laboratory. The results of this study demonstrate conclusively that the poor non-uniform results found in the original study were not caused by the fact that RJLG is not a certified laboratory, nor could they be attributed to the major alternative source of error we could identify e the effect of shipping. Thus, the follow-up study confirmed the results of the original. We believe that Harper et al.’s comparison of our results with prior PAT rounds reinforces our previous conclusions. They point out that prior PAT rounds found no statistical difference between muffle furnace (MF) and plasma asher (PA) results. This happens for one of two reasons: either there was no difference between the two preparation methods or the internal variability for each method was so large that such differences could not be statistically detected. Neither explanation answers a key question motivating our study: Do laboratories perform in the same manner in a blind study as when they knew they are being tested? As is well known in the industry, laboratories tend to perform better when they know they are being evaluated. If the past results are indeed valid, Cox's data clearly shows the presence of such an effect. Under blind conditions, laboratories performed poorly and there is no doubt as to the statistical significance of the results. Clearly the laboratories underestimate the silica content of filters more when using the MF preparation under blind conditions than in the former PAT rounds. Finally, Harper et al. perform a statistical analysis of our data in which they do not replicate our finding, using different methods, of a statistically significance difference. We welcome further discussion and evaluation of alternative statistical methods, but note that our results are supported by an independent test: the * RE: In response to Harper and Key-Schwartz Letter to the Editor: Preparation of respirable crystalline silica samples for subsequent analysis.
http://dx.doi.org/10.1016/j.yrtph.2016.10.019 0273-2300/© 2016 Elsevier Inc. All rights reserved.
reanalysis of the crucibles prepared by the MF methods found significant levels of silica (see Table 4 of the paper). In summary, we believe that the Harper, et al. letter does nothing to change the fact that two studies confirm that MF filter preparation is unreliable and undermines the reliability of the standards used to determine whether workers are at risk from exposure to silica. We join Harper et al. in calling for more careful scrutiny of methods, and we again urge careful review and further critical evaluation and testing of methods before approving their use in supporting the new standard (OSHA, 2016).
Transparency document Transparency document related to this article can be found online at http://dx.doi.org/10.1016/j.yrtph.2016.10.019.
References Cox Jr., L.A., Van Orden, D.R., Lee, R.J., Arlauckas, S., Kautz, R.J., Warzel, A.L., Bailey, K.F., Ranpuria, A.K., 2015. How reliable are crystalline silica dust concentration measurements? Regul. Toxicol. Pharmacol. 73, 126e136. Harper, M., Key-Schwartz, R.J., 2016. Letter to the Editor: preparation of respirable crystalline silica samples for subsequent analysis. Regul. Toxicol. Pharmacol. 83, 100e102. Lee, R.L., Van Orden, D.R., Cox, L.A., Arlauckas, S., Kautz, R.J., 2016. Impact of muffle furnace preparation on the results of crystalline silica analysis. Regul. Toxicol. Pharmacol. 80, 164e172. Occupational Safety and Health Administration (OSHA), 2016. Occupational exposure to respirable crystalline silica; final rule. Fed. Regist. 81, 16286e16890. Occupational Safety and Health Administration (OSHA), March 26, 2014. Informal Public Hearings for the Proposed Rule on Occupational Exposure to Respirable Crystalline Silica.
R.J. Lee, D.R. Van Orden* RJ Lee Group, Inc., 350 Hochberg Road, Monroeville, PA 15146, USA L.A. Cox Cox Associates Inc, 503 Franklin Street, Denver, CO 80218, USA S. Arlauckas, R.J. Kautz RJ Lee Group, Inc., 350 Hochberg Road, Monroeville, PA 15146, USA * Corresponding author. E-mail address: [email protected] (D.R. Van Orden).
4 October 2016 Available online 10 November 2016