acceptable ambient level hydrogen sulfide l.
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Acceptable Ambient Level Hydrogen Sulfide
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  1. EMC Air Quality Committee 12 February 2003 by Preston Howard, President Manufacturers & Chemical Industry Council of North Carolina MCIC Acceptable Ambient Level Hydrogen Sulfide

  2. 6 Affected MCIC Members Sites - All in Economically Depressed Regions • Blue Ridge Paper - Canton • International Paper • Riegelwood • Roanoke Rapids • PCS Phosphate - Aurora • Weyerhaeuser • New Bern • Plymouth

  3. All are Major Economic Hubs • Directly employ from 500 to 1200 on-site • Statewide 9000 total jobs • Thousands of “spin-off” jobs • Annual payroll $494 Millon • $750 Million in purchases from NC vendors

  4. Responsibilities • SAB - Risk Assessment • No considerations other than science • EMC - Risk Management • Practical considerations • Technical feasibility • Economic impact

  5. Regulated Sources • Six sites owned by MCIC member companies = 14% of all H2S emissions in NC • 86% of H2S emissions would not be subject to the new AAL • Is it prudent to spend $500 Million to control 14% of the emissions?

  6. H2S Emissions in North Carolina

  7. Jappinen et al. 1990 • “to assess the possible effects of low concentrations of H2S on respiratory function” • Exposed 10 asthmatics to 2 ppm for 30 min. • 2 ppm = 2700 ug/m3 • current AAL is 2100 ug/m3

  8. SAB Concluded that the bronchial obstruction experienced by 2 of the 10 asthmatics constituted an asthmatic response Jappinen noted that the “increase [in bronchial obstruction] was not statistically significant and did not result in clinical symptoms” Conflicting interpretations of Jappinen’s results

  9. Bruce Dalton, MD, FACOEM • “Jappinen study findings are consistent with population studies of residents living near industrial sources of hydrogen sulfide” • “the SAB’s recommendations are based on interpretations of the Jappinen study that are inconsistent with the data as published”

  10. “The SAB implies ...that exposure to low levels of hydrogen sulfide trigger asthma attacks . Such conclusions are not supported by the scientific and medical literature, nor are they shared by other bodies.” Michigan Environmental Science Board interpreted Jappinen - “asthmatic subjects [are] not more susceptible to [the] effects of H2S Vickie L. Tatum, Ph.D.

  11. Others • 1997 American Conference of Governmental Industrial Hygienists - “studies on respiratory function of pulp mill workers and asthmatics at 2 ppm hydrogen sulfide failed to find a statistically significant change produced by the hydrogen sulfide”

  12. “Real world” studies… • 11 different studies on respiratory health of residents near pulp mills and refineries • 10 studies found no evidence of significantly increased incidence of asthma or asthma-like symptoms • 1 study found increased incidence of asthma, but authors noted that other factors, such as mold in homes and pollen, appeared to play a role

  13. The 1 hr AAL derived from Jappinen should be discounted • Is not supported by Jappinen (the author) • Is not supported by scientific and medical literature • Is not supported by interpretations by other government agencies (Michigan ESB) • Is not supported by American Conference of Government Industrial Hygienists • Is not supported by population studies of residents living near industrial sources of H2S

  14. Vanhoorne et al. 1995 • Basis for SAB’s 24 hr AAL of 33 ug/m3 • Study of eye irritation complaints among workers at a viscose rayon plant • Workers were exposed to both hydrogen sulfide and carbon disulfide

  15. Quotes from Vanhoorne. . . • “the prevalence of eye complaints… is clearly associated with exposure. However, deciding which of the two suspected agents, H2S or CS2, was responsible proved impossible in this study.” • Last year EPA judged studies like Vanhoorne to be “unsuitable” due to the “co-exposure to other chemicals like CS2”

  16. Vanhoorne . . . • Since Vanhoorne involved the co-exposure of H2S and CS2, and since EPA has indicated that the use of studies involving such co-exposure is inappropriate, MCIC believes that the EMC should disregard the Vanhoorne study and the proposed AAL of 33 ug/m3 that was derived from it

  17. MCIC Position • The SAB offered a 24 hr AAL of 120 ug/m3, based on Brenneman study • MCIC’s experts have reviewed this derivation • Scientific disagreement over the Brenneman study is not extensive • MCIC believes that compliance with this 24 hour AAL is achievable at reasonable cost, if accompanied by an exemption for WWTP • MCIC has no objection to adoption of 120 ug/m3 (24 hr), with WWTP exemption and compliance 5 years following permit renewal

  18. What should the EMC do? • We know from staff about the severe economic hardship associated with 56 ug/m3 (1 hr) • We know there is considerable disagreement in the scientific and medical communities • Scientific complexity/disagreement causes confusion • Confusion breeds a tendency to “defer” the decision to the science experts - the risk assessors • Urge you not to shirk your risk MANAGEMENT responsibility by deferring a management decision to risk ASSESSORS • This decision is rightfully made by the EMC - you are the risk MANAGERS - you should decide the appropriate AAL

  19. High regard for SAB • DR. Lucier and his colleagues on the SAB are well respected • Our purpose here today is not to criticize the SAB • To the contrary, our purpose is to note for you that knowledgeable scientists and medical professionals disagree on the health effects of low level H2S exposure

  20. EMC’s Role as RISK MANAGER • Weigh the merits of the scientific arguments and assess the scientific uncertainty and disagreement • Consider the significant economic implications for the 4 companies as well as for entire regions of North Carolina • Assign an AAL that affords adequate protection for the public health without unnecessarily jeopardizing the jobs of working families