Acceptable Ambient Level Hydrogen Sulfide

1
Acceptable Ambient Level
Hydrogen Sulfide

• EMC Air Quality Committee
• 12 February 2003
• by
• Preston Howard, President
• Manufacturers Chemical Industry
• Council of North Carolina
• MCIC

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
Conflicting interpretations of Jappinens results

• 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

9
Bruce Dalton, MD, FACOEM

• Jappinen study findings are consistent with
  population studies of residents living near
  industrial sources of hydrogen sulfide
• the SABs recommendations are based on
  interpretations of the Jappinen study that are
  inconsistent with the data as published

10
Vickie L. Tatum, Ph.D.

• 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

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 SABs 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
• MCICs 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
EMCs 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