September 25, 2006

MEMORANDUM

SUBJECT:	Portland Cement Association (PCA) proposal to remove Hydrogen 	
	Chloride (HCl) emissions from the Portland Cement Manufacturing 		
Industry NESHAP

FROM:	Ted Palma 

		Sector Based Assessment Group/OAQPS/HEID (C539-02)

TO:		Keith Barnett 

		Metals and Minerals Group/OAQPS/SPPD (D243-02)

	After reviewing the material provide by the Portland Cement Association
(PCA) in support of removing Hydrogen Chloride (HCl) emissions from the
Portland Cement Manufacturing Industry NESHAP, I concur with PCA’s
conclusion that HCL emissions are not likely to either result in adverse
health effects to humans or result in any significant ecological
impacts.  

	Under section 112(d)(4) of the Clean Air Act, EPA has the authority to
determine that no further control of a substance is required if the
substance has an established health threshold, and granting the
exemption would provide “an ample margin of safety”, that is, in
protecting human health and the environment.

	A review of the EPA’s Integrated Risk Information System (IRIS) shows
a Reference Concentration for Chronic Inhalation Exposure (RfC) to HCl
of 0.02 mg/m3.  The RfC is an estimate (with uncertainty spanning
perhaps an order of magnitude) of a continuous inhalation exposure to
the human population (including sensitive subgroups which include
children, asthmatics and the elderly) that is likely to be without an
appreciable risk of deleterious effects during a lifetime.  Further,
under IRIS, HCl has not been classified as a carcinogen.  Thus, HCl
meets the definition of a “threshold” pollutant. 

	

	To show that the exemption would result in an “an ample margin of
safety” in protecting human health and the environment, PCA provides a
tiered-based dispersion modeling analysis of 112 kilns at 67 facilities
emitting HCl.   This represents about two-thirds of the facilities in
the industry and should adequately bound the range of emissions and
risks for the source category. 

	Following the EPA risk characterization guidance (USEPA, 2004), PCA
shows maximum modeled off-site impacts from the subject facilities will
result in chronic human inhalation exposures significantly less than RfC
(i.e., less than 50%).  Further, it is important to note that these
predicted impacts are located adjacent to facility property lines, many
times in locations where chronic exposure is not expected.  Impacts at
potential residential locations would be expected to be significantly
below those presented.   The assessment also examines acute impacts and
finds similar results well below established health criteria.

	The PCA assessment states that inhalation is the only pathway of
concern for exposure to humans for HCl.  A review of EPA risk guidance
does not list HCl as a Persistence and Bioaccumulation compound (PB-HAP)
and thus is not expected to be a concern for other exposure pathways. 
Finally, the assessment outlines a justification to show that HCl
emitted at these levels will not result in any harmful ecological
impacts. 

	Thus, based upon my review of the provided materials, I concur with PCA
that the current emissions of HCl will not result in adverse health
effects to humans or result in any significant ecological impacts.

References:

USEPA 2006, Presented at USEPA’s IRIS website on August 21, 2006 at:  
 HYPERLINK "http://www.epa.gov/iris/subst/0396.htm" 
http://www.epa.gov/iris/subst/0396.htm 

USEPA, 2004, Air Toxics Risk Assessment Reference Library -Volume 2 -
Facility-Specific Assessment; EPA-453-K-04-001B; RTP, NC; April 2004

Environ 2006; “Tiered Modeling Evaluation Of Potential Risks
Associated With HCl Emissions From Portland Cement Kilns” ENVIRON
International Corporation Groton, Massachusetts, July 31, 2006

PCA 2006; Letter to Office of Environmental Information Docket U.S.
Environmental Protection Agency Headquarters EPA Docket Center dated
August 1, 2006; RE:  National Emission Standards for Hazardous Air
Pollutants from the Portland cement Manufacturing Industry; Proposed
Rule; reopening of the public comment period.

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