Document ID: EPA-HQ-OPP-2011-0173-0043
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-09-20T04:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460      

	OFFICE OF CHEMICAL SAFETY AND

                                                                        
                      POLLUTION PREVENTION

	

  SEQ CHAPTER \h \r 1 MEMORANDUM

Date:		September 6, 2011

SUBJECT:	CRYOLITE.  Response to comments by the Fluoride Action Network
(FAN) 

on the Registration Review for Cryolite

 

PC Code:  075101	DP Barcode:   D391704

Decision No.:  N/A	Registration No.: N/A

Petition No.:  N/A	Regulatory Action: N/A

Risk Assessment Type: N/A	Case No.:  N/A

TXR No.:  N/A	CAS No.: 15096-52-3; 13775-53-6

MRID No.:  N/A	40 CFR: 180.145

		              								Ver.Apr. 2010

	          	

FROM:	  SEQ CHAPTER \h \r 1 Kit Farwell, D.V.M. 

		Risk Assessment Branch VII

		Health Effects Division (7509P)

		Office of Pesticide Programs

THROUGH:	Michael Metzger, Branch Chief		

		Risk Assessment Branch VII

		Health Effects Division (7509P)

		Office of Pesticide Programs

TO:		Molly Clayton, Chemical Review Manager

		Risk Management and Implementation Branch 3		  SEQ CHAPTER \h \r 1  
SEQ CHAPTER \h \r 1 

		Pesticide Re-Evaluation Division (7508P) 

		Office of Pesticide Programs

This memo responds to comments by the Fluoride Action Network (FAN) on
the Registration Review for Cryolite, July 5, 2011.  Nearly all of the
comments by FAN relate to fluoride, which is a degradation product of
cryolite.  The comments on fluoride will be addressed separately (see
Docket EPA-HQ-OPP-2005-0174 for comments on fluoride assessment).  The
only comment relating specifically to human health concerns for cryolite
was 3.4.1, and is addressed below.  



FAN comment 3.4.1:  OPP should require that testing for adverse effects
include cryolite and all of its degradation products and complexes. 

Cryolite degrades to fluoride, aluminum, and sodium in the environment,
but according to EPA, the only degradation product of concern is
fluoride, and the only effect of concern is severe dental fluorosis.
While OPP is requiring that free ion concentrations of Al3+, F-, and Na+
be used to estimate toxicity, this ignores the effects of complexes
formed from these ions. Aluminofluoride complexes are formed
spontaneously in water containing fluoride and trace amounts of
aluminum. These complexes have been found to stimulate various G
proteins, and thus may “mimic or potentiate the action of numerous
extracellular signals and significantly affect many cellular
responses” (Strunecka and Patocka, 1999). OPP should therefore
immediately require that toxicity testing of cryolite be extended to
include all of its degradation products, including the various
aluminofluoride complexes formed under different aquatic conditions.

EPA response:  Aluminum is the third most abundant element in the
earth's crust and is a component in food ingredients, food containers,
drinking water, and utensils used in food preparation.  As a
consequence, aluminum is commonly found in foods and most foods that
have been tested were found to contain 0.1 – 10 ppm aluminum.  A much
larger source of oral exposure to aluminum is reportedly from antacids
and buffered analgesics.  A 2001 review article reported that "(n)o
reports of dietary aluminum toxicity to healthy individuals exist in the
literature".  Because aluminum exposure to people is so ubiquitous, the
small amount of aluminum in dietary residues from cryolite is not
expected to have an adverse health effect.  

FAN was specifically concerned that aluminofluoride complexes would
affect G proteins and cellular signaling pathways.  However, cryolite
has already been evaluated in a number of toxicity studies, including a
battery of acute toxicity studies in different species, subchronic oral
toxicity studies in rats and dogs, chronic toxicity in rats and dogs,
carcinogenicity in rats and mice, developmental toxicity in rats,
rabbits, and mice, reproductive toxicity in rats, and in vitro
mutagenicity studies.  The oral exposure to cryolite in the many
toxicity studies with different animal species has allowed evaluation of
the toxicity potential for cryolite and its aluminum and fluoride
degradation products and complexes.  

For the above reasons, the aggregate fluoride risk assessment focused
upon dental fluorosis, the most sensitive endpoint for human health risk
assessment, which will be protective of other effects occurring at
higher dose.    

References:  

Aluminum in Foods and the Diet, JC Sherlock.  

Aluminum in Food and the Environment, editors RC Massey and D Taylor,
1989  

Safety Evaluation of Dietary Aluminum.  MG Soni, et al.  

Regulatory Toxicology and Pharmacology.  2001 Feb;33(1):66-79

Casarett & Doull's Toxicology, 7th edition. 

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