Document ID: EPA-HQ-OPP-2009-0364-0016
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2011-12-22T05:00Z

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                         WASHINGTON, D.C. 20460      

                                               	OFFICE OF PREVENTION, PESTICIDE
                                                                                            AND TOXIC SUBSTANCES
	

MEMORANDUM

Date:		December 23, 2009

SUBJECT:	Fluopyram - ToxSAC Meeting on July 16, 2009 
             
PC Code:  080302
DP Barcode:   NA
Decision No.:  NA
Registration No.:  NA
Petition No.: NA
Regulatory Action: NA
Risk Assessment Type:  Single Chemical Aggregate
Case No.: NA
TXR No.:  NA
CAS No.:  NA
MRID No.:  NA
40 CFR: NA
         									         	
FROM:	Jessica Kidwell, ToxSAC Executive Secretary
		Health Effects Division (7509P)		
	
THROUGH:	Elizabeth Méndez, ToxSAC Chair
		Health Effects Division (7509P)			

TO:		Myron Ottley, Toxicologist				
		RAB III, Health Effects Division (7509P)

ToxSAC Meeting Notes for 7/16/09 Meeting on Fluopyram

Team Members:	Myron Ottley, Toxicologist 			
				
ToxSAC Members:	Judy Facey,  Jessica Kidwell, Marquea King, Elizabeth Mendez, Whang Phang, Elissa Reaves, Jessica Ryman, Ed Scollon

Other Attendees: 	Marion Copley (HED/SIMB), Barry O'Keefe, Paula Deschamp
 

A. ENDPOINT SELECTION
THE TOXSAC WAS REQUESTED to provide comments on the points of departure selections and proposed Endpoints for the fluopyram risk assessment.

ToxSAC Response: The ToxSAC recommendations for endpoint selection are below.

Dietary Exposure Endpoints

Acute Dietary (General Population, including infants and children):  The acute neurotoxicity study in rats was selected for the acute dietary exposure scenario for the general population, including infants and children.  The point of departure (POD) was a NOAEL of 50 mg/kg/day.  The LOAEL of 125 mg/kg/day was based on decreased motor and locomotor activity in female rats. This acute endpoint is appropriate for the route and duration of exposure as well as for the population of concern.  

An overall safety factor of 1000 should be applied (100X for inter- and intra-species variability, The FQPA safety factor of was retained in the form of a database uncertainty factor (UFdb) of 10X for lack of a comparative thyroid assay.  
 
			aRfD= 50 mg/kg/day  =   0.050 mg/kg/day		
				1000 (includes UFdb of 10x)

			aRfD =   aPAD

Acute Dietary (Females 13-49 years old):   An acute dietary endpoint for females 13-49 years old was not identified.  No prenatal or fetal toxicity was observed in developmental or reproductive animal studies that could be attributed to a single dose.  In the absence of a hazard for this population, risk estimates need not be conducted for this exposure scenario.  

Chronic Dietary (all populations): The chronic toxicity/carcinogenicity study in rats was selected for the chronic dietary exposure scenario for all populations. The POD was a NOAEL of 1.2 mg/kg/day.  The LOAEL of 6 mg/kg/day was based on nephropathy, follicular cell hypertrophy in the thyroid, and increased liver weight with gross pathological histopathological findings.  This endpoint is appropriate for the duration and population of concern. The POD from the rat will be protective of thyroid effects (thyroid hyperplasia and thyroid follicular cell tumors) seen in mice.

An overall safety factor of 1000 should be applied (100X for inter- and intra-species variability, and a database UF of 10X for a lack of a comparative thyroid assay.  The FQPA safety factor was retained in the form of a database uncertainty factor (UFdb) of 10X for lack of a comparative thyroid assay.  

			cRfD=     1.2 mg/kg/day  = 0.0012 mg/kg/day			
				       1000

			cRfD =     cPAD 

Residential Exposure Endpoints

Incidental Oral Exposures (Short and Intermediate term): The 2-generation reproduction study in rats was selected for the incidental oral exposure scenarios (short- and intermediate-term).  The POD was an offspring NOAEL of 14.5 mg/kg/day. The offspring LOAEL of 82.8 mg/kg/day was based on decreased pup body weight and body weight gain and decreased spleen and thymus weight. This endpoint is appropriate for the population of concern (children) since this body weight/body weight gain effect occurred post-natally and is not an in utero effect.

The residential level of concern for MOE is 1000 (100X for inter- and intra-species variability, and a database UF of 10X for a lack of a comparative thyroid study).

Occupational and Residential Exposure Endpoints

Dermal Exposure (short- and intermediate-term):  

The 28-day dermal toxicity study in rats was selected for both the short- and intermediate-term dermal exposure scenarios.  The POD was a NOAEL of 300 mg/kg/day. The LOAEL of 1000 mg/kg/day was based on increased cholesterol in females, increased prothrombin time in males, increased liver weight (both sexes) and liver hypertrophy. The 28-day dermal toxicity study in rats is the appropriate route of exposure and measures all endpoints of concern. An oral study was not chosen for a dermal endpoint since no increased sensitivity was seen in the developmental rat or rabbit studies or in the 2-generation reproduction study in rats. The dermal endpoint is protective of effects from any in utero exposure.  This 28-day dermal toxicity study is appropriate for both the short- and intermediate-term exposures.  Since dermal absorption is so low (<1% in humans for the concentrate), it is unlikely that the internal dose would lead to a progression of toxicity.

The residential level of concern for MOE is 1000 (100X for inter- and intra-species variability, and a database UF of 10X for a lack a comparative thyroid study).  The occupational LOC for MOE is 1000 (100X for inter- and intra-species variability and 10X for a lack of a comparative thyroid study to protect the pregnant female worker).

Inhalation Exposure (short- and intermediate-term): The 2-generation reproduction study in rats was selected for the inhalation exposure scenarios (short- and intermediate-term).  The POD was an offspring NOAEL of 14.5 mg/kg/day. The offspring LOAEL of 82.8 mg/kg/day was based on decreased pup body weight and body weight gain and decreased in spleen and thymus weight. An oral study was not chosen for a dermal endpoint since no increased sensitivity was seen in the developmental rat or rabbit studies or in the 2-generation reproduction study in rats. This endpoint is appropriate for the population of concern (children).

The residential level of concern for MOE is 1000 (100X for inter- and intra-species variability, and a database UF of 10X for a lack of a comparative thyroid study). The occupational LOC for MOE is 1000 (100X for inter- and intra-species variability and 10X for a lack of a comparative thyroid study to protect the pregnant female worker).

B.  ToxSAC Comments on DERs

1. Pharmacokinetic studies:  The ToxSAC recommended that the evidence of sex differences (3-4 fold) which were seen in the pharmacokinetic studies should be discussed in the hazard characterization. The ToxSAC suggested that the toxicologist build a story tying together the ADME data and the toxicology data. It should include that absorption is very rapid, and that the sex differences seen in the ADME data are also reflected in the ACN study results. 

2.  Acute Neurotoxicity (ACN) Study: There was some discussion of whether the effects seen in the ACN study were neurotoxic or systemic. Several members of the ToxSAC pointed out that the transient but marked effect on motor and locomotor activity are reminiscent of effects seen after exposure to sedatives or anesthetics.  Thus, they considered the effects in the ACN to be indicative of a potentially neurotoxic effect which was supported by findings in the long term cancer study in rats.  The chronic toxicity/carcinogenicity study in rats showed possible clinical signs of neurotoxicity including limited use of hind limbs, reduced motor activity, and lethargy at the high dose.  Other members of the committee, however, viewed these effects as indications of generalized toxicity and not necessarily directly related to effects on the nervous system.  Regardless, of the etiology of the effect there was consensus that the decrease in motor and locomotor activity (↓70% ) seen on Day 0 in the ACN study was considered to be adverse and appropriate to establish an acute reference dose for the general population.  

3. Dermal Absorption Factor (DAF):  It was suggested that the DAF for humans be incorporated into the hazard characterization.  The ToxSAC concluded that the Triple Pack dermal absorption studies (i.e., parallelogram approach) were well conducted and that the calculations and the underlying assumptions were correct.  The hazard characterization should give more emphasis to the Triple Pack and should specifically state the dermal absorption factor for use in humans. Contact Jessica Ryman for specific language to use. 
   
4. 2-Generation Reproduction Study: The ToxSAC was in general agreement with this DER, but had several comments:  a) For the parental systemic LOAEL, do not include decreased body weight as part of the LOAEL since the decrease is too minimal (5-6%) (a 10% decrease is the cut off used for adverse effects for decreases in parental body weight); b) Since the basis of the LOAEL statement is cholesterol, hemoglobin, and hematocrit etc., it would be helpful to have that actual data in the DER. This information should be added in table format so the magnitude of the changes can be presented; c) In the DER it was suggested that a table of the organ weight changes for the spleen and thymus be added to see the magnitude of changes. This is important to include since Germany feels that a DIT study is needed; d) The ToxSAC recommends that PPS not be included in the LOAEL statement since the values are well within the historical control range for the laboratory.
   
5. Developmental Rat DER: DER says LOAEL is highest dose tested. Ureter effects should not be counted as a compound-related at any dose level since these effects are commonly seen in rats and are considered a normal aspect of renal development in late gestation of rats.  Thus only one visceral finding the thymic remnant present remains as part of LOAEL. 

5.  Developmental Rabbit DER:  The ToxSAC recommended that the body weight information, not just the body weight gain information, be added to the text as well as to the maternal LOAEL statement. 

 C.  Is there a need for a Developmental Immunotoxicity (DIT) study?

ToxSAC Response:  The ToxSAC agrees that a DIT study is not required at this time pending the results of the adult immunotoxicity study which is currently being conducted.  The 9-16% decreases in the spleen and thymus weights seen in the 2-generation reproduction study were not considered to be a sufficiently robust response to trigger a DIT study. (See table below). 
The effects of the test substance on spleen and thymus weights were not compelling.  The ToxSAC recommended that the data presentation in the DER could be improved with the addition of standard deviations (if available), however, statistically significant differences were observed for the majority of the data, and presentation will not change that. The ToxSAC also recommended additional characterization of the data.  For example, if there were no correlating histopathological changes in the spleen or the thymus, then a decrease in the weights is not compelling, since there is no histopathological evidence that these statistically significant changes were of biological importance. In addition, there were no indications in hematology parameters that would lead us to believe the mouse system is compromised.  Pending the results of the immunotoxicity study, it is recommended that the DIT issue be revisited.

Spleen 
Thymus
Adult                                    
Adult
P female                          -12% abs (p<0.05)  
P female                        -9% abs (p<0.05)  
F1 female                         -12% abs (p<0.05)  
F1 male                          -14% abs (p<0.05)  

21-day pup
21-day pup
F2 (M+F)                        -14% abs
F2 (M+F)                        -16% abs (p<0.01)
F2 (M+F)                         -9% rel
F2 (M+F)                         -9% rel (p<0.01)

D. Is there a need for a Comparative Thyroid Assay in the rat?

ToxSAC Response:  The ToxSAC determined that a comparative thyroid assay in the rat was needed.  In the fluopyram database, the thyroid was the target organ.  Thyroid effects were seen in the 28-day rat (increased thyroid weight), 90-day rat (changes in thyroid hormones and thyroid follicular cell hypertrophy), chronic rat (thyroid follicular cell hypertrophy), and the carcinogenicity study in the mouse (thyroid follicular cell hyperplasia and thyroid follicular cell tumors). The thyroid effects may be more sensitive. The benefits of a comparative thyroid assay are two fold: 1) the results would give information on thyroid toxicity and whether or not fluopyram is a direct acting thyroid toxicant; and 2) it would cover the neurotoxic type effects seen because thyroid hormone homeostasis is a precursor of developmental neurotoxicity in thyroid toxicant compounds. The thyroid is critical for fetal development, particularly for brain development.