\* MERGEFORMAT
                 UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                            WASHINGTON, D.C.  20460
                                                                      OFFICE OF
                                                            CHEMICAL SAFETY AND
                                                           POLLUTION PREVENTION

MEMORANDUM

Date:	April 5, 2011

SUBJECT:	Tetrachlorvinphos.  Request for Waiver of a Swine Magnitude of Residue Study
            
PC Code:  083701/083702
DP Barcode:  D320857
Decision No.:  359967
Registration No.:  Not Applicable
Petition No.: Not Applicable
Regulatory Action: Reregistration Follow-up
Risk Assessment Type: Not Applicable
Case No.: 0321
TXR No.: Not Applicable
CAS No.: 22248-79-9
MRID Nos.: None
40 CFR: 180.252


FROM:	Christine L. Olinger, Chemist
		Risk Assessment Branch VII
		Health Effects Division (7509P)
		Office of Pesticide Programs

THRU:	Alexandra LaMay, Biologist
		Michael S. Metzger, Chief,
		Risk Assessment Branch VII
		Health Effects Division (7509P)
		Office of Pesticide Programs

TO:	James Parker, CRM
		Risk Management and Implementation Branch II
		Pesticide Re-evaluation Division (7508P)
		Office of Pesticide Programs


Tetrachlorvinphos is an organophosphate insecticide used as a direct animal treatment and feed through on poultry, ruminants, and swine.  In a recent review of poultry and ruminant magnitude of residue (MOR) studies HED reiterated the reregistration requirement to also conduct a magnitude of residue study in swine (C. Olinger; 10/7/10; D320848, D320858, D320859, and D381350).  HED had previously recommended for this study in the Residue Chemistry Chapter to the Reregistration Eligibility Decision (RED) (F. Suhre, DP Barcode D199644, 7/6/94) and the HED Chapter to the RED (C. Swartz, 12/8/99, D261626).  In response, SRA International, on behalf of the Tetrachlorvinphos Task Force (TCVPTF), has requested a waiver of this study.  The Pesticide Re-evaluation Division (PRD) has requested HED review of this submission.



REGISTRANT WAIVER REQUEST

KMG-Bernuth, Inc. (KMG) has performed and submitted to the Agency two MOR studies, one in dairy cows (MRID No. 47193001) and one in poultry (MRID No. 4758301) as well as nature of the residue (NOR) studies in both animal species. The metabolite profile was identified and quantified in animals as a result of these studies.  
 
TCVPTF believes that the ruminant study would likely produce higher residues than a swine study, since the material would likely remain in a ruminant digestive system longer than swine.  According to their submission, it is well-documented that residence time in swine intestines is significantly shorter relative to that in a ruminant; a swine study would not be expected to provide any more meaningful information than can be inferred from the existing feeding studies. In addition, the TCVPTF has stated that both the NOR and MOR studies demonstrated the very poor absorption of TCVP following both oral and dermal administration.  This poor absorption is designed into Rabon Oral Larvicide products (by requiring [specifying] a very large particle size) because product efficacy is predicated upon TCVP passing through the animal and being excreted intact in order for it to be effective.  
 

HED RECOMMENDATION

HED has considered the product use information, existing guidance, and the registrant's submission.  The magnitude of residue data show that most of the residues are found as a result of the dermal treatment; residues from livestock treated only with the feed through were substantially less than the residues from both dermal and feed-through treatment.  This is consistent with the registrant's discussion on the poor oral absorption.  The application rates for ruminants and swine are generally comparable as noted in Table 1 at the end of this review (and is copied from the 10/7/10 review).  Note that in residue monitoring of livestock from 2001-2009 USDA Food Safety and Inspection Service (FSIS) has never detected residues of tetrachlorvinphos per se and the USDA Pesticide Data Program (PDP) has detected tetrachlorvinphos twice in milk at very low levels.

Residues in swine are not likely to be higher than the residues in ruminants.  Therefore, HED recommends for the waiver of the swine magnitude of residue study and will translate the ruminant data to swine.  The recommended tolerance levels for swine (hog) meat, meat by-products, and fat may be found in Table 2.

Table 1.   Summary of Registered Directions for Use of Tetrachlorvinphos. [1]
Application Type/Mode
                                  Formulation
                                [EPA Reg. No.]
                               Application Rate
                        Use Directions and Limitations
                                 Cattle, Beef
Direct animal spray 
                                    50% WP
                                  [61483-43]
                   0.5-1.0 gal of 0.35-0.5% solution/animal;
             (equivalent to a maximum rate of 18.9 g ai/animal)  
                                       
Apply as a low pressure coarse spray and apply only to point before runoff.  No retreatment restrictions are specified.  There is no withholding period from last application to slaughter.  

                                    23% EC
                                  [61483-50]
0.5-1.0 gal of a spray solution per animal with spray solution made by diluting 1 gal of 23% EC in 75 to 200 gal of water
                        (equivalent to 11 g ai/animal)
Do not treat more often than every 10 days.  Do not apply to calves under 6 months of age.  Brahman and Brahman-cross cattle should not be treated as they may show hypersensitivity to organophosphate pesticides.  Do not apply in combination with other organophosphate pesticides (e.g., trichlorfon).  There is no withholding period from last application to slaughter.
Feed through (oral) 
                                    7.76% G
                                  [61438-48]
                              70 mg/100 lb BW/day
                      (equivalent to 0.24 g ai/750 kg BW)
For use as an oral larvicide in cattle feeds to prevent the development of flies in the manure of treated cattle.  Concentrate must be mixed with feed.
Direct animal dusting
                                     3% D
                                  [61483-45]
                              1.7-3.4 g ai/animal
Apply to the upper portions of the back, neck, and poll by hand dusting or self-treating dust bag.  Repeat as necessary.
                               Cattle, Lactating
Direct animal spray
                                    23% EC
                                  [61483-50]
0.5 gal of a spray solution per animal with the spray solution made by diluting 1 gal of 23% EC in 200 gal of water
                         (equivalent to 4 g ai/animal)
Repeat as necessary (general label directions specify do not apply more than once a day).  Do not apply to calves under 6 months of age.  No milk discard is required.  Care should be taken that the spray does not come in direct contact with the cow's teats unless they are washed with an approved cleansing solution and dried before milking.  Apply the spray at least 20 minutes prior to milking or after milking has been completed.
Feed through (oral)
                                    97.3% G
                                  [61483-47]
                                       
                                    7.76% G
                                  [61438-48]
                              70 mg/100 lb BW/day
                      (equivalent to 0.24 g ai/750 kg BW
                                       
For use as an oral larvicide in cattle feeds to prevent the development of flies in the manure of treated cattle.  Concentrate must be mixed with feed.
Direct animal dusting
                                     3% D
                                  [61483-45]
                              1.7-3.4 g ai/animal
Apply to the upper portions of the back, neck, and poll by hand dusting or self-treating dust bag.  Repeat as necessary.
                                    Poultry
Direct animal spray 
                                    50% WP
                                  [61483-43]
                                       
                                       
1.0 gal of 0.5% solution/100 birds (equivalent to a maximum rate of 0.19 g ai/bird)
Spray the vent and fluff of wire cages from below.  Repeat when necessary but do not repeat more than every 14 days. 

                                    23% EC
                                  [61483-50]
1.0 gal of a spray solution per 100 birds with the spray solution made by diluting 1 gal of 23% EC in 50 gal of water

Direct animal dusting
                                     3% D
                                  [61483-45]
                             0.03 lb ai/300 birds
For individual treatment of poultry in wire cages.  Direct dust to vent and fluff area.  Group treatment may be preferred.  Dust should reach skin.  Wire rungs and corners should also be treated.
                                     Swine
Direct animal spray 
                                    50% WP
                                  [61483-43]
                    0.25 to 0.5 gal of 0.5% solution/animal
               (equivalent to a maximum rate of 9.5 g ai/animal)
Apply as a low pressure coarse spray and apply only to point before runoff.  Repeat in 2 weeks if necessary.  There is no withholding period from last application to slaughter.  
Feed through (oral)
                                    7.76% G
                                  [61438-48]
                              22.7 mg/1000 lb BW;
                             0.077 g ai/750 kg BW
For use as an oral larvicide in swine feeds to prevent the development of flies in the manure of treated cattle.  Concentrate must be mixed with feed.
Direct dusting of animal 
                                     3% D
                                  [61483-45]
                             2.6-3.4 g ai/animal 
Apply by conventional hand or power duster to each animal with special attention given to the neck and around the ear.  
[1]Note:  Application rates for backrubber and premise treatments are not included in this table as they are likely to lead to lower exposure than the direct application via sprays and dusts.  Only the use directions from products registered by the technical registrant, KMG-Bernuth, are included.


Table 2. 	Tolerance Reassessment Summary for Tetrachlorvinphos for Hog Commodities.
Commodity
                                  Established
                                 Tolerance [1]
                                     (ppm)
                             Maximum Residues [2]
                                     (ppm)
                           Reassessed Tolerance [3]
                                     (ppm)
Comments; 
Correct Commodity Definition
Hog, fat (of which no more than 0.1 ppm is tetrachlorvinphos per se)
                                      0.2
                         0.84 (0.56) subcutaneous fat;
                          0.75 (0.34) peritoneal fat
                                      1.0
Hog, fat (of which no more than 0.6 ppm is tetrachlorvinphos per se)
Hog, kidney (of which no more than 0.05 ppm is tetrachlorvinphos per se)
                                      1.0
                                      --
                                    Remove
See hog, meat byproducts
Hog, liver (of which no more than 0.05 ppm is tetrachlorvinphos per se)
                                      0.5
                                      --
                                    Remove
See hog, meat byproducts
Hog, meat (of which no more than 2.0 ppm is tetrachlorvinphos per se)
                                      2.0
                              0.27 (0.21) muscle
                                      0.3
Hog, meat (of which no more than 0.2 ppm is tetrachlorvinphos per se)
Hog, meat byproducts, except kidney and liver
                                      1.0
                            0.16 (<0.01) liver;
                             0.28 (0.015) kidney;
                         0.84 (0.56) subcutaneous fat;
                          0.75 (0.34) peritoneal fat;
                              0.27 (0.21) muscle
                                      1.0
Hog, meat byproducts (of which no more than 0.6 ppm is tetrachlorvinphos per se) [4]
[1]   Time-limited tolerances; current tolerance expression is for the combined residues of tetrachlorvinphos [(Z)-2-chloro-1-(2,4,5-trichlorophenyl)vinyl dimethyl phosphate] and its metabolites, 1-(2,4,5-trichlorophenyl)-ethanol (free and conjugated forms), 2,4,5-trichloroacetophenone, and 1-(2,4,5-trichlorophenyl)-ethanediol; should also include des-O-methyl tetrachlorvinphos.
[2]   Total residues of tetrachlorvinphos and its metabolites, TCVP-deme, TCPEone, TCPEol (free and conjugated forms), and TCPEdiol (free and conjugated), expressed in terms of parent equivalents; the value in parentheses represents the maximum residues of the parent tetrachlorvinphos.
[3]   Reassessed tolerance is based on the maximum residue from the respective magnitude of the residue study; the maximum residues of the parent tetrachlorvinphos are reported in the corrected commodity definition.
[4]  According to the 18 July 2007 Minutes of the HED ChemSAC meeting, the guidance document will be revised to include language detailing the use of the highest residue data for any tissue (liver, kidney, fat, skin or muscle) to determine the tolerance for meat byproducts.  A single tolerance on "meat byproducts" will be recommended based on that highest residue, and individual tolerances will no longer be set on liver, kidney, or meat byproducts (except liver and kidney).
