2 of 26 Executive Summary

The Health Effects Division (HED) Amitraz Re gistration Review Team has evaluated the

status of the human health assessments for the insecticide/acaricide amitraz to determine the scope of work necessary to support Registration Review. Amitraz is an insecticide/acaricide with registered uses on cattle, swine, dogs a nd pups. Amitraz was first registered in 1975. The

most recent risk assessment for Amitraz was co mpleted in July 2006. There is a pending new use under PRIA that may be included later in the registration review proce ss. The tolerances for meats, meat by-products, and milk will be maintained to support the animal health uses. The toxicology database is incomplete with seve ral major data gaps, sp ecifically related to developmental, reproductive and neurotoxic effect s, plus new requirements for Part 158. The total uncertainty factor is currently 100X (10X FQPA Safety Factor a nd 10X for intra-species variation).

The 2006 risk assessment identified no defici encies in the amitraz residue or product chemistry database. In the registration review process, the dietary exposure analysis should include updated percent crop tr eated information from BEAD relative to imported cottonseed, and the percent of treated cattl e and swine in the US. Also during registration review, the tolerance expression for amitraz as liste d in 40 CFR §180.287 should be revised.

1.0 Introduction

Amitraz [N'-(2,4-dimethylphenyl)-N-[[( 2,4-dimethylphenyl)imino]methyl]-Nmethylmethanimidamide] is an insecticide/m iticide used on cattle, swine, dogs and pups. Amitraz has active registrations fo r the control of pests such as ticks, mites, lice and mange. Currently, the U.S. technical registrations for Am itraz are held by Arysta Life Sciences and Ft. Dodge/Wyeth. Amitraz formulations include impregnated materials and emulsifiable concentrates. There are also dog shampoos and dips which are regulated under the FDA as veterinary medicines (21 CFR 524.86). HED has considered the most recent exposure and risk assessments for this chemical, updates to its to xicity, exposure and us age databases, and the latest Agency science policy a nd risk assessment methodologies.

2.0 Hazard Iden tification/Toxicology

Amitraz is an alpha-adrenoceptor agonist, wh ich causes an increase in nerve activity

within arachnids. It also exerts a toxic effect through the octopamine receptor, which binds to a neuromodulator, causing ticks to wi thdraw their mouth parts and fa ll off the host animal, as well as killing the pest (i.e. ti ck). The NOAEL is 0.125 mg/kg and the LOAEL is 0.250 mg/kg for all exposure scenarios based on oral studies in humans (the most sensitive species), which revealed clinical signs of sedation, disorientation and hypothermia fr om a single dose. (Section 12 describes the human studies in more detail.) Thes e effects were reversible within 12 hours, so the human oral endpoint is appropriate for assessing the exposur e to amitraz, regardless of duration. The 0.125 mg/kg/day dose will be protective, sin ce it required higher doses for other systemic effects, such as body weight change in animals. Amitraz is classified as producing “suggestive evidence of carcinogenicity” due to tumor responses in the mouse at the highest dose (but none in the rat) and SAR relations to th e reported carcinogen chlordimeform.3 of 26 Clinical signs of toxicity seen in animal tests include centr al nervous system depression, ataxia, ptosis, emesis, labored respiration, musc ular weakness, tremors, hypothermia, dry mouth, hypertension and bradycardia. The Registra tion Standard (TXR 005633), states that the pharmacotoxic profile suggests a depression of hypothalmic function. The endpoint for regulation is based upon clinical signs of sedation, disorienta tion and hypothermia in humans observed at the acute exposure of 0.25 mg/kg, th e LOAEL. The acute human oral exposure is protective for exposure s cenarios of longer duration. The CNS (Central Nervous System) effects of amitraz do not appear to be cumulative, i.e., do not accumulate with increased duration. In the 90-day repeat dose dog study, the CNS effects appear early on (within 3 hours of dosing), rapidly end, and recur daily after dosing throughout the study. In rodents, dimethylaniline (DMA) is an

intermediate metabolite at 1.4% or less composition. This DMA metabolite can be much higher in swine and bovine, up to 14.0% levels. A mee ting of HED’s Residues of Concern Committee may be needed to confirm that DMA is of concern.

The summary of toxicological dose and endpoi nts are listed in Table 1. The toxicology data base is incomplete with several major da ta gaps, especially in those areas relating to developmental, reproductive and neurotoxic e ffects. A NOAEL of 0.125 mg/kg bw established in a study conducted in human subjects was used for overall risk assessment. Since a human study was used for the POD, the 10X inter-species uncertainty factor is not needed. However, due to the existing data gaps, primarily due to deficiencies within the particular studies, the default 10X FQPA Safety Factor is retained in the form of a database uncertainty factor (UF DB )

for a total UF of 100. Without th e inclusion of the human studies , the total UFs would be 1000X. The specific study data gaps including the studie s required in accordance with the revised Part

158 are listed in Section 13.0.

Table 1 Summary of Toxicological Do se and Endpoints for Amitraz Risk Assessment

Exposure

Scenario Dose Used in Risk Assessment, UF Study and Toxicological

Effects

Acute Dietary (General population including infants and children) NOAEL = 0.125 mg/kg

UF = 100 1

Acute RfD = 0.00125 mg/kg

Acute PAD = 0.00125 mg/kg 2 combined human studies (a single oral dose and a single oral dose metabolism)

LOAEL = 0.25 mg/kg based on dry mouth, drowsiness, decreased temperature, decreased blood pressure and decreased heart rate.

Incidental Oral * NOAEL= 0.125 mg/kg

Residential

MOE = 100 1 2 combined human studies (a single oral dose and a single oral dose metabolism)

LOAEL = 0.25 mg/kg

(effects listed above)4 of 26 Table 1 Summary of Toxicological Do se and Endpoints for Amitraz Risk Assessment

Exposure

Scenario Dose Used in Risk Assessment, UF Study and Toxicological

Effects

Dermal * Oral NOAEL = 0.125 mg/kg

(dermal absorption rate 8%)

Residential

MOE = 100 1 2 combined human studies (a single oral dose and a single oral dose metabolism)

LOAEL = 0.25 mg/kg

(effects listed above)

Inhalation * Oral NOAEL = 0.125 mg/kg (inhalation absorption rate = 100%)

Residential

MOE =100 1 2 combined human studies (a single oral dose and a single oral dose metabolism)

LOAEL = 0.25 mg/kg
(effects listed above)

UF = uncertainty factor, LOC = level of concern

1 UF of 100 (10x for intra-species variations and 10x data base uncertainty factor). The FQPA safety factor is subsumed by the 10X database uncertainty factor for both acute dietary assessments, and dermal and inhalationassessments involving non-occupational exposures. Since a human study was used for the POD, the 10X interspecies Uncertainty Factor is not needed. * Because of the reversibility of the CNS effects, exposure s of all durations can be regarded as repeating one-day exposures. Therefore, the single-dose human oral endp oint is appropriate for assessing exposures to amitraz regardless of exposure duration.

3.0 Dietary Exposure

An acute probabilistic dietary exposure anal ysis for amitraz was conducted in support of the TRED (D300300, J. Morales, 30-APR-2004). Dri nking water was not included in the dietary

assessment as it was determined that amitraz is not expected to enter water-bodies or drinking water through currently regist ered uses. This decision will be re-examined during the registration review process. In particular, the previous determ ination that cattle and swine are

seldom treated outdoors with amitraz needs to be confirmed and perhaps the implications of this situation need to be reconsidered with regard to large, modern feed lots and other animal operations. The Biological and Economic Anal ysis Division (BEAD) provided percent crop treated information for the requested import uses on cotton seed and for dermal livestock treatments. Based on the percent treated estimat e from BEAD together with magnitude of the residue studies depicting dermal treatments of cattle and swine, HED had calculated anticipated

residue levels for the relevant livestock commod ities to include in the acute dietary analysis.

HED had determined that the acute assessment would be protective of any chronic dietary exposures to amitraz; therefore, a separate chronic dietary exposure assessment was not

conducted. This initial assessm ent showed some population subgroups exceeding 100% of the aPAD based upon an acute toxicological endpoint taken from a dog study.

Subsequently, this risk assessment was re vised using an acute endpoint based upon a human study (D309794, D320083). In this study, the acute dietary exposures for all population5 of 26 subgroups were determined to be below HED’s level of concern of 100% aPAD (the highest exposed population subgroup is Children 1-2 years old at 28% of the aPAD). However, a recent update from BEAD (D367939, C. Douc oure, 10/27/09) indicates that the previous estimate of

0.1% for cattle and swine head treat ed should be increased to 0.3% fo r cattle and 1.2% for swine. These changes will need to be incorporated into a revised dietary exposure analysis during the registration review process, along with any other relevant changes identified.

The 2006 dietary exposure assessment showed that exposure was acceptable given that the percentage of animals trea ted was estimated by BEAD to be less than 0.1%, nationwide. A driver of that exposure for infa nts and children was milk. Amitraz is allowed to be applied to dairy animals with no required wi thdrawal interval after treatment. The resulting amitraz residues used to calculate exposure through th e meat and milk of cattle are measured experimentally in field trials for individual animals after dosin g with known amounts of amitraz. These values are then corrected by the estimated na tional value for percent head of cattle treated.

For milk, real field practices by which re sidues may be incurred differ from this

theoretical scenario in that milk is not collected from a single animal, but is mixed together from many animals in a region, so that the residues are directly diluted by the local percent head treated. On the other hand, when th ere is a tick infestation that n eeds to be controlled locally, it is expected that a larger proportion of the dair y herd in that region w ill be treated than is represented by the national average percent head treated estimate provided by BEAD. Furthermore, HED generally expects that most fresh milk is mostly regionally produced and consumed, so the local percent head treated is more germane to estimating exposure through

fresh milk than the natio nal percent head treated.

For the above reasons, the theo retical exposures calculated in the last dietary exposure assessment may not be representative of actual re sidues. As a public health practice, the control of ticks in cattle is coordinated by the Animal and Plant Health Inspec tion Service (APHIS) of USDA, and EPA intends to work with APHIS on the amitraz dietary assessment of milk.

4.0 Residue Chemistry

The qualitative nature of the residue in pl ants and animals is adequately understood based on plant metabolism studies with apples, be ans, lemons, citrus, cotton, and pears, and animal metabolism studies with cattle and swine (d ermal application) as well as cattle, goats and hens (oral dosing). Tolerances for residues of amitraz in/on plant and animal commodities are currently expressed in terms of the combined residues of amitraz (N'-[2,4-dimethylphenyl]-N- [[(2,4-dimethylphenyl)imino]met hyl]]-N-methylmethanimidamide) and its metabolites containing the 2,4-dimethylaniline moiety, both calculated as the parent compound [40 CFR 180.287].

The amitraz risk assessment in 2006 determin ed that the residue chemistry database was complete and that no additional studies are needed. Since the registrant requested cancellation of all U.S. registrations on crops us ed as foods/feeds, the only source of amitraz

residues in foods arise from dermal uses on liv estock, and from imported treated cotton seed.

There are two adequate methods listed in FDA' s Pesticide Analytical Manual (PAM Vol. II) for purposes of data collection and enforcement of tolerances for residues of amitraz and its6 of 26 metabolites containing the 2,4-dimethylaniline moiety. Methods I (designed for animal tissues and milk) and II (designed for plant commodities) are both GLC methods with electron capture detection (ECD), and involve conversion of re sidues of amitraz and its metabolites containing the 2,4-dimethylaniline moiety to 2,4-DMA using acid and base hydrolysis, respectively. The

FDA PESTDATA database dated 11 /01 (PAM Volume I, Appendix I) indicates that amitraz has small recovery (<50%) using Multi-residue Meth od Section 302 (Luke Met hod; Protocol D) and that metabolite BTS-27919 is comple tely recovered using Section 302. The detection limits of the methods are 0.01 ppm for milk and 0.05 ppm for plant commodities and animal tissues.

HED now recommends revision of the tolerance e xpression to clarify: 1) that, as provided in FFDCA section 408(a)(3), the tolerance covers metabolites and degradates of amitraz not specifically mentioned; and 2) that compliance with the specified tolerance levels is to be determined by measuring only the specific com pounds mentioned in the tolerance expression. This change is recommended for the tolerance expression for plant and livestock commodities, because it clarifies the existing language.

Accordingly, in order to ensure that the to lerance expression adequa tely addresses both coverage and measurement issues, HED recomm ends that paragraph (a) of 40 CFR 180.287 be

rewritten to read as follows: “Tolerances are established for residues of the insecticide amitraz (N'-[2,4-dimethylphenyl]-N-[[( 2,4-dimethylphenyl)imino]methyl]]-N-methylmethanimidamide), including its metabolites and de gradates, in or on the commod ities in the table below. Compliance with the tolerance levels specified below is to be determined by measuring only

those amitraz residues convertib le to 2,4-dimethylaniline, expr essed as the stoichiometric equivalent of amitraz, in or on the following raw agricultural commodities:”

Commodity Parts Per Million Cattle, fat 0.1 Cattle, meat 0.02 Cattle, meat byproducts 0.2 Cotton, undelinted seed 1.0 Hog, fat 0.1 Hog, kidney 0.1 Hog, liver 0.1 Hog, meat 0.05 Hog, meat byproducts 0.3

Milk 0.03 Milk, fat 0.2

5.0 Residential Exposure

Residential exposure to am itraz is anticipated for i ndividuals who apply amitrazcontaining products to co mpanion animals via pet collars and spot-on formulations. In addition, EPA anticipates residential exposu re to individuals from contact with previously treated pets. An assessment of the amitraz-impregnated pet collar residential use was asse ssed in the June 26, 2006 memorandum, “Amitraz Revised Human Hea lth Risk Assessment for the Tolerance Reassessment Eligibility Decision” and included as a part of the July, 2006 amitraz TRED.7 of 26 Residential handler (applicator) exposure from the pet collar us e was not assessed since it was assumed that residential post-application exposur e estimates were protective for adult handler exposure. Residential post-app lication exposure was assessed for a pet collar containing 3.8 g ai and 2.4 g ai. It was assumed th at while longer-term durations of exposure could potentially occur based upon the use pattern of pet collars (i .e., up to 90 days), that a short-term exposure duration of 1 to 30 days best represents a seri es of repeating one-day exposures based upon the reversibility of the CNS effects demonstrated in the toxicity da tabase. The short-term duration is, therefore, protective for al l exposure durations. Estimated post-application adult dermal exposure assessed for the maximum rate pet collar (3.8 g ai) was not of concern to the Agency (i.e., an MOE ≥ 100). However, toddler dermal and inci dental oral (hand-to-mouth) exposures were of concern to the Agency. Because indivi dual toddler routes of exposure were of concern, these routes of exposure were not combined. Furthermore, the 3.8 g ai pet collar was not accepted for registration. Estimated post-applicati on adult dermal exposure assessed at the lower rate collar (2.4 g ai) was not of concern to the Agency. Combined toddler dermal and incidental oral (hand-to-mouth) exposure for this lo wer rate collar result ed in a MOE of 97.

It is important to note that the amitraz collar assessment was based upon a carbaryl collar study, “ Transferable Residues from Dogs Treated with 16% Carbaryl Collar (MRID 457922-01),” which was later determined to lack appropriate quality assurance and quality control (QA/QC) procedures and adequate documentation for all da ta generated in the laboratory and in the field (S. Tadayon, D320047). Upon maki ng this determination, the Agency upheld the prior requirement for confirmatory data for the as sessment of the carbaryl pet collar use. In response to this finding the study, “ Determination of Dislodgeable Resi dues of Carbaryl from the Hair of Dogs Wearing Colla rs Impregnated with Carbaryl (MRID 477394-02),” was submitted to the Agency. This study was determined to be acceptable for use in quantifying estimated exposure for the carbaryl pet collar use. The mo st recent carbaryl pet collar study is the only one which the Agency has identified that has b een conducted for the determination of human exposure from pet collars. Since the study which was used in the prior assessment is no longer valid, a comparison was drawn between the prior study and the current, acceptable carbaryl pet collar study. The prior study (MRID 457922-01) de termined that 2.6% of the total active ingredient (ai), carbaryl, in the collar was anticipated to transfer from the animal to an exposed person on the highest day of exposure (day of application). In comparison, the current study (MRID 477394-02) results in 1.6% antic ipated transfer of the ai fr om the treated animal to the exposed individual on the highest day of exposur e. Based upon this comparison, the Agency is satisfied that the post-application exposure asse ssment conducted previously for the amitraz pet collar (2.4 g ai) would result in a higher MOE if updated using da ta from the new carbaryl pet collar study.

An assessment of the amitraz pet spot-on pr oducts was conducted in the July 25, 2007 memorandum, “Occupational and Residential Ex posure Assessment for Proposed Section 3 Registration of Amitraz on Domestic Pets.” HED de termined that exposure to pesticide handlers is likely during the resi dential use of the spot-on product on dogs. However, exposure/risk from amitraz application to domestic pets was not a ssessed because handler contact was expected to be negligible. The spot-on product is designed to be self-contained as it is applied directly from the tube to the pet with the tip of the applicatorused to part the pet’s hair. Residential postapplication exposure from contact with dogs trea ted with the spot-on pr oduct was assessed using data from, "Haircoat Distribu tion of R-28153 and Amitraz after a Single Topical Application to Dogs (MRID 468783-01)”.8 of 26 Adult dermal post-application risk was not of concern to the Agency (i.e., an MOE ≥ 100). Combined dermal and hand-to-mouth exposures of a toddler to a medium-sized dog (22 -55 lbs) treated with the spot-on product (a pplication rate, 500 mg ai / treatm ent) was also not of concern to the Agency.

Conclusions

No residential data gaps were identified duri ng the registration review scoping process.

A residential assessment to assess handler exposure should be conducte d based upon the revision

of HED’s Residential SOPs which was reviewed by the Scientific Advisory Panel (SAP) in October 2009. Under the revised pet treatment SOP, residential handling ofpet collars and spoton products are assessed. An upda ted residential assessment may also be required if new data are identified which impact exposure estimates, ne w points of departure or uncertainty factors are selected, or revisions to exposure policies and procedures are made.

6.0 Aggregate Risk Assessment

Summary of Amitraz Aggregate Risk Assessment from 2004 TRED

Acute Aggregate (food)

The acute aggregate assessment generally combines acute dietary exposures with drinking water. Because there was no expecta tion of drinking water e xposure, the acute food exposure alone was compared to the acute re ference dose (i.e., the acute aggregate risk assessment is identical to the acute food-only dietary assessment). Th e acute dietary risk

estimates are below HED’s level of concern fo r adults and for the most highly exposed subpopulation (28% of the aPAD for children 1-2 yrs).

Short-, Intermediate- and Long-term Aggregate (food plus residential)

In general, short-, intermediate-, and long- term aggregate assessments combine average (chronic) dietary exposures with conservative short-, intermed iate- and long-term residential exposures. However, in the case of amitraz, a chronic dietary assessment was not performed since the acute dietary assessmen t is protective of any chronic exposures. In the 2004 TRED, residential post-application exposures from dog colla r uses (the residentia l scenario resulting in the highest estimated exposures) were combined with acute (high-end) dietary exposures to calculate aggregate risks to cove r short-, intermediate - and long-term exposures. Based on this approach, the resulting aggregate risk estimates are considered to be protective, and may overestimate risk.

The short-, intermediate- and long-term aggreg ate risk assessment takes into account the dietary exposures to amitraz in food (no expos ure through drinking wate r) along with the postapplication dermal exposure for adults and derm al and incidental oral exposures for toddlers resulting from the handling of amitraz-treated pets. An aggregate MOE of 100 or greater does

not exceed HED’s level of concern.9 of 26 For adults, aggregating the acute dietary expos ures with post-application dermal exposure from the lower rate (2.4 g ai) dog collars results in aggregate MOEs of 150 for the US population and 160 for females 13-49 years old.

For children (1-2 yrs), the combined dermal a nd incidental oral exposures from the lower rate, 2.4g ai, collar resulted in a MOE of 97. Combining this exposure with acute dietary exposure results in an aggregate MOE of 76 ba sed on conservative or worst-case assumptions,

which exceeds HED’s level of concern. A disc ussion of this aggreg ate MOE calculation is

described below in more detail.

Aggregate Risk Summary

Generally aggregate risk assessments combin e average (chronic) dietary exposures with estimates of residential exposures. For amitr az, the chronic dietar y assessment was not performed because the acute diet ary assessment is protective of any chronic dietary exposures. Consequently, this aggregate assessment fo r amitraz combines acute dietary exposures (considered high-end) with residential exposur es. HED notes however, that average (chronic) dietary exposures would more accurately reflect actual dietary exposures occurring over an intermediate-term to long-term timeframe than one-day dietary exposures estimated from the acute dietary assessment. To incur high-end dietary exposure, a pers on must have high-end consumption of a food commodity with high-end resi dues of amitraz. Since it is likely that there are significant differences between one day c onsumption estimates and average consumption estimates for many commodities, and since there is considerable variability in pesticide residues in/on foods, it is unlikely that an individual receives high-end di etary exposures over a period of greater than one day. HED believes the combina tion of acute (one-day) dietary exposure with residential post-application exposures is conser vative and will be protective of exposure to amitraz regardless of route of exposure and durati on of exposure. Reside ntial post-application exposures based on standard exposure input values and a non-route-specific toxic endpoint to estimate dermal risks combined with high-end acute dietary exposures, while protective, may

result in an over-estimate of the a ggregate (residential plus food) risk

In the registration review process, the re sidential exposure esti mates from dog collars should be updated to conform to revisions in th e recently revised residential SOPs. Together with any appropriate modifications to the dietary exposure assessment, this may result in changes to the aggregate risk assessment results summarized above.

7.0 Occupational Exposure

Occupational exposure to amitraz is anticipated to occur base d on the use pattern of the chemical. Occupational handlers can be potentially exposed from applications of the companion animal products, pet collar and spot-on, in a prof essional animal care setting. Handler exposure is also likely from the treatment of livestock via spray-dip machine for feeder and dairy cattle and enclosed animal premise treatment via lo w-pressure handwand for swine. Occupational post-application exposure from cont act with animals treated with pe t collar, spot-on product, the spray-dip machine and enclosed animal premise tr eatments are either not expected to occur or are expected to be signifi cantly less than residential pos t-application exposures.10 of 26 An occupational exposure assessment of the am itraz-impregnated pet collar has not been previously performed. An occupational asse ssment of the amitraz spot-on product was considered as a part of the July 25, 2007 memorandum, “Occupa tional and Residential Exposure Assessment for Proposed Section 3 Registra tion of Amitraz on Domestic Pets.” HED determined there is a potential fo r short- and intermediate-term handler exposure in occupational settings during the application of products containing amitraz. Proposed domestic pet spot-on use of amitraz could be performed by professional animal care workers; however, exposure/risk from application to dogs was not assessed because ha ndler contact is expected to be negligible. Post-application activit ies with an animal treated with spot -on product are either not expected to occur or are expected to be signi ficantly less than residential post-ap plication exposure s. Even if the spot-on pet treatment is administered by a professional animal care worker, minimal

involvement with the animal is assumed to occur after such treatment occurs.

Occupational assessments of exposure from the treatment of cattle via the spray-dip machine and swine via low pressure handwand trea tment to enclosed animal premises have not been assessed by the Agency.

Conclusions

No occupational data gaps were identified dur ing the registration review scoping process. An occupational assessment of handler exposure from the application of the pet collar product

should be conducted. In additi on, an occupational handler asse ssment should also be conducted for application to cattle via the spray-dip machine and swine via low pressure hand wand treatment to enclosed animal premises should be conducted. The Agency does not anticipate post-application occupational exposure from liv estock or premise treatments. An updated occupational assessment may also be required if new data are identified which impact exposure estimates, new PODs or uncertainty factors are selected, or revisions to exposure policies and procedures are made.

8.0 Public Health and Pesticide Epidemiology Data

For IDS, five incidents were identified for amitr az occurring in the United States from 2002 to the present for the single chemical only. The evaluation of incident data for amitraz has determined that the symptoms appear generic a nd are not confirmed to be related to exposure,

there is no clear evidence of a trend or exposure pattern. Therefor e, at this time, there are no remarkable case reports which suggest a plausibl e association between a moderate or severe health outcome and exposure to the pesticide amit raz, nor can it be discer ned any suggestion of a trend or pattern regarding the health effects due to the alleged exposure to the pesticide amitraz.

For NIOSH SENSOR, ten reported cases were id entified that involved amitraz. Of these ten cases, those that involve only amitraz and wher e exposure was determined to be definite, probable or possible were reviewed in detail, as these cases pr ovide more certain information about the potential effect of am itraz exposure. These selection cr iteria resulted in the exclusion of two cases. Of the eight remaining cases, four were professional app licator exposure (three treating dogs with dip, fourth unknown), two were unintentional ingestion, one was nonoccupational exposure and one other was unknown e xposure. All exposures were of low to moderate severity, except one unintentional dose case that involve s a six year old male who was given flea dip mistakenly by his grandmother w ho thought it was cough medicine. This case was11 of 26 determined high severity. The health effects most often reported include: dermal (13%), respiratory (25%), ocular (25%), cardiovascular (25%), gastrointe stinal (50%), and neurological (75%). Symptoms are not mutually excl usive; a patient may have many symptoms.

The applicator symptoms (three dog-dip cases) were mostly neurological with nausea and vomiting. Two of these cases were not weari ng all the appropriate personal protective equipment (PPE), but were wearing gloves. Th e third case was wearing the appropriate PPE. The fourth case exhibited dermal sympto ms. Details about this case are unknown.

Based on the low to moderate severity and low numb er of incident cases, there does not appear

to be a risk concern at this time that would warrant further investigation. The Agency will

continue to monitor the incident information a nd if a concern is triggered, additional analysis

will be included in the risk assessment.

9.0 Tolerance Assessment and International Harmonization

A summary of US tolerances, Codex Maximu m Residue Limits (MRLs), Mexican MRLs, and Canadian MRLs for amitraz is provided in Attachment 1. Several MRLs for amitraz have been established by Codex in various commodities . The Codex MRL expression differs from the U.S. tolerance expression. The Codex expressi on is the sum of amitraz plus metabolite BTS27271, calculated as BTS-27271. The U.S. expression consists of amitraz residues convertible to 2,4-dimethylaniline expressed as the stoi chiometric equivalent of amitraz.

The enforcement methods for amitraz toleranc es in the U.S. (Methods I and II of PAM Vol. II) consist of hydrolysis of all metabolite s containing the 2,4-DMA moiety to 2,4-DMA and determination using gas chromatography with electron capture detection. The enforcement method under the Codex system involves treatment of the RAC with acidic methanol to convert the parent compound to metabolite BT S-27271, followed by extraction, cleanup, and determination of BTS-27271 using gas liquid chro matography with flame ionization detection. Presently, compatibility between the Codex MRL and U.S. tolerance cannot be achieved due to

the differences between the to lerance definitions and analytical enforcement methods.

The current U.S. tolerances and Codex MRLs are identical in magnitude for hog, meat and cattle, meat byproducts. Although the US and Codex levels are not identical for the other commodities, the values are similar in all cases. There are several Codex MRLs for which there

are no U.S. tolerances.

10.0 Environmental Justice

Potential areas of environmental justice concer ns, to the extent possi ble, were considered in this human health risk assessment, in acco rdance with U.S. Executive Order 12898, "Federal

Actions to Address Environmental Justice in Minority Populations and Low-Income Populations," http://www.epa.gov/compliance/resour ces/policies/ej/e xec_order_12898.pdf . The Office of Pesticide Programs (OPP) typically cons iders the highest potenti al exposures from the legal use of a pesticide when conducting human health risk assessments, including, but not limited to, people who obtain drinking water from s ources near agricultural areas, the variability of diets within the U.S. (including different ag es, regions, and ethniciti es), and people who may be exposed when harvesting crops. Should these highest exposures indicat e potential risks of12 of 26 concern, OPP further refines the risk assessments to ensure that the risk estimates are based on

the best available information.

The Agency acknowledges that milk is dist ributed in a relative ly localized area. Therefore, the Agency is looking into whether da iry animals in certain localities where use has been reported such as southern Texas and Puerto Rico are treated at a higher frequency than dairy animals in other parts of the country. During registration review, EPA is seeking information on high dairy treatment areas and milk distribution in order to determine if some sub-populations are disproportionately exposed to amitraz residues in milk.

11.0 Cumulative

FQPA requires that EPA consider “availabl e information” concerning the cumulative effects of a particular pesticid e’s residues and “other substances that have a common mechanism of toxicity.” The Agency considers other subs tances because low-level exposures to multiple

chemical substances that cause a common toxic effect by a common mechanism could lead to the same adverse health effect, as would a higher level of exposure to any of the substances individually. Risks summarized in this documen t are those that result only from the use of

amitraz

. The Food Quality Protection Act (FQPA) requi res that the Agency consider “available information” concerning the cumulative effects of a particular pesticide’s residues and “other

substances that have a common me chanism of toxicity.” Unlike other pesticides for which EPA has followed a cumulative risk approach base d on a common mechanism of toxicity, EPA has

not made a common mechanism of toxicity finding as to amitraz and any other substances. In addition, amitraz does not appear to produce a to xic metabolite produced by other substances which have tolerances in the U.S. Therefore, fo r the purposes of tolerance reassessment, EPA has

not assumed that amitraz shares a common mech anism of toxicity with other compounds.

12.0 Human Studies

Humans are the most sensitive species tested w ith clinical signs similar to those observed in animals, reported within 160 minutes afte r ingestion and persis ting up to 12 hours (i.e. sedation, dry mouth, disorien tation, bradycardia, hypert ension and hypothermia).

In a human double-blind randomized crossove r study of acute neurotoxicity (Cass, L (1992) T-344, Amitraz: Report of A Double Blin d Tolerance Study of Amitraz in Six Adult Healthy Volunteers: Lab Project. Number RD 197/20170. Unpublished study prepared by Simbec Research Ltd. MRID 43283101), 6 male voluntee rs were given sequential oral doses of amitraz by capsule, at 0.0625 or 0.125 mg/kg with a placebo control. There were at least 14 days between treatments. Vital signs (pulse, respira tion rate, blood pressure, and body temperature), urine samples and ECGs were taken. Pupil re sponsiveness and psychomotor performance were evaluated. Minimal and transient changes in blood pressure, temperature, ECG rate, and psychomotor performance were observed at 0.125 mg/kg.

In a human metabolism study (Campbell J (198 4). A Comparison of the Metabolism of (14c)-Amitraz in Rats, Mice, Babo on and Human. FBC Limited. MRID 00160964 ), 2 male volunteers given 0.250 mg/kg by oral route experienced sedation, disorientation, and hypothermia. Based on the combined results of th e human oral toxicity and metabolism studies,

the acute oral NOAEL and LOAEL for human s are 0.125 mg/kg and 0.25 mg/kg, respectively.13 of 26 The human metabolism study show ed neurotoxic effects shor tly after dosing, which disappeared within 12 hours. Although the me tabolism study was limited to 2 subjects, both exposed human subjects experienced clear CNS effects that were cons istent with the animal data. This endpoint from the human oral and metabo lism studies (CNS effects at 0.25 mg/kg; NOAEL of 0.125 mg/kg) is appropriate for assessing ac ute exposures to amitraz. Because of the reversibility of the CNS effects, exposures of all durations can be regarded as repeating one-day (acute) exposures. Therefore, the human oral e ndpoint is appropriate for assessing exposures to amitraz regardless of exposure duration.

Both these studies were review ed by the EPA Human Studies Review Board in April 2006, and determined to be scientifically accepta ble (when considered to gether) and useable to establish a point of departure for assessing acute dietary risk. The HS RB recommended against

other uses of the data.

As discussed in section 5.0, th e 2006 risk assessment for amitraz pet collars (2.4 g ai) relied upon the study, Transferable Residues from Dogs Tr eated with 16% Carbaryl Collar (MRID 45792201). EPA recently concluded that MRID 45792201 lacks appropriate quality assurance and quality control (QA/QC) procedures and adequa te documentation for all data generated in the laboratory and in the field. As a result, th e Agency is no longer relying on

MRID 45792201. In future risk assessments for th e amitraz pet collar uses, EPA will rely on a different carbaryl pet collar study, Determination of Dislodgeable Resi dues of Carbaryl from the Hair of Dogs Wearing Colla rs Impregnated with Carbaryl (MRID 47739402).

13.0 Data Requirements

Toxicology

The following are brief descriptions of the toxicology data require ments. The rationale for requiring each study is listed in Appendix 2. Ov erall, there are multiple data gaps, often due to study deficiencies, with some being th e result of new requirements for Part 158.

870.3100 90-Day Oral Toxicity in Rats This study may be combined with th e sub-chronic neurotoxicity study, 870.6200. The previous study had no individual anim al data for clinical signs and gross

necropsy.

870.3150 90-Day Oral Toxicity in Dogs The previous study had too few animals. Oral toxicity in a non-rodent animal is a fundamental data need for assessing the risk of a compound.

870.3200 21/28 Day Dermal Toxicity The previous study had too few animals, concurrent infections, lack of

information on the substance tested and limited histopathology was provided.

870.3250 90 Day Dermal Toxicity (Conditionally Required)

This data need is listed in the Revised Part 158.14 of 26 870.3465 90-Day/28-Day Inhalation Study This requirement is based on the potential inhalation exposure to workers from all registered spray application uses. Th e exposure time may be reduced from 90 days to 28 days pending exposure patterns , plateauing of effects and considering the overall toxicity potential of amitraz. The previous study had limited individual animal data, analytical exposure concentra tions were not measured, the purity of test material was not reported, and the study protocol/environmental conditions reporting were incomplete. HED cannot waive the inhalation study because

amitraz does not meet the criteria of low toxicity via the inhalation route, low vapor pressure and the sub-chronic toxicity database is incomplete.

870.3700 Pre-natal Developmental Toxicity (rabbits) This study is a new data requirement for Part 158

870.3800 Two-Generation Reproduction Study This study should be modified to include the following: Due to the concern for the lack of stability of the test material in the diet, treatme nt should be via oral gavage administration. Previous study had limited data provided, mating was not 1 male to 1 female, no data on reproductive organs provided, litter data only provided for a few time points, and histopathol ogy data were not provided.

870.6200 Neurotoxicity (Adult): Acute and 90-Day This study is a new data requirement for Part 158

870.6300 Developmental Neurotoxic ity (Conditionally Required) This study may be combined with the reproduction study, 870.3800. Amitraz has shown signs of CNS effects, thus DNT n eeds to be considered in the evaluation.

870.7800 Immunotoxicity An immunotoxicity study is required as a part of new data requirements in the 40 CFR Part 158 for conventional pesticid e registration. Because the immune system is highly complex, studies no t specifically conducted to assess immunotoxic endpoints are inadequate to characterize a pest icide’s potential immunotoxicity. While data from he matology, lymphoid organ weights, and histopathology in routine chronic or subc hronic toxicity studie s may offer useful information on potential immunotoxic effects, these endpoints alone are insufficient to predict immunotoxicity. In the absence of required studies, EPA may use a database uncertainty factor of up to 10X. Once all data have been received and reviewed, the Amitraz Regi stration Review Team recommends that the points of departure and uncertainty f actors used for risk assessment purposes be re-examined and a new risk assessment done, if necessary.

14.0 References

Report of the Food Quality Protection Act (FQP A) Tolerance Reassessment Progress and Risk Management Decision (TRED) for Amitraz, July 200615 of 26 Roberts, TR, Hutson, DH, “Metabolic Pathways of Agrochemicals”, The Royal Society of Chemistry Information Services (1999)

Amitraz. Revised Human Health Risk Assessment for the Tolerance Reassessment Eligibility Decision (based on discussions of the Hu man Studies Review Board), July 26, 2006

Young, FM, et al, “Effects of the insecticide amitraz, an alpha-ad renergic receptor agonist, on human luteinized granulosa cells” (2 005) Human Reproduction 20(11): 3018-3025

W. Britton. Occupational and Residential Exposure Assessment for Proposed Section 3 Registration of Amitraz on Domestic Pets. D341879. 07/25/2007

W. Britton. Revisions for “Amendment to “Am itraz: Revised Residential Exposure Assessment for the Reregistration Eligibility Deci sion (11/19/2004, D310631)”: (D318939).” D310229.

07/27/2006

Amitraz. Reregistration List A Case No. 0234/Ch emical ID No. 106201. Nature of the Residue in Pigs Following Dermal Application of 14 C-Amitraz. MRID No. 42969301. CBRS No. 12801.

DP Barcode No. D196559.

Campbell, J.K. and D. Needham. (l984) A comparison of the metabolism of 14 C-amitraz in rat, mouse, baboon and human. FBC Limited, Chesterf ord Park Research Station, Saffron Walden, Essex CB10 1XL, January 17, 1984. MRID 00160964. Unpublished

Campbell, J.K. and D. Needham. (l984) Urinary excretion of 14 C-amitraz by two male humans following a single oral dose of 0.25 mg/kg body weight. FBC Limited, Chesterford Park Research Station, Saffron Walden, Essex CB10 1XL, February 4, 1984. MRID 46249601. Unpublished

Amitraz Multi-species Metabolism St udy, Data Evaluation Record, TXR# : 0052737

April 4-6, 2006 EPA Human St udies Review Board Meeti ng Report, June 26, 2006 (EPAHSRB-06-01)

Updated Review of Amitraz Incident Reports , DP Barcode : D368729

Determination of Dislodgeable Re sidues of Carbaryl from the Hair of Dogs Wearing Collars Impregnated with Carbaryl (MRID 47739402)

Transferable Residues from Dogs Tr eated with 16% Carbaryl Collar (MRID 45792201)

Cass, L (1992) T-344, Amitraz: Report of A Doubl e Blind Tolerance Study of Amitraz in Six Adult Healthy Volunteers: Lab Project. Nu mber RD 197/20170. Unpublished study prepared by Simbec Research Ltd. MRID 43283101)16 of 26 15.0 Attachments

Attachment 1: Maximum Residue Limits (MRL) Table Table 2. Summary of Amitraz US and Interna tional Tolerances and Maximum Residue Limits

US Canada Mexico 2 Codex

Residue Definition:

40 CFR 180.287 Amitraz (N'-[2,4- dimethylphenyl]-N-[[(2,4- dimethylphenyl)imino]methyl]]- N-methylmethanimidamide) and its metabolites containing the 2,4- dimethylaniline moiety calculated as the parent N

, N

-bis(2,4- xylyliminomethyl)methylamine, including the metabolite N -(2,4- dimethylphenyl)- N '-methyl

formamidine amitraz Sum of amitrax and N-(2,4- dimethylphenyl)-N’- methylformamidine calculated as N-(2,4- dimethylphenyl)-N’- methylformamidine.

Commodity Tolerance (ppm) /Max imum Residue Limit (mg/kg) Commodity US Canada Mexico 2 Codex
Cattle, fat 0.1
Cattle, meat 0.02 0.05 3

Cattle, meat bypr oducts 0.2 0.2 (kidney; liver) 0.2 3

Cotton, undelinted seed 1 1.0 1 0.5 Hog, fat 0.1 Hog, kidney 0.1 0.2 0.2 (edible offal) 3

Hog, liver 0.1 0.2 0.2 (edible offal) 3

Hog, meat 0.05 0.05 3

Hog, meat byproducts 0.3 Milk 0.03 0.01 (*) 3

Milk, fat 0.2 Pear 0.5 (pome fruit)

Cherries 0.5

Cucumber 0.5 Oranges 0.5

Peach 0.5 Sheep meat 0.1 3

Tomato 0.5 Apples 0.5

1 There are no US registrations on cottonseed as of May 3, 2006.

2 Available information for Mexico is dated (2004). Mexico adopts US tolerances or Codex MRLs for export purposes.

3 The MRL accommodates external animal treatment.17 of 26 Attachment 2. Data Needs For AMITRAZ Technical

Guideline Number: 870.3100 Study Title: Repeated Dose 90-Day Oral Toxicity Study in Rats Rationale for Requiring the Data This study is a fundamental requirement in Revised Pa rt 158 toxicology. This study may be combined with the sub-chronic neurotoxicity study, 870.6200. The previous study had no individual animal data for clinical signs and gross necropsy-- the data are insu fficient at this point to develop and incorporate quantitative determinations of this toxicity potential into our assessment.

Practical Utility of the Data How did the Agency make its re-registr ation decision without this data? The Agency was able to make a decision by adding a da tabase uncertainty factor of 10X, in lieu of having a an acceptable toxicity study to conduct the human hea lth risk assessment. The Agency was able to select doses and endpoints for conducting a risk assessment from the available studies.

How will the data be used and how could the da ta impact the Agency’s future decision-making?

After review and evaluation of the oral toxicity stud y, EPA will use the data to determine whether the 10X database uncertainty factor continues to be appropriate, or if the data show that the 10X uncertainty factor

should be reduced or removed.

Guideline Number: 870.3150 Study Title: Repeated Dose 90-Day Oral Toxicity Study in Dogs Rationale for Requiring the Data Oral toxicity in a non-rodent animal is a fundament al requirement in Revised Part 158 toxicology for assessing the risk of a compound. The previous study had too few animals-- the data are insufficient at this point to develop and incorporate quan titative determinations of this toxi city potential into our assessment.

Practical Utility of the Data How did the Agency make its re-registr ation decision without this data? The Agency was able to make a decision by adding a da tabase uncertainty factor of 10X, in lieu of having a an acceptable toxicity study to conduct the human he alth risk assessment. The Ag ency was able to select doses and endpoints for conducting a risk assessment from the available studies.

How will the data be used and how could the da ta impact the Agency’s future decision-making?

After review and evaluation of the oral toxicity stud y in dogs, EPA will use the data to determine whether the 10X database uncertainty factor continues to be appropriate, or if the data show that the 10X uncertainty factor should be reduced or removed.18 of 26 Guideline Number: 870.3200 Study Title: 21/28-Day Dermal Toxicity Rationale for Requiring the Data The 21/28-day dermal toxicity study is a new data requirement under 40 CFR Part 158 as a part of the data requirements for registration of a pesticide for non-food use.

The dermal toxicity Test Guidelines (OPPTS.870.3200) is intended to evaluate the toxic effects associated with continuous or repeated exposures to a test substance for a period of 21/28-days.

The Agency needs a 21/28-day dermal toxicity st udy for non-food use pesticides because the dermal route will be the primary route of exposures for chem icals designated with this used pattern (i.e., nonfood). The Agency believes that this study is requi red because the longer term oral studies (i.e., chronic or carcinogenicity studies) which are required for food-use pesticides are usually not required for nonfood use pesticides. Practical Utility of the Data

How will the data be used?

A route specific (i.e., dermal) study will provide critic al scientific information needed to characterize potential hazard to the human population exposed to the pesticide by the dermal route. This study will provide a dose and a toxicological endpoint of concer n for quantification of risks for dermal exposures. This study would eliminate the uncertainties associated w ith the use of an oral study with a default (100% oral equivalent) dermal absorption factor. In many cases, toxicity observed via the dermal route will be different than toxicity observed via oral exposure, due to absorption and distribution of the toxic agent after exposure or differences in metabolism (i.e., systemic versus local). This means that the route-to-route extrapolation (i.e., use of an oral dose/endpoint) in risk assessment could result in under or over estimation of risks from the dermal

route.

How could the data impact the Agency’s future decision-making?

If the dermal toxicity study indicates that the test mate rial poses either a greater or lesser risk than that calculated using an oral dose, (as used in the inte rim decision), the risk assessment would be revised to reflect the magnitude of potential risk derived from the new data. Also, the requested data would allow the Agency to determine if the risks were over-est imated or under-estimated. If the risks were underestimated, additional risk mitigation measures could be required. If the risks were over-estimated, risk mitigation measures could be reduced.19 of 26 Guideline Number: 870.3250 Study Title: 90-Day Dermal Toxicity Rationale for Requiring the Data The sub-chronic (90-day) dermal toxicity study is a new data requirement under 40 CFR Part 158 as a part of the data requirements for registration of a pesticide for non-food use.

The dermal toxicity Test Guidelines (OPPTS.870.3250) is intended to evaluate the toxic effects associated with continuous or repeated exposures to a test substance for a period of 90-days.

The Agency needs a 90-day dermal toxicity study for non-food use pesticides because the dermal route will be the primary route of exposures for chemicals designated with this used pattern (i.e., non-food). The Agency believes that this study is required b ecause the longer term oral studies (i.e., chronic or carcinogenicity studies) which are required for food-u se pesticides are usually not required for non-food use pesticides. A 21/28 day dermal toxicity test is insufficient to identify potential hazards for non-food use pesticides because of the con cern for the longer duration exposure associated with this use pattern. For example, professional applicators may be subjected to repeated exposure during the 3 month period of peak summer infestation. For this type of increased exposure, professional applicators may not be adequately protected using data from a 21/28-day study. Practical Utility of the Data

How will the data be used?

A route specific (i.e., dermal) study will provide critic al scientific information needed to characterize potential hazard to the human population exposed to the pesticide by the dermal route. This study will provide a dose and a toxicological endpoint of concer n for quantification of risks for dermal exposures. This study would eliminate the uncertainties associated w ith the use of an oral study with a default (100% oral equivalent) dermal absorption factor.

In many cases, toxicity observed via the dermal route will be different than toxicity observed via oral exposure, due to absorption and distribution of the toxic agent after exposure or differences in metabolism (i.e., systemic versus local). This means that the route-to-route extrapolation (i.e., use of an oral dose/endpoint) in risk assessment could result in under or over estimation of risks from the dermal

route. How could the data impact the Agency’s future decision-making?

If the dermal toxicity study indicates that the test mate rial poses either a greater or lesser risk than that calculated using an oral dose, (as used in the inte rim decision), the risk assessment would be revised to reflect the magnitude of potential risk derived from the new data. Also, the requested data would allow the Agency to determine if the risks were over-est imated or under-estimated. If the risks were underestimated, additional risk mitigation measures could be required. If the risks were over-estimated, risk mitigation measures could be reduced.20 of 26 Guideline Number: 870.3465 Study Title: 90-Day/28-Day Inhalation Toxicity Rationale for Requiring the Data Instead of conducting the inhalation study for 90-days, the Agency only needs a 28-day inhalation study because only short- and intermediate-term (but not lo ng-term) exposure to workers is expected based on amitraz's use pattern. A longer-term i nhalation study is required in situa tions in which a specific concern exists for increased hazard related to exposure via th e inhalation route. The 28-day inhalation toxicity study evaluates the potential hazard of a pesticide chem ical following repeated inhalation exposures. This study is critical for pesticides with use patterns in which there is potential for repeated human exposures (e.g., professional applicators, green house use, etc. ). The study design simulates the route of human exposure (inhalation). In this study, animals are e xposed (nose/whole body) to aerosol concentrations of the test material for 6 hours/day, 5 days/week for 28 days. A detailed toxicological examination including the histopathology of the respiratory system is conduc ted. This route-specific study would provide data for hazard characterization, dose response assessmen t, and a dose and endpoint for assessing potential

risks via the inhalation route. Practical Utility of the Data

How will the data be used?

This study will identify hazard (i.e., provide a dose and endpoint) following repeated inhalation exposures. The results will be used in ri sk assessments as appropriate.

How could the data impact the Agency’s decision-making? A sub-chronic inhalation study provides critical scientif ic information needed to characterize potential hazard to the human respiratory system from pestic ide exposure. In the case of amitraz, there is no acceptable inhalation study available. A 28-day repeat ed exposure study that follows the Test Guidelines (870.3465) will characterize hazard and provide data for a more refined inhalation risk assessment. Exposure time may be reduced 28 days pending exposure patterns, plateauing of effects and considering the overall toxicity potential of amitraz. This require ment is pending resolution of inhalation exposure for existing and possible future uses.21 of 26 Guideline Number: 870.3700 Study Title: Pre-Natal Developmental Toxicities-- Rabbit Rationale for Requiring the Data The pre-natal developmental toxicity study in a seco nd species (non-rodents) is a new data requirement under 40 CFR Part 158 as a part of the data requireme nts for registration of a pesticide for food and nonfood uses. The pre-natal developmental toxicity Test Guid elines (OPPTS.870.3700) is designed to provide general information concerning the effects of exposure of the pregnant test animals (non-rodent) on the developing organism; this may include death, st ructural abnormalities, or altered growth and an

assessment of maternal effects..

The Agency needs this study in a second species (non-rodents, prefer ably in rabbits) for food and nonfood use pesticides because the Agen cy believes that testing in two species (rodents and non-rodents) provides a balance assessment, eliminates uncerta inty of assessing of risk only in sensitive (or insensitive) species, and would adeq uately characterize potential hazards to pregnant women and their

fetuses. Practical Utility of the Data

How will the data be used?

This study will provide critical scientific information needed to characterize potential hazard to pregnant women and their fetuses exposed to the pesticide by th e oral route. This study can provide a dose and a toxicological endpoint of concern for quantification of risks for the sensitive population (i.e. pregnant females).

How could the data impact the Agency’s future decision-making?

If the results of this study indicate the non-rodent sp ecies to be more sensitive than the rodents, and provides data that indicates that the test material poses either a greater or lesser risk than that currently used, the risk assessment would be revised to reflect the magnitude of potential risk derived from the new data. Also, the requested data would allow the Agency to determine if the risks were over-estimated or

under-estimated. If the risks were under-estimated , additional risk mitigation measures could be required. If the risks were over-estimated, risk mitigation measures could be reduced.22 of 26 Guideline Number: 870.3800 Study Title: Two Generation Reproduction and Fertility effects Rationale for Requiring the Data This guideline for two-generation reproduction testing is designed to provide general information concerning the effects of a test substance on the integrity and performance of the male and female reproductive systems, including gonadal function, the estrous cycle, mating behavior, conception, gestation, parturition, lactation, and weaning, and on the growth and development of the offspring. The study may also provide information about the eff ects of the test substance on neonatal morbidity, mortality, target organs in the offspring, and prelim inary data on prenatal a nd postnatal developmental toxicity and serve as a guide for subsequent test s. Additionally, since the study design includes in utero as well as postnatal exposure, this study provides the opportunity to examine the susceptibility of the

immature/neonatal animal.

The data requirements in 40 CFR Part 158 requires a two-generation reproductive toxicity study for all chemicals with food use. The study should be modified due to the c oncern for the lack of stability

of the test material in th e diet, treatment should be vi a oral gavage administration.
Practical Utility of the Data How did the Agency make its re-registr ation decision without this data? The Agency was able to make a decision by adding a database uncertainty factor of 10X, in lieu of having a reproductive toxicity study to conduct the hu man health risk assessment . The Agency was able to select doses and endpoints for conducting a risk assessment from the available studies.

How will the data be used and how could the da ta impact the Agency’s future decision-making?

After review and evaluation of th e reproductive toxicity study, EPA will use the data to determine whether the 10X database uncertainty factor continues to be appropriate, or if the data show that the 10X uncertainty factor should be reduced or removed.23 of 26 Guideline Number: 870.6200 Study Title : Neurotoxicity Battery (Acute and Sub-Chronic Studies) Rationale for Requiring the Data

This is a new data requirement under 40 CFR Part 158 as a part of the data requirements for registration of a pesticide (food and non-food uses). The Neurotoxicity Screening Batte ry (OPPTS 870.6200) is designed to evaluate the potential adverse effects on the nervous system from exposure to pes ticide chemicals. The Ag ency believes that the guideline studies are inadequate in their assessment of behavioral effects and do not use optimal methods to evaluate the potential toxicity to the nervous tissue structure and function. To detect and characterize these potential effects more fully, a battery of more sensitive testing is required. The objective of this neurotoxicity battery testing is to evaluate the inci dence and severity of the functional and/or behavioral effects, the level of motor activity, and the histopathology of the nervous system. The acute neurotoxicity study is required to detect possible effects resulting from a single exposure. The sub-chronic neurotoxicity study is intended to detect possible effects resulting from repeated or long-term exposures. Practical Utility of the Data

How will the data be used?

The acute and sub-chronic neurotoxicity studies pr ovide critical scientific information needed to characterize potential hazard to the human populatio n on the nervous system from pesticide exposure. These studies can provide data on a wide range of fu nctional tests for evaluating neurotoxicity including sensory effects, neuromuscular effects, learning and memory and histopathology of the nervous system For example, animal studies with organophosphorous chemicals have shown neurotoxicity to be the primary toxic endpoints (e.g., cholinesterase inhibition) of concern in rodents and non-rodents. These animal studies can be used to select endpoints a nd doses for use in risk asse ssment of all exposure scenarios and are considered a primary data source for reliable reference dose calculation. The Agency has established an oral reference dose (RfD) for assess ing dietary risks for a number of chemicals (e.g., organophoshates and carbamates) where neurotoxicity was the most sensitive endpoint of concern.

How could the data impact the Agency's future decision-making?

If the acute or sub-chronic neurotoxicity studies show that amitraz poses either a greater or a diminished risk than that given in the interim decision’s conclu sion, the risk assessment for amitraz may need to be revised to reflect the magnitude of potential risk derived from the new data.

If the Agency does not have this data, a 10X database uncertainty factor may be applied when conducting a risk assessment using the currently available studies.24 of 26 Guideline Number: 870.6300 Study Title: Developmental Neurotoxicity Study Rationale for Requiring the Data A developmental neurotoxicity (DNT) study is cond itionally required for all pesticide chemicals to determine if developing mammals are susceptible to the neurotoxic effects of the test material especially in relation to effects that may persist into adulthood. The trigger for requiring the study is a weight-ofevidence evaluation that considers the kinds of eviden ce available, how that evidence fits together in drawing conclusions, and significant issues/strengths/limit ations. Specific to the weight of evidence for requiring a DNT is that the pesticide causes treatment-re lated neurological effects in adult animal studies. The criteria that were developed for determining th e need for a DNT were developed through extensive peer review including the FIFRA Scientific Advisory Panel. This study may be combined with the reproduction study, 870.3800

Amitraz was found to produce sedation, disori entation and hypothermia following acute oral administration to humans. This study was selected as the basis for all the toxicology doses and endpoints

selected for amitraz. Because amitraz has been show n to cause treatment-related neurological effects in human studies, a DNT study is warranted.

Practical Utility of the Data for Developmental Neurotoxicity Study

How will the data be used? The 10X database uncertainty factor may be remove d upon submission of the DNT study, effectively reducing human health risk estimates by an order of ma gnitude. In addition, the point of departure for the risk assessment may change based on the results of the study.

How could the data impact the Agency’s future decision-making? The removal of the 10x database uncertainty factor , along with a possible change in the point of departure, may change the Agency’s dietary assessment by impacting the dietary risk cup. In addition, the occupational and residential risk assessments may be changed, depending on the results of the requested study.25 of 26 Guideline Number: 870.7800 Study Title : Immunotoxicity Rationale for Requiring the Data

This is a new data requirement under 40 CFR Part 158 as a part of the data requirements for registration of a pesticide (food and non-food uses).

The Immunotoxicity Test Guideline (OPPTS 870.7800) prescribes functional immunotoxicity testing and is designed to evaluate the potential of a repeated chemical exposure to produce adverse effects (i.e., suppression) on the immune system. Immunosuppression is a deficit in the ability of the immune system to respond to a challenge of bacterial or viral infections such as tuberculosis (TB), Severe Acquired Respiratory Syndrome (SARS), or neoplasia. Because the immune system is highly complex, studies assessing functional immunotoxic endpoints are helpful in fully characterizing a pesticide’s potential immunotoxicity. These data will be used in combin ation with data from hematology, lymphoid organ weights, and histopathology in routine chronic or subchronic toxicity studies to characterize potential

immunotoxic effects. Practical Utility of the Data

How will the data be used?

These animal studies can be used to select endpoints and doses for use in risk assessment of all exposure scenarios and are considered a primary data source fo r reliable reference dose calculation. For example,

animal studies have demonstrated that immunotoxi city in rodents is one of the more sensitive manifestations of TCDD (2,3,7,8-tetrachlorodibenzo- p-dioxin) among developmental, reproductive, and endocrinologic toxicities. Additionally, the EPA has established an oral reference dose (RfD) for tributyltin oxide (TBTO) based on observed immunotoxicity in animal studies (IRIS, 1997).

How could the data impact the Agency's future decision-making?

If the immunotoxicity study shows that the test material poses either a greater or a diminished risk than that given in the interim decision’s conclusion, the ri sk assessments for the test material may need to be revised to reflect the magnitude of potential risk derived from the new data.

If the Agency does not have this data, a 10X database uncertainty factor may be applied for conducting a

risk assessment from the available studies.

Attachment 3: IDS ReportPage 26 of 26IDS ReportChemical: Amitraz106201Human IncidentsIncident NumberIncidentDateProduct NameRegistrationNumberCityStateExposureType*Incident Description016369 001 01-Jan-05 TAKTIC E.C. 05438200003 TX HC A 2 year old Female ingested less thana 1/4 teaspoon of the product that wasprescribed to treat her dog. Shereported blueness and her eyes turnedpurple.018212 001 31-Dec-06 TAKTICEMULSIFIABLECONCENTRATE,12.5% SOLUTION05438200003 REDLANDS CA HC A 20 year old Male reported Nausea,Vomiting, and Diarrhea after using theproduct.019496 001 26-Mar-08 TAKTIC E.C. 05438200003 BROOKLET GA HC Unknown Adult (18-64 years old)Female's friend used the product totreat a dog on 3 consecutive Saturdays.The friend did not wear gloves andreported Nausea, Dizziness, TunnelVision, Numbness, Sweating, andChest Tightness.020351 001 02-Nov-08 TAKTICEMULSIFIABLECONCENTRATE,12.5% SOLUTION05438200003 IN HB A 49 year old Male reported Lethargy,Blurred Vision, Numbness, and aSeizure two days following exposure tothe product. He was treated by aphysician.020463 004 23-Mar-08 PREVENTICPREVENTION PACK2 COLLARS00238200104 PA HC Unknown Adult (18-64 years old)Female applied the product to thefamily dog. She reported DermalIrritation and Rash on her face. Shewas evaluated by a physician anddiagnosed with a hypersensitivityreaction.