DocketNumber EPA-HQ-OPP-2007-1140 

### www.regulations.gov



# Silica Gel and Silicon Dioxide Proposed Interim Registration Review Decision Case Number 4081
June 2015

Approved by:

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# e**Y~r-: --i** **t_A _/** 

# 0-) Richard P. Keigwin, Jr. Director Pesticide Re-evaluation Division
Date: 

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### Table ofContents 

### Contents I
. Introduction
............................................................................................................................. 3 II. Use and Usage
......................................................................................................................... 4 Ill . 

### Scientific Assessments
............................................................ ...... .............. ...... ............ .... ...... 5 A. Human Health Assessment
.......... ...................... ... ................................................................. 5 Hazard Characterization and Dietary Risk
................ .. .......... ................ ......................... ........ 5 Residential and Occupational Exposure
................................................................................. 5 Aggregate Exposure and Risks
............................................................................................... 5 Food Tolerances
...................................................................................................................... 5 Hu1nan Incidents
..................................................................................................................... 5 B
. Environ1nental Assessment
................................................................................................... 6 Environmental Fate and Exposure
.......................................................................................... 6 Ecological Risk Conclusions
.............. ...... .................................................. ... ......................... 7 Endangered Species Assessment
............................................................................................ 7 Ecological Incidents
.................................................................. ....... ............... ... ..................... 9 C. Endocrine Disruptor Screening Program
........................ .... .............. ........ ............................ I0 IV. Proposed Interim Registration Review Decision
............................................................... I0 A. Pollinator Studies and Assessment
.................................................................... ....... ........... 11 

### V. Next Steps and Timeline
........................ .. .......................................................................... 12

2

### I. Introduction This document is the Environmental Protection EPA's (EPA or the EPA) 

### Proposed Interim Registration Review Decision for 

### silica gel andsilicon dioxide (silicates, silica silicates ordiatomaceous earth (DE)) and is being issued pursuant to 40 CFR sections 155.56 and 155.58. A registration review decision is the EPA's determination whether a pesticide meets, or does not meet, the standard for registration in the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). The EPA may issue, when it determines it to be appropriate, a proposed interim registration review decision before completing a registration review. Among other things, the proposed interim registration review decision may require new risk mitigation measures, impose interim risk mitigation measures, identify data or information required to complete the review, and include schedules for submitting the required data, conducting the new risk assessment and completing the registration review
. Further information on silica gel and silicon dioxide, can be found in EPA 's public docket (EPA-HQ-OPP-2007-1140) at www.regulations.gov. FIFRA, as amended by the Food Quality Protection Act (FQPA) of 1996, mandated the continuous review ofexisting pesticides. All pesticides distributed or sold in the United States generally must be registered by the EPA based on scientific data showing that they will not cause unreasonable risks to human health or to the environment when used as directed on product labeling. The registration review program is intended to make sure that, as the ability to assess and reduce risk evolves and as policies and practices change, all registered pesticides continue to meet the statutory standard ofno unreasonable adverse effects. Changes in science, public policy, and pesticide use practices will occur over time. Through the registration review program, the EPA periodically reevaluates pesticides to make sure that as these changes occur, products in the marketplace can continue to be used safely
. Information on this program is provided as www.epa.gov/oppsrrdI/registration review/. The Reregistration Eligibility Decision document (RED) for silica gel and silicon dioxide was completed in September 1991. In 2008, EPA initiated the registration review ofsilica gel and silicon dioxide with the opening ofthe silica gel and silicon dioxide registration review public docket (docket number EPA-HQ-OPP-2007-1140, accessible at www.regulations.gov.) Silica gel and silicon dioxide are formulated as dust or wettable powders (and sometimes combined with pyrethrins and piperonyl butoxide (PBO)) and have both indoor and outdoor uses in both commercial (e.g. , rights ofways, nursery greenhouses and industrial sites) and residential settings (e.g. , landscape maintenance, lawn and structural pest control)
. Pursuant to 40CFR§155.50, the EPA initiated registration review for case no. 4081 which includes silica gel (PC code no. 072602) and silicon dioxide (PC code no. 072604). The following timeline highlights significant events that have occurred during the registration review ofsilica gel and silicon dioxide:

• March 26, 2008

- The EPA published the 

### Silica andSilicates Summary Document, dated March 14, 2008 in docket number EPA-HQ-OPP-2007-1140 for a 60-day public comment period
. The 

### Summary Document included the EPA's 

### Preliminary Work Plan for Silica andSilicates, the 

### Problem Formulation.for Ecological RiskAssessment.for

3

### Silicon Dioxide andSilica Gel , dated November 16, 2007 and the 

### HED Registration Review ScopingDocument, dated November 16, 2007
.
• August 05, 2008

- The EPA published the 

### Silica andSilicates Final Work Plan. The EPA indicated that it would conduct a comprehensive ecological risk assessment that included an endangered species risk assessment, and that EPA would not conduct a human health risk assessment for the silica gel and silicon dioxide registration review.

• December I0, 2009

- Generic Data Call-In (GDCl-072602-847) for silica gel and silicon dioxide was issued. Data required by the EPA included: o GLN 830
.7050: UV/Visible absorption o GLN 850.2100: Avian acute oral toxicity test
• March 07, 2013

- The EPA published the 

### Environmental Fate andEcological Risk Assessment for the Registration Review of Silica, dated January 16, 2013 for a 60-day public comment period, during which time, no comments were received
.
• June 24, 2015

- The EPA is now publishing the 

### Silica andSilicates ProposedInterim Registration Review Decision, in docket number EPA-HQ-OPP-2007-1140, for a 60-day public comment period
. Additional information on silica gel and silicon dioxide can be found in the public docket, EPA-HQ-OPP-2007-1140, which can be accessed at www.regulations
.gov. 

### II. Use and Usage Silica gel and silicon dioxide are both derived from DE deposits which are commonly found in most soils. Silicon dioxide is DE, a naturally-occurring material composed ofthe shells of minute, single-celled algae
. Unlike silicon dioxide, silica gel has no registered outdoor uses. Silica gel is characterized as the amorphous form ofsilicon dioxide, which is made by the gelation ofsodium silicate and sulfuric acid. Because silica gel has no outdoor uses, the EPA considered environmental exposure solely from silicon dioxide when conducting its environmental fate and effects assessment. What little use data on silica gel and silicon dioxide is available indicates that less than 50,000 pounds is used annually
.

4

### III. Scientific Assessments A. Human Health Assessment 

### A summary ofthe EPA's human health analysis is presented below. For detailed information on EPA's human health assessment for silica gel and silicon dioxide, see the 

### Silica andSilicates Registration Review Summary Document, dated March 14, 2008, available in the public docket found at EPA-HQ-OPP-2007-1140-0005, which can be accessed at http://www.regulations.gov/
. Hazard Characterization and Dietary Risk 

### No toxicological endpoints were identified in the silica gel and sili con dioxide hazard database due to its low toxicity
. The EPA believes that exposure to silica gel and silicon dioxide from direct or indirect application to food commodities, or from residues in food handling and food preparation areas, would not result in risks ofconcern. The Food and Drug Administration (FDA) has classified silicon dioxide and silica gel as Generally Recognized as Safe (GRAS) food additives (21 CFR 182.90 and 182.1711). In addition, silicon dioxide has been exempted from the requirement ofa tolerance when applied to growing crops and raw agricultural commodities after harvest and to animals (40 CFR 180.1017 (a) and (b); and in food and feed processing and storage areas (40 CFR 185
. 1700 and 186.1700)
. Based upon these considerations, EPA determined that a quantitative human health risk assessment was not needed for silica gel and silicon dioxide, and therefore a dietary (food + drinking water) assessment was not conducted. Residential and Occupational Exposure 

### Silica gel and silicon dioxide are registered for homeowner uses (including crack and crevice treatment, pets, and etc.); therefore there is the potential for applicator and postapplication residential exposures to occur. However, based on the low toxicity ofsilica gel and silicon dioxide, the EPA has determined that residential exposures to these compounds would not be ofconcern, and, consequently, neither a residential handler nor a residential post-application assessment are needed
. While silica gel and silicon dioxide labels require the use ofa respirator to protect against irritating particles, the EPA has not identified any toxicological endpoints appropriate for a quantitative occupational assessment. Therefore, the EPA believes that neither occupational handler nor occupational post-application exposures would be ofconcern, and concluded that an occupational assessment is not needed. Aggregate Exposure and Risks 

### Due to the EPA's determination not to conduct either a dietary (food and drinking water) or residential risk assessment for the silicates, an aggregate risk assessment was not needed
.

5

### Food Tolerances Silica gel and silicon dioxide have been exempted from the requirement ofa tolerance when applied to growing crops and raw agricultural commodities after harvest (40 CFR 180.100I (c) and (d), to growing crops, raw agricultural commodities after harvest and animals (40 CFR 180.1017); and in food and feed processing and storage areas (40 CFR 185.1700 and 186.1700). 

### Human Incidents Based on a search conducted on June 2, 2015, the Agency's Incident Data System (IDS) has approximately 280 reported incidents associated with silica gel and silicon dioxide (between January I, 20 I0 to June 2, 2015)
. Ofthe reports identified in IDS database, 11 cases involved either silica gel or silicon dioxide (I0 ofmoderate severity, and I ofmajor severity). The one major severity case involved an 18-year old female who started experiencing migraines and seizures about a week after her mother treated their home (floorboards and baseboards)
. On June 2, 2015, the Agency also consulted the Centers for Disease Control and Prevention/National Institute for Occupational Safety and Health (CDC/NIOSH) Sentinel Event Notification System for Occupational Risk (SENSOR) database, and identified 138 cases from 1998 to 2011 involving silica gel and silicon dioxide. Ofthe reports identified in the SENSOR database, 9 cases involved a single active ingredient, either silica gel or silicon dioxide (all cases were oflow severity)
. Also, all 9 cases were worker related, 5 ofwhich were related to a single work event where silica dust was applied, and subsequently vacuumed in an office area while employees were present. B. 

### Environmental Assessment A summary ofthe EPA' s environmental assessment for silica gel and silicon dioxide is presented below
. For detailed discussions ofall aspects ofthe environmental risk assessment, see the 

### Environmental Fate andEcological Effects RiskAssessment for the Registration Review of Silica, (dated January 16, 2013), available in the public docket EPA-HQ-OPP-2007-1140 which can be accessed on http://www.regulations.gov/
. 

### Environmental Fate and Exposure While silica gel and silicon dioxide are registered for use on a variety ofagricultural crops, turf, industrial sites and homeowner uses, it is rarely applied as a broadcast, but more as a spot treatment. Therefore, movement ofsilica gel and silicon dioxide away from the treatment site via wind or rain is expected to be limited. Further, the U.S. Geological Survey (1984) reports that both silica gel and silicon dioxide are components ofU
.S. soils at approximately 2

- 31 %. While silica gel and silicon dioxide can potentially be transported to aquatic environments, exposure to aquatic organisms is not considered to be a concern since the mode ofaction ofthe ofthese compounds is negated when wet (i
.e., upon becoming wet, silica gel and silicon dioxide will clump, and thereby lose the ability to cut and desiccate target organisms)
.


### 6

### Ecological Risk Conclusions I. Terrestrial Species Based upon the low toxicity ofsilica gel and silicon dioxide, its ubiquitous presence in the environment, and its limited use as a pesticide, the EPA determined that a quantitative ecological assessment was not required for registration review. Based on available data, terrestrial vertebrates (including birds and mammals) are unlikely to be harmed from either dietary or dermal exposure to these compounds. Further, because ofthe ubiquitous nature ofthe silica gel and silicon dioxide, terrestrial invertebrates living on and in the soil are likely to have adapted to the these compounds
. However, EPA does expect that terrestrial invertebrates that do not live in or on the soil, (e
.g. , flying or leaf-dwelling insects), may be adversely affected by silica gel and silicon dioxide due to its insecticidal properties (i.e. to cut and dessicate). 2. Aquatic Organisms As noted above, because the mode ofaction is negated when silica gel and silicon dioxide become wet, the EPA does not anticipate that these compounds will adversely affect aquatic organisms (fish or invertebrates)
. 3. Plants Because terrestrial plants are likely to be routinely exposed to silica as wind-borne particles, and because both terrestrial and aquatic plants produce a form ofsilica (biogenic amorphous silica), adverse effects to plants (either terrestrial or aquatic) are not anticipated from exposure to silica gel or silicon dioxide. Endangered Species Assessment The ecological risk assessment supporting the EPA 's registration review decision for silica gel and silicon dioxide contains a completed Endangered Species Act (ESA) analysis, including effects determinations for endangered and threatened (listed) species and their designated critical habitat, and incorporates concurrence from the U.S. Fish and Wildlife Service (FWS) on EPA's "Not Likely to Adversely Affect (NLAA)" determination, based on informal consultation
. While EPA did not conduct a quantitative analysis ofsilica gel and silicon dioxide for either listed or non-listed species as part ofits ecological assessment, EPA made a "No Effect" determination for all listed species, with the exception of57 listed terrestrial invertebrate species for which an NLAA finding was determined. The EPA reached this conclusion based upon the following rationale: I
. Silica gel and silicon dioxide have a mechanical rather than a toxic mode of action; therefore, the potential for adverse effect is limited in time and space


### 7to the treated area, not off-site, and to a short interval after applications, since weathering renders silica gel and silicon dioxide inefficacious
. Although the time to effective weathering is not quantified, it is expected to be no longer than to the next rainfall. 2. Silica gel and silicon dioxide are naturally occurring substances, wide-spread in many soils at low concentrations. Thus, listed species are expected to be exposed to these compounds and are presumably adapted to low exposure concentrations. 3. It is uncertain whether listed terrestrial invertebrate species would visit treated areas, or remain on these areas during the time ofapplication, due to the attendant human disturbance. 4. Silica gel and silicon dioxide are used in organic agriculture and by homeowners seeking less-toxic alternatives to conventional pesticides. To the degree that silica gel and silicon dioxide are used in place ofconventional insecticides, EPA believes that the silicates are a much safer alternative in terms ofany potential impacts to listed terrestrial invertebrates
. On February I0, 2014, pursuant to section 7 ofthe ESA, EPA requested informal consultation with the FWS on silica gel and silicon dioxide, and concurrence with the NLAA determination for 57 listed terrestrial invertebrate species. On April 2, 2014, FWS issued a letter to EPA indicating its concurrence with the EPA's NLAA determinations for silica gel and silicon dioxide on 57 listed terrestrial invertebrates (see Appendix). In an email that preceded the April 2, 20I 4 letter, the FWS noted that one species, the Ash Meadows naucorid (Ambrysus amargosus) should be included among the listed species identified, and that there is "No Effect" to this species from silica gel and silicon dioxide (personal communication, email from Patrice Ashfield to Anita Pease, March 31, 2014). Subsequent to the issuance ofFWS's concurrence letter, the FWS Oregon Field Office highlighted potential concerns for specific silica gel and silicon dioxide use sites (i.e., pastures, vineyards) for two listed species ofbutterfly, namely the Fender's Blue butterfly (lcaricia icarioidesfenderi) and the Taylor's Checkerspot butterfly (Euphydryas editha taylori). This concern resulted in further work between EPA and FWS to ensure no adverse effects to these two species ofbutterfly was likely from exposure to silica gel and silicon dioxide use in pastures and vineyards. EPA provided additional information to the FWS regarding existing state-level pollinator protection requirements for silica gel and silicon dioxide, which are triggered by a state decision to register these compounds for a new use (via a section 18 or 24c label), and similar guidance available through other extension services. EPA also provided FWS with additional data showing low toxicity ofsilica gel and silicon dioxide to bees (used as a surrogate for butterflies) at rates exceeding current application levels. Based on this additional information provided by EPA, the FWS reaffirmed their concurrence with EPA's NLAA determination for the Fender's Blue and Taylor's Checkerspot butterflies (see Appendix for letter from C.Aubrey ofU.S. FWS to A.Pease ofU.S. EPA dated March 9, 20 15)
.



### 8EPA does not anticipate conducting any further analysis ofsilica gel and silicon dioxide for potential risks to listed species and/or designated critical habitat unless additional data or information are obtained that would otherwise inform this determination
. 

### Ecological Incidents On May 16, 2012, EPA searched its ecological incident databases, including the Ecological Incident Information System (EIIS), the Avian Incident Monitoring System (AIMS), and the Aggregate Incident Reports database. In the EllS , one ecological incident was identified that occurred in Texas in 1994 and involved six fish with possible exposure to silica gel. The incident was reported as an " intentional misuse" and considered "possibly" caused by silica gel, since there are no outdoor uses ofsilica gel. Furthermore, the product associated with the incident contained a pyrethroid and PBO. No ecological incidents were reported through the AIMS or the Aggregate Incident Reports database
.
C. 

### Endocrine Disruptor Screening Program As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse outcomes from exposure to chemicals
. Collectively, these studies include acute, subchronic and chronic toxicity, including assessments ofcarcinogenicity, neurotoxicity, developmental, reproductive, and general or systemic toxicity
. These studies include endpoints which may be susceptible to endocrine influence, including effects on endocrine target organ histopathology, organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and chronic studies that assess growth, developmental and reproductive effects in different taxonomic groups. As part ofits most recent registration decision for silica gel and silicon dioxide, EPA reviewed these data and selected the most sensitive endpoints for relevant risk assessment scenarios from the existing hazard database. However, as required by FFDCA section 408(p), silica gel and silicon dioxide are subject to the endocrine screening part ofthe Endocrine Disruptor Screening Program (EDSP)
. EPA has developed the EDSP to determine whether certain substances (including pesticide active and other ingredients) may have an effect in humans or wildlife similar to an effect produced by a "naturally occurring estrogen, or other such endocrine effects as the Administrator may designate. " The EDSP employs a two-tiered approach to making the statutorily required determinations. Tier I consists ofa battery of 11 screening assays to identify the potential ofa chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal systems. Chemicals that go through Tier I screening and are found to have the potential to interact with E, A, or T hormonal systems will proceed to the next stage ofthe EDSP where EPA will determine which, ifany, ofthe Tier 2 tests are necessary based on the available data
. Tier 2 testing is designed to identify any adverse endocrine-related effects caused by the substance, and establish a dose-response relationship between the dose and the E, A, or T effect. Under FFDCA section 408(p), the EPA must screen all pesticide chemicals. Between October 2009 and February 20I0, EPA issued test orders/data call-ins for the first group of67
9chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list of chemicals identified for EDSP screening was published on June 14, 2013 1 and includes some pesticides scheduled for Registration Review and chemicals found in water. For further information on the status ofthe EDSP, the policies and procedures, the lists ofchemicals, future lists, the test guidelines and the Tier I screening battery, please visit our website. 2 In the interim, EPA is making no human health or environmental safety findings associated with the EDSP screening ofthe silica silicates (silica gel and silicon dioxide). Before completing this Registration Review, the Agency will make an EDSP FFDCA section 408(p) determination
. 

### IV. Proposed Interim Registration Review Decision EPA has completed qualitative human health and ecological risk assessments, including an endangered species assessment for silica gel and silica dioxide. The EPA has also updated its silica gel and silicon dioxide data base by receiving the following data required under the registration review GDCI (GDCl-072602-847).

• GLN 830.7050: UV/Visible absorption • GLN 850.2100: Avian acute oral toxicity The EPA has determined that no human health risks are expected from the use of pesticide products that contain silica gel and silicon dioxide
. The EPA has also determined that potential ecological effects from the use ofpesticide products that contain silica gel and silicon dioxide would only be expected for terrestrial invertebrates that do not live in or on the soil, (e.g. flying or leaf-dwelling insects). The EPA believes that potential effects to these species would be limited in time, since the effects ofsilica gel and silicon dioxide only last until a rainfall event occurs (when the rain would cause the compounds to clump and lose its mode ofaction)
. In addition, EPA believes the potential effects to terrestrial invertebrates would also not be geographically widespread since silica gel and silicon dioxide are typically applied as a spot treatment. In accordance with 40 CFR Sections 155 .56 and 155.58, the EPA is issuing this Proposed Interim Registration Review Decision
. Pending the outcomes ofEDSP analysis for silica gel and silicon dioxide, the EPA has made the following Proposed Interim Decision:

• No changes are proposed to silica gel and silicon dioxide registrations or their labeling; • EPA has made a "No Effect" determination under the Endangered Species Act (ESA) for all listed species, excluding 57 listed terrestrial invertebrate species, for which a NLAA determination was made, and no modification ofdesignated critical habitat for such species. In letters dated April 2, 2014, and March 8, 2015, the FWS indicated its concurrence with the EPA's conclusion that silica gel and silicon dioxide are NLAA the 57 listed terrestrial invertebrate species.

1 See http://www.regulations.gov/# !documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of chemicals. 2 http://www.epa.gov/endo/ 10

### V. Next Steps and Timeline A. Interim Registration Review Decision A Federal Register Notice will announce the availability ofthis Proposed Interim Registration Review Decision for silica gel and silicon dioxide and allow a 60-day comment period. lfthere are no significant comments or additional information submitted to the docket during the comment period that leads the EPA to change its proposed decision, EPA may issue an Interim Registration Review Decision for silica gel and silicon dioxide (case 4081 ). However, a final decision for silica gel and silicon dioxide may be issued without having previously issued an interim decision. A final decision on the silica gel and silicon dioxide registration review case will occur after an EDSP FFDCA section 408(p) determination has been completed.

11

### Appendix FWS Correspondence for Informal Endangered Species Consultation on Silica Gel and Silocon Dioxide

12

## United States Department ofthe Interior FISH AND WILDLIFE SERVICE Washington, D
.C. 20240


### In Reply Refer To: FWS/ AES/DER/BCW05706l 09£30000-2014-1-0001 Ms. Anita Pease Associate Director U.S. Environmental Protection Agency Office ofPesticide Programs Environmental Fate and Effects Division 1200 Pennsylvania Ave., NW Washington, D
.C
. 20460 f.O D

- 2 2014

Subject: Informal Consultation on the Proposed Registration ofSilicon Dioxide and Silica Gel Dear Ms. Pease: This letter is in response to your February 10, 2014, email requesting the U
.S
. Fish and Wildlife Service's (Service) concurrence that the proposed registration ofsilicon dioxide and silica gel (Case No
. 4081) is not likely to adversely affect any listed species or critical habitat pursuant to section 7 ofthe Endangered Species Act of 1973 (16 U.S
.C
. 1531 

### -1544), as amended (ESA). This consultation is based on the provided Environmental Fate and Ecological Risk Assessment for the Registration ofSilicon Dioxide and Silica Gel. TheEPA is currently 

### in the final stages ofRegistration Review for the active ingredients ofsilica gel and silicon dioxide. Silica gel was first registered for use in 1956 and silicon dioxide in 1960. Through Registration Review, EPA determines whether a pesticide continues to meet the Federal Insecticide, Fungicide and Rodenticide Act standard for registration
. Silica gel is only registered for indoor uses, and therefore is not discussed further in this document. The EPA focused their risk assessment on silicon dioxide, in the form ofdiatomaceous earth (DE), which is currently registered for outdoor uses. Silicon dioxide is a biogenic form ofsilica, generally derived from DE deposits
. The insecticidal mode ofaction is physical (desiccation) rather than toxicological. When used as an insecticide, DE kills insects by abrading and absorbing oils from the insect's exoskeleton, leading to the dehydration and death ofthe insect. DE must be applied in pure form in sufficient concentration to be effective.Ms. Anita Pease According to EPA's risk assessment, there are at least 24 products with outdoor uses containing DE as the active ingredient. These products are formulated as dusts or wettable powders and can be applied using hand or electric puffer dusters or liquid spray equipment
. There is one DE product that may be applied by fixed winged aircraft on "unspecified field crops," but the application rate is limited to 0.625 lbs/acre and is thought to be a pesticide carrier rather than an efficacious component at that application rate (Konmic, 1998). The highest broadcast rate identified on the product labels is 83 lbs active ingredient/acre, though higher per acre rates are permissible for highly localized uses (e.g., crack and crevice)
. Use sites identified on product labels include agricultural crops (vegetables, fruits, grains, cotton, spices, tree nuts, tea), pastures, agricultural buildings and equipment, airports/landing fields, commercial animal kennels and sleeping quarters, commercial/institutional/industrial premises and equipment, golfcourse turf, household/domestic dwellings outdoorpremises, ornamentals (ground cover, herbaceous plants, non-flowering plants, woody shrubs, and vines), shade trees, residential lawns and gardens, and refuse/solid waste containers. Although labeled for a wide variety ofuse sites, DE-based insecticides are most frequently applied to pests in homes and gardens, and in the protection ofagricultural stored products (indoor use) (USEPA 2014). Some products are formulated in combination with other active ingredients [e.g., pyrethrins and piperonyl butoxide (PBO)] and are applied either as a wettable powder or as a dust when plants are wet. Pyrethrins are botanical insecticides derived from chrysanthemum flowers most commonly found in Australia and Africa. They work by altering nerve function, which causes paralysis in target insect pests, eventually resulting in death (EPA 2014). PBO acts as a synergist. Synergists are chemicals that primarily enhance the pesticidal properties ofother active ingredients, such as pyrethrins and synthetic pyrethroids (EPA 2006). Although products containing these other active ingredients were not analyzed in EPA's risk assessment, EPA concluded that any synergistic effects with pyrethrins and/or PBO are not expected due to the inert nature of 

### OE. In 1991, EPA completed a Reregistration Eligibility Decision on Silicon Dioxide and Silica Gel (EPA 1991). This assessment was used as the basis for EPA's cWTent risk assessment. At the time, it was concluded that silicon dioxide and silica gel do not pose wrreasonable risks to the environment, including non-target organisms, at labeled use rates because they are chemically unreactive in the environment, occur naturally in various forms and are practically non-toxic to non-target organisms. Silicon dioxide is ubiquitous in the natural environment and a major component ofmost soils. Most ofthe silica in soils is 

### in the crystalline form, which does not have insecticidal properties. However, most soils contain 2-3 percent amorphous silica, which does have insecticidal properties. The efficacy ofDE, an amorphous form ofsilica, is limited in time and space (EPA 2014). DE is toxic to insects when it is highly pure, of uniform small particle size, and has a high oil absorption capacity (Korunic 1997). Therefore, DE loses its effectiveness when it gets wet, clumps together, or becomes contaminated with other substances (e.g., clay or other soil particles) (EPA 2014). Any sign]ficant drift ofDE away from the application site would likely not be ofa high 

### 2

### Ms. Anita Pease enough concentration to be efficacious. Aquatic systems are not considered to be ofa concern because DE is not applied directly to water and diatoms are present in almost every aquatic system (EPA 2014)
. Runofffrom the target area is expected to be dominated by naturally occurring silicon dioxide, and thus DE would be indistinguishable from soil particles, naturally occurring diatoms or sediment (deposited or suspended) (EPA 2014). Species affected by application ofDE are expected to be terrestrial arthropods onthe treated area. The EPA made the determination ofno direct effect for all listed species except for 57 terrestrial non-subterranean arthropods (Appendix A) that may be exposed to DE at the site ofapplication. In addition, the EPA made the determination ofmay affect, not likely to adversely affect for indirect effects to terrestrial invertebrates, birds, terrestrial-phase amphibians and reptiles and mammals due to their reliance on insects as a food source. For the 57 non-subterranean terrestrial arthropods, EPA made the determination ofmay affect, not likely to adversely affect based on the following reasons: 1. DE has a mechanical rather than toxic mode ofaction; therefore, the potential for an adverse effect is limited in time and space, to the treated area, not off-site, and to a short interval after application, since weathering renders DE inefficacious. Although the time to effective weathering in not quantified, it is expected to be no longer than to the next rainfall. 2
. DE is a naturally occurring substance, wide-spread in many soils in low concentrations
. Thus, listed species are expected to be exposed to silica, and are presumably adapted to low exposure concentrations
. 3. 

### It is uncertain whether individuals would visit treated areas, or remain on these areas during the time ofapplication, due to the attendant human disturbance
. 4
. DE is used in organic agriculture and by homeowners seeking less-toxic alternatives to conventional pesticides. To the degree that DE is used in place ofconventional insecticides, EPA concludes that this compound is a much safer alternative to listed terrestrial invertebrates
. 

### Direct Effects After review ofthe 57 non-subterranean terrestrial arthropods identified by EPA, the Service concurs with EPA'sdetermination ofmay affect, not likely to adversely affect for the registration and application ofDE at appropriate use sites. The following summaries describe our rationale for our concurrence. American burying beetle The American burying beetle (Nicrophorus americanus) 

### eats carrion and insects (USFWS 2008a)
. Habitat generally includes deciduous and evergreen forests, sru:ub habitat, riparian forests and grasslands. The prevailing theory ofthe beetle's declme, rmderway for nearly a century and a serious concern by the 1920s (Ratcliffe 1996), points to habitat loss, degradation and fragmentation leading to a corresponding decrease in suitable carrion (USFWS 1991, Sikes and Raithel 2002)
. As more and more**l~d** 

### was developed or converted for agriculture and other uses, the resulting altered habitats 

### 3Ms. Anita Pease favored scavenging mammals and bird species that compete with carrion beetles for resources (USFWS 2008a). Onthe contemporary landscape, vegetation aspects of American burying beetle's habitat across large areas ofthe species' historic range, particularly east ofthe Mississippi River, are no longer suitable because ofdevelopment, habitat conversion for agricultural crops, grazing, oralterations that preclude the presence ofcarrion resources required by the burying beetle to thrive (USFWS 2008a). Based on the available information, adult American burying beetles are highly unlikely to find suitable carrion at sites registered for DE use due to competition with scavenging mammals and bird species now relatively common at those use sites. Even ifthe burying beetle were to find suitable carrion at one ofthese use sites, it would have to co-occur with the timing ofDE application and the Service believes that is highly improbable
. Butterflies There are 24 species oflisted butterflies for which EPA made the determination ofmay affect, not likely to adversely affect. These 24 species ofbutterflies share similar life history characteristics. These butterflies all occur in remnant native habitats and rely on one or several native host plants for larval development. Additionally, many ofthe adult forms rely on native nectar sources for food and are rarely found outside oftheir native habitat. In many cases, these native habitats are interspersed with agricultural lands or other human developments; however, it is highly unlikely that adults ofthese species would be found foraging far from their larval host plants. Based on the available information, it is highly improbable that the adults ofthese 24 species ofbutterflies would be found to forage in any ofthe DE registered use sites because they are unlikely to contain suitable nectar sources. Casey's June beetle Casey's June beetle (Dinacoma caseyi) distribution is confined to an area ofless than 800 acres in southern Palm Springs, California (USFWS 2009a). Casey's June beetle habitat is typically associated with broad, gently sloping, depositional surfaces that form at the base ofthe Santa Rosa Mountains in the dry Coachella Valley region by the overlapping or converging ofindividual alluvial fans (bajada) (Bates and Jackson 1987)
. Casey's June beetles emerge from underground burrows sometime between late March and early June, with abundance peaks generally occurring in April and May (Duff 1990; Barrows 1998). Females are always observed on the ground and are considered flightless (Duff 1990; Hovore 1995; Hovore 2003). During the active flight season, males emerge from the ground and begin flying near dusk (Hovore 2003). Males flying in the area are attracted to females by pheromones (Cornett 2004). Males are reported to fly back and forth or crawl on the ground where a female beetle has been detected (Duff 1990). After mating, females return to their burrows or dig a new burrow and deposit eggs. Casey's June beetle continues to be impacted by threats to the individual including loss of individuals due to attraction to swimming pools and light sources (USFWS 2013a). Lights attract male beetles away from habitat and females resulting in wasted energy, and they are frequently trapped and die in lights that have broken covers (K. Osborne 2012, pers. comm., in USFWS 2013a). Based on available information, designated use sites (e.g
., home properties), are no longer suitable habitat for Casey's June beetles. Females do not fly and would not be anticipated to found outside their preferred habitat. Although 4

### Ms
. Anita Pease males do fly in search offemales, and have been attracted to lights, it is highly unlikely that they would be attracted to DE treated use sites since females would not be present. Delhi sands flower-loving fly The Delhi Sands flower-loving fly (Rhaphiomidas terminatus abdominalisis) 

### is generally found in areas containing Delhi fine sands soil type (USFWS 2008b)
. Oviposition (egglaying) occurs within loose, sandy soils 

### in late summer months and may primarily occur near telegraph weed (Rogers and Mattoni 1993; Kingsley 1996)
. Larval stages develop completely underground and emerge as adults from 

### July through September
. Adults are most active during the wannest, sunniest parts ofthe day, and both males and females extract nectar from California buckwheat and other plants (Kingsley 1996)
. Based on the Delhi sands flower-loving fly's association with specific habitats and nectar sources, it is highly unlikely that adult flies would 

### be attracted to or exposed to DE treated use sites. Delta green ground beetle Currently, the delta green ground beetle (Elaphrus viridis) 

### is only known to occur at the Jepson Prairie in Solano County, California (USFWS 2009b). 

### It is believed that adults emerge from diapause and females lay their eggs in early winter, and then the species disappears from view until active adults reappear the following winter (USFWS 2009b)
. It is also believed that, as vernal pool habitats become 

### dry, the beetle larvae crawl into cracks in the soil, and survive the hot, 

### dry summer and fall as diapausing pupae (USFWS 2009b)
. The beetle is typically found along the margins ofvernal pools and in bare areas along trails and roadsides, where individuals often hide in cracks in the mud and under low

-growing vegetation (USFWS 

### 2009b)
. Based on the delta green ground beetles association with vernal pool and prairie habitats, it is highly unlikely that adult beetles would be attracted to or exposed to DE treated use sites
. Hawaiian damselflies The five listed Hawaiian damselflies are all associated with stream and riparian habitats. In four ofthe five species, the immature larval stages (naiads) are aquatic
. The flying earwig Hawaiian damselfly (Megalagrion nesiotes), 

### thought to be 

### terrestrial or semi

terrestrial, occupies habitat along a single east Maui stream on the adjacent steep, moist, riparian talus slope
. Adults ofthe five Hawaiian damselflies rarely venture far from their breeding sites or outside ofthe riparian corridor
. Based on the available information, the Service concludes that it is highly improbable that the adults ofthese five species of damselflies would be exposed to DE registered use sites
. Hawaiian pomace and picture-wing flies The 14 listed Hawaiian pomace and picture-wing flies are all associated with larval host plants and are restricted to the natural distribution ofthose plants
. In most cases, the larvae feed on the decaying stems or bark oftheir associated host plants. In one case, Drosophila musaphiliathe, 

### the female ofthe species lay eggs upon

### ~oa**(Acac~a ~o~),**  and the larvae develop in a slime flux that occasionally appears on certain trees with mJured plant tissue and seeping sap (Montgomery 1975)
. Based on the available**inf?nnatio~ ,**  

### it is highly improbable that the adults ofthese thirteen species ofpomace and p1cture

-wmg flies would forage on plants otherthan those found in their native habitat
. 

### 5Ms. Anita Pease

Hine's Emerald Dragonfly The Hine's emerald dragonfly (Somatochlora hineana) is currently found in Illinois, Michigan, Missouri and Wisconsin (USFWS 2013b)
. The dragonfly is apparently restricted to wetland habitats characterized by thin soils over dolomite bedrock with marshes, seeps, and sedge meadows (USFWS 200 I). Other components ofthis wetland complex habitat include open, vegetated areas and nearby or adjacent forest edge (USFWS 2001 ). Areas ofopen vegetation serve as places to forage, while forests, trees, or shrubs provide shaded areas for the dragonfly to perch and roost (USFWS 2001). The life cycle ofHine's emerald dragonfly is similar to most dragonflies 

### in that it is comprised ofthe following stages: aquatic egg, aquatic larva and a terrestrial/aerial adult (Corbet 1962). Fully adult Hine's emerald dragonflies can live at least 14 days (Soluk et al. 1996), and may live four to six weeks (Mierzwa et al. 1995). Most dragonfly adults are general predators throughout their entire life cycle, feeding primarily on insects they can capture while flying (USFWS 2001). Adult Hine's emerald dragonflies capture aerial prey in flight and have been observed foraging on small dipterans (gnats and othertwowinged flies) (Vogt and Cashatt 1994)
. Typically, flight courses are irregular and occur over herbaceous habitat, often near clusters ofshrubs or the forest edge (Cashatt and Vogt 1990; Vogt and Cashatt 1990, 1994; Nuzzo 1995)
. Hine's emerald dragonflies forage over meadows, successional fields, narrow roads and along Lake Michigan (Vogt and Cashatt 1994). In contrast to feeding flights, male territorial patrols are concentrated near aquatic habitats. The Hine's emerald dragonfly spends the majority ofits life within the aquatic community and adjacent native upland habitat. Although foraging adults may take short ventures outside ofthis habitat, it is unlikely that they would rest orperch within a DE treated use site. Mount Hermon June beetle The Mount Hermon June beetle (Polyphy/la barbata) is a small, dark-brown scarab beetle, with light, irregular and broken stripes on the elytra (USFWS 2009). Seasonal activity in this species occurs between May and August and lasts approximately 12 weeks (Arnold 2003, 2004a, 2005, 2006, 2007). Females are flightless and emerge from burrows only to mate, after which they immediately return underground. Activity in this species is strictly crepuscular, with males emerging at dusk and emitting a crackling sound as they fly low over ground or brush likely following pheromonal cues to find females for mating (Arnold 2004b). Little is known about the entirety ofthe life cycle; however, Arnold (2004b) believes that it likely is a 2- to 3-year life cycle, with the majority oftime spent underground
. Arnold (2000, 2001) also believes, based on markrecapture studies, that adult males live for no longer than one week. It is likely, considering their short lifespan, that adult males do not feed, focusing instead solely on reproduction over consecutive days until their energy reserves are expended (Hazeltine 1993). Based on available information, designated use sites (e.g., home properties), are no longer suitable habitat for Mount Hermon June beetles
. Considering the likelihood that male beetles do not forage, but instead focus solely on seeking out females to mate, it is highly improbable that males ofthis species would be attracted to orexposed to DE treated use sites. 

### 6

### Ms. Anita 

### Pease Sphinx moths There are two listed species ofsphinx moths. One is located in Hawaii and one in California. Both sphinx moths share vary similar life history traits that include reliance on native host plants for egg laying and larval food and suitable soil beneath the host plants that allows larvae to burrow and construct shallow pupal chambers. In Hawaii, the Blackburn's sphinx moth (Manduca blackburni) larvae have been found to feed upon the non-native tree tobacco (Nicotiana glauca). Based on the available information, it is highly improbable that the adults ofthese two species ofsphinx moths would be found to forage in any ofthe DE registered use sites
. Tiger beetles The four listed tiger beetles are all habitat specialists. These beetles rely on specific soils (e.g., sandy deposits, moist salt flats, sandy clay) to construct larval burrows. For example, the Ohlone tiger beetle (Cicindela oh/one) 

### is endemic to Santa Cruz County, California, where it is known only from coastal terraces supporting patches ofnative grassland habitat (Freitag et al. 1993)
. Adult Ohlone tiger beetles are typically found along trails or barren areas among low, sparse vegetation within the grassland habitat (USFWS 2009c). Ohlone tiger beetles require these open areas for construction oflarval burrows, thermoregulation, and foraging (USFWS 2009c)
. Both adults and larvae of tiger beetles feed exclusively on other arthropods
. Based on the tiger beetles dependence on specific endemic habitats and the fact that they forage on arthropods within those habitats, it is highly improbable that adult tiger beetles would be attracted to orexposed to DE treated use sites
. Valley 

### elderberry longhorn beetle The valley elderberry longhorn beetle (Desmocerus californicus dimorphus) 

### is endemic to the Central Valley ofCalifornia
. The beetle is found only in association with its host plant, elderberry (Sambucus sp.) (USFWS 2006)
. Adults feed on the foliage and perhaps flowers and are present from March through early July (USFWS 2006)
. Based on the valley elderberry longhorn beetle's association with elderberry bushes, it is highly improbably that the beetle would forage on plants other than elderberry
. Zayante band-winged grasshopper The Zayante band

-winged grasshopper (Trimerotropis infantilis) 

### is known only from the Zayante sandhills ofSanta Cruz County, California. The adult flight activity period of the grasshopper extends from July until the first ground

-soaking rains ofthe winter (usually around early Nov
.) (Arnold 2004e). Adults may live for more than a month and usually are found either directly on sandy soil or on the foliage ofthe silver bush lupine (Lupinus albifrons), 

### which makes up over 60 percent oftheir diet (Chu 2002). Females oviposit eggs directly into loose, sandy soil. The eggs over-winter in the soil, and nymphs begin to appear in May, with the first adults appearing in July (USFWS 2009d). Based on the Zayante band-winged grasshopper's association with sandy soils and silver bush lupine, it is highly improbable that adult grasshoppers would be attracted to or exposed to DE treated use sites
. 

### 7

### Ms. Anita Pease
In summary, we concur with your detennination that the use ofDE at registered use sites may affect, but is not likely to adversely affect the aforementioned insect species
. The potential for these insect speciesto come into contact with DE is extremely unlikely, and therefore, we consider the risk to 

### be discountable. 

### Indirect Effects The Service concurs with EPA's determination ofmay affect, not likely to adversely affect for indirect effects for terrestrial invertebrates, birds, terrestrial-phase amphibians and reptiles and mammals due to their reliance on insects as a food source. The reduction 

### in available food source (i.e., insects), for the above listed taxa, would 

### be insignificant and discountable due to the highly localized and short-term nature in that reduction of food at DE registered use sites. 

### In addition, it is highly improbable that those listed taxa, with the exception ofbirds and possibly some amphibians, would even forage in DE registered use sites. This concludes informal consultation on the national registration ofsilicon dioxide and silica gel. Therefore, unless new information reveals effects ofthe proposed action that may affect listed species in a manner or to an extent not considered, or a new species is listed, no further action pursuant to the Act is necessary. 

### Ifyou have any questions please contact Keith Paul ofmy office at (703) 358-2675.

Attachments Patrice Ashfield Chief, Branch ofConsultation and Habitat Conservation Plans, Ecological Services 

### 8

### Ms
.

### Anita Pease Literature Cited Arnold, R. A. 

### 2000. Monitoring report for the Mount Hermon June beetle at the Quail Hollow Quarry in 2000. Report prepared for: Granite Rock, Watsonville, California; County ofSanta Cruz Planning Department, Santa Cruz, California; U.S. Fish and Wildlife Service, Region I Eastside Federal Complex, Portland, Oregon; California Department ofFish and Game, Yountville, California. Arnold, R. A. 

### 2001. 2001 monitoring report for the Mount Hermon June beetle at Hanson Aggregates' Felton Quarry
. Report prepared for: Hanson Aggregates Mid-Pacific Region, Pleasanton, California; U.S. Fish and Wildlife Service, Region I Eastside Federal Complex, Portland, Oregon; U
.S. Fish and Wildlife Service, Ventura Field Office, Ventura, California; Center for Natural Land Management, Fallbrook, California; County ofSanta Cruz Planning Department, Santa Cruz, California. Arnold, R
. A. 

### 2003. 2003 monitoring report for the Mount Hermon June beetle at Hanson Aggregates' Felton Quarry. Report prepared for:Hanson Aggregates Mid-Pacific Region, Pleasanton, California; U
.S
.Fish and Wildlife Service, Region 1 Eastside Federal Complex, Portland, Oregon; U
.S. Fish and Wildlife Service, Ventura Field Office, Ventura, California; Centerfor Natural Land Management, Fallbrook, California; County ofSanta Cruz Planning Department, Santa Cruz, California. Arnold, R. A. 

### 2004a. 2004 monitoring report for the Zayante band winged grasshopper at Hanson Aggregates' Felton Quarry
. Report submitted to Hanson Aggregates Mid-Pacific Region, Pleasanton, California; U
.S
. Fish and Wildlife Service, Region 1Eastside Federal Complex, Portland, Oregon; U.S. Fish and Wildlife Service, Ventura Field Office, Ventura, California; Center for Natural Land Management, Fallbrook, California; County ofSanta Cruz Planning Department, Santa Cruz, California
. Arnold, R. A. 

### 2004b. Zayante band winged grasshopper. Pages 81-91 in J.M. McGraw (author), Sand.hills conservation and management plan: a strategy for preserving native biodiversity in the Santa Cruz sandhills. Report submitted to the Land Trust ofSanta Cruz County, Santa Cruz, California
. 310 pp. Arnold, 

### R. A. 

### 2005. 2005 monitoring report for the Mount Hermon June beetle at Hanson Aggregates' Felton Quarry. Report prepared for: Hanson Aggregates Mid-Pacific Region, Pleasanton, California; U.S. Fish and Wildlife Service, Region l Eastside Federal Complex, Portland, Oregon; U.S
. Fish and Wildlife Service, Ventura Field Office, Ventura, California; Center for Natural Land Management, Fallbrook, California; County ofSanta Cruz Planning Department, Santa Cruz, California
. Arnold, R
. A. 

### 2006
. 2006 monitoring report for the Mount Hermon June beetle at Granite Rock's Quail Hollow Quarry. Report prepared for: Granite Rock, Watsonville, California; County ofSanta Cruz Planning Department, Santa Cruz, 

### 9Ms
. Anita Pease California; U.S. Fish and Wildlife Service, Region 1Eastside Federal Complex, Portland, Oregon; California Department ofFish and Game, Yountville, California
. Arnold, R. A. 2007. Monitoring report for the Zayante band winged grasshopper at the Quail Hollow Quarry in 2007. Report submitted to Granite Rock, Watsonville, California; County ofSanta Cruz Planning Department, Santa Cruz, California; U.S. Fish and Wildlife Service, Region 1Eastside Federal Complex, Portland, Oregon; California Department ofFish and Game, Yountville, California. Barrows, C. 1998
. Results ofSearches for Casey's June Beetle, Spring 1998. Unspecified submission recipient. Bates, R. L. and J.A Jackson. 1987. Glossary ofGeology. American Geological Institute, Alexandria, Virginia. 788 pp. Cashatt, E.D., and T.E. Vogt. 1990. The Illinois 1990 status survey for the Ohio emerald dragonfly (Somatochlora hineana Williamson). Report to the U
.S
. Fish and Wildlife Service. Illinois State Museum, Springfield, Illinois. 20 p. Chu, J. 2002. Diet for an Endangered Insect: What Does the Zayante Band-Winged Grasshopper Eat? Master Thesis, Department ofEnvironmental Studies, San Jose State University. Corbet, P.S
. 1962. A Biology ofDragonflies. H.F. & G. Witherby Ltd., facsimile reprint 1983 by E.W
. Classey Ltd., Oxon, United Kingdom. 247 pp. Cornett, J.W. 2004
. Analysis ofthe Distribution and Abundance ofthe Casey's June Beetle (Dinacoma caseyi) in Palm Springs, California, prepared for Smoke Tree Ranch, Inc., Palm Springs, California. Duff, R. 1990. Dinacoma caseyi: Current Status ofEndangered Species. Unspecified submission recipient. Freitag, R., D.H. Kavanaugh, and R. Morgan. 1993. A new species ofCicindela (Cicindela) (Coleoptera: Carabidae: Cicindelini) from remnant native grassland in Santa Cruz County, California. Coleopterists Bulletin, 46: 113-120. Haziltine, W
. 1993. Distribution ofthe scarab beetle, Polyphylla barbata Cazier. 5 pages and 4 figures. Unpublished report, dated July 13. Oroville, California. Hovore, F. 1995. Report offield surveys: Coachella Valley Multi-species HCP, Invertebrates

- Palm Springs June beetle (Dinacoma caseyi). Unspecified submission recipient. Hovore, F
. 2003
. Report offocused surveys for Casey'sJune beetle: Smoketree Ranch and vicinity, prepared for Krieger & Stewart, Inc., Riverside, California. 

### 10

### Ms. Anita Pease Kingsley, K.J. 1996
. Behavior ofthe Delhi Sands flower-loving fly (Diptera, 

### Mydidae), a little-known endangered species. Annals ofthe Entomological Society of America 89:883-891. Korunic, Z
., 1997. Rapid assessment ofthe insecticidal value ofdiatomaceous earths without conducting bioassays. Journal ofStored Products Research 3, 219

-229. Korunic, Z
. 1998
. Diatomaceous earths, a group ofnatural insecticides
. Journal of Stored Products Reasearch
. 34:2-3
. pp87-97. Mierzwa, K.S
., A.P. Smyth, and E.D. Cashatt. 1995. Population dynamics ofthe Hine's emerald dragonfly (Somatochlora hineana) in 

### Illinois. In 

### K.S. Mierzwa, (editors)
. The Hine'semerald dragonfly in Illinois: an assessment ofpopulation dynamics and habitat use. TAMS Consultants, Inc., Chicago, Illinois
. P 9-48. Montgomery, S.L. 1975
. Comparative breeding site ecology and the adaptive radiation ofpicture-winged Drosophila 

### (Diptera: Drosophilidae) in Hawaii. Proceedings of the Hawaiian Entomological Society 12:65-103. Nl1Zzo, V
.A. 1995
. Hine's emerald dragonfly (Somatochlora hineana) 

### breeding and foraging habitat at three sites in the lower Des Plaines Rivers Valley, Illinois
. In 

### K
.S. Mierzwa, (editors). The Hine's emerald dragonfly in Illinois: An 

### assessment ofpopulation dynamics and habitat use. TAMS Consultants, Inc
., Chicago, Illinois. p 49-75
. Ratcliffe, B
.C
. 1996
. The carrion beetles (Coleoptera: Silphidae) ofNebraska. Bulletin 

### ofthe University ofNebraska State Museum. Vol. 13, 100 p. Rogers, R. and M. Mattoni. 1993. Observations on the narural history and conservation biology ofthe giant flower-loving flies, Rhaphiomidas 

### (Diptera: Apioceridae)
. Dipterological Research 4(1-2):21-34
. Sikes, D
.S. and Raithel, R.J. 2002. A review ofhypothesis ofdecline ofthe endangered American burying beetle (Silphidae: Nicrophorus americanus 

### Olivier)
. Journal of Insect Conservation 6: 103-113> Soluk, D.A., B.J
. Swisher, and D.S. Zercher. 1996
. The ecology ofHine's emerald dragonfly (Somatochlora hineana): 

### monitoring populations and determining patterns ofhabitat use in the Des Plaines River valley. Activity summary and report ofpreliminary results (January-August 1996)
. Illinois Natural History Survey, Champaign, Illinois. 35 p. U
.S. Environmental Protection Agency
. 1991. Reregistration Eligibility Docwnent, Silicon Dioxide and Silica Gel (Case No. 4081)
. Office ofPesticide Programs, Specia] Review and Registration Division, Washington, D.C
. 32 p. U.S. Environmental Protection Agency. 2006
. Reregistration Eligibility Decision Document for Piperonyl Butoxide (PBO)
. United States Environmental Protection Agency, Office ofPrevention, Pesticides and Toxic Substances. 11

### Ms. Anita Pease
U.S. Environmental Protection Agency. 2014. Environmental Fate and Ecological Effects Risk Assessment for the Registration for the Registration Review ofSilica (CaseNo. 4081)
. U.S. Environmental Protection Agency, Office ofChemical Safety and Pollution Prevention, Environmental Fate and Effects Division, Washington, D
.C
. 97 p. U.S. Fish and Wildlife Service
. 1991. American Burying Beetle (Nicrophorus americanus) Recovery Plan. Newton Comer, Massachusetts
. 62 p. U.S
. Fish and Wildlife Service
. 2001. Recovery Plan for the Hine's Emerald Dragonfly (Somatochlora hineana Williamson). U.S
. Fish and Wildlife Service, Region 3, Fort Snelling, Minnesota
. September 2001. 133 p. U.S. Fish and Wildlife Service. 2006. Five-year Review: Valley elderberry longhorn beetle (Desmocerus ca/ifornicus dimorphus). U.S. Fish and Wildlife Service, Sacramento Fish and Wildlife Office, Sacramento, California. September 2006. 30p
. U
.S
. Fish and Wildlife Service. 2008a. Five

-year Review: American Burying Beetle (Nicrophorus americanus)
. U.S
. Fish and Wildlife Service, New England Field Office, Concord, New Hampshire
. March 2008. 53 p. U.S. Fish and Wildlife Service. 2008b. Five-year Review: Delhi Sands Flower-loving Fly (Rhaphiomidas terminatus abdominalis). U.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office, Carlsbad, California
. March 2008. 30 p. U
.S
. Fish and Wildlife Service
. 2009a
. Endangered and Threatened Wildlife and Plants; Listing Casey's June Beetle (Dinacoma caseyl) as Endangered and Designation of Critical Habitat. Federal Register 74:32857-32875
. U.S
. Fish and Wildlife Service
. 2009b
. Five-year Review; Delta Green Ground Beetle (Elaphrus viridis)
. U.S. Fish and Wildlife Service, Sacramento Fish and Wildlife Office, Sacramento, California
. January 2009
. 29 p. U.S
. Fish and Wildlife Service
. 2009c. Five-year Review; Ohlone tiger beetle (Cicindela oh/one)
. U.S. Fish and Wildlife Service, Ventura Fish and Wildlife Office, Ventura, California. November 2009
. 27 p. U.S. Fish and Wildlife Service
. 2009d
. Five-year Review: Zayante band-winged grasshopper (Trimerotropis infantilis) and Mount Hermon June beetle (Polyphylla barbata)
. U
.S
. Fish and Wildlife Service, Ventura Fish and Wildlife Office, Ventura, California
. August 2009
. 33 p. U
.S. Fish and Wildlife Service. 2013a
. Recovery Outline for Casey's June Beetle (Dinacoma caseyi)
. U
.S. Fish and Wildlife Service, Carlsbad Fish and Wildlife Office, Carlsbad, California
. March 2013. 21 p. 12

### Ms
. Anita Pease U.S. Fish and Wildlife Service. 2013b. Five-year Review: Hine's Emerald Dragonfly (Somatochlora hineana). 

### U.S. Fish and Wildlife Service, Chicago Ecological Services Field Office, Barrington, Illinois. May 2013
. 50 p. Vogt, T.E., and E.D. Cashatt. 1990. The Wisconsin 1990 status survey for the 

### Ohio emerald dragonfly (Somatochlora hineana 

### Williamson). Report to the U
.S
. Fish and Wildlife Service. Illinois State Museum, Springfield, Illinois
. 9 p. Vogt, T.E., and E.D
. Cashatt. 1994
. Distribution, habitat, and field biology of Somatoch/ora hineana 

### (Odonata: Corduliidae). Annals ofthe Entomological Society ofAmerica 87(5): 599-603.

### Ms. 

### Anita Pease 14 Annendix A. EPA's and FWS' Determinations for Listed Terrestrial Arthropods Common Name Scientific Name Medium Taxa EPA FWS Determination Determination American burying beetle Nicrophoru:r americanu:r Terrestrial Insect NLAA Concur Bay checkerspot butterfly Euphydryas editha bayensis Terrestrial Insect NLAA Concur Bee Creek Cave harvestman Texella redde/li Subterraneous Arachnid No effect No effect Behrcn's silvcrspot butterfly Speyeria zerene behrensii Terrestrial Insect NLAA Concur Blackburn's sphinx moth Manduca blackburni Terrestrial Insect NLAA Concur Blackline Hawaiian damselfly ·Mega/agrion nigrohamatum Terrestrial Insect NLAA Concur niPro/ineatum Bone Cave harvestman Texe/la reye:ri Subterraneous Arachnid No effect No effect Brak.en Bat Cave Meshweaver Cicurina venii Subterraneous Arachnid No effect No effect Callippe silverspot butterfly Speyeria callippe cal/ippe Terrestrial Insect NLAA Concur Carson wandering skipper P:reudocopaeodeseunu:r Terrestrial Insect NLAA Concur obscuru:r CaseysJune Beetle Dinacoma caseyi Terrestrial Insect NLAA Concur Coffin Cave mold beetle Balrisodes texanu:r Subterraneous Insect No effect No effect Cokendolpher Cave Harvestman Texe/la colcendo/pheri Subterraneous Arachnid No effect No effect Comal Springs dryopid beetle Stygoparnu:r coma/ensis Freshwater Insect No effect No effect Comal Spring.s riffle beetle Hetere/mis coma/ensis Freshwater Insect No effect No effect Crimson Hawaiian damselfly Mega/agrion leptodemus Terrestrial Insect NLAA Concur Delhi Sands flower-loving fly Rhaphiomidas termiootus Terrestrial Insect NLAA Concur abdominalis Deltagreen ground beetle Elaphru:r viridis Vernal Pool Insect NLAA Concur El Segundo blue butterfly Euphi/otes banoideral/yni Terrestrial Insect NLAA Concur Fender's blue butterfly Jcaricia icarioidesfenderi Terrcstrial Insect NLAA Concur Florida leafwing butterfly Anaea troglodytaj/oridali:r Terrestrial Insect NLAA Concur Flying earwig Hawaiian Megalagrion ne:riote:r Terrestrial Insect NLAA Concur damselflv Government Canyon Bat Cave Cicurina vespera Subterrancous Arachnid No effect No effect Meshweaver Government Canyon Bat Cave Neo/eptoneta microps Subtcrrancous Arachnid No effect No effect Soider Hawaiian picture-wing fly Drosophila sharpi Terrestrial Insect NLAA Concur Hawaiian picture-wing fly Drosophila digres:ra Terrestrial Insect NLAA Concur Helotes mold beetle Batrisodes venyivi Subterraneous Insect No effect No effect Hine's emerald dragonfly Somatoch/ora hineana Terrestrial Insect NLAA Concur Hungerford's crawling water Brychius hungerfordi Freshwater Insect No effect No effect Beetle Kamer blue butterfly Lycaeides me/issa samuelis Terrestrial Insect NLAA Concur Kauai cave wolfspider Ade/ocosa anop:r Terrestrial Arachnid No effect No effect Kem primrose sphinx moth Euproserpinu:r euterpe Terrestrial Insect NLAA Concur Kretschmarr Cave mold beetle Texamaurops redde/li Subterrancous Insect No effect No effect Laguna Mountains skipper J>yrgus rura/i:r/agunae Terrestrial Insect No effect No effect

### Ms. 

## Anita Pease 15 Lange's metalmark butterfly Apodemia mormo langei Terrestrial Insect NLAA Concur Lotis blue butterfly Lycaeides argyrognomon /otis Terrestrial Insect NLAA Concur Media's Cave Meshweaver Cicurina madla Subterraneous Arachnid No effect No effect Miami Blue Butterfly Cyc/argus**(~Hemiargus)** Terrestrial Insect NLAA Concur thomasi bethunebakeri Mission blue butterfly lcarfcia icarioides Terrestrial Insect NLAA Concur missiommsis Mitchell's satyr Butterfly Neonympha milchel/ii Terrestrial Insect NLAA Concur milchel/ii Mount Charleston blue butterfly Plebejus sharia Terrestrial Insect NLAA Concur chares/onensis Mount Hermon June beetle Polyplryl/a barbara Subterraneous Insect NLAA Concur Myrtle's silverspot butterfly Speyeria zerene myrlleae Terrestrial
. Insect NLAA Concur Northeastern beach tiger beetle Cicinde/a dorsalis dorsa/is Terrestrial Insect NLAA Concur Oceanic Hawaiian damselfly Megalagrion oceanicum Terrestrial Insect NLAA Concur Ohlone tiger beetle Cicindela oh/one Terrestrial Insect NLAA Concur Oregon silverspotbutterfly Speyeriazerene hippolyta Terrestrial Insect NLAA Concur Pacific Hawaiian damselfly Megalagrionpacificum Terrestrial Insect NLAA Concur Palos Verdes blue butterfly G/aucopsyche /ygdamus Terrestrial Insect NLAA Concur oafasverdesensis Pawnee montane skipper Hesperia leonardus monlana Terrestrial Insect NLAA Concur Puritan tiger beetle Cicindefapuritana Coastal Insect NLAA Concur Quino checkerspot butterfly Euphydryas edilha quino (=E. Terrestrial Insect NLAA Concur e. wriKhti) Robber Baron Cave Meshweaver Cicurina baronia Subterraneous Arachnid No effect No effect Saint Francis' satyr butterfly Neonympha mitchel/ii Terrestrial Insect NLAA Concur francisci Salt CreekTigerbeetle Cicindela nevadica Terrestrial Insect NLAA Concur lincolniana San Bruno elfin butterfly Caflophrys mossii bayensis Terrestrial Insect NLAA Concur Schaus swallowtail butterfly Heraclides aristodemus Terrestrial Insect NLAA Concur oonceanu.s Smith's blue butterfly Eupliifotes enople:r :rmithi Terrcstrlal fnsect NLAA Concur Spruce-fir moss spider Microhexura montivaga Terrcstrial Arachnid No effect No effect Taylor's Chcckerspotbutterfly Euphydryas edilha tay/ori Terrestrial Insect NLAA Concur TDo.tb Cav.cgrolllld**b~** .R.hmJ.i.nJ!pun.phone Subterraneous Insect No effect No effect Tooth Cave pseudoscorpion Tarlarocreagris texana Subterraneous Arachnid No effect No effect Tooth Cave Spider leptoneta myopica Subterraneous Arachnid No effect No effect Uncompahgre fritillary butterfly Bo/oria acrocnema Terrestrial Insect No effect No effect Unnamed ground beetle Rhadine infernafis Subterraneous Insect No effect No effect Unnamed ground beetle Rhadine exilis Subtcrraneous Insect No effect No effect Unnamed ground beetle Drosophila montgomeryi Terrestrial Insect NLAA Concur Unnamed ground beetle Drmophila differens Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila ochrobasis Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila hemipeza Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophifa tarpliytricliia rcrrestn'al Insecr NLAA Concur

### Ms. Anita Pease 16

Unnamed ground beetle Drosophila substenoptera Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila obatai Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila neoclavisetae Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila muf/i Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila heteroneura Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila aglaia Terrestrial Insect NLAA Concur Unnamed ground beetle Drosophila musaphilia Terrestrial Insect NLAA Concur Valley elderberry longhorn beetle Desmocerus californicus Terrestrial Insect NLAA Concur dimorohus Zayante band-winged grasshopper Trimerotropis infantilis Terrestrial Insect NLAA Concur

# United States Department ofthe Interior FISH AND WILDLIFE SERVICE

In Reply Refer To: FWS/AES/DER/BCH/059656 09£30000-20l4-I-0001 Ms
. Anita Pease Associate Director U
.S. Environmental Protection Agency Office ofPesticide Programs Environmental Fate and Effects Division 1200 Pennsylvania Ave., NW Washington, D.C
. 20460
. Washington, D.C
. 20240**~~\ ~**  

### - g 2015

Subject: Review ofInformal Consultation on the Proposed Registration of Silicon Dioxide and Silica Gel for Two Butterfly Species Dear Ms
. Pease: Thank you for your letter dated February l0, 2015, requesting our concurrence that the continued registration ofsilicon dioxide (as diatomaceous earth) (DE) and silica gel (Case No
. 408I) is not 

### likely to adversely affect the Fender's Blue butterfly 

### (lcaricia icarioides fenderi) nor the Taylor's Checkerspot butterfly (Euphydryas editha taylori) 

### pursuant to section 7 ofthe Endangered Species Act of 1973 (16 U.S
.C
. 1531 -1544), as amended (ESA). On April 2, 2014, the U.S
. Fish and Wildlife Service (Service) issued a letter ofconcurrence with the Environmental Protection Agency's (EPA) determination of"may affect, not likely to adversely affect" for direct effects on 57 non-subterranean terrestrial arthropods
. The Service also concurred with EPA's determination of"may affect, not likely to adversely affect" for indirect effects for terrestrial invertebrates, birds, terrestrial-phase amphibians, reptiles and mammals. Subsequent to the issuance ofour letter ofconcurrence, our Oregon Fish and Wildlife Office highlighted potential concerns for specific use sites (e.g., pasture, vineyards) for the two aforementioned listed butterfly species in the Willamette Valley
. To address this concern, EPA and the Service held several follow-up discussions to explore potential effects to these two butterfly species. 

### In Oregon, there are currently no approved state labels for the use ofDE in pastures or vineyards; however, these use sites may be approved over the course ofthe 15-year registration action. Your team spent a considerable amount oftime conducting additional research regarding the potential impact ofDE to insects and we appreciate the additional information you submitted
.

### Ms. Anita Pease 

### 2
Based on this additional review ofinformation and requirements, you confirmed your original determination of"may affect, not likely to adversely affect" for the two listed butterfly species due to the following: I) the existence ofstate-level pollinator protection requirements for DE, which are triggered by a state decision to register DE for a new use (via a section 18 or 24c label), and similar guidance available through other Extension Services; and, 2) on additional data showing low toxicity ofDE to bees (as a surrogate for butterflies) at rates exceeding current application levels
. Based on the information provided by EPA, the Service reaffirms our concurrence with your determination of"may affect, not likely to adversely affect" the Fender's Blue and Taylor's checkerspot butterflies. The Service greatly appreciates the additional effort put forth by EPA to address our concerns on this matter and the supplemental information provided on the national registration ofsilicon dioxide and silica gel. Therefore, unless new information reveals effects ofthe proposed action that may affect listed species in a manner or to an extent not considered, or a new species is listed, no further action pursuant to the ESA is necessary. 

### Ifyou have any questions please contact Keith Paul ofmy office at (703) 358-2675
. 

# Ro( Craig Aubrey

.....- Chief, Division ofEnvironmental Review, Ecological Services