Appendix B: EPA Exposure Assessment

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Appendix B: EPA Exposure Assessment

Methodology

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1. Introduction

The EPA’s exposure assessment methodology has been developed to estimate exposure to pesticides used for commercial agricultural purposes. It calculates risk quotients and the control measures necessary to reduce bystander, operator and re-entry worker exposure to acceptable levels. In addition it estimates the buffer zones required to protect aquatic organisms in a still water body from pesticide spray drift. The purpose of this document is to explain the approach, so that stakeholders can understand how the exposure and risk assessments are carried out.

2. Data input

The exposure assessment modelling approach requires the following variables as a minimum

 Formulation type (liquid, powder, granule, powder)

 Application rate for ground boom, airblast or aerial application (g.a.i./ha) as applicable.

 Acceptable Operator Exposure Level (AOEL) (mg/kg bw/day)

 Dermal absorption of the active ingredient

 Aquatic LC50 value divided by 10 or another appropriate safety factor (mg/l)

In addition, there are many variables that can be varied to refine an assessment or default values can be used. The following sections describe these variables and how they are used in the risk assessment process.

3. Operator exposure and risk

An operator’s exposure is estimated using the UK CRD version of the BBA operator exposure model (Chemicals Regulation Directorate, 2016c).

To estimate operator exposure the following information is required

 application rate

 application type

 formulation type

Information about the following variables can also be used (or if they are not available default values are used).

 Dermal absorption from spray

 Dermal absorption from product

 Work rate

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EFSA has published guidance on the assessment of dermal absorption of pesticides which can be used to inform the interpretation of dermal absorption studies (EFSA, 2012). The EFSA guidance also includes details of procedures to follow when reading across dermal absorption information between formulations and for the extrapolation of dermal absorption data on an active ingredient to a formulated product.

When substance specific dermal absorption data are not available default values can be used in the

assessment. The EPA has adopted default values proposed by Aggarwal et al. which are based on a review of studies on over 150 active ingredients, rather than the default values listed in the EFSA guidance

(Aggarwal et al. 2015). The default values used are 6% for liquid concentrates, 2% for solid concentrates and 30% for spray dilutions. The EFSA guidance includes options to further refine dermal absorption values based on physical chemical properties or data on oral absorption. Guidance from the OECD can also be used to inform decisions on the appropriate dermal absorption value to be used (OECD 2011).

Information on the work rate (or area treated per day) should ideally come from the applicant or from feedback from users. If no information is provided then the default values in the European Food Safety Authority (EFSA) exposure assessment model, listed in table 1, can be used. These values are consistent with feedback that the EPA received during the Organophosphate and Carbamate reassessment

(APP201045). For handheld application it can be assumed that 1 hectare would be treated per day.

Table 1 Area treated per day (EFSA, 2014)

Crop Area treated per day (ha)

Bare soil 50

Berries and other small fruits (low) 50

Brassica vegetables 50

Bulb vegetables 50

Cane fruit 10

Cereals 50

Citrus fruit 10

Fruiting vegetables 50

Golf course turf or other sports lawns 50

Grassland and lawns 50

Grapes 10

Hops 10

Leaf vegetables and fresh herbs 50

Legume vegetables 50

Oilfruits (high crops) 10

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Oilseeds 50

Ornamentals 10

Pome fruit 10

Root and tuber vegetables 50

Stone fruit 10

Tree nuts 10

The UK CRD version of the BBA operator exposure model calculates exposure using the results of actual measurements carried out in the field (Chemicals Regulation Directorate, 2016c). These values represent the geometric mean values of these studies and hence may not be as conservative as some other operator exposure models which are based on the 75^th percentile of exposure datasets. The impact of wearing different forms of PPE is estimated using exposure reduction factors which have also been empirically derived. These protection factors are based on the 2014 EFSA operator, worker, resident and bystander exposure model and are outlined below in table 2 (EFSA, 2014).

Table 2 PPE and RPE exposure reduction factors used

PPE Exposure reduction coefficients

Dermal Component Inhalation

Gloves (liquid) 0.1 Hands

Certified protective coverall

0.05 Body

Hood and visor 0.05 Head

FP1, P1 and similar 0.8 Head 0.25

FP2, P2 and similar 0.8 Head 0.1

Gloves (solids mixing and loading) 0.05

Risk is estimated by comparing exposure to the Acceptable Operator Exposure Level (AOEL). The AOEL is a health based exposure guidance value against which non-dietary exposures to pesticides are currently assessed. It is intended to define a level of daily exposure throughout a spraying season, year on year, below which no adverse systemic health effects would be expected (EFSA, 2014). The AOEL is normally derived by applying an assessment factor (most often 100) to a No Observed Adverse Effect Level (NOAEL) (corrected if appropriate for incomplete absorption) from a toxicological study in which animals were dosed daily for 90 days or longer. Less often, the critical NOAEL comes from a study with a shorter dosing period

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(e.g. a developmental study) or a longer dosing period (e.g. a chronic toxicity/carcinogenicity study). The AOEL represents the internal (absorbed) dose available for systemic distribution from any route of exposure and is expressed as an internal level (in milligrams/kilogram body weight/day).

Exposure and risk are estimated under the following Personal Protective Equipment (PPE) scenarios:

 No PPE during mixing, loading and application;

 Gloves only during mixing and loading;

 Gloves only during application;

 Full PPE during mixing, loading and application (excluding respirator);

 Full PPE during mixing, loading and application (including FP1, P1 and similar respirator achieving 75 % inhalation exposure reduction)

 Full PPE during mixing, loading and application (including FP2, P2 and similar respirator achieving 90 % inhalation exposure reduction

The level of PPE that is required is determined based on which scenario reduces exposure to an acceptable level.

4. Re-entry worker exposure and risk

The re-entry worker exposure is based on dermal exposure through contact with foliar residues only;

inhalation exposure or exposure to other contaminated surfaces (e.g. soil) is not accounted for. If required it is possible to estimate exposure via these routes using the approaches outlined in the EFSA model (EFSA, 2014). Re-entry exposure is calculated using the formula below which was developed by other regulators (Chemicals Regulation Directorate, 2016b, EUROPOEM, 2002).

Re-entry worker exposure = DFR x TC x WR x AR x DA BW

These parameters with default values where they exist are:

 DFR is the Dislodgeable Foliar Residue (3 µg/cm² per kg a.i./ha)

 TC is the Transfer coefficient for the anticipated activity being performed (cm2/hr, defaults in Table 3)

 WR is the work rate per day (default is 8 hrs/day; note that it is possible to change this value if it is deemed necessary)

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 AR is the Application rate (kg/ha)

 BW is the Body weight (70 kg)

 DA is the dermal absorption, expressed as a proportion. The appropriate dermal absorption value for exposure to dried dispersed residue should be the higher of the values for the concentrate and the spray dilution (EFSA, 2012).

4.1.1. Transfer coefficients

Transfer coefficients refer to the amount of contact between a re-entry worker and foliage. These are regarded as independent of the active ingredient/product used and depend on the crop type and the activity that the re-entry worker is carrying out (EUROPOEM, 2002). In the absence of data, the Agency will use the values in Table 3 obtained from overseas regulators.

Table 3 Default transfer coefficients used for the re-entry worker risk assessment

Crop Activity Transfer coefficient

(cm²/hr)

Source of transfer coefficient

Vegetables Reach/Pick 2500 (EUROPOEM, 2002)

Fruit from trees Search/Reach/Pick 4500 (EUROPOEM, 2002)

Berries Reach/Pick 3000 (EUROPOEM, 2002)

Ornamentals Cut/Sort/Bundle/Carry 5000 (EUROPOEM, 2002)

Turf Mowing 1000 NOHSC re-entry exposure model

Turf Transplanting, Hand weeding

20000 NOHSC re-entry exposure model

Pasture Mowing 500 (European Food Safety Authority, 2010)

Cereals Scouting, Irrigation, Weeding mature/full foliage plants

1000 (USEPA, 2007a)

These transfer coefficients all assume that re-entry workers are wearing long trousers and long sleeved shirts and are not wearing gloves. If there is a substance for which the crop or activity is unknown, a default reasonable worst case of 5200 cm²/hr should be used unless judgement indicates that an alternative value may be more appropriate.

4.1.2. Impact of wearing PPE

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The impact of wearing gloves on worker exposure can be considered using the transfer coefficient values outlined in the EFSA operator, worker, resident and bystander model (EFSA 2014). However, the impact of wearing gloves cannot be calculated for some crops/activities because TC attributable to hands only are not available.

Table 4. Impact of gloves on re-entry worker transfer coefficients (EFSA, 2014)

4.1.3. Multiple applications

The effect of multiple applications on re-entry worker exposure is considered in the assessment. The DFR is the only parameter that is altered by multiple applications.

The DFR immediately following the n^th application (DFRn(a)) is estimated by assuming first order dissipation and using the following equation derived from the FOCUS guidance (FOCUS, 1997):

DFRn(a) = DFRsingle-application x (1-e^-nki)/(1-e^-ki)

Where

 n is the number of applications

k is the rate constant for foliar dissipation i is the interval between applications (days)

Crop Transfer coefficients for

workers not wearing gloves (cm²/hr)

Transfer coefficients for re- entry workers wearing gloves (cm²/hr)

Vegetables 2500 580

Ornamentals 5000 1400

Berries 3000 750

Fruit trees 4500 2250

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If k is unknown, the FOCUS default of 0.0693, corresponding to a half-life foliar of 10 days, is used (FOCUS Working Group on Surface Water Scenarios, 2003).

The reduction in DFRn(a) over time after last application is then given by:

DFRn(a)+t = DFRn(a) x e^-kt

where

 t is days since last application.

4.1.4. Risks to re-entry worker immediately after application

Risk to re-entry workers immediately after the final treatment is estimated using the following approach, which compares the predicted exposure to the AOEL.

The absorbed dose is calculated by:

DFRn(a) x C x D

Where

 C = TC x WR x AR/BW

 D = Dermal absorption

Therefore the risk to re-entry workers immediately after the final application is given by the following equation:

RQ = DFRn(a) x C x D/AOEL

4.1.5. Calculation of Re-Entry Intervals (REI)

The REI is determined as being the day when the exposure multiplied by the dermal absorption equals the AOEL, i.e.

DFRn(a)+t x C x D = AOEL

Substituting DFRn(a) x e^-kt for DFRn(a)+t, setting t as the REI (R) and rearranging the equation, gives:

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DFRn(a) x e^-kR x C x D = AOEL

e^-kR = AOEL/DFRn(a) x C x D

e^kR = DFRn(a) x C x D/AOEL

R = ln(DFRn(a) x C x D/AOEL)/k

5. Bystander exposure and risk

5.1.1. Default exposure parameters

The following exposure parameters can be changed by the user or, if they are not, default values obtained from overseas regulators (outlined here in brackets) will be used:

 Distance from the edge of the application area at which a toddler’s exposure will be estimated (8 m)

 Turf transferable residue grass (0.05) (EFSA, 2014)

 Turf transferable residue object (0.2) (EFSA, 2014)

 Transfer coefficients (2600 cm²/hr) (EFSA, 2014)

 Exposure duration (2 hrs) (EFSA, 2014)

 Toddler body weight (15 kg) (Chemicals Regulation Directorate, 2016a)

 Saliva extraction factor (0.5) (EFSA, 2014)

 Surface area of hands (20 cm²) (EFSA, 2014)

 Frequency of hand to mouth events (9.5 events)/hour ( EFSA, 2014)

 Ingestion rate grass (25 cm²/day) (EFSA, 2014)

 Ingestion rate soil (100 mg/day) (Chemicals Regulation Directorate, 2016a)

 Fraction of residue remaining in the soil (1) (USEPA, 2007b)

 Soil density factor (6.7 x 10^-4cm³/mg) (USEPA, 2007b)

5.1.2. Exposure calculations

The approach used estimates the exposure to contaminated residues of a toddler 8 m (default) away from the edge of the area to which the substance was applied (i.e. exposure is to surfaces on which spray has deposited; not through direct contact with the spray).

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Exposure is estimated using the equations from the European Food Safety Authority (EFSA) which account for dermal exposure, hand-to-mouth exposure and object-to-mouth exposure (EFSA, 2014). In addition, incidental ingestion of soil is taken into account using a modified exposure equation from the United States Environmental Protection Agency (USEPA) (USEPA, 2007b). These equations are all listed in Appendix C.

Dermal absorption is also factored into the dermal exposure assessment. In this case the dermal absorption value used is the value for the diluted spray. The same approach is used as for the operator exposure assessment in terms of using a default value (30 %) when specific data are not available and refining these based on physical chemical properties or data on oral absorption.

Spray drift is estimated using models specific to the type of application equipment. For pesticides applied by ground boom or airblast sprayer, the AgDrift model is used. The model is based on data from a series of field trials carried out in the United States (APVMA, 2009b) in which the percentage of the application rate

deposited is plotted against distance from the area of application. These deposition curves were taken from the Australian Pesticides and Veterinary Medicines Authority (APVMA) website (APVMA, 2010). For ground boom applications there are deposition data for the following scenarios which represent the 90^th percentile of the spray drift data collected:

 High boom (1.27 m above the ground) fine droplets

 High boom (1.27 m above the ground) coarse droplets

 Low boom (0.5 m above the ground) fine droplets

 Low boom (0.5 m above the ground) coarse droplets

For airblast application there are the following scenarios which represent the 95^th percentile of the spray drift data collected. These scenarios represent different types of orchard which have different foliage densities:

 Sparse orchard (Sparse orchards or small trees)

 Dense orchard (Citrus/tall trees)

 Vineyard

Spray drift deposition from aerial application is estimated using the AGDISP (v8.15) model along with appropriate New Zealand input parameters. The input variables for this modelling are shown in Appendix B.

The following options are available:

 Forestry herbicides (very coarse, coarse and medium droplets)

 Forestry insecticides/fungicides (very fine, fine and medium droplets)

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 Agricultural herbicides (very coarse, coarse and medium droplets)

 Agricultural insecticides/fungicides (very fine, fine and medium droplets)

For ground based applications the most appropriate value should be used. If there is any uncertainty the most conservative value should be used. If the applicant is able to produce an alternative spray drift deposition dataset which has been collected using international best practice and is considered to be acceptable, these data could be used for the exposure assessment.

For aerial application it should be easy to determine which scenarios are applicable based on a substance’s proposed use, however, if there is any uncertainty then the most conservative scenario should be used. The finest droplet size categories would be expected to produce the highest exposures and should be used in the absence of any other information.

5.1.3. Bystander risk

Risk is estimated by comparing predicted exposure to the Acceptable Operator Exposure Level (AOEL).

Although it could be argued that it is more appropriate to compare bystander exposures with an acute reference dose, it is possible that a bystander who resides adjacent to a treated area or who regularly walks around areas treated with plant protection products could receive repeated exposures. There is also the potential for bystanders to be ‘residents’ and have a longer-term exposure. Therefore the use of the default AOEL based on studies up to 90 days duration is considered to also be an appropriate health based exposure guidance value to be protective of bystanders (European Commission, 2006).

In the event of a substance being identified as posing a high risk through aerial application then more detailed spray drift modelling may be possible. The results of this additional modelling (spray drift deposition data) can then be used for the exposure assessment.

5.1.4. Buffer zone required to reduce the bystander exposure to the AOEL

Buffer zones are estimated based on the distance required to reduce bystander exposure to the AOEL, in a two-step process:

 The percentage of the application rate that would deliver an exposure equal to the AOEL is calculated.

 The distance at which this percentage is deposited is calculated.

5.1.5. Multiple applications and bystander exposure

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If it is known that multiple applications are intended the exposure is estimated immediately after the final application.

The following equation is used to calculate the concentration of the pesticide in soil and in grass after

multiple applications. This equation which assumes first order degradation is used to estimate the cumulative concentration in soil (FOCUS, 1997).

PECfinal = PECone application x (1- e^-nki) / (1-e ^–ki)

Where

 PEC = predicted environmental concentration

 n = number of applications

 k= ln2/ DT 50 (days) where DT50= foliar half life (days) for dermal, hand to mouth and object to mouth systemic exposure and DT50= soil half life (days) for the oral dose from soil on the day of application

 i= interval between two consecutive applications (days)

 e = constant= 2.718

The user needs to input information on ‘n’, ‘k’, ‘i’ and DT50 (foliage). Foliar half life will frequently not be

available. In such cases an assumption will be made that the foliar half is 10 days, which is the default value assumed in the European FOCUS (FOrum for Co-ordination of pesticide fate models and their Use) suite of environmental exposure models (FOCUS Working Group on Surface Water Scenarios, 2003).

6. Toddler exposure to a treated surface (recreational exposure)

The EPA estimate the direct exposure of a toddler to a surface (for example, a lawn or sports field) that has been treated with pesticides, referred to as recreational exposure. This uses the same approach as the bystander exposure assessment; apart from the fact that the spray drift variable is not considered (i.e. the equations in Appendix C are used without consideration of the drift factor).

As in the exposure of bystanders to spray drift residues, when calculating the risk of bystanders exposed directly to a treated area, a Risk Quotient (RQ) is estimated by dividing the predicted exposure by the AOEL.

7. Aquatic risk assessment

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The approach the EPA uses for aquatic risk assessment is not based on directly estimating a risk quotient value, but is based on determining what, if any, downwind buffer zones are required to produce an

acceptable concentration in a waterbody. This is done using the following approach. Firstly the concentration of pesticide that would result from overspraying a waterbody is estimated. The calculation is as follows:

Application rate (AR) [g a.i./ha])

≡ 0.1AR [mg a.i./m²]

Since 1 m³ contains 1000 litres, the concentration in the receiving water (C0) will be:

≡0.1AR x 100/(depth x 1000)

≡0.01AR/depth [mg/l]

Where

 AR is application rate

 depth is the depth of the receiving water in cm (default 30 cm).

This concentration is reduced by 3 factors:

 Degradation

 Partitioning to suspended solids

 Partitioning to sediment.

Degradation and partitioning are assumed not to occur on the day of application (Day 0) which is in accordance with the FOCUS model. Partitioning is assumed to occur within 24 h from Day 1, so the

concentration on Day 1 and beyond is pC0 where C0 is the concentration on Day 0 and p is the proportion in the water phase. The average concentration over the period of exposure is then given by:

C0(1+p(t-1))/t

where

 t is the number of days post-treatment.

 ‘p’ is calculated for sorption to suspended solids and sediment in Sections 7.1.1 and 7.1.2.

7.1.1. Suspended solids

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psusp-solids= 1/(1+(focsusp x Koc x suspwater x 10-6)) (ECB, 2003) Where

 focsusp is the fraction of organic carbon in the suspended solids (default 0.1 (ECB, 2003))

 Koc is the organic carbon normalised sorption value (l/kg)

 suspwater is the suspended solids concentration in water (default 15 mg/l (ECB, 2003))

 10^-6 is a units conversion (l/kg x mg/l to kg/kg)

Where Koc is unknown it can be estimated from the Kow value using the following formula from Seth et al.

(1999)

Koc = 0.35 x Kow

7.1.2. Sediment

psediment = water depth/(water depth + (Effective sediment depth x SBD x focsed x Koc)) (Focus steps 1 and 2, 2010)

Where

 water depth has a default of 30 cm (FOCUS, 2003)

 Effective sediment depth is the depth of sediment to which sediment will sorb (default 1 cm;

FOCUS, 1997)

 SBD is sediment bulk density (default 0.8; FOCUS, 2003))

 focsed is the fraction of organic carbon in the sediment (default 0.05; Focus steps 1 and 2, 2003)

 Koc is the organic carbon normalised sorption value.

7.1.3. Degradation

For degradation the average concentration over t days is calculated using the following formula (FOCUS, 2003)

C0 x (1-e^-kt)/kt

If it is assumed there is no degradation on Day 0, then the average concentration can be calculated as follows

(C0+(t-1)( C0 x (1-e^-k(t-1))/k(t-1)))/t

Therefore, the reduction in C0 due to degradation (pdeg)

= 1+d(t-1))/t

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Where

 k is the degradation rate constant (ln2/DT50)

 t is the averaging period

 d is 1-e^-k(t-1)/k(t-1)

The exposure concentration is then calculated as:

C = C0 x pdeg x psusp-solids x psediment x dilution

C can be viewed as a point estimate with no dilution within the receiving water, i.e. the concentration in a receiving water at a certain distance from the field. However, if it is assumed that there will be instantaneous mixing within the pond, C0 will also be affected by the width of the pond (dilution). The EPA approach considers the impact that dilution will have by considering the width of the water body. The default width is 50 m. If a point value is required (i.e. no account taken for dilution across the pond), the width of the pond needs to be set to 0.

The ratio of exposure concentration to effects concentration is then 0.01AR/(depth x LC50/Uncertainty factor¹) and the drift factor (the reduction in deposition that will give rise to a concentration in the receiving water equal to the LC50/Uncertainty factor) is the inverse of this ratio. The buffer zone delivering this reduction is estimated using the appropriate spray drift curve.

7.1.4. Multiple applications and aquatic assessment

Exposure of the aquatic environment following multiple exposures uses the same equation as for bystander exposure except that the aquatic half life (DT50 (aquatic))is used instead of the foliar or soil half life.. Extreme care should be taken when choosing which DT50 value to use. The ideal DT50 value to use is the degradation value for the whole system. If another value is used it must be ensured that double counting (i.e. using a DT50 value for water only and also separately accounting for portioning into sediment by using a Kd or Koc value) does not occur.

1 This varies from 10 for non-threatened species and 20 for threatened species.

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8. References

Aggarwal M, Fisher P, Hüser A, Kluxen FM, Parr-Dobrzanski R, Soufi M, Strupp C, Wiemann C, Billington R.

(2015) Assessment of an extended dataset of in vitro human dermal absorption studies on pesticides to determine default values, opportunities for read-across and influence of dilution on absorption. Regul Toxicol Pharmacol.72(1): 58-70. doi: 10.1016/j.yrtph.2015.02.017.

APVMA, Standard Spray Drift Risk Assessment Scenarios, Available online at http://archive.apvma.gov.au/archive/spray_drift/scenarios.php Accessed 11/01/2016

California Environmental Protection Agency, Guidance for the preparation of human pesticide exposure assessment documents, Available online at http://www.cdpr.ca.gov/docs/whs/pdf/hs1612.pdf Accessed 11/01/2016

Chemicals Regulation Directorate, Bystander Exposure Guidance, Available online at

http://webarchive.nationalarchives.gov.uk/20151023155227/http://www.pesticides.gov.uk/Resources/CRD/Mi grated-Resources/Documents/B/Bystand-expos-guidance.pdf Accessed 16/03/2016a.

Chemicals Regulation Directorate, Guidance for post-application (re-entry worker) exposure assessment.

Available at

http://webarchive.nationalarchives.gov.uk/20151023155227/http://www.pesticides.gov.uk/Resources/CRD/Mi grated-Resources/Documents/R/Re-entry-worker-guidance.pdf Accessed 16/03/2016b

Chemicals Regulation Directorate, PSD’s interpretation of the German Operator Exposure Model Available online using the following link

http://webarchive.nationalarchives.gov.uk/20151023155227/http:/www.pesticides.gov.uk/guidance/industries/

pesticides/topics/pesticide-approvals/pesticides-registration/applicant-guide/the-applicant-guide-completing- an-application-overview-for-operator-and-consumer-exposure.htm#quantitative

Accessed 16/03/2016c.

ECB (2003) Technical Guidance Document on Risk Assessment. Part II Available at

https://echa.europa.eu/documents/10162/16960216/tgdpart2_2ed_en.pdf Accessed 16/03/16

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EUROPOEM II project (2002) Post application exposure of workers to pesticides in agriculture, report of the re-entry working group. FAIR-CT96-1406.

European Commission (2006) Draft guidance for the setting and application of acceptable operator exposure levels (AOELs). SANCO 7531 - rev.10. Available at

http://ec.europa.eu/food/plant/pesticides/guidance_documents/docs/7531_rev_10_en.pdf Accessed 22/02/2016

European Food Safety Authority (2012) Guidance on dermal absorption. EFSA Panel on Plant Protection Products and their Residues (PPR). EFSA Journal 2012;10(4):2665 Available at

http://www.efsa.europa.eu/sites/default/files/scientific_output/files/main_documents/2665.pdf Accessed 19/01/2016

European Food Safety Authority (2014) Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment for plant protection products EFSA Journal 2014;12(10):3874 doi: 10.2903/j.efsa.2014.3874 Available at http://www.efsa.europa.eu/en/efsajournal/pub/3874 Accessed 11/01/2016

Forum for the Co-ordination of pesticide fate models and their Use (1997) Soil persistence models and EU registration: Available online at

http://ec.europa.eu/food/plant/protection/evaluation/guidance/soil_en.pdf Accessed 16/03/16

FOCUS Working Group on Surface Water Scenarios (2003) Focus surface water scenarios in the EU evaluation process under 91/414/eec SANCO/4802/2001-rev.2 final (May 2003)

OECD 2011 OECD Guidance notes on dermal absorption. Series on Testing and Assessment, No. 156.

ENV/JM/MONO(2011)36 http://www.oecd.org/chemicalsafety/testing/48532204.pdf Accessed 05/02/2016

Richardson B, Thistle HW (2006) Measured and predicted aerial spray interception by a young Pinus radiata canopy. Transactions of the American Society of Agricultural and Biological Engineering 49(1): 15-23.

Seth R, Mackay D, and Muncke J. (1999) Estimating of organic carbon partition coefficient and its variability for hydrophobic chemicals. Environ Sci Technol 33: 2390-4

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Teske, M.E. Bird, S.L. Esterly, D.M. Ray, S.L Perry, S.G. A user’s guide for AgDrift ® 2.0.05: A tiered approach for the assessment of spray drift of pesticides 2002.

USEPA, 2007b, Standard Operating Procedures (SOPs) for Residential Exposure Assessments, Contract No. 68-W6-0030, Work Assignment No. 3385.102

USEPA, 2007b Reregistration Eligibility Decision for Carbofuran; Available online at https://archive.epa.gov/pesticides/reregistration/web/pdf/carbofuran_red.pdf

Accessed 16/03/2016

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Appendix A Equations used for exposure assessment

Children’s dermal exposure

Systemic exposures via the dermal route will be calculated using the following equation (EFSA, 2014):

SE (d) = AR x DF x TTR x TC x H x DA BW

Where:

SE(d) = systemic exposure via the dermal route AR = field application rate

DF = spray drift value

TTR = turf transferable residues – the US EPA default value of 5 % will be used

TC = transfer coefficient – a value of 2600 cm²/h will be used for the estimate, this is to be consistent with the EFSA (2014) model

H = exposure duration for a typical day (hours) – this will be assumed to be 2 hours which matches the 75th percentile for toddlers playing on grass in the US EPA Exposure Factors Handbook

DA = percent dermal absorption (product specific or default value)

BW = body weight – 15 kg which is the average of UK 1995-7 Health Surveys for England values for males and females of 2 and 3 yrs

Children’s hand-to-mouth exposure

Hand-to-mouth exposures will be calculated using the following equation (EFSA, 2014):

SE(h) = AR x DF x TTR x SE x SA x Freq x H x OA BW

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Where:

SE(h) = systemic exposure via the hand-to-mouth route AR = field application rate

TTR = turf transferable residues – the US EPA default value of 5% derived from transferability studies with wet hands will be used

SE = saliva extraction factor – the default value of 50% will be used

SA = surface area of the hands – the assumption used will be that 20 cm² of skin area is contacted each time a child puts a hand in his or her mouth (this is equivalent to the palmer surface of three figures and is also related to the next parameter (Freq))

Freq = frequency of hand to mouth events/hour – for medium to long term exposures a value of 9.5 is used as per the EFSA (2014) model.

H = exposure duration (hours) – this will be assumed to be 2 hours (as above) OA = oral absorption (% enter as a fraction)

BW = body weight - 15kg (as above)

Children’s object-to-mouth exposure

Object to mouth exposures will be calculated using the following equation (EFSA, 2014):

SE(o) = AR x DF x TTR x IgR x OA BW

Where:

SE(o) = systemic exposure via mouthing activity AR = field application rate

TTR = turf transferable residues; the default value of 20% transferability from object to mouth assessments will be used. This is based on guidance from EFSA who used the same value as the USEPA (EFSA, 2014).

IgR = ingestion rate for mouthing grass/day – this will be assumed to be equivalent to 25cm² of grass/day (EFSA, 2014)

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OA = oral absorption (% enter as a fraction) BW = body weight - 15kg (as above)

Children’s incidental ingestion of soil

The approach that will used to calculate doses attributable to soil ingestion is (US EPA, 1997):

ADOD = AR (μg/cm²) x DF x F (cm) x IgR (mg/day) x SDF (cm³/mg) x OA BW (kg)

Where:

ADOD = oral dose on day of application (μg/kg/day) AR = field application rate

F = fraction or residue retained on uppermost 1 cm of soil (%) (Note: this is an adjustment from surface area to volume)

SDF = soil density factor - volume of soil (cm³) per milligram of soil IgR = ingestion rate of soil (mg/day)

OA = oral absorption (% enter as a fraction) BW = body weight (kg)

Assumptions (all come from the USEPA, 2007b):

F = fraction or residue retained on uppermost 1 cm of soil is 100 percent based on soil incorporation into top 1 cm of soil after application (1.0/cm)

IgR = ingestion rate of soil is 100 mg/day

SDF = soil density factor - volume of soil (cm³) per gram of soil; to weight 6.7 x 10^-4 cm³/mg soil) BW = body weight of a toddler is 15 kg (as above)

Total exposure

Total exposure will be calculated as the sum of the above equations:

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∑ Exposure = SE (d) + SE (h) + SE (o) + ADOD

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Appendix B Input variables used for the aerial AGDISP v8.15 modelling

Input variables for the Aerial Agricultural Fungicide/Insecticide scenario

Aircraft: FW Air Tractor AT-402B

 Wing semispan: 7.79 m

 Weight: 4000 kg

 Typical speed: 60 m/s

 Propeller RPM: 2000

 Propeller Radius: 1.33 m

 Biplane separation: 0

 Planform area: 26.02 m²

 Engines: 1

 Engine vertical: 0 m

 Engine forward: 4.35 m

 Engine Horizontal: 0 m

 Wing Vertical: 0.3622m

 Boom Vertical: - 0.38 m

 Boom Forward: - 0.3 m

 Release height: 3 m

 Swath width: 24 m

 Swath displacement: 2 m

 Droplet size: American Society of Agricultural and Biological Engineers (ASAE) Very Fine to Fine, ASAE Fine to Medium, ASAE Medium to Coarse

 Water rate: 20 l/ha

 Spraylines: 10

 Side slope angle: 0 degrees

 Canopy height: 0 m

 Active Fraction: 0.075

 Non volatile fraction: 0.075

 Boom length relative to wingspan: 73 %

 Number of nozzles: 60

 Wind Speed: 3 m/s

 Temperature: 210C

 Relative Humidity: 46 %

 Surface roughness: 0.005

 Atmospheric stability: Overcast

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Input variables for the Aerial Agricultural Herbicide scenario

Aircraft: FW Air Tractor AT-402B

 Wing semispan: 7.79 m

 Weight: 4000 kg

 Propeller RPM: 2000

 Propeller Radius: 1.33 m

 Biplane separation: 0

 Planform area: 26.02 m²

 Engines: 1

 Engine vertical: 0 m

 Engine forward: 4.35 m

 Engine Horizontal: 0 m

 Wing Vertical: 0.3622m

 Boom Vertical: - 0.38 m

 Boom Forward: - 0.3 m

 Droplet size: ASAE Medium to Coarse, ASAE Coarse to Very Coarse and ASAE Very Coarse to Extremely Coarse

 Spraylines: 10

 Side slope angle: 0 degrees

 Temperature: 210C

 Surface roughness: 0.005

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Input variables for the Aerial Forestry Fungicide/Insecticide scenario

Aircraft: Bell 206B JetRanger III

 Rotor radius: 5.08 m

 Weight: 1451 kg

 Rotor RPM: 274

 Boom vertical: -2.74 m

 Boom Forward: 1 m

 Droplet size: ASAE Very Fine to Fine, ASAE Fine to Medium, ASAE Medium to Coarse

 Spraylines: 10

 Sideslope angle: 20 degrees

 Temperature: 21 0C

 Canopy roughness : 1.4 m

 Canopy displacement: 7 m

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Input variables for the Aerial Forestry Herbicide scenario

Aircraft: Bell 206B JetRanger III

 Rotor radius: 5.08 m

 Weight: 1451 kg

 Rotor RPM: 274

 Boom vertical: -2.74 m

 Boom Forward: 1 m

 Swath width: 7.5 m

 Droplet size: ASAE Medium to Coarse and ASAE Coarse to Very Coarse, ASAE Very Coarse to Extremely Coarse

 Spraylines: 10

 Sideslope angle: 20 degrees

 Temperature: 21 0C

 Surface roughness: 0.0488 m

Appendix B: EPA Exposure Assessment