Bystanders to commercial pesticide use

By rearranging this equation and incorporating Equation B.4, the re-entry interval (REI) is given by:

𝑅𝐸𝐼 =ln (𝐷𝐹𝑅𝑛(𝑎)𝐶𝐷 𝐴𝑂𝐸𝐿⁄ ) 𝑘

Equation B.8 If an applicant identifies that a risk quotient will be greater than one, then substance- or ingredient- specific information on the following parameters can be used to refine the risk assessment:

 dermal absorption

 DFR data

 DT50 foliar data

B.5.8. Alternative options considered

Please see section B.4.8 for reasons why the 2014 EFSA operator, worker, resident and bystander exposure model is not used.

where:

PEC = predicted environmental concentration following a single application SE(d) = systemic exposure via the dermal route

SE(h) = systemic exposure via the hand-to-mouth route SE(o) = systemic exposure via mouthing activity ADOD = soil ingestion oral dose on day of application

It is considered to be a suitable model for bystanders because it:

 estimates the exposure to a child (toddler) bystander as our most sensitive target human

 takes into account dermal exposure, hand and object to mouth activity (consistent with UK and EFSA approaches) and soil ingestion exposure (an addition based on the USEPA approach)

 allows the spray droplet size and height of application for the use pattern in New Zealand to be taken into account with the spray drift.

The four elements that make up the model in Equation B.9 are calculated using the following EFSA and USEPA equations:

𝑆𝐸(𝑑) =(𝐴𝑅)(𝐷𝐹)(𝑇𝑇𝑅)(𝑇𝐶)(𝐻)(𝐷𝐴) 𝐵𝑊

Equation B.10 𝑆𝐸(ℎ) =(𝐴𝑅)(𝐷𝐹)(𝑇𝑇𝑅)(𝑆𝐸)(𝑆𝐴)(𝐹𝑟𝑒𝑞)(𝐻)(𝑂𝐴)

𝐵𝑊

Equation B.11 𝑆𝐸(𝑜) =(𝐴𝑅)(𝐷𝐹)(𝑇𝑇𝑅)(𝐼𝑔𝑅_𝑔)(𝑂𝐴)

𝐵𝑊

Equation B.12 𝐴𝐷𝑂𝐷 =(𝐴𝑅)(𝐷𝐹)(𝐹)(𝐼𝑔𝑅𝑠)(𝑆𝐷𝐹)(𝑂𝐴)

𝐵𝑊

Equation B.13 where:

AR = field application rate BW = body weight

DA = percent dermal absorption DF = spray drift value

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

Freq = frequency of hand to mouth events H = exposure duration for a typical day IgRg = ingestion rate for mouthing grass/day IgRs = ingestion rate of soil

OA = oral absorption (fraction) SA = surface area of the hands

SDF = soil density factor = volume of soil (cm³) per milligram of soil SE = saliva extraction factor

TC = transfer coefficient

TTR = turf transferable residues.

If it is known that multiple applications are intended, the exposure is estimated immediately after the final application, with the concentration of the pesticide in soil and grass calculated using Equation B.14, which assumes first-order degradation to estimate the cumulative concentration in soil (FOCUS, 1997):

𝑃𝐸𝐶𝑚𝑢𝑙𝑡𝑖𝑝𝑙𝑒 = 𝑃𝐸𝐶𝑠𝑖𝑛𝑔𝑙𝑒(1 − 𝑒^{−𝑛𝑘𝑖} 1 − 𝑒^−𝑘𝑖)

Equation B.14 where:

PECmultiple = predicted environmental concentration after several applications n = number of applications

I = interval between two consecutive applications (days) k = ln2/DT50 (days)

DT50 = foliar half-life (days) for dermal, hand to mouth and object to mouth systemic exposure and soil half-life (days) for the oral dose from soil on the day of application.

B.6.3. Assumptions and uncertainties

A toddler is assumed to be exposed to all of the spray that is deposited on a surface. This could potentially overestimate exposure as it assumes spray stays on the surface where it is applied and there is no

dissipation before or during exposure. The toddler is also assumed to be in contact with the sprayed surface for two hours a day and will be exposed multiple times.

Risks to bystanders are calculated 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 also considered to be an appropriate health- based exposure guidance value to be protective of bystanders (EC, 2006).

The assumptions for decay curves, wind direction and particle sizes are the same as for the spray drift refinements in C.3 and C.4.

B.6.4. New Zealand specific parameters

For aerial pesticide applications, the applicant is required to provide New Zealand specific parameters, from which spray drift values (DF) are derived. These are discussed in more detail in section C.4, and the aircraft parameters previously used by the EPA are summarised in Table C.5.

B.6.5. Default values

The parameter values in Table B.8 are used as defaults in the bystander assessment. Substance (or active ingredient) specific foliar half-lives should be used when they are available.

Table B.8 Bystander assessment default parameter values

Parameter Value Source

Distance from the edge of the application area at which a toddler’s exposure will be estimated

8 m Lloyd & Bell (1983)

Turf transferable residue grass 0.05 EFSA (2014)

Turf transferable residue object 0.2 EFSA (2014)

Transfer coefficients 2,600 cm²/hr EFSA (2014)

Exposure duration 2 hr EFSA (2014), USEPA (2011) ⁽¹⁾

Toddler body weight 15 kg ⁽²⁾ Chemicals Regulation Directorate

(2016c)

Saliva extraction factor 0.5 EFSA (2014)

Surface area of hands 20 cm^{2 (3)} EFSA (2014)

Parameter Value Source Frequency of hand to mouth events 9.5 events per hour EFSA (2014)

Ingestion rate grass 25 cm²/day EFSA (2014)

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

Fraction of residue retained on

uppermost 1 cm of soil 1 USEPA (2012)

Soil density factor 6.7 x 10^-4 cm³/mg USEPA (2012)

Dermal absorption 0.3 ⁽⁴⁾ Aggarwal et al. (2015)

Foliar half life 10 days FOCUS (2003)

(1) 75th percentile for toddlers playing on grass in the USEPA Exposure Factors Handbook, 2011. (2) Average of UK 1995-7 Health Surveys for England values for males and females of 2 and 3 years. (3) Skin area is contacted each time a child puts a hand in his or her mouth, equivalent to the palmar surface of three figures. (4) Dermal absorption value for a diluted spray (see section B.3 and Table B.1).

B.6.6. Model outputs

The output of the model used is the combined exposure value from Equation B.9.

B.6.7. Risk

The risks to bystanders adjacent to a treatment area immediately after the final treatment are estimated by calculating a risk quotient (RQ) comparing the modelled exposure to the Acceptable Operator Exposure Level (AOEL):

𝑅𝑄 = 𝑃𝐸𝐶

𝐴𝑂𝐸𝐿=𝑆𝐸(𝑑) + 𝑆𝐸(ℎ) + 𝑆𝐸(𝑜) + 𝐴𝐷𝑂𝐷 𝐴𝑂𝐸𝐿

Equation B.15 The results of this additional modelling (spray drift deposition data) can then be used for the exposure

assessment.

A buffer zone can protect bystanders by increasing the distance between the treatment area and the bystander and so reduce the bystanders’ exposure. This is 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.

More information on buffer zones is provided in sections C.3 and C.4.

B.6.8. Alternative options considered

Please see section B.4.8 for reasons why the 2014 EFSA operator, worker, resident and bystander exposure model is not used.