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Guidance Document Reviewing the Data Currently Used to Estimate

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					Guidance Document Summarising Data Currently Used to Estimate
Exposure to Operators through Inhalation or Hand Exposure When
Mixing/Loading Plant Protection Products

This guidance describes:

         The origins of the data currently used in UK Predictive Operator
         Exposure Model (UK POEM) to estimate exposure during the mixing
         and loading of pesticides.

         Values from other data used with UK POEM to predict exposure from
         mixing and loading solid formulations, including German model data,
         data from the EUROPOEM database and from the US Pesticide
         Handlers Exposure Database (PHED).
Introduction
Liquid formulations
The data in UK POEM for estimating dermal exposure when mixing/loading liquid
formulations are shown below (see section 2, tables 1 and 2). The guidance
document „Estimation of Exposure and Absorption of Pesticides by Spray
Operators‟ (SC8001) provides further information on the use of this data.
For liquid formulations of low volatility it has been determined that the amount of
active substance entering the breathing zone is generally below the limit of
determination.1 Therefore these mixing /loading data relate to non volatile
formulations and provide only measurements of hand contamination

Solid formulations
There are no data in UK POEM for mixing/loading solid formulations. Hence, the
exposure values utilised in the current version of UK POEM for dermal and
inhalation exposure when mixing and loading solid formulations are 75 th
percentile surrogate values (or maximum values for small data sets i.e. less than
10 data of measured values) taken from the German model (BBA (1992) Uniform
Principles for Safeguarding the Health of Applicators of Plant Protection
Products).

A comparison of the German model mixing and loading data with data available
within EUROPOEM and the US Pesticides Handlers Exposure Database (PHED)
has resulted in the identification of 2 new values for inhalation exposure when
mixing/loading a WG and WP formulation for vehicle mounted application. These
values are summarised below.

A detailed summary of the comparison of the data previously utilised from the
German model data with the respective EUROPOEM and PHED datasets is
available from PSD upon request.




1
    Lloyd G.A. (1979) “Developments in Personal Protection” Proceedings of the British Crop
         Protection Conference - Pests and Diseases p 821.
1       Liquid Formulations

Single-trip containers

Data from UK POEM on levels of hand contamination resulting from pouring
operations using various types of pesticide containers are summarised in Table 1
and Table 2, below. Further information on the effect of pack size and design on
operator exposure during mixing and loading can be found in PSD‟s operator
exposure guidance on packaging.

Levels of hand contamination when handling the concentrate are affected by:
           the number of containers that must be opened and used (this is
           influenced by the size of the container, the application rate of the
           product, the size of the area to be treated and/or the tank capacity of
           the application equipment); and
           the level of hand contamination arising from each container pouring
           operation (this is influenced by the capacity and neck diameter of the
           container).

Table 1     Levels of hand contamination resulting from individual pouring
            operations using containers with narrow neck diameters (< 45 mm).

   Container capacity (litres)      Hand contamination (ml of formulation/pouring operation)*
              1**                                               0.01
               5                                                0.20
              10                                                0.50
              20                                                0.50
*       These values, based on tracer studies under laboratory conditions, represent the
                                                   th
        upper limit of the class containing the 75 percentile measurement. Measurements
        were taken when pouring the entire contents of the container directly into a simulated
        sprayer tank (induction hoppers were not used). The monitored tasks did not involve
        the removal of secondary (induction) seals or the rinsing of containers and closures.
**      The value for 1 litre containers is currently used for smaller containers for the
        professional users. See separate section below for the corresponding values for
        amateur users.



Table 2     Levels of hand contamination resulting from individual pouring
            operations using containers with wide neck diameters (45 mm and 63
            mm closures*).

Container capacity (litres)     Hand contamination (ml of formulation/pouring operation)**
      1 all designs***                                      0.01
        2 all designs                                       0.01
5 wide neck 45mm or 63mm                                    0.01
    10 wide neck 45 mm                                      0.10
     10 wide neck 63 mm                                              0.05
   20 litre wide neck 63 mm                                          0.05
*         The „45 mm‟ and „63 mm‟ measurements refer to standard closure sizes for screw
          caps, not the inner diameter of the container neck (which will be smaller).
**        These values, based on tracer studies under laboratory conditions, represent the
                                                      th
          upper limit of the class containing the 75 percentile measurement. Measurements
          other than those for the wide neck 20 litre container were taken when pouring the
          entire container contents directly into a simulated sprayer tank (induction hoppers
          were not used). In subsequent studies for 5 and 10 litre containers, measurements
          were taken during part pouring operations (i.e. dispensing several sequential doses
          from a single container): in this situation, levels of hand contamination were lower than
          the values reported above. Measurements for the wide neck 20 litre container were
          taken when pouring both the entire contents of the container and incremental aliquots
          into an induction hopper (pouring into the top of the sprayer tank was not considered
          for this large container). In practice, it may be difficult to manipulate 20 litre containers
          when using induction hoppers, especially when attempting to use integrated pressure
          rinsing devices (which may not be fully effective on containers of greater than 10 litres
          capacity). The monitored tasks did not involve the removal of secondary (induction)
          seals or the rinsing of containers and closures.
***       The value for 1 litre containers is currently used for smaller containers for the
          professional users. See separate section below for the corresponding values for
          amateur users.



When filling certain types of application equipment, for example, the narrow-
necked reservoirs used with some spot guns and CDA lances, levels of operator
contamination may be higher than those predicted on the basis of the pouring
data summarised above.

Closed transfer systems

Although various „closed transfer systems‟ (CTS) are available for use with
single-trip containers, Studies commissioned by PSD demonstrate that some of
these systems may not result in reduced levels of operator contamination when
handling the pesticide. In particular, systems that require adaptors to be
connected to, and removed from, individual pesticide containers may
occasionally result in higher levels of contamination than those arising from
conventional open pouring operations. Therefore, it is not currently considered
appropriate to reduce the exposure estimates predicted by the UK POEM when
estimating the level of exposure resulting from the use of „closed transfer
systems‟ for single-trip containers.


Amateur use

In the case of the amateur user, measurements of hand contamination have
been obtained from studies conducted using a range representative pesticide
products approved for home and garden use. Results of these studies are
available in the following reports PA1722 & PS2007. The results from these
studies confirmed that the design of the measuring device and the presence of
the secondary seal were the most critical features that influence the risk of
exposure to pesticides used in the home and garden. As a result of the findings
from these studies, UK POEM has been updated with the following new values
for liquid concentrate handling:
          Home garden, in-cap measure 1 ml per pouring operation
          Home garden, separate measure 0.1 ml per pouring operation
          Home garden, integral squeeze-to-fill measure 0.01 ml per pouring
          operation
Further information is available from the respective guidance documents on
amateur use and packaging for home and garden pesticides.


Solid Formulations
The exposure values previously utilised in UK POEM for dermal and inhalation
exposure when mixing and loading solid formulations are 75th percentile
surrogate values (or maximum values for small data sets) taken from the German
model (BBA (1992) Uniform Principles for Safeguarding the Health of Applicators
of Plant Protection Products). A comparison of the German model data with data
available within EUROPOEM and the US Pesticides Handlers Exposure
Database (PHED) has been made.

A comparison of the German model mixing and loading data with data available
within EUROPOEM and the US Pesticides Handlers Exposure Database (PHED)
has resulted in the adoption of new values for inhalation exposure when
mixing/loading a WG and WP formulation for vehicle mounted application. These
values are summarised below.

A detailed summary of the comparison of the data previously utilised from the
German model data with the respective EUROPOEM and PHED datasets is
available from PSD upon request.

  Table 3 Summary of inhalation and hand exposure data for mix/load of
WG/WP formulations for application with vehicle mounted/hand-held equipment

                                WG                                 WP
                  Vehicle mounted     Hand-held      Vehicle mounted     Hand-held
                    equipment         equipment        equipment         equipment
   Inhalation
                      0.0358            0.0628           0.21               1.534
   exposure
                 (EUROPOEM data)     (German data)    (PHED data)       (German data)
  (mg/kg a.s.)
 Hand exposure         5.72              171.4           13.6               171.4
  (mg/kg a.s.)     (German data)     (German data)   (German data)      (German data)

				
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