Page 8 - Volume 2, Issue 1, January 2009

Glass and Machera

6

PPE contamination would be a factor to be

taken into account when selecting appro-

priate PPE to be worn for a particular pes-

ticide application task. Therefore, imperme-

able coveralls (e.g. CE marked Type 3 or Type

4 garments) should be worn for certain tasks

involving hand held application techniques.

However, in reality the climatic conditions in

Southern Europe make the wearing of such

PPE difficult. Therefore the types of cover-

alls worn by pesticide applicators tends to

be constructed of permeable material such

as cotton or cotton/polyester mixtures.

Working patterns in different regions of EU

In using models or evaluating data from

operator exposure studies the working pat-

terns typical for the region where the pes-

ticide is to be used need to be considered.

For mechanised applications such as tractor

mounted or trailed boom sprayers the oper-

ator can be expected to work longer hours

than a manual application, and treat much

larger areas. Table 1 shows the default val-

ues of the three models.

As the common acceptance directive is

developed, there is likely to be greater ten-

dency for pesticides to be approved for use

over more than one country, which provides

another uncertainty factor into the risk as-

sessment. For example, in the studies pub-

lished by Glass

et al.

(2002), the working pat-

terns in southern Spain were very different

from those in Greece or Portugal, in terms

of the length of the working day, types of

application equipment used and the pro-

tective clothing worn.

Derivation of the AOEL and Risk Assess

ment

The AOEL is “the maximum amount of

the active substance to which the operator

may be exposed without any adverse health

effects”, as defined in Annex VI to Directive

91/414/EEC. In this definition, “operators”

are represented by mixer/loaders, applica-

tors and re-entry workers, but the term may

be extended to include non-occupational

exposed groups (bystanders). The AOEL is

based on the highest level at which No Ad-

verse Effect (NOAEL) is observed in tests of

the most sensitive relevant animal species.

To translate the NOAEL values into an AOEL,

assessment factors accounting for uncer-

tainties in extrapolation from toxicity data

to the exposed human population are ap-

plied. Often, the AOEL values relate to the

internal (absorbed) dose available for sys-

temic distribution from any route of absorp-

tion and expressed as internal levels (mg/kg

body weight/day) (AOEL systemic). Thus, de-

pending on the route specific NOAEL (oral,

dermal, inhalation), the degree of oral/der-

mal/inhalation absorption should be con-

sidered in the correction of the AOEL and

the estimation of AOEL systemic.

Following the setting of the systemic

AOEL, a comparison to the estimated dose

of exposure is performed. The systemic dose

of exposure is the sum of the exposure from

the dermal route, corrected for the degree

of dermal absorption and the exposure from

the inhalation route considering 100% ab-

sorption of the inhaled amount. The exam-

ined PPP is considered to be safe for the op-

erator for the specific application scenario,

when the systemic dose of exposure is low-

er than the systemic AOEL.

Discussion

There is a number of factors to consider

when using predictive operator exposure

Table 1.

Standard daily work rates for agriculture used for the models (Kangas & Sihvonen

1996).

Application method

UK

Dutch

German

Tractor, downward application 50 ha

10 ha

20 ha

Tractor, upward application

30 ha

6 ha

8 ha

Hand-held equipment

1 ha (or 400 L spray dilution)

1 ha