Dermal and Inhalation Exposure of Workers during Control of Oak Processionary Moth (OPM) by Spray Applications

The caterpillars of the oak processionary moth (OPM) form stinging hairs, which release an irritant poison. They cause skin and eye irritation and sometimes even breathing difficulties and allergic reactions. OPM is mainly controlled by spraying insecticides. Insecticides applied for protection of human health must be authorized under the Biocidal Products Regulation (BPR) (EU) No 528/2012. In order to assess safety of professional use, which is a key requirement for the authorization, a risk assessment based on exposure estimation has to be performed. However, no exposure data specific for OPM control was available until now. Existing models for agricultural spray applications such as Agricultural Operator Exposure Model cover different spray patterns and equipment and were therefore considered too unreliable for assessment of OPM control.

We have studied dermal and inhalation exposure of certified pest control operators resulting from spraying DimilinTM 80 WG suspensions with vehicle-mounted spraying (VMS) and with handheld spraying (HHS) devices for control of OPM. Exposure resulting from these applications, from weighing and portioning of the granular product and from cleaning of contaminated spraying devices was studied. Dermal exposure was investigated by whole body dosimetry using disposable chemical protective coveralls and cotton gloves as samplers. Inhalation exposure was measured using personal air samplers. The active substance diflubenzuron was quantified by gas chromatography-mass spectrometry with positive chemical ionization and by high-performance liquid chromatography for dermal and inhalation measurements, respectively.

The exposure was dominated by the dermal pathway. HHS results in considerably higher operator exposure than VMS. Comparison with data from typical agricultural spraying applications revealed that OPM control results in much higher exposure of operators for both, vehicle-mounted and handheld equipment.

Comprehensive data on potential dermal and inhalation exposure is presented in this article, along with typical figures for handled and applied amounts of product and respective task durations. This data is suitable for risk assessments in regulatory frameworks such as the European BPR.