Non-dietary exposure – OPEX calculations (Operator / Worker / Bystander / Resident)

“Before Plant Protection Products [PPPs] are placed on the market, they are assessed to ensure they do not have any harmful effect on human health. One aspect of this risk assessment considers exposure via non-dietary routes, including inhalation, dermal absorption and ingestion.” (

HCP has specialist expertise in conducting OPEX calculations. This risk assessment ensures that PPPs are ‘safe’ for people when preparing and applying the PPP or when working with the treated crop following application.

Application of a PPP to a horticultural crop often differs to the application of the same PPP made to a broadacre arable crop. This means an OPEX evaluation needs to be conducted prior to an EAMU application being made.

The OPEX assessment is generally carried out for one of the following reasons:

  • Handheld application method. This is particularly relevant to ornamental crops, protected leaf vegetables and herbs, and to post-harvest applications. Also relevant to spot treating with herbicides.
  • Hand harvest. Horticultural crops are often harvested by hand, particularly fruit and cut flowers.
  • Protected crops. Exposure in a protected growing situation is likely to carry a higher potential risk than out-of-doors.
  • Ornamental crops. It is assumed that ornamental crops tend to be handled to a greater extent than most other crops.
  • Inclusion of mitigations. Gloves and worker clothing can mitigate against exposure and enable an authorisation.

On occasion EAMUs have been noted as being unusable due to the restrictions placed on the authorisation, i.e. non-entry periods, or full-cover workwear in a glasshouse for many weeks subsequent to PPP application.

HCP works closely with growers to ensure EAMU authorisations and associated PPE requirements are fit for purpose.

HCP also works closely with the GB regulator to effect beneficial changes to mitigation options.