Services in Human Risk Assessment

The people who have to be the subject of a risk evaluation are very different from each other:

• Direct users of products, their names depend on the regulation: operators (pesticides); industrial, professional or non-professional users (biocides); workers (REACH).
• Indirectly exposed people : workers during re-entry, bystanders or residents (pesticides); industrial, professional users and general public (biocides); consumers (REACH).

A risk assessment can be done under various contexts :

• Preliminary evaluation during the development of new substances and/or new products. This evaluation allows refining the characteristics and uses of the product (e.g. the table of GAPs for pesticides) in order to conduct all the studies necessary to the building of the most relevant dossier for registration or renewal of this substance/product.
• Regulatory evaluation for the writing of a dossier to place or renew a product authorization according to the most recent formats and guidance documents.

When a human exposure evaluation has to be refined for one or several population(s), all the possible tools are considered to try satisfying at best the regulatory requirements for a substance/product/scenario combination.

According to the type of product, to the target, to the mode of application, the exposure levels are calculated on the basis of models. For pesticides, biocides and products regulated under REACH, the respective regulations are taken into account. The types of populations and the relevant models are also adjusted.

Exposure assessment using models

The calculation models which are available to evaluate the exposure of a person to substances/products seem to be easily accessible to everyone. This is true for some classical scenarios when the evaluated product contains a substance of low toxicity. Then calculating an acceptable risk is easy.

However, as soon as the scenario for a product is less common or when no relevant calculation model exists and/or when the acceptable dose level is low for a substance, obtaining an acceptable risk becomes tricky.

Refinement of an assessment

To refine the calculations, several ways are possible. The strategy to be followed to choose the best approach requires a level of expertise higher than for a basic exposure assessment.

In addition to the use of personal protective equipment and the use of data/models from other regulations, it can be necessary to generate specific measurements, on a case-by-case basis: dermal absorption, dislodgeable residues, field exposure studies… These studies must be conducted by approved and competent CROs.

Study monitoring

Monitoring of those studies is critical. If nobody in your company has the skill or the availability for an efficient monitoring, Isabelle Thouvenin can do it for you and can help selecting an appropriate CRO. Next she is able to monitor the work done at the chosen CRO from the study design until the report signature in order to obtain a high quality and relevant study report by the deadline initially determined.

Modelling

Isabelle Thouvenin built the French exposure models in amateur gardens and in amenities (in cooperation with working groups gathering industrials and officials). She was also involved in the building of the Southern European Greenhouse model from ECPA and of the seed treatment model from the SeedTropex task force. 

Then, in addition to a very good knowledge of many risk assessment models, the building and the update of models, including the discussion with European competent authorities, appear amongst the proposed valuable services. All these services are applicable mainly to pesticides and biocides but also to products falling within other regulations (in particular REACH).

You would be getting the experience of a hands-one consultant who has delivered more than 30 major human exposure (OpEx) studies since 2003. With a few exceptions, the measurements were related to products falling within the pesticide regulations.

Examples of field studies include:

• Operators or workers (re-entry) in various outdoor crops (cereals, grapes…)
• Operators, bystanders in seed treatment factories (maize, oilseed rape, sugar beet…)
• Operators in private gardens (non-professional exposure)
• Operators in amenities (professional exposure)
• Operators in empty buildings (silos)
• Fumigation (exposure of operators, bystanders, residents and workers)
  • Indoors (Greenhouses, Containers)
  • Outdoors (Fields).

Isabelle Thouvenin has the expertise to be your single point of contact for all the studies of this type. The methodological experience gained in situations cited above is applicable to other products like biocides for which some very different scenarios will require the generation of exposure measurements to obtain an acceptable risk.

Then we are able to conduct any exposure study for you, including:

• Developmental studies
• Regulatory studies conducted according to Good Laboratory Practices (GLP)*.

The methodology is generally using passive dosimetry (dermal and/or by inhalation) or using urinary biomonitoring; it depends on the properties of the measured substance. Potential and/or actual exposure can be measured according to the objectives of the study.

There exists a very general framework to conduct exposure studies provided in the OCDE/GD(97)148 guidance document. The design of a study on the basis of this framework allows for many options of measurements and situations. Isabelle Thouvenin, your specialist in risk assessment, offers to consider the study design which is the most appropriate to meet your needs.

* Direction of GLP studies: exposure studies to products are applicable to many situations: seed treatment, empty building treatment, fumigation in containers, fields or greenhouses; agricultural or non-agricultural uses, mechanized or manual… The measurements include external dermal dosimetry (mainly whole-body dosimetry), inhalation exposure and/or urinary biomonitoring. Almost all studies are conducted according to the Good Laboratory Practices (GLP) to meet regulatory requirements. Within this GLP framework, Isabelle Thouvenin uses to work with Staphyt acting as Test Facility and she calls upon various laboratories for the analytical phase of those studies, according to the sponsor requests and to specific needs of each study.