A new methodological guide to developing reference values

The chemicals we may be exposed to on a daily basis or through our occupational activities can have adverse health effects. To safeguard human health, ANSES develops various reference values that should not be exceeded. In order to standardise and update the methods used to set these values, ANSES has published a new methodological guide. This document is intended for anyone involved in the development, selection and use of reference values. To mark its publication, Aurélie Mathieu and Fatoumata Sissoko, ANSES’s expert appraisal coordinators, discuss the guide’s objectives, content and key changes.

What do we mean by reference values?

Aurélie Mathieu: There are two main types of reference values: health reference values and populational internal exposure levels.

Health reference values (HRVs) all have one thing in common: they establish a link between exposure to a chemical agent and occurrence of an adverse health effect. They are based solely on health criteria. ANSES develops several types of HRVs depending on the populations concerned and the exposure settings:

for the general public: toxicity reference values (TRVs), indoor air quality guide values (IAQGVs), health-based guideline values for drinking water (DW HBGVs), health-based indoor settled dust guidelines (ISDGs);
for the occupational population: occupational exposure limits (OELs) and biological limit values (BLVs) for the biological monitoring of occupational exposure (BMOE).

ANSES also recommends populational internal exposure levels determined from the results of studies such as Esteban or ENNS. These values are based on measurements taken from biological samples such as blood, hair or urine. They are used to monitor the internal biological exposure of the general public or workers to chemical agents.

How are these reference values then used?

Fatoumata Sissoko: Certain reference values are used in health risk assessments and assist the public authorities in implementing risk management measures. The public authorities also use some of them to set regulatory limits to prevent chemical risks in the course of our occupational activities or associated with the quality of indoor air or drinking water.

For certain values, ANSES specifies the measurement methods that are technically applicable. The methodology used to assess the measurement methods is described in a report that has just been updated.

How does ANSES establish reference values?

Aurélie Mathieu: Reference values are developed by ANSES as part of a process of collective expert appraisal, which ensures the independence, transparency and impartiality of the work carried out. This means that these values are discussed and then validated by multidisciplinary expert groups, on the basis of the most robust and up-to-date scientific knowledge.

For each chemical agent studied, the experts compile the available data on its health effects and analyse them in depth. The values are then calculated using methods that may vary depending on the type of reference value in question.

Why was it necessary to publish a new guide to developing reference values?

Fatoumata Sissoko: ANSES is the reference body in France for developing health reference values.

Up until now, ANSES had produced several methodological guides, often specific to a particular type of value. We have now compiled all the methods into a single guide. This has enabled both the harmonisation of the methods used to establish these values and the updating of practices by incorporating recent developments in scientific knowledge.

What are the main new features of this guide?

Aurélie Mathieu: This new guide incorporates several major methodological developments. It improves how epidemiological studies are taken into account, includes the latest European and international recommendations on modelling – particularly regarding the dose-response relationship – and clarifies the methods for collecting data and conducting literature reviews.

For the first time, it also recommends a method specifically for establishing health-based indoor settled dust guidelines (ISDGs), a new type of value developed by ANSES.

Who is this methodological guide intended for?

Fatoumata Sissoko: This guide is intended for ANSES staff and experts working in risk assessment, as well as for all stakeholders who use or rely on reference values: public decision-makers, government departments, consultancy firms, manufacturers, occupational physicians and occupational health and safety experts, as well as anyone involved in environmental and health monitoring. It ensures that they can correctly interpret and apply the various recommended values.

Find out more

View the methodological guide to developing reference values (PDF in French)