Bruno Le Bizec
Towards a broader view of the consumer chemical exposome Strategies and Technical solutions

Long-term management of human health requires a comprehensive understanding of the environmental influences that affect it. To achieve this, there is a need for comprehensive, high-quality data on exposure in order to study the causes of certain diseases in humans and thus manage situations more effectively. Food is one of the major routes by which humans are exposed to chemical substances; whether they are of natural or synthetic origin, intentionally produced or not, they are hazards that can enter the food chain at different levels and, depending on their toxicity and levels of exposure, pose a risk to consumers.
While some substances have been well known for decades (e.g. mycotoxins, heavy metals or dioxins), others have been identified more recently as presenting a food-related risk, such as perfluorinated compounds or chloroparaffins. It is therefore accepted that a considerable number of additional substances likely to present a risk to human health are present in the food chain, even though they have not yet been described. The total number of substances of concern of human or natural origin already assessed, regulated or monitored is small compared to the 105 industrial chemicals described as being in use.
In addition, several hundred new chemical substances are produced each year due to rapid innovation in the chemical industry or new processing trends. This facet of the human chemical exposome has stimulated methodological research capable of revealing these substances. Several strategies are being deployed by laboratories to solve the particular problem of detecting emerging contaminants in the food chain. The first focuses on substances that are already known or have recently been described, and aims to develop effective analytical approaches for objectively identifying the presence of these contaminants in foodstuffs and measuring their concentration levels in order to help characterise consumer exposure.
The second of these approaches explores emerging issues in a more global way, using research strategies based on particular chemical motifs (e.g. halogen-driven data processing), specific effects (e.g. involving metabolomics) or the modelling of probable structures. The innovative analytical strategies implemented as part of these two approaches will be detailed in order to illustrate the identification of emerging hazards in the food chain with the aim of broadening knowledge of consumer chemical exposure.

Frans Verstraete
EU Policy on contaminants in food: Recent developments and outlook

The EU legislation on contaminants Council Regulation (EEC) No 315/93 of 8 February 1993 provides that food containing a contaminant in an amount which is unacceptable from the public health viewpoint shall not be placed on the market (food can only be placed on the market when it is safe). Furthermore, it is foreseen that contaminant levels shall be kept as low as can reasonably be achieved by following good practices at all stages of the production chain and in order to protect public health, maximum levels for specific contaminants shall be established where necessary.
In recent years, regulatory levels for several contmainants have been established and updated and this to take account of the outcome of risk assessments performed by the European Food Safety Authority (EFSA). The maximum levels are established in Commission Regulation (EU) 2023/915 of 25 April 2023 on maximum levels for certain contaminants in food and repealing Regulation (EC) No 1881/2006. Despite these frequent updates to the EU contamaints legislaiton, there is still a lot of work ahead!
In the presentation, recent and future developments on EU legislation on contaminants in food shall be presented. Climate change, changes in dietary patterns, novel/new foods, Green deal policies (Farm to Fork strategy, Biodiversity strategy), circular economy etc entail new challenges for the safety of the food chain. In addition, in order to continue to ensure a high level of food safety it is necessary not to address single contaminants individually but also address more attention to the combined exposure to multiple contaminants. In addition, particular attention shall be paid to the analytical requirements and analytical challenges for an effective EU policy on contaminants in food. Indeed, for an effective risk management and enforcement, it is not only sufficient that a method of analysis is available, but the method of analysis must be able to be used for routine control, be reliable, sensitive, quick and preferably cheap.

Akobuije Chijioke, Richard A. Allen, Steven E. Fick, Benjamin J. Reschovsky, Jared H. Strait, Randall P. Wagner
Primary sound standard based on dynamic Fabry-Pérot refractometry

We describe an optical sound standard in which the sound pressure is measured by using a high-finesse optical cavity to observe the induced change in the refractive index of the medium (acousto-optic effect). The optical refractive index of a substance varies with density, and for a compressible substance it will therefore vary in time in an acoustic field. To accurately measure the refractive index changes due to acoustic density variations, we enhance the induced optical phase shifts using a high-finesse optical cavity. By tracking the shift in the optical cavity resonance frequency we sensitively track the shift of the refractive index of the cavity medium and thereby the acoustic pressure in the cavity. We perform the optical measurement at standard telecom wavelength (1550 nm), thereby minimizing the cost of the optoelectronic components required. We report initial measurements in an acoustic resonator, comparing the pressure indicated by the optical cavity to the pressure indicated by a condenser microphone, at 1 kHz and 2 kHz acoustic frequencies.

W. Sabuga
Recent research results on piston gauges

Since the end of 20th century, a big progress has been achieved in the pressure metrology based on piston gauges. It includes a significant reduction of measurement uncertainty, an extension of the measurement range to lower pressures for piston gauges used as primary pressure standards and new measurement techniques for different pressure types. The paper gives a review of this progress with presenting main new approaches applied and results achieved.

A. Rezki, Z. Silvestri, D. Bentouati, J.-P. Wallerand, C. Guianvarc’h, M. Himbert, P. Otal
Status and performance of the LNE-Cnam Fabry-Perot refractometer

We present the status of the single-cavity Fabry-Perot interferometer developed at the LNE-Cnam laboratory used for thermodynamic pressure measurements within the range of 100 Pa to 100 kPa. After characterizing the intrinsic parameters of the refractometer, this optical sensor is used to measure the refractivity of nitrogen. Then, using the Lorentz-Lorenz equation and knowing the refractive virial coefficients at 532 nm, it is possible to deduce its density. Measuring the temperature of the gas makes it possible to determine its pressure using an equation of state.
Once the temperature and pressure stability of the gas inside the optical sensor have been achieved at sub-mK and mPa levels, respectively, the expanded uncertainty of the sensor is evaluated to be [(𝟓𝟎 𝐦 𝐏𝐚 )^𝟐 + (𝟐𝟐 × 𝟏𝟎^−𝟔 ∙ 𝒑)^𝟐 ]^(𝟏/𝟐). In order to further decrease this uncertainty, several approaches and solutions are given, leading to more accurate and reliable pressure measurements. The developed optical cavity operates as a high-resolution pressure sensor with an objective of complementing and eventually replacing conventional pressure standards, such as the force-balanced piston gauge and capacitance diaphragm gauge, that are based on the classical definition of pressure.