Développement d'un dispositif de mesure en temps réel ou quasi temps réel des isocyanates dans l'air. // development of a device for real-time or near-real-time measurement of isocyanates in the air.

Topic description

Les diisocyanates sont des composés chimiques largement utilisés dans l'industrie, notamment pour la production de mousses polyuréthanes, adhésifs et revêtements. Leur toxicité est liée au groupe fonctionnel isocyanate (–NCO), responsable d'effets respiratoires et cutanés sévères tels que l'asthme, la sensibilisation et l'hyperréactivité bronchique. Classés cancérogènes 2B et allergisants respiratoires, ils ne présentent pas de seuil d'innocuité connu, rendant toute exposition potentiellement nocive.

Afin de réduire les risques, la réglementation européenne a récemment renforcé la prévention. Depuis août, une formation obligatoire est imposée aux travailleurs. De plus, la directive (UE) / fixe de nouvelles valeurs limites contraignantes pour le groupe NCO (6 µg/m³ sur 8 h ; 12 µg/m³ sur 15 min), soit une réduction d'un facteur ~3,5 par rapport aux anciennes VLEP. L'expression des limites en concentration de NCO, indépendamment du composé, facilite la surveillance et ouvre la voie au développement de méthodes de mesure en temps réel, essentielles pour mieux protéger les salariés exposés.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Diisocyanates are chemical compounds mostly used in the manufacture of polyurethane foams, adhesives, coatings, and sealants. They are skin and respiratory sensitizers. They can cause severe respiratory health effects such as asthma, isocyanate sensitization, bronchial hyperreactivity, and the development of skin diseases. Routes of absorption other than inhalation can also cause systemic immunological effects such as respiratory sensitization. The European CHemicals Agency (ECHA) recommends Occupational Exposure Limits (OELs) based on the NCO group concentration, applied to all diisocyanates. Indeed, the NCO group has been clearly established by numerous studies as the cause of isocyanate toxicity. Regulations concerning the use of these compounds in the workplace have changed significantly in and. Since August, workers handling diisocyanates must undergo specific training on their hazards and good practices. Furthermore, European Directive of March establishes binding OELs of 6 µg NCO/m3 over 8 hours and 12 µg NCO/m3 over 15 min. Given the difficulty of measuring these low concentrations, a limit value of 10 μg NCO/m3 in relation to a reference period of 8 hours and a short-term exposure limit value of 20 μg NCO/m3 apply until 31 December. These new OELs in NCO group concentration are 3.5 times lower than the current OELs given for each diisocyanate. The binding nature of these new OELs makes it mandatory to assess employee exposure to diisocyanates.
Since the new limit values are given in terms of NCO group concentration, the separation of diisocyanates that may be sampled simultaneously is no longer necessary. This simplifies the measurement of these substances and also enables the development of real-time or near-real-time device. Diisocyanates are classified as carcinogens of 2B category by the IARC and/or respiratory allergens. It is not possible to determine levels below which exposure would not cause adverse health effects. Therefore, it appears important to be able to quickly detect occupational exposure to diisocyanates to better protect employees. Real-time or semi-real-time detection of the NCO functional group, can address this issue. Indeed, to protect employees from potential exposure to diisocyanates and avoid any health effects, it is important to identify exposing operations by quickly obtaining measurement results. Since diisocyanates are very reactive compounds, this type of measurement is particularly indicated.
Objectives and Work Phases
The objective of this thesis will be to develop a real-time or near-real-time measurement device for diisocyanates in workplace air. Thus, the thesis will be divided into several stages. Firstly, based on the state of the art, various technologies for measuring NCO group concentrations will be tested. Various detection solutions will be investigated in order to select the most sensitive and adaptable one for individual sampling. The second phase of the thesis will be dedicated to the study of aerosol sampling. The sampling chamber will be sized to sample the inhalable fraction of the aerosol. The sampling flow rate, diameter, and geometry of the sampling orifice will be studied. Recent developments in the laboratory using microfluidics may also benefit the development of a prototype. The final stage of the thesis will be dedicated to the assessment of the sensitivity, selectivity, and the potential influence of relative humidity or other interfering factors. The reversibility of the measurement will also be studied.
------------------------------------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------------------------------------------------------------------------------------------------------

Début de la thèse : 01/11/

Funding category

Funding further details

Associations, fondations, programmes privés étrangers