CE34 - Contaminants, écosystèmes et santé

Understanding and preventing toxic Non-Intentionally Added Substances (NIAS) formation in commonly used plastic parts – NIAS

NIAS

Thermoplastics polymers are always compounded with additives. These additives, sometimes with interactions with impurities present in the polymer, are reacting during the compounding and processing steps used to produce a material. These unwanted chemical reactions lead to many toxic Non-Intentionally Added Substances, called NIAS.

Identifying how NIAS are forming

This project is studying by processing three major, well-characterised polymers with their most common additives in order to understand how NIAS are formed, evaluate their toxicity, see if their occurrence can be decreased by modifying processing parameters and assess if polymer recycling is increasing NIAS amounts.

Polymers and additives will be compounded and processed in well-defined and controlled conditions owing to the use of a mini-processing polymer laboratory. At each step of compounding or processing, NIAS will be extracted, identified, their toxicology estimated and their chemical synthesis related to the thermo-mechanical histories experienced during compounding and processing, using a numerical simulation of the processes.

Work on polypropylene is progressing well. The presence of NIAS is confirmed, for the moment in the form of degradation products of the additives. We have not identified any chemical reactions between additives. At this stage, it is still too early to decide whether the influence of processing is a factor to be taken into account. This will be studied by considering the specific mechanical energy in the internal mixer.

Study of NIAS production on polypropylene and polystyrene:

Influence of the presence of contaminants in the initial polymer.

Influence of recycling steps.

Relations with the thermo-mechanical history on internal mixer.

First toxicological tests on selected NIAS.

None at this stage

Thermoplastics polymers are always compounded with additives. These additives, sometimes with interactions with impurities present in the polymer, are reacting during the compounding and processing steps used to produce a material. These unwanted chemical reactions lead to many toxic Non-Intentionally Added Substances, called NIAS. The presence of NIAS is known, but their occurrence is only measured in the limited case of food-grade products.
The current published literature on NIAS is studying industrial polymer-based products, having thus no knowledge of the exact chemical composition of the additives used and of the processing conditions.
This project is departing from these studies by processing three major, well-characterised polymers with their most common additives in order to understand how NIAS are formed, evaluate their toxicity, see if their occurrence can be decreased by modifying processing parameters and assess if polymer recycling is increasing NIAS amounts. Such methodology is a step beyond the present state-of-the art.
To reach these objectives, polymers and additives will be compounded and processed in well-defined and controlled conditions owing to the use of a mini-processing polymer laboratory. At each step of compounding or processing, NIAS will be extracted, identified, their toxicology estimated and their chemical synthesis related to the thermo-mechanical histories experienced during compounding and processing, using a numerical simulation of the processes.
We will (a) demonstrate how NIAS are formed, even in very classical and simple conditions, with only a few additives used, (b) show that by modifying processing conditions, NIAS amount and danger can be decreased and (c) assess the safety of recycling.

Project coordination

Patrick Navard (ASSOCIATION POUR LA RECHERCHE ET LE DEVELOPPEMENT DES METHODES ET PROCESSUS INDUSTRIELS)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ICN Institut de Chimie de Nice
LCPO LABORATOIRE DE CHIMIE DES POLYMERES ORGANIQUES
ARMINES CEMEF ASSOCIATION POUR LA RECHERCHE ET LE DEVELOPPEMENT DES METHODES ET PROCESSUS INDUSTRIELS

Help of the ANR 500,283 euros
Beginning and duration of the scientific project: October 2021 - 42 Months

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