PhD defense by Mihaela Kathrin Lerch
On Tuesday 4 October 2022 Mihaela Kathrin Lerch will defend her PhD thesis "PFAS in Paper Based Food Contact Materials – Mass Spectrometric Identification and Migration Tests in Food Simulants and Real Food".
Supervisor: Associate Professor Kit Granby
Co-Supervisor: Senior Researcher Khanh Hoang Nguyen
Assessment committee:
Associate Professor Lene Duedahl-Olesen, DTU Food
Associate Professor Nicoline Juul Nielsen, Copenhagen University
Professor Stuart Harrad, University of Birmingham
Chairperson:
Assistant Professor Amelie Sina Wilde
Science summary:
Food contact materials (FCMs) such as paper plates or food packaging are ever-present in our daily routines. This makes the safety of these products indispensable for today’s society. Nonetheless, paper based FCMs are often impregnated with per- and polyfluorinated alkyl substances (PFAS) that are potentially toxic chemicals. Their function is to prevent the raw packaging material to soak through during direct contact with food. The close proximity of the toxic chemicals (e.g., linked to cancer and endocrine disruption) to food can result in the migration of PFAS and cause a risk to the consumer. In 2019, Denmark comprehensively banned the use of PFAS in FCMs; however, comparable Europe-wide legislation is missing. Additionally, current risk assessment procedures (proposed by the European Food Safety Authorities, EFSA) are prone to underestimate consumer risk. The reasons for this are, firstly, the limitation of toxicological guideline values to only four PFAS, which is not enough to represent this vast group of chemicals, and secondly, the design of typically performed migration test procedures that use food simulants instead of real food and target only a limited number of PFAS. To determine whether these measures are sufficient, we started with a critical literature study to identify the current understanding of the migration of PFAs into paper based FCMs. Based on this literature study, knowledge gaps were identified to form points of action for our experimental studies. We performed targeted migration studies with PFAS treated paper FCMs investigating the migration from muffin cups into muffins and from microwavable paper plates into tomato soup and oatmeal porridge. Furthermore, ethanol mixtures were used to simulate these food products. Simulation of food with lipophilic character such as oatmeal porridge with 50% ethanol:water mixture (v:v) resulted in comparable PFAS migration of 12 compounds, but the use of 20% ethanol:water mixture (v:v) to imitate food with slight lipophilic properties, such as tomato soup, showed large discrepancies for the migration of fluorotelomer alcohols, a subgroup of PFAS.
Afterward, detected PFAS concentrations in real food were used to calculate dietary exposure to estimate consumer risk. Three different forms of risk assessment procedures were compared. The EFSA-proposed procedure considering only four PFAS resulted in daily dietary exposures below the proposed tolerable intake limits. However, the use of more comprehensive assessment procedures showed dietary exposure values above the guideline values, indicating the possibility of adverse health effects for consumers and the need for improvement of EFSA risk assessment procedures. Additionally, to allow the detection of a wide range of PFAS, a PFAS suspect screening approach was developed and applied to identify currently not detected PFAS in food simulants after contact with paper FCMs.
Co-Supervisor: Senior Researcher Khanh Hoang Nguyen
Assessment committee:
Associate Professor Lene Duedahl-Olesen, DTU Food
Associate Professor Nicoline Juul Nielsen, Copenhagen University
Professor Stuart Harrad, University of Birmingham
Chairperson:
Assistant Professor Amelie Sina Wilde
Science summary:
Food contact materials (FCMs) such as paper plates or food packaging are ever-present in our daily routines. This makes the safety of these products indispensable for today’s society. Nonetheless, paper based FCMs are often impregnated with per- and polyfluorinated alkyl substances (PFAS) that are potentially toxic chemicals. Their function is to prevent the raw packaging material to soak through during direct contact with food. The close proximity of the toxic chemicals (e.g., linked to cancer and endocrine disruption) to food can result in the migration of PFAS and cause a risk to the consumer. In 2019, Denmark comprehensively banned the use of PFAS in FCMs; however, comparable Europe-wide legislation is missing. Additionally, current risk assessment procedures (proposed by the European Food Safety Authorities, EFSA) are prone to underestimate consumer risk. The reasons for this are, firstly, the limitation of toxicological guideline values to only four PFAS, which is not enough to represent this vast group of chemicals, and secondly, the design of typically performed migration test procedures that use food simulants instead of real food and target only a limited number of PFAS. To determine whether these measures are sufficient, we started with a critical literature study to identify the current understanding of the migration of PFAs into paper based FCMs. Based on this literature study, knowledge gaps were identified to form points of action for our experimental studies. We performed targeted migration studies with PFAS treated paper FCMs investigating the migration from muffin cups into muffins and from microwavable paper plates into tomato soup and oatmeal porridge. Furthermore, ethanol mixtures were used to simulate these food products. Simulation of food with lipophilic character such as oatmeal porridge with 50% ethanol:water mixture (v:v) resulted in comparable PFAS migration of 12 compounds, but the use of 20% ethanol:water mixture (v:v) to imitate food with slight lipophilic properties, such as tomato soup, showed large discrepancies for the migration of fluorotelomer alcohols, a subgroup of PFAS.
Afterward, detected PFAS concentrations in real food were used to calculate dietary exposure to estimate consumer risk. Three different forms of risk assessment procedures were compared. The EFSA-proposed procedure considering only four PFAS resulted in daily dietary exposures below the proposed tolerable intake limits. However, the use of more comprehensive assessment procedures showed dietary exposure values above the guideline values, indicating the possibility of adverse health effects for consumers and the need for improvement of EFSA risk assessment procedures. Additionally, to allow the detection of a wide range of PFAS, a PFAS suspect screening approach was developed and applied to identify currently not detected PFAS in food simulants after contact with paper FCMs.