The identification and implications of reaction and breakdown products from starting substances used to produce food contact plastics

Transcription

1 The identification and implications of reaction and breakdown products from starting substances used to produce food contact plastics Dr Malcolm Driffield

2 Presentation overview Fera at a glance Introduction to food contact materials Introduction to NIAS Project Reaction and breakdown products from starting substances used to produce food contact plastics Summary

3 The Food and Environment Research Agency An executive agency of the parent Government department - Department of Environment Food and Rural Affairs (Defra) Agency a not-for-profit organisation that nevertheless covers its full economic costs

4 Our role Regulation Policy and inspectorate functions for plant health, bee health and plant varieties and seeds Research Robust scientific research, analysis and evidence for government and commercial customers worldwide Response Advice, guidance and support as part of the UK s capability to respond and recover in emergency situations

5 A very wide range of work areas including... Food and environmental safety Crop and food security Land use and sustainability Wildlife management Plant pests and diseases National Bee Unit FAPAS etc. Government Decontamination Service...

6 Food and Environmental Safety Programme Environmental contaminants e.g. dioxins, PCBs, metals Natural toxicants e.g. mycotoxins Pesticides Veterinary drugs Processing contaminants Additives and colours Authenticity and profiling Deliberate adulteration Packaging migration

7 Food packaging Packaging is beneficial Protects foodstuff from spoilage However the transfer of chemicals from packaging to food (migration) may have a negative impact on the quality and safety of the food No food contact material is completely inert Need to ensure the safety of these materials Controls in place to ensure consumer safety

8 What is migration? The mass transfer from an external source into food by sub-microscopic processes May impact food in two ways Food safety migration of harmful substances Food quality migration of substances which impart taint or odour Migration occurs from: Food packaging Materials and articles used in food manufacture, transport and storage Materials and articles used in food preparation and consumption

9 Factors effecting migration Migration is a diffusion process It is dependent on: The nature of the food contact material The nature of the foodstuff The nature of the migrating substance The nature, the extent and the type of contact between the food contact material/article and the foodstuff The duration of the contact The temperature of the contact

10 What migrates? Known ingredients needed to make the food contact material Monomers and starting substances, catalysts, solvents and suspension media, additives etc. Known or unknown isomers, impurities, reaction products and breakdown products of these ingredients Possible contaminants Recycled materials Contamination from indirect food contact sources; inks, coatings, adhesives, secondary packaging

11 The problem being addressed (1) Article 3 of the EU Framework Regulation Chemical migration from food packaging materials should not endanger human health Recital 13 of Directive 2007/19/EC A general requirement to assess the safety of ALL potential migrants, including impurities, reaction and breakdown products and the onus is on the business operator to do so Neither the EU commission, Member States, or industry, really know what is reasonably achievable in the assessment of NIAS Hundreds of plastic formulations and manufacturing conditions

12 The problem being addressed (2) US FDA x TIC Scan _029.d Information on new substances/oligomers with MW<1000 Da Counts vs. Acquisition Time (min) x TIC Scan _002.d Levels as low as 10 ppb Counts vs. Acquisition Time (min)

13 FSA funded research UK Food Standards Agency Joint project with TNO (Netherlands) An investigation into the reaction and breakdown products from starting substances used to produce food contact plastics (A03054) Aim To identify and catalogue the reaction and breakdown products formed from starting substances used to make six major food contact polymers

14 Project approach Selection of polymers and associated additives followed by manufacture Prediction of impurities/reaction products/breakdown products Extraction and analysis of test plastics and controls Confirmation of identities of predicted substances Examination and interpretation of the data for any non-predicted substances

15 Polymers selected Polyethylene (HDPE) Polypropylene (PP) Polystyrene (PS) The 5 volume polymers Polyvinyl chloride (PVC) Polyethylene terephthalate (PET) Polyamide (PA) Finds use in demanding applications - good barrier properties, high temperature resistance High content of nitrogen which might make the reaction chemistry different HDPE will be used as an example here

16 Plastics additives Use Level (wt%) HDPE Base polymer Tetrakis(2,4-di-tert-butylphenyl)[1,1-biphenyl]-4,4 - diylphosphonite Antioxidant 0.1 Octadecyl 3,5-di-t-butyl-4-hydroxyhydrocinnamate Antioxidant 0.1 Oleamide Slip agent 0.1 Titanium dioxide Inorganic colourant 5.0 N,N-Bis-(2-hydroxyethyl)alkyl(C13-C15)amine Antistatic agent 0.25 Glycerol monooleate Lubricant 1.0 Sodium (C10-C18) alkyl sulfonate Lubricant 1.0 2,5-Bis(5'-tert-butylbenzoxazol-2-yl)thiophene Optical brightener 0.1

17 Risk assessment Three components: (a) the identification of the substances present in the material or article (b) an estimation of their migration level leading to an estimate of possible consumer exposure (c) a risk assessment which considers the potential exposure in context with any hazard (nature and potency) posed by the substance

18 Risk assessment Three components: (a) the identification of the substances present in the material or article - Predicted substances - Extraction and analysis of test polymers and controls (b) an estimation of their migration level leading to an estimate of possible consumer exposure (c) a risk assessment which considers the potential exposure in context with any hazard (nature and potency) posed by the substance

19 Database of predicted substances prepared Scientific literature examined for known reactions Knowledge of the chemistry of the additives used to predict reaction products HDPE 8 additives 85 predicted substances and classes of substances e.g. octadecyl-3,5-di-t-butyl-4-hydroxyhydrocinnamate oxidation dealkylation

20 Oxidation reaction H 3 C CH 3 OH CH 3 CH3 H 3 C CH 3 O CH 3 CH3 H 3 C CH 3 OH CH 3 CH3 H 3 C CH 3 H 3 C CH 3 H 3 C CH 3 R = C 18 H 37 R O O R O O R O O Octadecyl-3,5-di-t-butyl-4- hydroxyhydrocinnamate Quinone methide Cinnamate Dimers Dimers

21 Dealkylation reaction H 3 C CH 3 OH CH 3 CH3 C H 3 CH 3 OH H 3 C CH 3 H 3 C Thermal degradation + H 2 C CH 3 R = C 18 H 37 H 3 C R O O R O O Octadecyl-3,5-di-t-butyl-4- hydroxyhydrocinnamate

22 Extraction and analysis Carried out for Additives only Control polymer samples with no additives Polymer with additives included HDPE Direct analysis by thermodesorption (TD) GC-MS Solvent extraction followed by liquid injection GC-MS Solvent extraction followed by LC-TOF-MS (NMR)

23 TD-GC-MS - HDPE Abundance 5.5e+07 5e e+07 4e+07 HDPE TIC: rxn_230107_008.d Peaks in both attributed to internal standard and short chained alkanes Abundance Average of to min.: rxn_230107_010.d (-) e+07 3e e+07 2e e m/z--> Abundance #799: 2-Propanone, 1-hydroxy- 1-hydroxypropanone (4 µg/dm 2 ) 1e Time--> Abundance 5.4e e+07 5e e e e e+07 4e e e e e+07 3e e e e e+07 2e e e e e+07 1e Time--> HDPE + additives TIC: rxn_230107_010.d 2 new peaks detected m/z--> 0 Abundance m/z--> Abundance m/z--> Average of to min.: rxn_230107_010.d (-) #918: Propylene Glycol propylene glycol (144 µg/dm 2 ) Neither compound in predicted database

24 Solvent extraction followed by GC-MS - HDPE Additives, polymer controls and polymers + additives all extracted into ethanol and isooctane Impurities found in some additives e.g. Oleamide (slip agent) also included other fatty acid amides and esters These were added to the database

25 GC-MS chromatograms e.g. isooctane extract Abundance TIC: RXN_LSCREEN_060207_014.D HDPE Time--> Abundance HDPE + additives TIC: RXN_LSCREEN_060207_017.D Time-->

26 HDPE GC-MS results Mainly PE oligomers 87 new substances detected in HDPE + additives only extracts 25 substances in EtOH 15 attributed to additives and impurities 81 substances in isooctane (some the same as in EtOH) 31 attributed to additives and impurities Estimated concentration range µg/dm 2

27 Non-volatile and polar compounds by LC-TOF-MS Instrument on loan as a part of Agilent/Fera collaboration Mass accuracy, fragmentation and isotope patterns used to aid identification Excel database searched

28 LC-TOF-MS - HDPE Isooctane and ethanol extracts evaporated and residue re-dissolved in acetonitrile HDPE (EtOH, ESI+) HDPE + additives (EtOH, ESI+)

29 LC-TOF-MS HDPE results 26 new substances detected in HDPE + additives only extracts 4 attributed to additives 6 attributed to additive impurities Identity proposed for 4 16 reaction and breakdown products Identity proposed for 14 Estimated concentration range µg/dm 2

30 Stacked 1 H 1D NMR plot - HDPE

31 Overview of substances detected - HDPE TD-GC-MS 0 additives 0 impurities 2 substances detected 2 reaction/breakdown products - identities proposed for 2 Solvent extraction GC-MS - 0 predicted 4 additives 29 impurities 87 substances detected - identities proposed for 10-3 predicted 54 reaction/breakdown products - identities proposed for predicted LC-TOF-MS 4 additives 6 impurities 26 substances detected - identities proposed for 4-0 predicted 16 reaction/breakdown products - identities proposed for 14-2 predicted

32 Risk assessment Three components (a) the identification of the substances present in the material or article (b) an estimation of their migration level leading to an estimate of possible consumer exposure (c) a risk assessment which considers the potential exposure in context with any hazard (nature and potency) posed by the chemical

33 Migration modelling Worst case migration calculated applies the convention that 1 kg of food is packaged in 6 dm 2 of plastic and that all substances present in the plastic transfers to the foodstuff Over-estimation for some plastic/substance combinations Migration from FCMs can be regarded as an elementary physical process Predicted by mathematical calculations and models Diffusion theory (D p ) Partitioning effects (k p,f )

34 Estimation of migration levels Assessment of significance of the levels detected in the polymers carried out by migration modelling commercially available software package Migratest Lite (kindly provided by FABES) Migration potentials estimated and modelling performed Defined as mono-layer plastics 10 days at 40 o C

35 Consequences HDPE (PP and PVC) contained the most NIAS relatively high diffusivity polymers as identity of some substances unknown, migration potentials of NIAS>10 µg/kg identified Substances present with the potential to migrate at concentrations >10 µg/kg [10 µg/kg generally defined as the concentration in the food at which a non-permitted ingredient should be not detectable, this is used for non- CMR substances (carcinogens, mutagens and reprotoxins) and does not imply a threshold of concern]

36 Risk assessment Three components (a) the identification of the substances present in the material or article (b) an estimation of their migration level leading to an estimate of possible consumer exposure (c) a risk assessment which considers the potential exposure in context with any hazard (nature and potency) posed by the chemical

37 Potential exposure and associated hazards A number of substances that would previously have been reported as NIAS have been identified Migration potential/exposure potential can be linked with consideration of the hazard associated with the substance A large number of substances remain either unidentified or with an ambiguous identification only Migration potential/exposure potential can NOT be linked with consideration of the hazard associated with the substance

38 Summary of project A03054 Six polymers were prepared containing additives chosen to be representative of those typically used in plastic materials and articles intended for contact with food Theoretical list of possible impurities/degradation products/reaction products was prepared for each of the plastic/additive combinations A suite of analytical methods were applied to the plastics themselves and to extracts of the materials Migration modelling to determine the significance of the levels of the substances estimated in the plastics

39 Additive purity and the impact on NIAS Many unexpected impurities in the additives Illustrates the demands placed when considering migration potential at the low ppb levels These impurities have the potential to persist in the finished plastic food contact material and may migrate They may decompose under the process and fabrication conditions, or they may interact with each other to form other substances, all with the potential to migrate

40 Limitations of analytical methods to identify and measure NIAS This project represented the state-of-the-art with two highly experienced and well equipped institutes Many substances identified and concentrations estimated A number of substances that would previously have been unknown have been identified A large number of substances remain either unidentified or with an ambiguous identification

41 Implications for other food contact materials and articles The same approach has been applied elsewhere Defra Link Project can coatings Working closely with Industry Irradiated FCM plastics Bio-based FCMs Advanced chromatographic and spectrophotometric methods are also applicable to extracts of other materials Expect the same findings

42 What else is required? This analytical approach would provide a useful demonstration of due diligence It may need to be considered along with other complementary approaches toxicological evaluation of the whole migrate and/or threshold concepts such as threshold of regulation or thresholds of toxicological concern

43 Acknowledgements Fera E. Bradley, D. Speck, N. Harmer, S. Jones, M. Scotter and L. Castle TNO L. Coulier, R. Bas, S. Steegman, M. Tienstra and B. Muilwijk Food Standards Agency Report A _A03054_reaction_and_breakdown_products_final_report.pdf Agilent J. Zweigenbaum