Non-targeted screening for contaminants in paper and board food-contact materials using effect-directed analysis and accurate mass spectrometry

Abstract

Due to large knowledge gaps in chemical composition and toxicological data for substances involved, paper and board food-contact materials (P&B FCM) have been emerging as a FCM type of particular concern for consumer safety. This study describes the development of a step-by-step strategy, including extraction, high-performance liquid chromatography (HPLC) fractionation, tentative identification of relevant substances and in vitro testing of selected tentatively identified substances. As a case study, we used two fractions from a recycled pizza box sample which exhibited aryl hydrocarbon receptor (AhR) activity. These fractions were analysed by gas chromatography (GC) and ultra-HPLC (UHPLC) coupled to quadrupole time-of-flight mass spectrometers (QTOF MS) in order tentatively to identify substances. The elemental composition was determined for peaks above a threshold, and compared with entries in a commercial mass spectral library for GC-MS (GC-EI-QTOF MS) analysis and an in-house built library of accurate masses for substances known to be used in P&B packaging for UHPLC-QTOF analysis. Of 75 tentatively identified substances, 15 were initially selected for further testing in vitro; however, only seven were commercially available and subsequently tested in vitro and quantified. Of these seven, the identities of three pigments found in printing inks were confirmed by UHPLC tandem mass spectrometry (QqQ MS/MS). Two pigments had entries in the database, meaning that a material relevant accurate mass database can provide a fast tentative identification. Pure standards of the seven tentatively identified substances were tested in vitro but could not explain a significant proportion of the AhR-response in the extract. Targeted analyses of dioxins and PCBs, both well-known AhR agonists, was performed. However, the dioxins could explain approximately 3% of the activity observed in the pizza box extract indicating that some very AhR active substance(s) still remain to be identified in recycled low quality P&B.

Addressing Hazardous Implications of Additive Manufacturing: Complementing Life Cycle Assessment with a Framework for Evaluating Direct Human Health and Environmental Impacts

“…Because the chemical constituents are not all known, chemical composition testing would be required as well as another round of toxicology assessments of the new individual chemical constituents. In a recent example, a chemical screen of a sample of a pizza box revealed many unidentifiable compounds-this demonstrates the uncertainty in content of even industrially produced products (Bengtström et al 2016). With this complexity in mind, we agree with John Warner, a strong advocate for product chemical safety, who recently laid out an argument for standard testing of finished products (Warner and Ludwig 2016).…”

“…In a recent example, a chemical screen of a sample of a pizza box revealed many unidentifiable compounds—this demonstrates the uncertainty in content of even industrially produced products (Bengtström et al. ). With this complexity in mind, we agree with John Warner, a strong advocate for product chemical safety, who recently laid out an argument for standard testing of finished products (Warner and Ludwig ).…”

Exploring the chemistry of complex samples by tentative identification and semiquantification: A food contact material case

“…We recently showed that quantifications could be decoupled from identification, and this allows for rough concentration estimates of virtually an unlimited amount of unidentified substances. Furthermore, studies by Bengtström et al and Rosenmai et al showed that untargeted screening can be used in a bio‐guided strategy to find hazardously compounds present in extracts from cardboard food packaging materials. This approach aims to avoid wasting effort identifying and quantifying irrelevant compounds by employing prioritization .…”

“…Yet, ideally elucidation, quantification, and prioritization should be performed on any present substance to assess which substances are risk relevant or risk irrelevant. It may be viable to adapt a strategy similar to recent literature and combine it with the latest semiquantification (SQ) approach to obtain a chemical exploration tool that can prioritize chemical substances based on adjustable endpoints.…”

Rethink how chemical hazards are tested

“…A better way to understand a product's impact on human health and the environment is to test the final product. For example, one study that screened a sample of pizza box 6 revealed many unidentifiable compounds, raising questions about the content and safety of everyday products.…”