Identification of ethylene oxide in herbs, spices and other dried vegetables imported into Italy

Dynamic headspace GC-MS/MS analysis of ethylene oxide and 2-chloroethanol in dry food commodities: a novel approach

With frequent RASFF notifications from the EU countries, the residue testing of ethylene oxide (EtO) and its metabolite 2-chloroethanol (2-CE) in food commodities has become essential to check their compliance with MRLs. This study, for the first time, aimed at establishing a dynamic headspace-GC-MS/MS method for the simultaneous determination of these two analytes in acetonitrile extracts of cumin, ashwagandha, chilli powder, turmeric powder, guar gum, locust bean gum, and ginger powder. The samples (4 g) were extracted using acetonitrile (10 mL). A dispersive-solid phase extraction cleanup step with primary secondary amine sorbent (50 mg/mL) reduced the interfering signal of (matrix-derived) acetaldehyde by >40% in chilli powder, ginger, turmeric, and guar gum. This cleanup was not required for sesame seeds. With high selectivity and sensitivity, the GC-MS/MS approach identified and quantified both compounds simultaneously. At the spiking levels of 0.01, 0.02, and 0.05 mg/kg, the recoveries and precision were satisfactory (70-120%, RSDs, ≤15%). The headspace method-performance was similar to liquid injections. The method provided reproducible results when evaluated by two different laboratories. The method provided high-precision results for incurred residue analysis. Given its efficiency, the validated method is anticipated to improve the effectiveness of monitoring of EtO residues in food commodities.

Confirmation of the full conversion of ethylene oxide to 2-chloroethanol in fumigated foodstuffs: possible implications for risk assessment

This study describes the extension of a gas chromatography mass spectrometry (GC-MS) method, initially devoted to the analysis of ethylene oxide (EO) in ice cream, to a larger range of food items including herbs, spices, vegetables, inorganic salts, food supplements, thickeners, etc. Results are reported as EO_Total according to EC 2015/868 definition (expressed as EO equivalents as the sum of native EO and 2-chloroethanol (2-CE) after acidic hydrolysis) with a limit of quantification at 0.01 mg/kg regardless of the food item. Its ruggedness was demonstrated through fortification experiments on hundreds of samples. Re-analysis of 146 positive food samples without hydrolysis demonstrated that not EO but 2-CE is the predominant analyte detected in the different processed ingredients suspected to have been previously treated with EO. A series of eight contaminated dried herbs and spices were also re-analysed by four ISO 17025 accredited commercial laboratories making use of different analytical strategies for EO determination in foods. Each laboratory reported EO_Total levels within the same concentration range, but the resulting reproducibility ranged from 23% to 41% depending on the sample. Additionally, we show that results of free EO from methods based on conversion to 2-iodoethanol may lead to artefactual detection of native EO (false positive). An official method of analysis applicable for different food matrices would be useful to avoid discrepancies of results. Altogether, these data re-enforce the fact that in absence of native EO in food items, risk assessment of EO in foodstuffs should consider the predominance of 2-CE. A toxicological risk assessment using the food additive xanthan gum as a case study is discussed.

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

Analysis of ethylene oxide in ice creams manufactured with contaminated carob bean gum (E410)

Residues of ethylene oxide (EO), a banned fumigant in the EU, were found at amounts above the maximum residue limit (MRL) in carob (locust) bean gum (additive E410). The pesticide entered the food chain via stabiliser blends that are used as minor ingredients in the manufacture of ice cream. Consequently, all products that contained the non-compliant ingredient were withdrawn or recalled in several countries across the EU, in most cases irrespective of whether the pesticide residue was detectable or not in the final product. This is the first report of a reliable method to determine EO and its metabolite/marker compound 2-chloroethanol (2-CE), either together or independently in ice cream, with a limit of quantification at 0.01 mg EO/kg and recovery in the range of 87-104% across the levels investigated (0.01, 0.02 and 0.06 mg EO/kg). The method applies QuEChERS extraction and isotope dilution gas chromatography coupled with tandem mass spectrometry (GC-MS/MS). High resolution mass spectrometry (HRMS) confirmed the specificity of low mass ions. Data on the stability of EO and 2-CE under thermal conditions revealed that 2-CE is relatively stable in an ice cream matrix (ca. 80% recovery of spiked material). Importantly, this study also demonstrates that not EO, but 2-CE is the predominant analyte detected in the contaminated samples, which is new information of significance in terms of the overall risk assessment of EO in foodstuffs.

Epoxidation of Ethylene by Whole Cell Suspension of Methylosinus trichosporium IMV 3011

Methane monooxygenase (MMO) has been found in methanotrophic bacteria, which catalyzes the epoxidation of gaseous alkenes to their corresponding epoxides. The whole cell suspension of Methylosinus trichosporium IMV 3011 was used to produce epoxyethane from ethylene. The optimal reaction time and initial ethylene concentration for ethylene epoxidation have been described. The product epoxyethane is not further metabolized and accumulates extracellularly. Thus, exhaustion of reductant and the inhibition of toxic products make it difficult to accumulate epoxyethane continuously. In order to settle these problems, regeneration of cofactor NADH was performed in batch experiments with methane and methanol. The amount of epoxyethane formed before cosubstrate regeneration was between 0.8 and 1.0 nmol/50 mg cells in approximately 8 h. Combining data from 7 batch experiments, the total production of epoxyethane was 2.2 nmol. Production of epoxyethane was improved (4.6 nmol) in 10% gas phase methane since methane acts as an abundant reductant for epoxidation. It was found that the maximum production of epoxyethane (6.6 nmol) occurs with 3 mmol/L methanol. The passive effect of epoxyethane accumulation on epoxyethane production capacity of Methylosinus trichosporium IMV 3011 in batch experiments was studied. Removal of product was suggested to overcome the inhibition of epoxyethane production.