Polychlorinated alkanes (PCAs): Occurrence and possible mitigation in edible oils and spreadable fats from the Dutch market

Chlorinated paraffins (CPs) are high production volume chemicals of growing concern because of their ubiquitous presence in food samples, their persistence, and their bioaccumulation potential. These cheap-to-produce plasticizers often present as very complex mixtures of primarily polychlorinated alkanes (PCAs) [1]. In the studies presented here, the occurrence of PCAs was investigated in 94 edible oil and 20 spreadable fat samples from the Dutch market. Additionally, mitigation of PCAs during refinement was investigated in 13 paired crude and refined edible oils obtained from a Dutch contract refining company [2].

All samples were treated with concentrated sulphuric acid overnight, followed by further clean-up on a deactivated silica column. Analysis was done using a LC-ESI-HRMS instrument (R=140.000 FWHM, m/z 120-1500, full scan) with peak deconvolution and linear regression based on the average sample chlorination degree.

Stockholm Convention-restricted short chained PCAs (ΣPCAs-C_10-13) were detected in lower amounts than medium chained PCAs (ΣPCAs-C_14-17) in 81 out of 94 edible oil samples, with an overall range of ΣPCAs-C_10-20 < LOQ to 6000 ng/g (mean: 610 ng/g). Remarkably, the 16 analysed palm oils ranged ΣPCAs-C_10-20 70-6000 ng/g (mean: 1370 ng/g), with homologue group patterns often being dominated by short chain PCAs. Most of these samples were unrefined or cold filtered. Spreadable fat samples also presented higher medium chain PCA levels in products containing palm oil (35 ng/g) than in the palm oil free products (17 ng/g). In the paired crude and refined samples, a marked decrease in concentrations of both short and medium chain PCAs was observed after the refining process (average reduction: 80% and 60%, respectively). While oil refinement seems to mitigate part of the PCA contamination, oils and fats should still be considered important dietary sources of PCAs.

[1] Fernandes et al. (2023), TrAC 169, 117363.

[2] Shen et al. (2023), Food Cont. 153, 109889.