Quaternary ammonium compounds (QAC) in food
Overview of the surface-active industrial chemicals
Dec 2023. Due to the wide range of applications of quaternary ammonium compounds (QACs), residues of these compounds are frequently found in food. Efficient analysis of these active substances is therefore of importance.
We will give you an overview of the chemical structure and applications of QACs. Get an overview of the foods in which QAC residues can be found as well as the toxicological consideration and legal classification.
Chemical structure and applications
Quaternary ammonium compounds (QAC) are industrial chemicals from the group of cationic surfactants. This means that they have a hydrophilic (water loving) positively charged head group and a lipophilic (fat loving) alkyl group. This dual molecular structure gives QAC a surface-active effect, enabling them to suspend two immiscible liquids or emulsify insoluble solids.
Due to their surface-active characteristics, QACs are used in cleaning agents and emulsifiers in the cosmetic and pharmaceutical industries, among others.
In addition, some QACs have an antiseptic effect, as their surface-active properties can damage the cells of fungi, viruses and bacteria. Benzalkonium chloride (BAC, a mixture of alkylbenzyldimethylammonium chlorides with alkyl chain lengths of C8, C10, C12, C14, C16 and C18) and didecyldimethylammonium chloride (DDAC, a mixture of alkyl-quaternary ammonium salts with alkyl chain lengths of C8, C10 and C12) are of particular importance. Due to their surface-active effect, QACs are often used in preparations for surface, hand and wound disinfection. In the context of the coronavirus pandemic, the worldwide use of disinfectants containing QAC has increased significantly.
QAC residues in food
In food production, disinfectants containing QACs are mainly used in particularly cleaning-intensive sectors such as the dairy, fish and meat processing industries. In this context, QACs can migrate into these fat- and protein-rich matrices if the disinfectants used are not removed by sufficient hot rinsing water.
The issue of QACs received specific attention in the summer of 2012, when DDACs and BACs were found in plant fortifiers, which led to increased findings in culinary herbs. It could not be ruled out that the use of these QAC-containing products caused residues to be present at such a level that the products could no longer be considered marketable in accordance with Section 9 of the LFGB. The plant fortifiers concerned were subsequently removed from the market[1]. In addition, there were indications that the use of QAC in fertilisers had been common practice over a period of time[2].
Toxicological evaluation
The levels of DDACs and BACs normally found do not indicate an acute or chronic health risk to the general population. However, individual findings have shown levels where an acute health risk to children and adults cannot be excluded. The symptoms are mainly mild, reversible irritation of the gastrointestinal tract.
The German Federal Institute for Risk Assessment (BfR) has therefore established an ADI (Acceptable Daily Intake) of 0.1 mg per kg body weight per day for DDAC and BAC and an Acute Reference Dose (ARfD) of 0.1 mg per kg body weight[3,4].
Legal regulation
According to Commission Regulation (EU) 2023/377 and Regulation (EC) No 396/2005 a temporary maximum residue limit (MRL) of 0.1 mg/kg is currently applicable for benzalkonium chloride (mixture of alkylbenzyldimethylammonium chlorides with alkyl chain lengths of C8, C10, C12, C14, C16 and C18). For didecyldimethylammonium chloride (mixture of alkyl-quaternary ammonium salts with alkyl chain lengths of C8, C10 and C12) the MRL for plant matrices was reduced from 0.1 mg/kg to 0.05 mg/kg with the entry into force of Regulation (EC) No. 2023/377 (14/09/2023). For animal matrices, the MRL of 0.1 mg/kg continues to be valid.
It should be noted that the provisional MRLs for BACs and DDACs will be reviewed again within seven years of the publication of Regulation (EC) No 2023/377 in order to make further adjustments if necessary[5,6].
Analysis
For a long time, the group of quaternary ammonium compounds could only be analysed by a single method. However, the Eurofins laboratories for food and feed analysis in Germany have successfully integrated the sum parameters benzalkonium chloride and didecyldimethylammonium chloride into their QuEChERS-based multi-methods. This means that they can be analysed quickly and cost-effectively in addition to a wide range of pesticides according to the valid residue definition and the corresponding limit of quantification.
Please note: The use of disinfectants with QAC in areas where laboratory samples are taken or by persons who come into contact with the samples may lead to positive results in the laboratory analysis.
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Relevant sources
[1] ECHO-Stoffbericht „Quartäre Ammoniumverbindungen (QAV), Landesamt für Natur, Umwelt und Verbraucherschutz Nordrhein-Westfalen, 2014, page 1 following (in German)
[2] Bundesamt für Verbraucherschutz und Lebensmittelsicherheit: Rückstände von quartären Ammoniumverbindungen in Lebensmitteln (Federal Office of Consumer Protection and Food Safety: Residues of quaternary ammonium compounds in foodstuffs – in German)
[3] BfR opinion No 032/2012, 13 July 2012: Health assessment of benzalkonium chloride residues in food
[4] BfR opinion No 027/2012, 09 July 2012: Health assessment of didecyldimethylammonium chloride (DDAC) residues in food
[5] Commission Regulation (EU) 2023/377 as regards maximum residue levels for benzalkonium chloride (BAC), chlorpropham, didecyldimethylammonium chloride (DDAC), flutriafol, metazachlor, nicotine, profenofos, quizalofop-P, sodium aluminium silicate, thiabendazole and triadimenol in or on certain products
[6] Regulation (EC) No 396/2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin
