Phthalates are an emerging class of contaminants due to their widespread applications across industry. For many years, phthalates have been used in the manufacturing of food packaging, and today also can be found in many plastic kitchen tools. Recent cases of phthalate contamination in certain food products and ongoing health concerns over the consumption of phthalates have led some regulators to set new phthalate limits in food contact materials (FCMs) and foodstuffs.
To support adherence to these regulatory limits, robust and sensitive analytical methods are required. While gas chromatography-mass spectrometry (GC-MS) is widely used for this purpose, the reliable identification and quantitation of phthalates can be challenging, particularly when it comes to analyzing fatty food matrices such as cooking oils. Here, we look at a novel GC-MS workflow for phthalate testing that overcomes these challenges to enable accurate determination in foods.
Phthalates in the Food Industry
Phthalates are a family of man-made chemicals that are commonly used across a number of industries such as plasticizers to soften plastics such as polyvinylchloride (PVC). Diethylhexyl phthalate (DEHP) (Figure 1) is one of the most widely used, accounting for almost 40 percent of global phthalate consumption.
In the food and beverage industry, phthalates are often used to increase the flexibility and durability of film packaging and plastic materials. Because they are weakly bound to the polymeric matrix, however, phthalates can potentially leach out into food, especially in the presence of heat or solvents. Due to the lipophilic nature of phthalates, leaching into fatty foods is of particular concern.
Phthalates can also enter food items during processing due to the use of PVC in food production and processing systems, as well as from other environmental sources, such as indoor air dust. In some countries, phthalates are intentionally added as a clouding agent to a variety of foods and beverages, including sports drinks, fruit juice, and tea-based drinks.
In the United States and Europe, contaminated food has been identified as the main source of human exposure to phthalates. Cream-based dairy products and vegetable oils in U.S. and EU consumer markets have been found to contain high concentrations of DEHP, and consumption of these products has been linked to increases in DEHP urinary metabolite levels.
Phthalate Consumption Health Risks
Phthalates have been used as plasticizers in the food industry for more than 50 years, but only relatively recently have they been understood to pose a risk to our health. Epidemiological studies link high phthalate metabolite levels to endometriosis in women and decreased male reproductive hormones, while prenatal exposure to phthalates is associated with reduced masculinization in newborn boys. Phthalate exposure also has been linked with autism development, although this has recently been disputed. DEHP is also listed as “reasonably anticipated to be a human carcinogen” according to the U.S. National Toxicology Program.
Given these health risks, phthalate residues in foods and beverages are regulated internationally, and several expert panels, mostly in the EU and U.S., have carried out risk assessments on these compounds. For example, a special EU Food Safety Authority panel (the Food Contact Materials, Enzymes, and Processing Aids Panel) recently released an updated draft opinion stipulating a group tolerable daily intake of 50 µg/kg body weight per day for four phthalates, including DEHP. This corresponds to a limit of 0.1 percent of phthalates in FCMs.
Challenges with Detecting Phthalates in Food
Given the potential risk to human health, phthalate testing is necessary to ensure foods adhere to regulatory guidelines. Since phthalate compounds need to be detected in food at low concentrations, GC-MS is widely used to determine the phthalate content of foodstuffs due to its inherently high separation efficiency and the selectivity of quadrupole MS. This analysis method may conceal several challenges, however.