In an article published on January 6, 2024, in the journal Environment International, Brennan H. Baker from the University of Washington and Seattle Children’s Research Institute, Seattle, United States, and co-authors evaluated if the consumption of ultra-processed food during pregnancy influences phthalate exposure, while also discussing socioeconomic disparities related to this exposure.
The study cohort consisted of 1031 pregnant women from the Conditions Affecting Neurocognitive Development and Learning in Early Childhood (CANDLE) Study. The women filled out a questionnaire (Block Food Frequency Questionnaire), noting their consumption of 114 food and beverage items during their second trimester and also provided urine samples. Frequencies of participant’s intake of all foods, both ultra-, and minimally- processed, were summed up. Using liquid chromatography-tandem mass spectrometry, 16 phthalate metabolites and phthalic acid (CAS 88-99-3), were measured in second trimester urine.
The study showed that the women’s’ diets were composed of 9.8 – 59% of ultra-processed foods, defined as industrial formulations typically with 5 or more (often many more) ingredients according to the NOVA food processing classification system (used by Baker et al.). The scientists reported that “each 10 % higher dietary proportion of ultra-processed foods was associated with 13.1 %” higher urinary levels of the molar sum of five di(2-ethylhexyl) phthalate metabolites (ΣDEHP). Conversely, a higher intake of minimally processed food related to lower urinary ΣDEHP. Further, ΣDEHP urinary concentration increased especially with increased intake of (ultra-processed) hamburgers/cheeseburgers, followed by French fries, sodas, and cakes.
Furthermore, the results “indicated that lower income and education levels were associated with 1.9 % (0.2 %-4.2 %) and 1.4 % (0.1 %-3.3 %) higher ΣDEHP, respectively, mediated via increased ultra-processed food consumption.” The authors highlighted that socioeconomic barriers prevent consumers from following dietary recommendations aimed at reducing phthalate exposure. This, according to the authors, makes it necessary that policies mandate changes in food packaging and processing equipment, to reduce phthalate exposure for the entire population.
It is well-established that phthalates are present in several types of foods and beverages (FPF reported), especially fast foods (FPF reported and here). They have been linked to several human health outcomes including endocrine-disrupting effects (FPF reported and here), cardiovascular disease (FPF reported), and behavioral disorders (FPF reported). Current regulatory ‘safe’ limits were shown to be insufficiently protective of human health (FPF reported). Besides the packaging, phthalates can also stem from food processing (FPF reported) and dairy farming equipment (FPF reported).
Another study shows that ultra-processed food is not only an exposure source for chemicals but also microplastics. Madeleine H. Milne from the University of Toronto, Canada, and co-authors investigated the plastic particle levels in various US protein-rich food products, including seafood, terrestrial meats, and plant-based foods. In their article, published on December 28, 2023, in the journal Environmental Pollution, the authors describe that they aimed to assess how processing levels, as well as the packaging material and food brand, influence microplastic contamination of foodstuffs.
For their research, they purchased 111 samples in and around Portland, Oregon, US, covering 13 protein types and classified them into three processing levels: (1) “unprocessed”, obtained unmodified from vessels (e.g. shrimp), (2) “minimally-processed”, bought cut and packaged in plastic in grocery stores (e.g., chicken breast), and (3) “highly-processed” which were significantly processed before being packaged (e.g., plant-based nuggets, tofu block). All samples were chemically digested and sieved such that plastic particles > 50 µm could be identified. Suspected plastic particles were analyzed by dissecting microscopy and spectroscopic methods (Raman and µ-FTIR).
The researchers reported microplastics to be present in 88% of the samples and in all types of products tested. Mean particle concentrations per product type ranged from 0.01 particles/g in chicken breast to 1.3 particles/g in breaded shrimp. The comparison of different types of samples showed that microplastic levels were significantly higher in highly-processed compared to minimally-processed products.
The authors speculate that contact with plastic food processing equipment increases as food processing increases, leading to higher levels of microplastics in ultra-processed foods. Conversely, they “found little evidence to suggest packaging is a major source of contamination in the products studied.” Only seven protein samples contained microplastics with characteristics that matched those of the packaging. However, the study only captured particles > 50 µm meaning that, if plastic particles below that size had been assessed, the findings might indicate a larger influence of the plastic packaging.
No significant differences were found between seafood, terrestrial meats, and plant-based proteins, and neither between different grocery store types, nor different product brands. Milne and co-authors also calculated the mean annual exposure of US adults to microplastics via the consumption of the studied proteins which was 11,000 ± 29,000 particles but could reach up to 3.8 million microplastics per year.
References
Baker, B. H. et al. (2024). “Ultra-processed and fast food consumption, exposure to phthalates during pregnancy, and socioeconomic disparities in phthalate exposures.” Environment International. DOI: 10.1016/j.envint.2024.108427
Milne, H. M. et al. (2023). “Exposure of U.S. adults to microplastics from commonly-consumed proteins.” Environmental Pollution. DOI: 10.1016/j.envpol.2023.123233
