Red Dye 40 vs Perfluorinated Compounds (PFAS): which is worse?

What is Red Dye 40?

Red Dye 40 (Allura Red AC) is a synthetic petroleum-derived azo dye that produces a bright red-orange color. It belongs to the monoazo chemical class and is highly water-soluble, with the formula C18H14N2Na2O8S2. It replaced amaranth (Red Dye 2), which was banned in the US in 1976 following cancer concerns.

What is Perfluorinated Compounds (PFAS)?

Per- and polyfluoroalkyl substances (PFAS) are a large family of synthetic chemicals characterized by extremely strong carbon-fluorine bonds. They are used in food packaging (grease-resistant coatings), non-stick cookware (PTFE/Teflon), food processing equipment, firefighting foam, and many industrial applications. The 'forever chemicals' moniker reflects their extreme environmental persistence.

Documented risks

Red Dye 40: Red Dye 40 has been linked to several health concerns, particularly in children. The most documented association is with hyperactivity and ADHD-related behavior. A landmark 2007 study in The Lancet (McCann et al.) found that a mixture of six artificial dyes including Red 40, combined with sodium benzoate, significantly increased hyperactivity scores in children ages 3 and 8–9. This prompted EFSA to require the 'may have adverse effect on activity and attention in children' warning label across the EU and UK. A 2012 meta-analysis in Neurotherapeutics (Arnold et al.) confirmed a small but statistically significant deleterious effect of artificial food colors on children's behavior, even in those without diagnosed ADHD. The authors described the effect as a public health issue rather than merely an ADHD issue. Regarding carcinogenicity: commercial batches of Red 40 contain trace amounts of benzidine, an IARC Group 1 human carcinogen. A 1994 study in Food and Chemical Toxicology documented benzidine contamination. The FDA maintains that exposure is below harmful thresholds, but the Center for Science in the Public Interest (CSPI) has cited this contamination in multiple ban petitions. Allergic reactions are documented: Red 40 can trigger histamine release leading to hives, rhinitis, and in rare cases anaphylaxis. Cross-reactivity with aspirin is established in aspirin-sensitive individuals. Gut health: A 2021 study in Nature Communications (Kwon et al.) found Red 40 may worsen inflammatory bowel disease and induce colitis-like symptoms in genetically susceptible mice by triggering immune responses in gut-associated lymphoid tissue. In April 2025, HHS Secretary RFK Jr. announced the FDA would phase out Red 40 and 7 other petroleum-based dyes from the US food supply.

Perfluorinated Compounds (PFAS): PFAS are among the most extensively studied and harmful groups of synthetic chemicals in the modern environment. Their unique carbon-fluorine bond stability means they do not break down in the environment or in human body tissues — contributing to bioaccumulation over a lifetime. Health effects documented in human epidemiological studies include: - Cancer: PFOA (perfluorooctanoic acid) and PFOS (perfluorooctanesulfonic acid) have been associated with kidney cancer, testicular cancer, thyroid cancer, bladder cancer, and non-Hodgkin lymphoma in occupationally exposed workers and community members with contaminated drinking water. IARC classified PFOA as Group 1 (human carcinogen) in 2023 and PFOS as Group 2B. - Endocrine disruption: PFAS disrupt thyroid hormone signaling and sex hormone balance. Multiple studies find associations between PFAS exposure and hypothyroidism, early puberty in girls, and reduced sperm quality. - Immune suppression: studies have found that PFAS exposure is associated with reduced vaccine response in children and adults, suggesting PFAS may impair immune function. - Developmental effects: prenatal PFAS exposure has been associated with lower birth weight, developmental delays, and reduced immune response in infants. - Cholesterol: PFAS exposure consistently raises LDL cholesterol levels, increasing cardiovascular disease risk. The 2023 EPA MCLG (maximum contaminant level goal) for PFOA and PFOS is zero — reflecting the agency's conclusion that there is no safe level. The EPA set enforceable MCLs in drinking water in 2024. The DuPont/3M PFOA/PFOS contamination of drinking water in communities near Teflon manufacturing facilities led to a $671 million settlement (DuPont/Chemours, 2017) and $10.3 billion 3M settlement (2023) — among the largest environmental contamination settlements in history.