Caramel Color IV vs Butylated Hydroxytoluene: which is worse?

What is Caramel Color IV?

Caramel Color IV (Class IV caramel, E150d) is a food coloring made by heating sugar with both ammonium and sulfite compounds. This production method creates a unique set of reactive byproducts, notably 4-methylimidazole (4-MEI), which has been linked to cancer in animal studies. It is the most widely used caramel coloring in beverages like Coca-Cola and Pepsi.

What is Butylated Hydroxytoluene?

Butylated hydroxytoluene (BHT) is a synthetic lipophilic phenolic antioxidant preservative derived from petroleum. It is a white crystalline solid with chemical formula C15H24O. Like BHA, it prevents fat oxidation and is widely used in food, cosmetics, pharmaceuticals, jet fuel, and rubber.

Documented risks

Caramel Color IV: The primary concern with Caramel Color IV is 4-methylimidazole (4-MEI), a byproduct of the ammonia-sulfite caramel production process. The National Toxicology Program (NTP) found that 4-MEI caused lung cancer in male and female mice at high doses in 2-year bioassay studies, leading to California listing 4-MEI as a known carcinogen under Proposition 65 in 2011. The Prop 65 safe harbor level is 29 micrograms 4-MEI per day (the level that would cause 1 additional cancer per 100,000 people over a 70-year lifetime). CSPI testing in 2011-2012 found Coca-Cola and Pepsi sold in California contained 4-MEI levels that, at typical consumption rates, would exceed this threshold — triggering voluntary reformulation by both companies to reduce 4-MEI in their US products. The FDA reviewed 4-MEI and concluded that typical exposure levels 'are not a safety concern.' EFSA's evaluation found the NTP findings concerning but noted the margin of safety at typical European exposure levels. The cancer mechanism in mice involves high doses that may not extrapolate to typical human cola consumption.

Butylated Hydroxytoluene: BHT's carcinogenicity profile is complex and bidirectional. Some NTP bioassays found liver tumors in female mice at high doses, while other studies suggested BHT might inhibit tumor initiation in certain contexts. A 1986 NTP bioassay found liver tumors in female mice but anti-carcinogenic effects in the rat forestomach — making BHT's net carcinogenicity uncertain. IARC has not formally classified BHT in a specific Group due to this conflicting evidence. The NTP notes that BHT's carcinogenicity data are complex. The 'Report on Carcinogens' does not currently list BHT, unlike BHA, but the NTP has noted inconclusive evidence. Potential endocrine disruption: a 2017 study in Environmental Science & Technology found BHT disrupted thyroid hormone levels in female rats. Multiple animal studies have demonstrated weak estrogenic effects. The American Academy of Pediatrics' 2018 policy statement on food additives mentioned BHT as a synthetic preservative warranting reduced childhood exposure. Kellogg's Frosted Flakes in the US contains BHT to preserve freshness; the European version uses mixed tocopherols (vitamin E) instead — a commercially meaningful difference demonstrating feasibility of substitution. Japan banned BHT for food use based on its precautionary approach. The EU restricts it with ADI-based maximum permitted levels.