| 2-Bromo-2-Nitropropane-1,3-Diol | Not A Fan | Formaldehyde-releaser, potential allergen. |
| Behentrimonium Methosulfate | Better (Not In My Top Picks) | Gentle plant-based conditioner, but made using dimethyl sulfate (a probable carcinogen); the EU’s safety panel has never reviewed it. |
| Benzalkonium Chloride | Not A Fan | Strong disinfectant and known skin allergen that also irritates the eyes and airways. The EU and Canada cap it at 0.1% and require an eye-contact warning. |
| Benzisothiazolinone | Not A Fan | Moderate skin sensitizer; the EU reviewed it and refused to permit it in cosmetics. The US and Canada set no limit. |
| Benzyl Alcohol | Better (Not In My Top Picks) | The 2026 Allergen of the Year; its production relies on benzyl chloride, a probable carcinogen. The EU caps it at 1% and requires it on the label. |
| Butane / Propane / Isobutane | Not A Fan | Aerosol propellants that barely absorb, but can carry cancer-linked benzene or 1,3-butadiene that you breathe in. The EU and Canada limit the 1,3-butadiene impurity. |
| Butylated Hydroxyanisole (BHA) | Not A Fan | Potential carcinogen and endocrine disruptor. |
| Butylated Hydroxytoluene (BHT) | Not A Fan | Potential carcinogen and endocrine disruptor. |
| Chemical UV Filters in Sunscreens (e.g., Avobenzone, Homosalate, Octinoxate, Octisalate, Octocrylene, Oxybenzone) | Not A Fan | The FDA found that only two ingredients (zinc oxide and titanium dioxide) can be classified as safe and effective, based on currently available information. |
| Citrus Paradisi (Grapefruit) Seed Extract | Not A Fan | Potential contamination with benzalkonium chloride, triclosan, and methylparaben. |
| Cocamide DEA | Not A Fan | Possible carcinogen (IARC Group 2B); listed under California Proposition 65 as known to cause cancer. |
| Cocamidopropyl Betaine | Better (Not In My Top Picks) | Mild coconut-based cleanser with no cancer or hormone concerns; its one real drawback is allergy. |
| Cocamidopropyl Hydroxysultaine | Better (Not In My Top Picks) | Mild coconut-based cleanser that does not absorb; trace manufacturing impurities can trigger allergies in some people. |
| Cyclohexasiloxane | Not A Fan | Persistent, bioaccumulative, and toxic to the environment. |
| Cyclopentasiloxane | Not A Fan | Persistent, bioaccumulative, and toxic; the EU listed it as a Substance of Very High Concern (2018) and is phasing it out of cosmetics by June 2027. May carry traces of a reproductive toxicant. |
| Cyclotetrasiloxane | Not A Fan | Persistent, bioaccumulative, and toxic to the environment; is suspected to be toxic to reproduction. |
| Diazolidinyl Urea | Not A Fan | Formaldehyde-releaser, potential allergen. |
| DMDM Hydantoin | Not A Fan | Formaldehyde-releaser, potential allergen. |
| Fragrance or Natural Fragrance | Not A Fan | Undisclosed ingredients, may interfere with the endocrine system, cause allergies, increase the risk of cancer. |
| Glyoxal | Not A Fan | Formaldehyde-releaser, potential allergen. |
| Imidazolidinyl Urea | Not A Fan | Formaldehyde-releaser, potential allergen. |
| Iodopropynyl Butylcarbamate (IPBC) | Not A Fan | Potential allergen. |
| Lauramidopropyl Betaine | Better (Not In My Top Picks) | Gentle coconut-based surfactant; trace impurities (DMAPA and amidoamine) can cause allergic reactions, and the EU’s safety panel has never studied it. |
| Lead & Other Heavy Metals (higher than EU or Canadian limits) | Not A Fan | Found in the makeup pigments and dyes as contaminants. |
| Methylchloroisothiazolinone (MCI) | Not A Fan | Skin sensitizer (patch-test allergen). The EU permits it only in rinse-off products at 0.0015%, in a fixed 3:1 blend with methylisothiazolinone; the US sets no limit. |
| Methylisothiazolinone (MI) | Not A Fan | Contact allergen. The EU bans it in leave-on cosmetics and caps rinse-off use at 15 ppm; the US sets no limit. |
| Mineral Oil | Not A Fan | Depending on a degree of its purification, may contain various amounts of carcinogenic Polycyclic Aromatic Hydrocarbons (PAHs) and other petroleum contaminants. |
| Ethylparaben / Methylparaben | Better (Not In My Top Picks) | Synthetic preservatives that pass through skin. These two show the weakest hormone-like activity of the parabens, and the EU allows each at 0.4%. I accept them only in Better products, never in Best. |
| Propylparaben / Butylparaben | Not A Fan | The higher-concern parabens. The EU caps them at 0.14% combined and bans them in diaper-area products for young children; Butylparaben sits on the EU’s endocrine Candidate List and shows the strongest hormone-like activity. |
| Phenoxyethanol | Better (Not In My Top Picks) | Recognized allergen, made using ethylene oxide. The EU caps it at 1% and is reviewing it as a possible hormone disruptor (no verdict yet); the US and Canada set no limit. |
| Polysorbates | Not A Fan | Made with ethylene oxide (a known carcinogen) and may hold residual 1,4-dioxane (a probable carcinogen). The EU has never reviewed them and bans the ethylene oxide used to make them. |
| Propyl Gallate | Better (Not In My Top Picks) | Antioxidant with no cancer link, but a documented skin allergen that penetrates skin and shows hormone activity in lab studies. |
| Propylene Glycol | Better (Not In My Top Picks) | Humectant with a long safety record, but a recognized allergen (2018 Allergen of the Year) made using propylene oxide, a possible carcinogen. Sensitive or eczema-prone skin may do better without it. |
| PTFE (Polytetrafluoroethylene, aka Teflon) | Not A Fan | Undisclosed ingredients of PTFE are linked to infertility, high cholesterol, insulin resistance, diabetes, impaired immunity, and cancers. |
| Quaternium-15 | Not A Fan | Potential formaldehyde releaser. |
| Sodium Hydroxylmethylglycinate | Not A Fan | Formaldehyde-releaser, potential allergen. |
| Sodium Laureth Sulfate and other ethoxylated ingredients | Not A Fan | Mild foaming cleanser, but made with ethylene oxide (a known carcinogen), leaving traces of 1,4-dioxane (a probable carcinogen). I rate all ethoxylated ingredients Not A Fan. |
| Stearalkonium Chloride | Better (Not In My Top Picks) | Conditioner with little absorption or irritation, but made with carcinogenic benzyl chloride and can form trace nitrosamines with certain preservatives; never reviewed by the EU’s safety panel. |
| Synthetic Dyes/Pigments (e.g., Blue 1 Lake, Red 6, Red 6 Lake, Red 40 Lake) | Not A Fan | Besides the residues of heavy metals, they may have the residues of carcinogenic or endocrine-disrupting by products of petroleum. |
| Talc | Not A Fan | Linked to lung irritation and ovarian cancer; in 2024 the IARC classified talc (asbestos-free) as probably carcinogenic to humans (Group 2A). |
