Yes, we’re talking about the same formaldehyde that’s used to preserve dead bodies. As gross as it sounds, this compound is an extremely common preservative in the cosmetic world. It’s in nail polish, hair gel, eyelash glue, hair-straightening products, body soaps and washes, and even baby shampoo!

Besides formaldehyde itself, there are substances categorized as formaldehyde-releasers that also help preserve cosmetic products. Examples of such releasers are imidazolidinyl urea, sodium hydroxymethyl glycinate, and benzyl hemiformal, in case you’re taking notes.

“Fragrance” and “parfum” are such broad words – they don’t give you a hint as to exactly what chemicals they are – but these vague words show up on countless beauty labels today. Cosmetic companies are allowed to label their products that way to protect their trade formulas. That leaves us, consumers, with less access to valuable information about the products we buy.

In truth, a single fragrance is typically a formulation of various substances, often synthetic ones. The International Fragrance Association (IFRA) currently lists over 3,600 chemicals that can potentially go into scent formulations (as of 2022).

Phenylenediamine (PD) is a primary ingredient in hair dyes and henna tattoos. It causes oxidation, which helps fix the colour to hair strands or the skin. You know those annoying side effects of dyes such as dermatitis or skin itch? Those are likely due to this chemical.

That’s not all that phenylenediamine does, however. Clinical studies have found that this compound could be toxic to the liver and kidneys. And yes, these studies examined dermal (skin) exposure to phenylenediamine. Worse, multiple scientific analyses have linked this chemical to cancers like prostate cancer and breast cancer. This was primarily observed among hairdressers and other people who used hair dyes.

Phenylenediamine as a cosmetic ingredient is somewhat restricted in Canada, but not completely banned.

Phthalates (pronounced like thal-eights) are synthetic chemicals that are primarily used to manufacture plastics, making them flexible. However, these compounds are also used as fragrance stabilizers and solvents in personal care products like shampoos, nail polish, hairsprays, lotions, and aftershaves. When you check product labels, you’ll probably find long phthalate names such as dibutyl phthalate and diethylhexyl phthalate.

Yet another type of preservative, parabens are a family of chemicals that is common in makeup, hair products, moisturizers, shaving products, and even some food items. Though a few forms of parabens are naturally occurring, the commercially-used ones are synthetic, and they typically have long compound names like butylparaben, ethylparaben, methylparaben, and propylparaben.

As preservatives, parabens inhibit the growth of spoilage microorganisms. Unfortunately, these chemicals are also endocrine disruptors, messing with our body’s hormonal function. When these compounds reach our bloodstream, they mimic the hormone estrogen, and studies suggest that this weakens reproductive health and may even cause breast cancer.

Governments in Europe and in Canada acknowledge the potential health risks from parabens but have not banned these chemicals from personal care and food products.

PFAS are a group of compounds dubbed “forever chemicals.” They’re so called because they’re virtually indestructible in the natural world, and when they get inside our bodies, they accumulate. And they don’t just sit there either – PFAS are linked to diseases such as lower immune response, thyroid dysfunction, decreased fertility, slow infant growth, and kidney cancer.

PFAS are most commonly used as water-repellant coatings, such as in food packaging and non-stick cookware. But these chemicals are in cosmetics as well – they’re the makeup industry’s magic ingredient for those “waterproof,” “smudge-proof,” or “long-lasting” products. So you’ll likely find PFAS in nail polish, mascaras, foundations, eyeshadows, blush, and lipsticks. Some foam cleansers have PFAS as well, as these compounds repel oil, too.

PEG compounds are commonly incorporated into cosmetics because they act as surfactants – substances that make other molecules easier to spread and combine. For instance, when you foam up a store-bought shampoo or soap, the surfactant loosens dirt from your skin and combines it with water so it can be washed away. PEGs also improve the spreadability of conditioners, lotions, and lipsticks.

These compounds may be handy, but they’re associated with several health issues. Some researchers found indications that PEGs may be cytotoxic or harmful to living cells. There are also clinical investigations showing PEGs as damaging to organs such as kidneys and digestive glands.

You’ve probably heard of silicone-based creams, foundations, and lipsticks, which tout a moisturizing and smoothing effect on skin. Silicones and siloxanes (two interchangeable terms) work by filling wrinkles with microscopic particles that reflect light off of the skin, so that the overall complexion appears smoother. But as brilliant as that sounds, there’s a dark side to these compounds.

This one’s a classic. Triclosan has long been used as an antimicrobial agent in many toiletries. It has a two-fold function: to act as preservative by limiting bacteria growth in the product itself, and to cleanse the skin by killing microbes. Thus, you’ll typically find triclosan in soaps and cleansers, mouthwashes and toothpastes, and hand sanitizers.

Unfortunately, triclosan is also an endocrine disruptor that affects not just estrogen levels but androgen levels as well. And as endocrine-disrupting chemicals do, triclosan may increase the risk of cancer, particularly breast cancer.