If you are the kind of shopper who reads the ingredients label carefully on your food as well as your skincare, it can be overwhelming to keep up with what is “bad” or “good.” Popular ingredients one year can be deemed controversial the next. Growing consumer concern can prompt companies to stop using particular ingredients, such as parabens, which makes it tough to separate hype from facts.
It is also important to note that not all “bad” ingredients are created equally. Some skincare ingredients are thought to be harmful to health, such as formaldehyde and hydroquinone, while others that seem benign, such as fragrance, can be a common cause of skin irritation. Also adding to the confusion of what is safe (or not) is that different countries have different regulations. An ingredient banned in Europe may be widely available in the US, and vice versa.
Here’s a look at some of the most controversial skincare ingredients.
Scent can be intensely personal. Some people love fragrance while for others it can trigger headaches, asthma and itching. According to the American Academy of Dermatology, fragrance is one of the most common causes of allergic contact dermatitis (which is basically a rash), along with poison ivy, nickel, nail cosmetics, latex and cement. Many skincare products have fragrance but adding to the confusion is that some products are listed as “fragrance free” while others are “unscented.” However, unscented doesn’t mean fragrance free, as the scent may come from a naturally perfumed ingredient, such as an essential oil. If you are sensitive to fragrance, look for the EPA Safer Choice label which verifies that products are fragrance free. 
SLS is short for sodium laureth sulfate, which can be found in shampoo as well as lip balm, foundation, exfoliants and cleansers. SLES (sodium laureth sulfate) has a similar chemical formula to SLS. As Healthline explains, SLS is a “surfactant. This means it lowers the surface tension between ingredients, which is why it’s used as a cleansing and foaming agent.” Chemical Safety Watch notes that SLS can be derived from natural sources like coconut and palm kernel oil and can also be manufactured in a laboratory setting. The main concern regarding SLSs was whether they cause cancer. In a 2015 paper published in the National Center for Biotechnology Information (NCBI), the authors note, “The most egregious claim by far is that SLS is carcinogenic… There is no scientific evidence supporting that SLS is a carcinogen.” SLS may cause irritation though. The AAD lists SLS as a rosacea trigger, along with menthol and camphor. Some people find that sulfates in shampoo work a little too well to clean the hair and find that it leaves tresses too dry, and prefer a sulfate free shampoo. As McGill University’s Office for Science and Society notes, “Sulfates are also irritants, so if you get shampoo in your eyes a lot (like me), you may notice that sulfate containing shampoos sting a bit more.” Some people, especially those with dry skin, find that facial cleansers with SLS are also drying.
Parabens are preservatives used in skincare, and have been around since the 1950s, after bacteria-contaminated facial lotions caused a small outbreak of blindness. The American Chemical Society estimates that parabens are present in about 85% of personal care products. Parabens became controversial around 2004, when Dr. Philippa Darbre of the University of Reading published a paper detailing that parabens were found in cancerous breast tumors, leading people to question whether parabens contributed to cancer. The Breast Cancer Prevention Partners notes that parabens are endocrine disruptors, and the Campaign for Safe Cosmetics (CSC) reports that parabens have also been linked to reproductive, immunological, neurological and skin irritation problems. 
However, critics of Dr Darbre point out that that non-cancerous breast tissue was not examined for the study to see if it also had traces of parabens. As BreastCancer.org states, “Parabens have been found in breast tissue and breast cancers, but this really doesn’t mean much. Parabens have been found in many other tissues because of their wide use.” Due to customer concerns, many companies stopped using parabens in their products and other countries have limited the amount of parabens used in cosmetics. In 2014, the EU banned five types of parabens. The FDA’s position on parabens is that “FDA scientists continue to review published studies on the safety of parabens. At this time, we do not have information showing that parabens as they are used in cosmetics have an effect on human health.” 
Oxybenzone is a chemical sunscreen that has been used in products for about 40 years, and it helps block UVA and UVB rays. Sunscreens are either chemical or physical (such as zinc oxide) and some studies suggest that chemical sunscreens are absorbed into the body and enter the bloodstream, which has raised some concerns. According to the Environmental Working Group, some studies suggest chemical sunscreens may disrupt hormones, and may cause allergies. In 2019 the FDA said that the physical sun blockers zinc oxide and titanium dioxide are proposed to be safe and effective, while the FDA proposes that it needs more safety information for 12 remaining sunscreen ingredients, including oxybenzone.
Triclosan has been around since the 1960s and was first used as a pesticide, according to WebMD. It is a preservative with antibacterial and antifungal properties and has been used in soaps, body washes and some cosmetics as well as toothpaste. The National Resources Defense Council says that “Specifically, the chemical disturbs thyroid, testosterone, and estrogen regulation, which can create a host of issues including early puberty, poor sperm quality, infertility, obesity, and cancer.” According to the FDA, “Some short-term animal studies have shown that exposure to high doses of triclosan is associated with a decrease in the levels of some thyroid hormones. But we don’t know the significance of those findings to human health. Other studies have raised the possibility that exposure to triclosan contributes to making bacteria resistant to antibiotics.” In 2017, the FDA banned triclosan in over-the-counter healthcare antiseptic products. 
Phthalates are a group of chemicals that are found in body washes, fragranced lotions and cosmetics, as well as products such as toys and vinyl flooring. They help make skincare products smoother. According to the Campaign for Safe Cosmetics, they have been linked to “endocrine disruption, developmental and reproductive toxicity, and cancer, have been banned from cosmetics in the European Union, but still remain prevalent in U.S. products.”The FDA states that “It’s not clear what effect, if any, phthalates have on human health. An expert panel convened from 1998 to 2000 by the National Toxicology Program (NTP), part of the National Institute for Environmental Safety and Health, concluded that reproductive risks from exposure to phthalates were minimal to negligible in most cases.” 
Sulfates are essentially detergents that make soap, toothpaste and shampoo foam, and one of the most common is sodium lauryl sulfate (see above). Other sulfates include ammonium laureth sulfate (ALS) and sodium alkyl sulfate. According to Healthline, sulfates are produced from petroleum and plant sources such as coconut and palm oils. The primary concern with sulfates is that some people think they are carcinogens. As a 2015 paper in the NCBI explained, “LS is not listed as a carcinogen by the International Agency for Research on Cancer (IARC); U.S. National Toxicology Program; California Proposition 65 list of carcinogens; U.S. Environmental Protection Agency; and the European Union. In 1998, the American Cancer Society published an article attempting to correct the public’s misconception of SLS. Regardless, false claims about SLS proliferated throughout the digital media, causing consumers to develop significant concerns about SLS in household cleaning products.” 
Hydroquinone is highly effective in fading the look of dark spots and hyperpigmentation. It works by blocking a melanin-producing enzyme called tyrosinase. It is a controversial ingredient though and the Campaign for Safe Cosmetics says that it has been banned in Europe and is restricted in Canada due to concerns it may be a carcinogen and cause a permanent darkening of the skin.  In 2006 the FDA proposed a ban on over-the-counter sales of cosmetic products containing hydroquinone, and recommended that the drug be studied further by the National Toxicology Program (NTP), but would still be available in the interim.
Although most people know that lead can be found in old paint and pipes, it is sometimes found in pigmented lipsticks. In 2017 the Campaign for Safe Cosmetics randomly purchased more than 30 lipsticks in four cities and sent them to a lab for lead testing. More than half came back with levels of lead. The cosmetics companies stated that only trace levels of lead were found, which occur naturally in minerals. The FDA states that it has analyzed hundreds of lipsticks for lead and “we found that levels of lead in these products were from below the detection limit to about 7 ppm.”
Petrolatum, or petroleum jelly, is a moisturizing ingredient found in skincare products and lip balms. The AAD recommends petroleum jelly for soothing cracked heels, diaper rash and helping injured skin heal as it creates a barrier. The Campaign for Safe Cosmetics notes that “When properly refined, petrolatum has no known health concerns. However, with an incomplete refining history, petrolatum could potentially be contaminated with polycyclic aromatic hydrocarbons, or PAHs” which it notes may be a carcinogen.  The EU mandates that for cosmetic use, the full refining history of the petrolatum must be known and proven to be non-carcinogenic.
PEGs are short for polyethylene glycol, or petroleum based compounds that are used in skincare as thickeners and moisture carriers. The Environmental Working Group lists it as “Classified as expected to be toxic or harmful” and “Classified as medium human health priority.” The David Suzuki Foundation lists PEGS as one of their “Dirty Dozen” ingredients, explaining “Depending on manufacturing processes, PEGs may be contaminated with measurable amounts of ethylene oxide and 1,4-dioxane. The International Agency for Research on Cancer classifies ethylene oxide as a known human carcinogen and 1,4-dioxane as a possible human carcinogen. Ethylene oxide can also harm the nervous system.” 
Think of a nanoparticle as a tiny delivery system in skincare. According to a 2018 paper published in the NCBI, they help with “enhanced skin penetration, controlled and sustained drug release, higher stability, site specific targeting, and high entrapment efficiency.” The same article notes that there are concerns about its use in cosmeceuticals “as there are possibilities of nanoparticles to penetrate through skin and cause health hazards.” The authors note “There are huge controversies regarding the toxicity and safety of the nanomaterials; various researches are being carried out to determine the possible health hazard and toxicity. Meticulous studies on the safety profile of the nanomaterials are required.”