Comparative Health Risks from Benzene in Sunscreens

In recent years, there have been concerns over unexpected contaminants detected in a myriad of consumer products. This development has led to a proliferation of lawsuits. The two most common are toxic tort actions and class action suits. Generally, the toxic tort actions concern a plaintiff alleging injuries, most often cancer, resulting from a toxic exposure. The class action suits usually focus on allegations that (1) the consumer product labeling or instructions did not inform consumers regarding the presence of and risks and dangers from a contaminant, or (2) the consumer product contains a contaminant that presents a substantial risk of harm to the consumer. The legal claims are asserted under state statutes enacted to protect consumers from unfair methods of competition, unfair or deceptive acts or practices, and false advertising in connection with the sale of consumer goods. In addition, common law claims such as unjust enrichment and breach of implied and express warranties are often included. The relief sought in these class actions includes compensatory damages for the economic loss resulting from purchasing a product that the plaintiffs would not have bought but for the defendants’ misrepresentations, disgorgement of profits and revenues, attorney fees and all costs associated with prosecution of the lawsuit, and punitive damages.

The contaminants targeted in these lawsuits have ranged from asbestos (often in talc powder) to heavy metals to per- and polyfluoroalkyl substances (PFAS) to volatile organic compounds (e.g., benzene), and many other substances. The consumer products targeted have exploded over the last five years, including but not limited to cosmetics, household cleaners, personal cleaning products, hair products, clothing, food products and packaging, construction products, cookware, electronics, and baby products.

A common critical issue in these lawsuits is whether the presence of a contaminant is in high enough concentrations for the product to present any meaningful risk of harm to users. The reality of living in industrialized societies is that eliminating all exposures to contaminants is not possible because some are present even in ambient air and drinking water, albeit typically at concentrations considered too low to provide any meaningful risk to the public. Accordingly, marshaling the relevant scientific data and expert analyses of the data is critical to legal representation in these cases.

The following expert analysis and case study presentation illustrates the application of these principles within the context of recent concerns raised regarding the presence of benzene in sunscreens.

Benzene in Personal Care Products

The unexpected detection of benzene in multiple personal care products raised concerns about health impacts, including cancer risk. The initial detection of benzene in spray sunscreens was speculated by the U.S. Food and Drug Administration (FDA) and others to be an unintended manufacturing by-product related to inactive ingredients such as thickening agents, spray propellants, fragrance ingredients, or petrochemicals. In addition to spray sunscreens, some hand sanitizers, sun aftercare lotions, athlete’s foot and jock itch sprays, deodorant and antiperspirant sprays, and dry shampoo and conditioner sprays have also been found to have measurable benzene concentrations.

A study by Hudspeth et al. reports testing 661 sunscreen and after-sun care samples, representing 108 brands, including aerosol and pump spray products, lotions, creams, gels, and sticks. Using a headspace sampling with gas chromatography–mass spectroscopy detection, they found that 29% of the samples had detectable benzene, with concentrations above 2 parts per million (ppm) in 11% of the products analyzed. Of these, 32 of the 40 most contaminated products (80%) were sprays with levels of benzene greater than 0.1 ppm (6.26 ppm maximum concentration). The authors reported sensitivity of the analytical technique as low as 0.05 ppm in sunscreen matrices. These findings led to the voluntary recalls of various consumer products and widespread news reporting of benzene in consumer products.

Some of these products are regulated by the FDA either as drugs (antiperspirants and sunscreen) or cosmetics (after-sun gels and lotions). For benzene, the FDA only allows the presence of benzene at concentrations not to exceed 2 ppm if the drug product offers a “significant therapeutic advance” where the use of benzene for manufacturing is “unavoidable.” However, the FDA states that drug manufacturers should avoid knowingly using benzene in the manufacture of drug substances because of its unacceptable toxicity.

Benzene Inhalation and Absorption from Use of Sunscreen

Benzene is a known human carcinogen, which at sufficient exposure concentrations can cause multiple health effects. The most sensitive target organ for benzene is the bone marrow, where benzene exerts its toxicity. Such exposures to benzene can cause decreases in red blood cells (leading to anemia), decreases in white blood cells (which can affect the immune system and increase the chance for infection), and leukemia. Because of this, understanding the potential for health effects requires understanding the potential absorption or systemic delivery of benzene for the corresponding benzene exposure concentration. As such, concentrations of benzene in the blood are a relevant metric of systemic benzene exposure since they are relevant for the concentration of benzene in the bone marrow.

Benzene from sunscreens can enter the body through either an inhalation route of exposure (breathing sprays, or volatilization of creams) or a dermal route of exposure (through the skin after application). We used a conservative screening approach whereby we incorporated quantitative adjustments considering the pharmacokinetics of benzene in combination with exposure models to estimate potential systemic delivery of benzene, both via inhalation and dermally, from use of sunscreens.

For inhalation exposure, we evaluated two potential scenarios: one more conservative and the other more realistic. For the conservative scenario, we assumed 1 oz (28 g) of sunscreen (lotion, spray, or aerosol) was applied to the entire body (18,000 cm² of skin) as recommended by the American Academy of Dermatology, leading to 28,000 mg of sunscreen applied. The sunscreen was assumed to be applied in a closed room or shower (2 ft × 2 ft × 6 ft box, with a volume of 24 ft³, or 0.68 m³). We assumed a 1 ppm concentration of benzene in the sunscreen and conservatively assumed 100% of the benzene volatilizes into the air. In this scenario, we assumed a completely sealed room, with no potential for additional dilution through doors, sinks, or other outlets. These assumptions led to 28 µg of benzene in the 0.68 m³ shower box, for a concentration of about 13 parts per billion (ppb) in the air. We assumed the individual was breathing at an alveolar ventilation rate of 210 L/hr. Under these assumptions, the calculated benzene intake would be 8.6 µg benzene per application event.

For the more realistic scenario, we assumed sunscreen was applied in a sealed bathroom (8 ft × 6 ft × 4 ft box, with a volume of 192 ft³, or 5.4 m³), using the same sunscreen application rates as the smaller box model, leading to 28,000 mg of sunscreen applied with limited ventilation (approximately 0.25 air exchanges per hour at 1 cm/sec), and the individual remained in the bathroom for 15 minutes. Again, a concentration of 1 ppm of benzene in the sunscreen was assumed, leading to 28 µg of benzene in the 5.4 m³ shower box, for a benzene concentration of about 6.0 µg/m³ in the air, or approximately 1.6 ppb. In this more realistic model, the average breathing zone benzene concentration rises quickly to approximately 16 µg/m³, then decreases in the first 5 minutes to fall below 7.8 µg/m³ as the benzene dilutes within the bathroom box. We assumed the same breathing rate as before (210 L/hr). Under these assumptions, the calculated benzene intake would be 1.2 µg benzene per application event.

For dermal exposure, we assumed the same application rate of sunscreen as in the inhalation modeling (1 oz or 28 g of sunscreen containing 1 ppm of benzene applied over the entire body) and conservatively assumed a 100% absorption rate through the skin. Note that these assumptions do not consider evaporation losses during absorption—realistically, some of the product, especially the benzene that is volatile, would evaporate from the skin. Because we assumed all benzene was absorbed dermally, we did not calculate inhalation exposure in this model. Furthermore, these exposure calculations only represent intake and did not consider elimination by metabolism, urinary clearance, or ventilation. However, all these clearance processes are identical for inhalation or dermal exposure, so the ratio of blood concentrations would be the same as the ratio of intakes. Under these assumptions, the calculated benzene intake from dermal application of sunscreens would be 28 µg benzene per application event.

Comparison to Benzene Intake from Other Exposures

To put exposures from sunscreen use into context, the estimated blood benzene concentrations can be compared to blood concentrations resulting from other typical benzene exposures (see tbl. 1), such as exposure resulting from walking on a busy city street or ingestion of food and beverages, as well as from occupational exposures. Benzene is present in the air of many cities on busy streets at a concentration of up to 6.5 ppb. Converting this to µg/L of air (0.0208 µg/L) and assuming 100% absorption (breathing of 210 L/hr would determine the total amount absorbed), the resulting intake is approximately 4.4 µg/hr. This is more than double what would occur from inhalation following a realistic exposure scenario applying sunscreen. There are also common exposures to benzene in food and beverages. For example, the maximum benzene concentrations reported in food range from 1 to 190 ppb, with concentrations above 100 ppb reported in at least one sample of cola (138 ppb), raw bananas (132 ppb), and coleslaw (102 ppb). Benzene is readily absorbed orally, so any amount in food would be equivalent to intake. Using this last example, eating a banana containing 132 ppb benzene would lead to ingestion of 15 µg of benzene (132 ppb benzene in a 4 oz (0.113 kg) banana without skin).