The Relationship Between Benzophenone-3 and Pregnancy

What Is Benzophenone-3?

Benzophenone-3 (BP-3), also referred to as oxybenzone, is found naturally in flowering plants, and is a chemical compound we constantly interact with. From applying cosmetics with benzophenone-3 to smelling BP-3 in our fragrances, products containing BP-3 are common in our day-to-day lives.¹ BP-3 is used in sunscreens, cosmetics, and plastic surface coatings for food products because of its ability to absorb and disperse the sun’s harmful ultraviolet (UV) radiation.¹ However, the biological impact of the compound in humans has not yet been fully elucidated. Researchers only recently identified that the phenol family of chemicals BP-3 stems from may be linked to birth defects, sparking many individuals to question BP-3’s side effects. With growing consumer concerns over the compound, the US Food and Drug Administration (FDA) and researchers have sought to examine the full impact of BP-3’s potential effects on the reproductive system.

Analyzing Benzophenone-3’s Effects in Different Organisms

Humans

In a systematic review, researchers analyzed thousands of articles in multiple databases to obtain relevant information about BP-3 in cosmetics. In one study, high urinary concentrations of BP-3 were correlated with shorter term pregnancies or decreased gestational age in women, reducing a pregnancy’s duration on average by about half a week.² Furthermore, another study found that high urinary concentrations of BP-3 were linked to greater birth weight in male babies.³ Another study found that high BP-3 concentrations in sub-fertile women, a group at risk for abnormal glucose tolerance, were associated with a lower mean glucose level and lower odds of an abnormal glucose load test.⁴

Animals

When analyzing the effects of high doses of BP-3 in mice, male mice had a significant increase of sperm production, while female mice also experienced a marked increase in their estrogen activity.⁵ BP-3 also impacted the reproductive systems of fish, as Japanese medaka hatched less eggs.⁶ Similarly, zebrafish also showed a decrease in hatched embryos.⁷

How Much BP-3 Is Absorbed from Sunscreen Application 

While these effects are concerning, it is important to take into consideration the levels at which these occurred and how much BP-3 is absorbed from daily application of sunscreens and other products.

The FDA conducted a small, randomized clinical trial which assessed this by comparing the systemic exposure of BP-3 from maximal recommended use—applying 2 mg of sunscreen per 1 cm² four times per day for four days—of two sprays and one lotion sunscreen. The study found that both sprays and lotion demonstrated significant systemic absorption of BP-3, with maximal plasma concentration levels of 209.6 ng/mL and 194.9 ng/mL of the sprays and 169.3 ng/mL for the lotion. All three demonstrated increasing levels at Day 4 compared to Day 1, indicating drug accumulation, and noted a residual concentration at Day 7 above 23 ng/mL for all three formulations.⁸ These values are all above the 0.5 ng/mL threshold used by the FDA to determine if carcinogenic and other risk assessment needs to be done.

A larger follow up clinical trial by the FDA showed that systemic BP-3 levels exceeded 0.5 ng/mL after a single application of 2 mg/cm² to 75% of body surface area (estimated area not covered by swimwear) and remained above that threshold until 23 hours after application. The systemic exposure following 3 additional days of four times daily sunscreen application remained above this threshold for over 21 days. The levels of absorption were higher in the lotion formulation than with the spray formulation.⁹

Of note, regarding the levels at which were used in some animal studies that show altered estrogen activity, a study found it would take about 35 years of a person applying 2 mg/cm² of sunscreen to their whole body to achieve the same serum concentration that the mice were subjected to.¹⁰

So, Can Benzophenone-3 Actually Disrupt Your Hormones?

BP-3 in cosmetics and sunscreens is ubiquitous in everyday life, and the review’s findings suggest that this chemical compound may influence the reproductive systems across multiple species. Specifically, BP-3’s adverse effects may be caused by the compound’s ability to disrupt the endocrine (hormonal) system—particularly estrogens and androgens. However, the exact levels at which this potential hormone disruption are still unknown, and there is no conclusive data that the BP-3 levels from sunscreen application can affect the endocrine system.^11,12

What is known, however, is that studies have shown that there is significant absorption of BP-3 after topical application of sunscreen. BP-3 can be detected in the blood, urine, amniotic fluid, and breast milk.⁸ Researchers are still determining whether this level of absorption is harmful or not for consumers, and if so, at what level it is harmful. Research needs to be conducted to elucidate this relationship and the FDA is investigating the matter further.¹³ In the meantime, in Europe it is required to list whether a product has BP-3, or oxybenzone, and many newly made sunscreens in the United States now exclude the ingredient. However, it is important to note that there have been no adverse systemic effects reported in humans since the chemical began use in 1978.¹⁴ Nonetheless, it is important for consumers to be more aware of the presence of BP-3 in their cosmetics before they purchase their favorite sunscreen or cosmetics.