Skip to Main Navigation
Skip to Page Content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it's official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you're on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Share This:
https://ntp.niehs.nih.gov/go/uvfilters

UV Filters

Bottle of suncreen on a beach

Research Overview

Status: Ongoing
Substances: 2-Hydroxy-4-methoxybenzophenone

Background Information

Millions of people use sunscreen lotions, creams, and sprays on their skin to prevent sunburn and resulting skin damage. Specific chemicals, known as ultraviolet (UV) filters, are added to sunscreens to absorb or block UV radiation from the sun. UV filters can offer protection against both UVA and UVB rays. Although products containing UV filters are applied to the skin, the UV filter, along with the body’s breakdown products from them have been found in urine, indicating that they make their way into the body. UV filters are regularly used in cosmetics for sun protection purposes, and in other products like plastics, toys, or furniture finishes to limit UV degradation. People may be exposed to these chemicals when food comes into contact with plastics that contain UV filters.

NTP Studies

NTP is working to assess the safety of UV filters through a variety of studies in rodent models. For example, NTP conducted a long-term study on 2-hydroxy-4-methoxybenzone (HMB) – one of the most common UV filters – to test the toxicity and carcinogenicity of chronic exposure to this chemical in rats and mice.

What did the studies find?

See table below for the most up-to-date information on the variety of projects taking place at NTP. For general descriptions of the various studies, please see the FAQs.

Chemical
  • Known by other names
Two-year chronic toxicity studies & Endocrine disruptor screening panel studies Modified one generation study Toxicokinetic studies Absorption, distribution, metabolism, & excretion studies
2-Hydroxy-4-methoxybenzophenone (HMB)
  • Oxybenzone
  • Benzophenone-3
Type of filter: UVB, UVA
Two-year chronic toxicity studies: Ongoing

Endocrine disruptor screen panel studies: Ongoing

Supporting files:
Ongoing

Supporting files:
Findings:
  • Concentrations of HMB metabolites increased with increasing dose
  • No differences between male and female rats
Supporting files:
Mutlu et al. 2017
Findings:
  • HMB and metabolites were detected in rat plasma after exposure through diet
Supporting files:
Mutlu et al. 2017
Ethylhexyl methoxycinnamate (EHMC)
  • Octinoxate
Type of filter: UVB
Two-year chronic toxicity studies: N/A

Endocrine disruptor screen panel studies: Ongoing

Supporting files:
Ongoing

Supporting files:
Findings:
  • EHMC was absorbed and excreted primarily in urine by 72 h after oral administration to rats and mice
  • Following dermal application, 34-42% was absorbed in rats and 54-62% in mice by 72 h
Supporting files: Fennell et al. 2018
Findings:
  • Two potential reproductive and developmental toxicants were produced by metabolism of EHMC
  • EHMC was cleared from rodent liver cells; less rapidly from human liver cells
Supporting files: Fennell et al. 2018
Octylsalicylate (OSAL)
  • 2-Ethylhexyl salicylate
Type of filter: UVB
Two-year chronic toxicity studies: N/A

Endocrine disruptor screen panel studies: Ongoing
N/A N/A N/A
Octocrylene (OCRY)
  • Octocrilene
  • 2-Propenoic acid, 2-Cyano-3,3-diphenyl-, 2-ethylhexyl ester (9CI)
Type of filter: UVB
Two-year chronic toxicity studies: N/A

Endocrine disruptor screen panel studies: Ongoing
N/A N/A N/A
Avobenzone
  • 1-(4-Methoxyphenyl)-3-(4-tert-butylphenyl)propane-1,3-dione
  • Butylmethoxydibenzoylmethane 4-tert-butyl-4'-methoxydibenzoylmethane
Type of filter: UVB
Two-year chronic toxicity studies: N/A

Endocrine disruptor screen panel studies: Ongoing
N/A N/A N/A
Ensulizole
  • Phenylbenzimidazole sulfonic acid
Type of filter: UVB
Two-year chronic toxicity studies: N/A

Endocrine disruptor screen panel studies: Ongoing
N/A N/A N/A
Homosalate
  • 3,3,5-Trimethylcyclohexyl 2-hydroxybenzoate
Type of filter: UVB
Two-year chronic toxicity studies: N/A

Endocrine disruptor screen panel studies: Ongoing
N/A N/A N/A
Padimate-O
  • 2-Ethylhexyl 4-(dimethylamino)benzoate
  • 2-Ethylhexyl-p-dimethyl-aminobenzoate
  • 2-Ethylhexyl dimethyl PABA
Type of filter: UVB
Two-year chronic toxicity studies: N/A

Endocrine disruptor screen panel studies: Ongoing
N/A N/A N/A

Informational Resources

FAQ

Q: How do NTP's studies on UV filters relate to humans?
A: Results from the NTP draft report on the toxicity of the UV filter, HMB, suggest that at very high concentrations, HMB may display slight endocrine disruption in animal models. Additionally, when HMB was given to animals through repeated doses, NTP found some evidence of carcinogenic activity in one of the two rodent species tested. These findings do not suggest that UV filters will cause harm if used by humans in a typical application. It is also important to note that sun exposure without application of a sunscreen that blocks the UV rays can damage skin, and sustained exposure is associated with skin cancer in both animals and humans.

Q: What is the endocrine disruptor screening panel?
A: The Endocrine Disruptor Screening Panel (EDSP) is a series of tests that aim to determine if chemicals and environmental contaminants interact the estrogen, androgen, and thyroid hormone systems.

Q: What is a modified one generation study?
A: The modified one generation study, or MOG study, measures developmental and reproductive toxicity parameters, and enables the setting of appropriate dose levels for a cancer bioassay through evaluation of target organ toxicity based on chemical exposure that starts during gestation. This gives scientists the power to detect adverse effects where there is a prenatal exposure, but evaluations occur postnatally.

Q: What are toxicokinetic studies?
A: A toxicokinetic study is essentially the study of how a substance acts inside an animal's body. Toxicokinetic studies test how much of the chemical gets in to the body and characterize how long it stays in the body.

Q: What is an Absorption, Distribution, Metabolism, & Excretion (ADME) study?
A: This type of study describes in more detail what happens to a chemical in the body in four different stages:

    1. For a chemical to reach a tissue, it must be absorbed into the bloodstream - often through mucous surfaces like the digestive tract - before being taken up by cells.
    2. Next, the chemical needs to be carried to the muscle or organ it will act on, most often via the bloodstream through a process known as distribution.
    3. The chemical then begins to break down through metabolism. As metabolism occurs, the original chemical is converted to new compounds called metabolites.
    4. Finally, compounds and their metabolites need to be removed from the body by excretion, usually through the urine or in the feces.

Q: There are some who say that UV filters are an endocrine disrupting chemical. Did your studies find this to be true?
A: In our cell-based studies, HMB added to the culture media interacted with the estrogen receptor at very high doses but did not result in the estrogen receptor producing any biological effects. In a short-term study in a rodent model, used to characterize estrogenic action, HMB given orally did not exhibit estrogenic activity. While some results suggest it may affect the endocrine system, we do not have the level of detail needed to be sure.

Q: In your two-year chronic toxicity and carcinogenicity studies, why did you give HMB to animals through food instead of applying it to skin?
A: Our study aimed to mimic continuous exposure of HMB in the animals. Rodents ate throughout the day and thus had continual exposure, similar to applying and reapplying sunscreen to skin. This method models the amount of UV filters people could be exposed to via repeated application of sunscreens to the skin or by eating food that has touched UV filter-containing plastics.

Q: Who nominated HMB and why?
A: HMB was nominated for study by the National Cancer Institute due to high prevalence of the chemical in commercial products such as sunscreens and cosmetics, and lack of carcinogenicity data.

Q: What’s next for NTP on UV filter research?
A: NTP is in the process of reporting the reproductive and developmental toxicity data on another UV filter, known as ethylhexylmetoxycinnimate, or EHMC. We are working on a report summarizing cell-based and short-term animal studies done with these UV filters: avobenzone, ensulizole, homosalate, padimate-o, octylmethoxycinnamate, octylsalate, and octocrylene.

Stay Informed & Contact Us

Laptop on wooden desk with email screen

Stay Informed

Subscribe to receive email to stay informed about this area of research and other NTP information.

Contact Us

For questions or additional information, email us or use our contact form.