Oxybenzone

Repeated dose toxicity: dermal

Administrative data

Endpoint:

sub-chronic toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: well documented guideline study performed under GLP

Cross-reference

Reason / purpose for cross-reference:

reference to same study

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1992

Report date:

1992

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 411 (Subchronic Dermal Toxicity: 90-Day Study)

GLP compliance:

yes

Remarks:

according to 21 CFR 58

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Oxybenzone

EC Number:

205-031-5

EC Name:

Oxybenzone

Cas Number:

131-57-7

Molecular formula:

C14H12O3

IUPAC Name:

2-benzoyl-5-methoxyphenol

Test material form:

solid: particulate/powder

Remarks:

migrated information: powder

Details on test material:

The HMB used in these studies was obtained from American Cyanamid Co. (Bridgewater, NJ), and samples were analyzed at Midwest Research Institute (Kansas City, MO). The infrared, ultraviolet/visible, and nuclear magnetic resonance spectra were consistent with the structure of HMB and with available literature references. Elemental analysis results for carbon were slightly high but agreed with theoretical values for hydrogen. Karl Fischer analysis for water indicated less than 0.04%. Analysis by two thin-layer chromatography systems indicated a single spot; no impurities with relative peak areas of greater than 0.1% of the major peak were detected by gas chromatography.

Test animals

Species:

other: rats and mice

Strain:

other: Fischer 344 and B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

Rats and mice used in the 13-week studies were obtained from Taconic Farms (Germantown, NY). Rats were housed 5/cage for the feed study and were housed individually for the dermal studies. Animals received NIH-07 diet (Zeigler Bros., Gardners, PA) and water ad libitum throughout the studies. Blood samples were collected, and the sera analysed for viral titers from 5 animals per sex and species at study start and at termination in the 13-week studies. Temp.: 72 ± 3°F; relative humidity--50 ±15%; fluorescent light 12 h/d; 10 air changes/h. Age of animlas at start of study was 6 weeks for males and 7 weeks for females.

Administration / exposure

Type of coverage:

not specified

Vehicle:

other: one group acetone and another group in lotion

Details on exposure:

The dermal vehicles were formulated to concentrations of 0, 5, 10, 20, 40, or 80 mg/ml. A constant volume of 0.25 ml for rats and 0.1 ml for mice was applied over a fixed standard area (10%) of the interscapular region. The area was clipped 24 hours prior to the initial application, and weekly thereafter, with an electric clipper.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Dose formulation stability studies indicated that acetone solutions of HMB were stable for at least 3 weeks in the dark in sealed vials at room temperature, as were solutions stored for 3 hours open to light and air. HMB also was stable under similar conditions when formulated as part of a lotion comprised of lanolin oil (5.4%), white petrolatum (2.6%), stearic acid (4.3%), propyl paraben (0.05%), propylene glycol (5.4%), methyl paraben triethanolamine (0.1%), disodium EDTA (0.05%), and deionized water (80%). Stability studies conducted on a feed blend indicated a small but significant loss (~2%) after 3 weeks' storage in the dark in sealed containers at room temperature. No significant losses were observed with similar blends kept at 5¡C or -20¡C. Feed blends stored open to air and light for 3 days in a rat cage exhibited losses (~2%).

Duration of treatment / exposure:

for 13 weeks

Frequency of treatment:

5 days per week

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
12.5 mg/kg bw/d
Basis:
nominal per unit body weight

Doses / concentrations 2

Remarks:

Doses / Concentrations:
25 mg/kg bw/d
Basis:
nominal per unit body weight

Doses / concentrations 3

Remarks:

Doses / Concentrations:
50 mg/kg bw/d
Basis:
nominal per unit body weight

Doses / concentrations 4

Remarks:

Doses / Concentrations:
100 mg/kg bw/d
Basis:
nominal per unit body weight

Doses / concentrations 5

Remarks:

Doses / Concentrations:
200 mg/kg bw/d
Basis:
nominal per unit body weight

No. of animals per sex per dose:

10 males and 10 females per dose group

Control animals:

yes, concurrent vehicle

Positive control:

no positive control

Examinations

Observations and examinations performed and frequency:

13-Week Studies, Dermal: Observed 2 x d for mortality/moribundity; 1 x wk for clinical signs of toxicity; site of application examined weekly; weighed initially,weekly, and at necropsy.

Sacrifice and pathology:

Necropsy performed on all animals; the following tissues were examined microscopically from all high dose and controls: Gross lesions, adrenal gland, brain, esophagus, eyes (if grossly abnormal), femur with bone marrow, gall bladder (mice), heart, intestine (duodenum, jejunum, ileum, cecum, colon, rectum), kidney, liver, lungs and bronchi, mandibular and mediastinal lymph nodes, nasal cavity with turbinates, ovary, pancreas, parathyroid, pituitary, preputial or clitoral gland (rats only), prostate, salivary gland, seminal vesicle, spinal cord (if neurologic signs present), spleen, stomach (forestomach and glandular), testis and epididymis, thymus, thyroid, trachea, urinary bladder, uterus. In addition to all gross lesions, the kidney was examined in all dose groups. Organ weights obtained from all core study animals include: liver, thymus, right kidney, right testis, heart, and lungs.

Other examinations:

Hematology, Clinical Chemistry, and Urinalysis: Hematology, clinical chemistry, and urinalysis were evaluated in rats, only, on day 3, day 15, and week 12. Sperm Morphology/Vaginal Cytology:
Dermal: sperm morphology and vaginal cytology were evaluated in rats exposed to 0, 12.5, 50.0, and 200.0 mg/kg HMB and in mice exposed to 0, 22.8, 91.0, and 364.0 mg/kg HMB.

Statistics:

Two approaches were employed to assess the significance of pairwise comparisons between dosed and control groups in the analysis of continuous variables. Organ and body weight data, which are approximately normally distributed, were analyzed using the parametric multiple comparisons procedures of Williams (1971, 1972) and Dunnett (1955). Clinical chemistry and hematology data, which typically have skewed distributions, were analyzed using the nonparametric multiple comparisons methods of Shirley (1977) and Dunn (1964). Jonckheere's test (Jonckheere, 1954) was used to assess the significance of dose-response trends and to determine whether a trend-sensitive test (Williams, Shirley) was more appropriate for pairwise comparisons than a test capable of detecting departures from monotonic dose-response (Dunnett, Dunn). If the P-value from Jonckheere's test was greater than or equal to 0.10, Dunn's or Dunnett's test was used rather than Shirley's or Williams' test.
The outlier test of Dixon and Massey (1951) was employed to detect extreme values. No value selected by the outlier test was eliminated unless it was at least twice the next largest value or at most half of the next smallest value.

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Dermal irritation:

no effects observed

Mortality:

no mortality observed

Body weight and weight changes:

no effects observed

Food consumption and compound intake (if feeding study):

no effects observed

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

not examined

Ophthalmological findings:

no effects observed

Haematological findings:

no effects observed

Clinical biochemistry findings:

no effects observed

Urinalysis findings:

no effects observed

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

effects observed, treatment-related

Description (incidence and severity):

increased kidney weights

Gross pathological findings:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

13-Week Dermal Studies in Rats, with the Acetone Vehicle
All animals survived to the end of the studies. No chemically-related changes were observed in body weight gains, food consumption, clinical observations, reproductive system evaluations, necropsy findings, or by histologic examination of skin samples from the site of application. Relative kidney weights were increased in a non-dose-related manner in female rats treated topically with 25 mg/kg or larger doses of HMB.
In male rats, there were no changes that were considered chemically-related in serum hematologic, biochemical, or urinary variables at any time point. In female rats, there were decreases in reticulocyte counts in animals in all dose groups at 12 weeks, increases in platelet counts in animals in the 50, 100, and 200 mg/kg dose groups at 15 days, and an increase in WBC count produced by a lymphocytosis in the 200 mg/kg group at 12 weeks. There were no relevant changes in biochemical or urinalysis variables in female rats at any time point.

Effect levels

Dose descriptor:

NOAEL

Effect level:

200 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: The dermal studies were limited by the reduced systemic exposure achievable by this route, but indicated that rats and mice are generally similarly affected by oral and dermal exposures. Thus, the high dose in this study is considered as NOAEL.

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

In the dermal 13-week part of the study (see also oral 13-weeks study) no NOAEL was derived by the study authors but in absence of adverse dose dependant effects seen, the high dose of 200 mg/kg bw/d can be considered as NOAEL.

Executive summary:

In the dermal 13-week part of the study (see also oral 13-weeks study) no NOAEL was derived by the study authors but in absence of adverse dose dependant effects seen, the high dose of 200 mg/kg bw/d can be considered as NOAEL. The study indicated that rats and mice are generally similarly affected by oral and dermal exposures.