2-ethylhexyl salicylate

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

The substance has been investigated for endocrine effects in an uterotrophic assay, an estrogen receptor binding study and an androgen receptor binding study, none of them revealing any finding of concern. Compared to controls, no significant changes were noted in any of these investigations. Thus, the substance does not give concerns for endocrine activity based on current knowledge.

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Remarks:

based on test type (migrated information)

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

September 06 to November 05, 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: guideline test with GLP

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

OECD Guideline 421 (Reproduction / Developmental Toxicity Screening Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

other: RccHanTM: WIST(SPF)

Sex:

male/female

Details on test animals or test system and environmental conditions:

Animals: Rat, RccHanTM: WIST(SPF)
Rationale: Recognized by international guidelines as a recommended test system.
Breeder: Harlan Laboratories, B.V. Kreuzelweg 53 5961 NM Horst / Netherlands
Number of Animals: 44 males: 11 per group 44 females: 11 per group

Age (at Start of Treatment): 11 weeks
Body Weight Range
(at Start of Treatment): Males: 312 to 351 g Females: 208 to 244 g
Identification: Cage card and individual animal number (ear tattoo).
Pups: On day 1 post partum, pups were individually tattooed with Indian ink.
Randomization: Performed after at least three days of acclimatization using a computer-generated random algorithm. Body weights (recorded on the day of allocation) were taken into consideration in order to ensure similar mean body weights in all groups.
Acclimatization: Under test conditions after health examination. Only animals without any visible signs of illness were used for the study.
Husbandry
Room Numbers, Füllinsdorf: E0441A (acclimatization) and E0441 (after acclimatization) Conditions: Standard laboratory conditions. Air-conditioned with 10 - 15 air changes per hour, continuously monitored environmental conditions (temp. range: 22 ± 3 °C; relative humidity range: 30 - 70%). Values outside of these ranges occasionally occurred, usually following room cleaning, which was considered not to have any influence on the study. These data were not reported but were retained in the raw data. There was 12-hour fluorescent light / 12-hour dark cycle with music during the light period.
Accommodation: In groups of three to five animals in Makrolon type-4 cages with wire mesh tops up to the day of ran-domization and afterwards individually in Makrolon type-3 cages with wire mesh tops and sterilized standard softwood bedding (‘Lignocel’ J. Rettenmaier & Söhne GmbH & CoKG, 73494 Rosenberg/Germany, imported by Provimi Kliba SA, 4303 Kaiseraugst / Switzerland) with paper enrichment (ISO-BLOX from Harlan Laboratories B.V., Netherlands), batch/ lot nos. 100099. During the pre-pairing period, cages with males were interspersed amongst those holding females to promote the development of regular estrus cycles.

Diet: Pelleted standard Harlan Teklad 2018C (batch no. 43/12) rodent maintenance diet (Provimi Kliba SA, 4303 Kaiseraugst / Switzerland) was available ad libitum. .
Water: Community tap-water from Füllinsdorf was available ad libitum in water bottles.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

Four groups of 11 males and 11 females were treated by gavage with Neo Heliopan OS once daily. Males were treated over a 14-day pre-pairing period and during the pairing period up to one day before necropsy. Females were treated throughout the pre-pairing, pairing, gestation and lactation period up to the day 3 post partum.

Vehicle and Control Item
Identification: Corn oil
Source: Carl Roth GmbH
Batch Number: 292189296
Expiry Date (Retest Date): 02-Aug-2017
Storage Conditions: Room temperature (20 ± 5 °C)

Details on mating procedure:

During the pairing period, females were housed with sexually mature males (1:1) until evidence of copulation was observed. The females were removed and housed individually if:

- the daily vaginal smear was sperm positive, or
- a copulation plug was observed.

The day on which a positive mating was determined (copulation plug or sperm) was designated day 0 post coitum.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

On the first treatment day samples from the control group as well as three samples (top, middle and bottom) of about 1 g of each concentration were taken prior to dosing for analysis of concentration and homogeneity. To confirm the stability (8 days) samples of about 1 g of each concentration were taken from the middle of each aliquot used on day 7 of the treatment. During the last week of the treatment, samples were taken from the middle to confirm concentration.
The aliquots for analysis of dose formulations were frozen (-20 ± 5 °C) and delivered on dry ice to B. Bürkle (Harlan Laboratories Ltd., Zelgliweg 1, 4452 Itingen / Switzerland) and stored there at -20 ± 5 °C until analysis.

The samples were analyzed by GC coupled to an FID detector following an analytical procedure provided by the Sponsor and adapted at Harlan Laboratories. The test item was used as the analytical standard. Analyzed samples were not discarded without written consent from the study director.

In conclusion, the results indicate the accurate use of the test item and corn oil as vehicle during this study. Application formulations were found to be homogeneously prepared and sufficient formulation stability under storage conditions was approved.

Duration of treatment / exposure:

Males: 28 days Females: Approximately 7 weeks

Frequency of treatment:

Once daily

Details on study schedule:

Two females did not mate during the 14-day pairing period and a second pairing of these females with a male in the same group, which had already mated successfully, was carried out. Although mating was not observed also during the second pairing period, both females had body weight gain indicating pregnancy. Therefore the second mating period was interrupted.
All dams were allowed to give birth and rear their litters (F1 pups) up to day 4 post partum. Day 0 was designated as the day on which a female had delivered all her pups.

Remarks:

Doses / Concentrations:
0, 25, 80, 250 mg/kg/day
Basis:
actual ingested

No. of animals per sex per dose:

11

Control animals:

yes, concurrent vehicle

Details on study design:

Method: Oral, by gavage
Rationale for Method: Administration by gavage is a common and accepted route of exposure for this type studies.
Frequency of Administration: Once daily
Target Dose Levels: Group 1: 0 mg/kg/day (control group)
Group 2: 25 mg/kg/day
Group 3: 80 mg/kg/day
Group 4: 250 mg/kg/day
Rationale for Dose Level Selection: The dose levels were selected based on a previous dose range-finding toxicity study in Han Wistar rats, Harlan Laboratories Study D54872, using dose levels of 0, 100, 300 and 1000 mg/kg/day, resulting in mortality and adverse toxic effects at the dose level
of 1000 mg/kg bw/day and adverse toxic effects at the dose level of 300 mg/kg bw/day.
Dose Volume: 4 mL/kg body weight
Dose Concentrations: Group 1: 0.00 mg/mL
Group 2: 6.25 mg/mL
Group 3: 20.00 mg/mL
Group 4: 62.50 mg/mL
Duration of Acclimatization Period: Minimum 5 days
Duration of Treatment Period: Males: 28 days Females: Approximately 7 weeks

Positive control:

no data

Parental animals: Observations and examinations:

Viability / Mortality: Twice daily
Clinical Signs: Daily cage-side clinical observations (once daily, during acclimatization and up to day of necropsy). Additionally females were observed for signs of difficult or prolonged parturition, and behavioral abnormalities in nesting and nursing.
Food Consumption: Males: Pre-Pairing period days 1 - 4, 4 - 8, 8 - 11 and 11 - 14; after pairing period weekly.
Females: Pre-Pairing period days 1 - 4, 4 - 8, 8 - 11 and 11 - 14; gestation days 0 - 7, 7 - 14 and 14 - 21 and days 1 - 4 of the lactation.
No food consumption was recorded during the pairing period.
Body Weights: Recorded daily from treatment start to day of necropsy.

Oestrous cyclicity (parental animals):

not applicable

Sperm parameters (parental animals):

no data

Litter observations:

Pup Data: The litters were examined for litter size, live births, still births and any gross anomalies. The sex ratio of the pups was recorded. Pups were weighed individually (without identification) on days 0 (if possible), 1 and 4 post partum.

Postmortem examinations (parental animals):

Males were sacrificed after treatment for 28 days, when no longer needed for the assessment of reproductive effects.
If birth did not occur on the expected date (day 21 post coitum), the dam was sacrificed on day 25 post coitum.
At the scheduled sacrifice, all animals were weighed and sacrificed by an injection of sodium pentobarbital. All P generation animals were exsanguinated.
All parent animals and pups, except those excessively cannibalized, were examined macroscopically for any structural changes, either at the scheduled necropsy or during the study if death occurred to establish, if possible, the cause of death. For the parent animals, special attention was directed at the organs of the reproductive system. For the parent animals, special attention was directed at the organs of the reproductive system.
Specimens of abnormal tissue were fixed in neutral phosphate buffered 4% formaldehyde solution.
The number of implantation sites and corpora lutea was recorded for all dams with litters. The uteri of non-pregnant females were placed in a solution of ammonium sulfide to visualize possible hemorrhagic areas of implantation sites.
Organ Weights and Preservation
Organs were trimmed from any adherent tissue, and their wet weight taken. If not indicated otherwise in the table, organs were preserved in neutral phosphate buffered 4% formaldehyde solution.
Histotechnique
All organ and tissue samples to be examined by the principal investigator were processed, embedded and cut at an approximate thickness of 2 - 4 micrometers and stained with hematoxylin and eosin. Additionally, the testis was stained by PAS-hematoxylin.
Histopathology
Slides of all organs and tissues listed collected at terminal sacrifice from the animals of the control and high-dose groups were examined by the principal investigator. The same applied to all occurring gross lesions and to all animals, which died spontaneously or had to be terminated in extremis.

Qualitative assessment of the male reproductive organs was performed. Special emphasis was made on the stages of spermatogenesis and histopathology of interstitial cell structure.

Histological examination of ovaries was carried out on any females that did not give birth. In addition, microscopic examination of the reproductive organs of all infertile males was made.

Postmortem examinations (offspring):

Pups and dams were sacrificed on day 4 post partum. All parent animals and pups, except those excessively cannibalized, were examined macroscopically for any structural changes, either at the scheduled necropsy or during the study if death occurred to establish, if possible, the cause of death.

Statistics:

The following statistical methods were used to analyze food consumption, body weights and reproduction data:

• Means and standard deviations of various data were calculated.

• The Dunnett-test [see References (2)] (many to one t-test) based on a pooled variance estimate was applied if the variables could be assumed to follow a normal distribution for the comparison of the treated groups and the control groups for each sex.

• The Steel-test [see References (3)] (many-one rank test) was applied instead of the Dunnett-test when the data could not be assumed to follow a normal distribution.

• Fisher's exact-test [see References (4)] was applied if the variables could be dichotomized without loss of information.

Reproductive indices:

fertility indices, mean precoital time, post-implantation loss,

Offspring viability indices:

mean litter size, pup sex ratios and viability indices.

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

At the dose level of 250 mg/kg bw/day, one female (no. 78) was found dead on day 23 of the gestation period.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At the dose levels of 250 and 80 mg/kg bw/day, reduced food consumption was noted during lactation.At the dose level of 250 mg/kg bw/day, statistically significant reduction in body weight gain was noted on day 4 of the lactation period.

Food consumption and compound intake (if feeding study):

effects observed, treatment-related

Description (incidence and severity):

At the dose levels of 250 and 80 mg/kg bw/day, reduced food consumption was noted during lactation.At the dose level of 250 mg/kg bw/day, statistically significant reduction in body weight gain was noted on day 4 of the lactation period.

Organ weight findings including organ / body weight ratios:

no effects observed

Histopathological findings: non-neoplastic:

no effects observed

Other effects:

not specified

Reproductive function: oestrous cycle:

not specified

Reproductive function: sperm measures:

not specified

Reproductive performance:

no effects observed

1 Viability / Mortality
At the dose level of 250 mg/kg bw/day, one female (no. 78) was found dead on day 23 of the gestation period. During necropsy, fetuses were found in uterus of this female. A slight body weight loss was noted in this female on day 22 of the gestation period but no other signs and no macroscopical or microscopical findings indicating bad condition of this female were noted.
Death of the female was most probably a result of difficult parturition and considered to be test-item related.
All remaining animals of P generation survived the scheduled study period.
2 Clinical Signs or Observations
No test item-related findings were noted in males or females at any dose level.
In one female (67) at the mid-dose level, hunched posture and ruffled fur were noted from day 2 of the lactation period onwards. Further, slight swelling in axillary region was observed in one female (no. 79) at the high-dose level from day 9 of the gestation period onwards. Because of isolated occurrence, these findings were considered not to be related to the treatment with the test item.
No further findings were noted in males or females at any dose level.
3 Food Consumption of Males
The overall differences in mean food consumption at the dose levels of 25, 80 and 250 mg/kg bw/day were respectively: +0.9%, -0.9% and +1.7% during the pre-pairing period (percentages refer to the respective values in the control group).
4 Food Consumption of Females
Pre-Pairing, Gestation and Lactation Periods

At the dose levels of 250 and 80 mg/kg bw/day, reduced food consumption was noted during lactation. Mean food consumption was 16.4 and 19.8 g/animal/day at the dose levels of 250 and 80 mg/kg bw/day, respectively and 22.2 g/animal/day in the control group. Although the differences were not statistically significant, they were dose dependent and therefore considered to probably be related to the treatment with the test item.

No effects on food consumption were noted at the dose level of 80 mg/kg bw/day.

The overall differences in mean food consumption at the dose levels of 25, 80 and 250 mg/ kg bw/day were respectively: -5.6%, -0.6% and -4.4% during the pre-pairing period, -2.4%, +6.2% and +4.8% during the gestation period and +1.4%, -10.8% and -26.1% during the lactation period (percentages refer to the respective values in the control group).
5 Body Weights of Males
Pre-Pairing and Pairing Periods

At the dose level of 250 mg/kg bw/day, slight but statistically significant reduction in body weight gain was noted on day 13 of the pre-pairing period. Body weight gain was also slightly lower on further days at the end of this period but without statistical significance. No significant differences in absolute body weights were noted at this dose level.
At the dose levels of 25 and 80 mg/kg bw/day, no test item-related effects on absolute body weights or body weight gain were noted.
The overall differences in mean body weight gain at the dose levels of 0, 25, 80 and 250 mg/kg bw/day were respectively: +15%, +15%, +13% and +13% during the pre-pairing period and +11%, +9%, +9% and +10% during the pairing period (percentages refer to the body weight gain within the period).
At the low- and mid-dose levels, statistically significantly lower body weight gains were noted on individual days during the pairing period. Because the differences were minor and did not follow dose dependency, they were considered not to be related to the treatment with the test item.
6 Body Weights of Females
Pre-Pairing, Pairing, Gestation and Lactation Periods
At the dose level of 250 mg/kg bw/day, statistically significant reduction in body weight gain was noted on day 4 of the lactation period. No significant differences in absolute body weights were noted at this dose level at any time.
At the dose levels of 25 and 80 mg/kg bw/day, no effects on absolute body weights or body weight gain were noted.
The overall differences in mean body weight gain at the dose levels of 0, 25, 80 and 250 mg/kg bw/day were respectively: +8%, +7%, +9% and +6% during the pre-pairing period, +51%, +55%, +56% and +48% during the gestation period and +5%, +2%, +2% and ±0% during the lactation period (percentages refer to the body weight gain within the period).
Mating Performance and Fertility:
No effects on mating performance, fertility index or conception rate were noted at any dose level.
No effects on gestation index were noted at the dose level of 25 mg/kg bw/day; it was 100% at this dose level.
Duration of Gestation :
At the dose levels of 250 and 80 mg/kg bw/day, prolonged gestation period was noted. Mean duration of gestation was 22.6 and 22.0 days at the dose levels of 250 and 80 mg/kg bw/day, respectively, compared to 21.5 days in the control group.
Mean prolongation of the gestation at the high- and mid-dose levels was not statistically significant. However, it was dose dependent and the values were beyond the biological background (historical control data included values of gestation length from 21.2 to 21.8 days).
Therefore this finding was considered to be test item-related.
At the dose level of 25 mg/kg bw/day, mean gestation of duration was the same like the control value; 21.5 days and therefore not affected by the treatment.
Corpora Lutea Count :
No effects on corpora lutea count were observed at any dose level.
Implantation Rate and Post-Implantation Loss :
Number of implantations was not affected by the treatment with the test item at any dose level. At the dose level of 25 mg/kg bw/day, no effects on post-implantation loss were noted.

Dose descriptor:

NOAEL

Remarks:

(fertility)

Effect level:

250 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Observed effect not relevant to impairment of the fertility.

Remarks on result:

not determinable due to absence of adverse toxic effects

Clinical signs:

not specified

Mortality / viability:

mortality observed, treatment-related

Description (incidence and severity):

Higher post-implantation loss resulted in lower litter size at the dose levels of 250 and 80 mg/kg bw/day.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At the dose level of 250 mg/kg bw/day, reduced body weights of pups were noted.

Sexual maturation:

no effects observed

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

no effects observed

Histopathological findings:

no effects observed

Litter Size at First Litter Check

Higher post-implantation loss resulted in lower litter size at the dose levels of 250 and 80 mg/kg bw/day.
Mean number of living pups per dam was 5.3 and 9.2 at the high- and mid-dose levels, respectively, compared to 12.0 in the control group. Further, birth index (number of pups borne alive as a percentage of implantations) was also reduced and it was 42.9% and 66.2% at the high- and mid-dose levels, respectively, compared to 88.2% in the control group. Reduction in the mean number of pups per dam was statistically significant at the high-dose level whereas reduction in birth index was statistically significant at both dose levels. These effects were considered to be test item-related.

No effects on litter size were noted at the dose level of 25 mg/kg bw/day. Mean number of pups was 13.1 per dam and birth index was 94.2% at this dose level.

Postnatal Loss Days 0 - 4 Post Partum

Postnatal loss was considered not to be affected by the treatment with the test item.

During lactation, a total number of 18, 3, 10 and 13 pups (which corresponded to mean number per dam of 1.8, 0.3, 1.0 and 1.4) were lost at the dose levels of 0, 25, 80 and 250 mg/kg bw/day, respectively.
Litter Data - F1 Pups
1 External Examination at First Litter Check and during Lactation

No test item-related observations were noted in pups during the first litter check or during lactation at any dose level.

Following findings were recorded: no milk in the stomach and/or pups cold to touch in one litter at each low- and mid-dose levels and in two litters at the high-dose level; these findings were predominantly observed in the litters affected by post-natal loss. One pup at the high-dose level had a wound. Several pups which were dead at first litter check were partially cannibalized. All these findings were considered to remain within the normal biological background.
2 Sex Ratios

Pups sex ratio was not affected by exposure to the test item at any dose level.
3 Body Weights to Day 4 Post Partum
At the dose level of 250 mg/kg bw/day, reduced body weights of pups were noted. Mean body weights of pups were 5.0 g compared to 6.0 g in the control group on day 1 of the lactation period; this difference was statistically significant. Body weights of pups at the high dose level remained lower than the respective control value also on day 4 of the lactation period. Mean body weights were 7.6 g compared to 9.2 in the control group; this difference was however not longer statistically significant. Body weight gain of pups at the high-dose level was similar to the body weight gain in the control group.
No test item related effects on body weights or body weight gain in pups were noted at the dose levels of 25 and 80 mg/kg bw/day.
In general, mean body weights of pups on day 1 post partum were: 6.0 g, 5.9 g, 6.3 g and 5.0 g, at the dose levels of 0, 25, 80 and 250 mg/kg/day respectively, body weight gain of pups during the first four days of the lactation period was +44.4%, +42.7%, +48.0% and +44.6%, respectively.

At the mid-dose level, statistically significantly higher body weight gain was noted. In the absence of increased body weight gain at the high dose level, this was considered not to be related to the treatment with the test item.
4 Macroscopical Findings
No test item related findings were found in pups at any dose level.
Incidentally, tan discoloration of kidneys was noted in one pup at the low-level. No further findings were noted at any dose level.

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

250 mg/kg bw/day

Based on:

test mat.

Sex:

not specified

Basis for effect level:

body weight and weight gain

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Reproductive effects observed:

yes

Lowest effective dose / conc.:

80 mg/kg bw/day

Treatment related:

yes

Relation to other toxic effects:

reproductive effects in the absence of other toxic effects

Dose response relationship:

yes

Conclusions:

Based on the results of this study, the NOEL of general systemic toxicity is considered to be 80 mg/kg bw/day in females and 250 mg/kg bw/day in males. The NOAEL for fertility is 250 mg/kg bw/day. Observed effects are considered to be related to developmental toxicity and are described in the relevant section.

Executive summary:

This study was performed to generate preliminary information concerning the effects of test article on male and female reproductive performance such as gonadal function, mating behavior, conception and parturition. The test item was administered in corn oil as vehicle at dosages of 25, 80, and 250 mg/kg body weight/day, and controls received the vehicle only. Test article was administered to male rats for 28 days and to female rats for 14 days prior to pairing, through the pairing and gestation periods until the F1 generation reached day 4 post partum.

 

At the high dose level, one female was found dead on day 23 of the gestation period which was considered to be a result of birth complications. No further adverse effects were noted in males or females at any dose level. At the dose levels of 250 and 80 mg/kg bw/day a reduction in gestation index as well as an increase in incidence of post-implantation loss resulting in a lower litter size were noted. These effects were statistically significant and dose dependent and therefore considered to be test item-related and adverse. Based on the individual data, increased post-implantation loss occurred predominantly in females with prolonged gestation. A prolonged gestation was noted at the high- and mid-dose level, which were considered to be test item-related. No compensation for lower body weights occurred during lactation. Reduction of pup absolute body weights was considered to be adverse.

 

Based on the results of this study, where in males only slight changes in body weight gain were noted at the high-dose level, the NOAEL (No Observed Adverse Effect Level) for general toxicity in males was considered to be 250 mg/kg bw/day. Because of the death of one female at the dose level of 250 mg/kg bw/day, NOAEL (No Observed Adverse Effect Level) for general toxicity in females was considered to be 80 mg/kg bw/day. The observed effects of prolonged gestation, reduced gestation index and increased post-implantation loss resulting in lower litter size at the dose levels of 250 and 80 mg/kg bw/day are considered to be related to developmental toxicity. As a consequence, the NOAEL for fertility was determined to be 250 mg/kg bw/d.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

250 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

No effects on mating performance, fertility index or conception rate were noted at any dose level (0, 25, 80 and 250 mg/kg bw/d were investigated).

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Additional information

Weight of Evidence was applied based on the an oral OECD 421 reproduction toxicity screening study with 2-ethylhexyl salicylate and a 3-generation oral reproduction toxicity study with the read-across substance methyl salicylate. The two studies gave consistent results with NOAEL of 386 mg/kg bw/day in the 3-generation study and no evidence of fertility effects at 250 mg/kg bw/day in the OECD 421 study, respectively.

Additionally, for 2-ethylhexyl salicylate, an uterotrophic assay in rats revealed no estrogenic activity and no specific binding was observed in vitro to the androgen and estrogen receptors.

Data with inhalative or dermal exposure are not available. The assessment of the potential of ethylhexyl salicylate to impair fertility has been completed with read-across data from studies on Methyl salicylate (MeS) and Acetylsalicylic acid (ASA). A read-across justification is provided as attachment to IUCLID section 13 respectively as appendix to the CSR.

The potential for MeS to affect male and/or female fertility has been assessed in rats and mice in several multi-generation studies, with the study by Collins et al (1971) considered to be the key study for this endpoint.

In a 3-generation study (Collins et al., 1971), MeS was administered to male and female Osborne-Mendel rats in the diet at 500, 1500, 3000 and 5000 ppm.  Parental generation rats were fed MeS for 100 days prior to mating, then throughout two mating, gestation and lactation periods.  F1 and F2 rats received the test compound throughout the study, which terminated with the weaning of the F3 offspring.  No statistically significant decrease was reported in fertility index at any dose for any generation.  Adverse effects were reported on offspring, representing embryo-foetal toxicity primarily in terms of reduced viability (decreases in litter size, number of live-born progeny, number of survivors to PND4 and PND5 and number of survivors to weaning).

In a 2-generation study Wistar rats received MeS in the diet at 2500 and 5000 ppmfor 60 days prior to mating, then throughout the study. Each generation of rats was mated twice.  This study reported a non-significant decrease in mating performance for the first generation, and reduced viability of pups.

Abbott and Harrisson also reported data on male and female mice exposed to MeS in the same manner at the same dietary concentration as rats (2500 and 5000 ppm) from 30 days prior to mating. No adverse effects were reported on any reproductive parameter.

Two 2-generation studies have been conducted on MeS in CD-1 Mice by gavage according to the NTP continuous breeding protocol (NTP, 1984a, 1984b).  At dose levels of 25, 50 and 100 mg/kg bw/day MeS for 7 days prior to mating then for a 98 day cohabitation period, no effects were reported on fertility, number of pups per litter, percentages of live pups or pup weight.  Necropsy of F₁mice revealed no effects on body or organ weights or sperm motility, density or morphology.  In a second study at the higher dose levels of 100, 250 and 500 mg/kg bw/daythere was no effect on fertility index.  Reduced pup viability was reported at the high dose, with only a 3% reduction in pup weight at the mid dose level.

As conclusions on above studies, no statistically significant effect on fertility was reported in any study.

The studies above show a number of deficiencies in relation to current guidelines in terms of parameters studied, however their results are consistent. In addition, 2-year chronic toxicity studies (Webb, 1963) in rats and dogs showed no abnormalities in sexual organs (testes/prostate or ovaries/uterus).

The adverse effects on reduced viability of offspring represent developmental toxicity rather than reduction of the fertility of either male or female animals. It can therefore be concluded that 2-ethylhexyl salicylate is not likely to have any significant adverse effect on fertility.

Short description of key information:
No effects on mating performance, fertility index or conception rate were noted at any dose level.

Justification for selection of Effect on fertility via oral route:
One study available with information on fertility

Effects on developmental toxicity

Description of key information

In a valid Reproduction / developmental toxicity screening study with 2-ethylhexyl salicylate in rats, the developmental NOAEL was set to 25 mg / kg bw / d based on the observation of an increase in pots-implantation loss in combination with prolonged gestation, leading to lower litter size and reduced gestation index. 

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

September 06 to November 05, 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: guideline test with GLP

Reason / purpose for cross-reference:

reference to same study

Qualifier:

according to guideline

Guideline:

other: OECD guideline 421 (Reproduction / Developmental Toxicity Screening Test)

GLP compliance:

yes (incl. QA statement)

Limit test:

no

Species:

rat

Strain:

other: RccHanTM: WIST(SPF)

Details on test animals or test system and environmental conditions:

Animals: Rat, RccHanTM: WIST(SPF)
Rationale: Recognized by international guidelines as a recommended test system.
Breeder: Harlan Laboratories, B.V. Kreuzelweg 53 5961 NM Horst / Netherlands
Number of Animals: 44 males: 11 per group 44 females: 11 per group

Age (at Start of Treatment): 11 weeks
Body Weight Range
(at Start of Treatment): Males: 312 to 351 g Females: 208 to 244 g
Identification: Cage card and individual animal number (ear tattoo).
Pups: On day 1 post partum, pups were individually tattooed with Indian ink.
Randomization: Performed after at least three days of acclimatization using a computer-generated random algorithm. Body weights (recorded on the day of allocation) were taken into consideration in order to ensure similar mean body weights in all groups.
Acclimatization: Under test conditions after health examination. Only animals without any visible signs of illness were used for the study.
Husbandry
Room Numbers, Füllinsdorf: E0441A (acclimatization) and E0441 (after acclimatization) Conditions: Standard laboratory conditions. Air-conditioned with 10 - 15 air changes per hour, continuously monitored environmental conditions (temp. range: 22 ± 3 °C; relative humidity range: 30 - 70%). Values outside of these ranges occasionally occurred, usually following room cleaning, which was considered not to have any influence on the study. These data were not reported but were retained in the raw data. There was 12-hour fluorescent light / 12-hour dark cycle with music during the light period.
Accommodation: In groups of three to five animals in Makrolon type-4 cages with wire mesh tops up to the day of ran-domization and afterwards individually in Makrolon type-3 cages with wire mesh tops and sterilized standard softwood bedding (‘Lignocel’ J. Rettenmaier & Söhne GmbH & CoKG, 73494 Rosenberg/Germany, imported by Provimi Kliba SA, 4303 Kaiseraugst / Switzerland) with paper enrichment (ISO-BLOX from Harlan Laboratories B.V., Netherlands), batch/ lot nos. 100099. During the pre-pairing period, cages with males were interspersed amongst those holding females to promote the development of regular estrus cycles.

Diet: Pelleted standard Harlan Teklad 2018C (batch no. 43/12) rodent maintenance diet (Provimi Kliba SA, 4303 Kaiseraugst / Switzerland) was available ad libitum. .
Water: Community tap-water from Füllinsdorf was available ad libitum in water bottles.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on exposure:

Four groups of 11 males and 11 females were treated by gavage with Neo Heliopan OS once daily. Males were treated over a 14-day pre-pairing period and during the pairing period up to one day before necropsy. Females were treated throughout the pre-pairing, pairing, gestation and lactation period up to the day 3 post partum.

Vehicle and Control Item
Identification: Corn oil
Source: Carl Roth GmbH
Batch Number: 292189296
Expiry Date (Retest Date): 02-Aug-2017
Storage Conditions: Room temperature (20 ± 5 °C)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

On the first treatment day samples from the control group as well as three samples (top, middle and bottom) of about 1 g of each concentration were taken prior to dosing for analysis of concentration and homogeneity. To confirm the stability (8 days) samples of about 1 g of each concentration were taken from the middle of each aliquot used on day 7 of the treatment. During the last week of the treatment, samples were taken from the middle to confirm concentration.
The aliquots for analysis of dose formulations were frozen (-20 ± 5 °C) and delivered on dry ice to B. Bürkle (Harlan Laboratories Ltd., Zelgliweg 1, 4452 Itingen / Switzerland) and stored there at -20 ± 5 °C until analysis.

The samples were analyzed by GC coupled to an FID detector following an analytical procedure provided by the Sponsor and adapted at Harlan Laboratories. The test item was used as the analytical standard. Analyzed samples were not discarded without written consent from the study director.

In conclusion, the results indicate the accurate use of the test item and corn oil as vehicle during this study. Application formulations were found to be homogeneously prepared and sufficient formulation stability under storage conditions was approved.

Details on mating procedure:

During the pairing period, females were housed with sexually mature males (1:1) until evidence of copulation was observed. The females were removed and housed individually if:

- the daily vaginal smear was sperm positive, or
- a copulation plug was observed.

The day on which a positive mating was determined (copulation plug or sperm) was designated day 0 post coitum.

Duration of treatment / exposure:

Males: 28 days Females: Approximately 7 weeks

Frequency of treatment:

Once daily

Duration of test:

Approximately 7 weeks

No. of animals per sex per dose:

11

Control animals:

yes, concurrent vehicle

Details on study design:

Method: Oral, by gavage
Rationale for Method: Administration by gavage is a common and accepted route of exposure for this type studies.
Frequency of Administration: Once daily
Target Dose Levels: Group 1: 0 mg/kg/day (control group)
Group 2: 25 mg/kg/day
Group 3: 80 mg/kg/day
Group 4: 250 mg/kg/day
Rationale for Dose Level Selection: The dose levels were selected based on a previous dose range-finding toxicity study in Han Wistar rats, Harlan Laboratories Study D54872, using dose levels of 0, 100, 300 and 1000 mg/kg/day, resulting in mortality and adverse toxic effects at the dose level
of 1000 mg/kg bw/day and adverse toxic effects at the dose level of 300 mg/kg bw/day.
Dose Volume: 4 mL/kg body weight
Dose Concentrations: Group 1: 0.00 mg/mL
Group 2: 6.25 mg/mL
Group 3: 20.00 mg/mL
Group 4: 62.50 mg/mL
Duration of Acclimatization Period: Minimum 5 days
Duration of Treatment Period: Males: 28 days Females: Approximately 7 weeks

Maternal examinations:

Viability / Mortality: Twice daily
Clinical Signs: Daily cage-side clinical observations (once daily, during acclimatization and up to day of necropsy). Additionally females were observed for signs of difficult or prolonged parturition, and behavioral abnormalities in nesting and nursing.
Food Consumption: Males: Pre-Pairing period days 1 - 4, 4 - 8, 8 - 11 and 11 - 14; after pairing period weekly.
Females: Pre-Pairing period days 1 - 4, 4 - 8, 8 - 11 and 11 - 14; gestation days 0 - 7, 7 - 14 and 14 - 21 and days 1 - 4 of the lactation.
No food consumption was recorded during the pairing period.
Body Weights: Recorded daily from treatment start to day of necropsy.

Ovaries and uterine content:

Ovaries were checked for discoloration and uteri for fetus content and discoloration.

Fetal examinations:

Pup Data: The litters were examined for litter size, live births, still births and any gross anomalies. The sex ratio of the pups was recorded. Pups were weighed individually (without identification) on days 0 (if possible), 1 and 4 post partum. Pups and dams were sacrificed on day 4 post partum. All parent animals and pups, except those excessively cannibalized, were examined macroscopically for any structural changes, either at the scheduled necropsy or during the study if death occurred to establish, if possible, the cause of death.

Statistics:

The following statistical methods were used to analyze food consumption, body weights and reproduction data:

• Means and standard deviations of various data were calculated.

• The Dunnett-test [see References (2)] (many to one t-test) based on a pooled variance estimate was applied if the variables could be assumed to follow a normal distribution for the comparison of the treated groups and the control groups for each sex.

• The Steel-test [see References (3)] (many-one rank test) was applied instead of the Dunnett-test when the data could not be assumed to follow a normal distribution.

• Fisher's exact-test [see References (4)] was applied if the variables could be dichotomized without loss of information.

Indices:

Reproductive indices recorded were fertility indices, mean precoital time, post-implantation loss, and offspring viability indices were mean litter size, pup sex ratios and viability indices.

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
At 250 mg/kg bw/d slight but non-significant changes on weight gain were noted.

Dose descriptor:

LOAEL

Effect level:

25 mg/kg bw/day

Based on:

test mat.

Basis for effect level:

other: developmental toxicity

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:yes

Details on embryotoxic / teratogenic effects:
Treatment with the test item at the dose levels of 250 and 80 mg/kg bw/day caused a reduction in gestation index (number of females with living pups as a percentage of females pregnant) as well as an increase in incidence of post-implantation loss resulting in a lower litter size. Further, at the dose levels of 250 and 80 mg/kg bw/day, prolonged gestation period was noted. These findings were considered to be test item-related adverse effects.

Dose descriptor:

NOAEL

Effect level:

80 mg/kg bw/day

Based on:

test mat.

Sex:

not specified

Basis for effect level:

reduction in number of live offspring

Abnormalities:

not specified

Developmental effects observed:

yes

Lowest effective dose / conc.:

80 mg/kg bw/day

Treatment related:

yes

Relation to maternal toxicity:

developmental effects in the absence of maternal toxicity effects

Dose response relationship:

yes

1 Viability / Mortality

At the dose level of 250 mg/kg bw/day, one female (no. 78) was found dead on day 23 of the gestation period. During necropsy, fetuses were found in uterus of this female. A slight body weight loss was noted in this female on day 22 of the gestation period but no other signs and no macroscopical or microscopical findings indicating bad condition of this female were noted. Death of the female was most probably a result of difficult parturition and considered to be test-item related. All remaining animals of P generation survived the scheduled study period.

2 Clinical Signs or Observations

No test item-related findings were noted in males or females at any dose level. In one female (67) at the mid-dose level, hunched posture and ruffled fur were noted from day 2 of the lactation period onwards. Further, slight swelling in axillary region was observed in one female (no. 79) at the high-dose level from day 9 of the gestation period onwards. Because of isolated occurrence, these findings were considered not to be related to the treatment with the test item. No further findings were noted in males or females at any dose level.

3 Food Consumption of Males

The overall differences in mean food consumption at the dose levels of 25, 80 and 250 mg/kg bw/day were respectively: +0.9%, -0.9% and +1.7% during the pre-pairing period (percentages refer to the respective values in the control group).

4 Food Consumption of Females Pre-Pairing, Gestation and Lactation Periods

At the dose levels of 250 and 80 mg/kg bw/day, reduced food consumption was noted during lactation. Mean food consumption was 16.4 and 19.8 g/animal/day at the dose levels of 250 and 80 mg/kg bw/day, respectively and 22.2 g/animal/day in the control group. Although the differences were not statistically significant, they were dose dependent and therefore considered to probably be related to the treatment with the test item. No effects on food consumption were noted at the dose level of 80 mg/kg bw/day. The overall differences in mean food consumption at the dose levels of 25, 80 and 250 mg/ kg bw/day were respectively: -5.6%, -0.6% and -4.4% during the pre-pairing period, -2.4%, +6.2% and +4.8% during the gestation period and +1.4%, -10.8% and -26.1% during the lactation period (percentages refer to the respective values in the control group).

5 Body Weights of Males Pre-Pairing and Pairing Periods

At the dose level of 250 mg/kg bw/day, slight but statistically significant reduction in body weight gain was noted on day 13 of the pre-pairing period. Body weight gain was also slightly lower on further days at the end of this period but without statistical significance. No significant differences in absolute body weights were noted at this dose level. At the dose levels of 25 and 80 mg/kg bw/day, no test item-related effects on absolute body weights or body weight gain were noted. The overall differences in mean body weight gain at the dose levels of 0, 25, 80 and 250 mg/kg bw/day were respectively: +15%, +15%, +13% and +13% during the pre-pairing period and +11%, +9%, +9% and +10% during the pairing period (percentages refer to the body weight gain within the period). At the low- and mid-dose levels, statistically significantly lower body weight gains were noted on individual days during the pairing period. Because the differences were minor and did not follow dose dependency, they were considered not to be related to the treatment with the test item.

6 Body Weights of Females Pre-Pairing, Pairing, Gestation and Lactation Periods

At the dose level of 250 mg/kg bw/day, statistically significant reduction in body weight gain was noted on day 4 of the lactation period. No significant differences in absolute body weights were noted at this dose level at any time. At the dose levels of 25 and 80 mg/kg bw/day, no effects on absolute body weights or body weight gain were noted. The overall differences in mean body weight gain at the dose levels of 0, 25, 80 and 250 mg/kg bw/day were respectively: +8%, +7%, +9% and +6% during the pre-pairing period, +51%, +55%, +56% and +48% during the gestation period and +5%, +2%, +2% and ±0% during the lactation period (percentages refer to the body weight gain within the period).

Mating Performance and Fertility:

No effects on mating performance, fertility index or conception rate were noted at any dose level. No effects on gestation index were noted at the dose level of 25 mg/kg bw/day; it was 100% at this dose level.

Duration of Gestation :

At the dose levels of 250 and 80 mg/kg bw/day, prolonged gestation period was noted. Mean duration of gestation was 22.6 and 22.0 days at the dose levels of 250 and 80 mg/kg bw/day, respectively, compared to 21.5 days in the control group. Mean prolongation of the gestation at the high- and mid-dose levels was not statistically significant. However, it was dose dependent and the values were beyond the biological background (historical control data included values of gestation length from 21.2 to 21.8 days). Therefore this finding was considered to be test item-related. At the dose level of 25 mg/kg bw/day, mean gestation of duration was the same like the control value; 21.5 days and therefore not affected by the treatment. Corpora Lutea Count : No effects on corpora lutea count were observed at any dose level. Implantation Rate and Post-Implantation Loss : Number of implantations was not affected by the treatment with the test item at any dose level. At the dose level of 25 mg/kg bw/day, no effects on post-implantation loss were noted.

Conclusions:

Based on the observation of increased post-implantation loss, reduction in gestation index and lower litter size, the NOAEL for developmental toxicity is detremined to be 25 mg/kg bw/d.

Executive summary:

This study was performed to generate preliminary information concerning the effects of test article on male and female reproductive performance such as gonadal function, mating behavior, conception and parturition. The test item was administered in corn oil as vehicle at dosages of 25, 80, and 250 mg/kg body weight/day, and controls received the vehicle only. Test article was administered to male rats for 28 days and to female rats for 14 days prior to pairing, through the pairing and gestation periods until the F1 generation reached day 4 post partum.

At the high dose level, one female was found dead on day 23 of the gestation period which was considered to be a result of birth complications. No further adverse effects were noted in males or females at any dose level. At the dose levels of 250 and 80

mg/kg bw/day a reduction in gestation index as well as an increase in incidence of post-implantation loss resulting in a lower litter size were noted. These effects were statistically significant and dose dependent and therefore considered to be test itemrelated

and adverse. Based on the individual data, increased post-implantation loss occurred predominantly in females with prolonged gestation. A prolonged gestation was noted at the high- and mid-dose level, which were considered to be test itemrelated.

No compensation for lower body weights occurred during lactation. Reduction of pup absolute body weights was considered to be adverse. No test item-related observations were noted in pups during the first litter check or during lactation at any dose level. Pups sex ratio was not affected by the exposure to the test item at any dose level. Treatment with the test item at the dose level of 250

mg/kg bw/day caused a reduction in body weights of pups recorded on day 1 and 4 of the lactation period. During this period, body weight gain of pups at the high-dose level was similar to body weight gain of pups in the control group. Reduction in absolute body weights of pups was considered to be test item-related adverse effect. No test item-related effects on body weights or body weight gain of pups were noted at the dose levels of 25 and 80 mg/kg bw/day. No test item-related macroscopical findings were found in pups at any dose level.

Based on the observation of increased post-implantation loss, reduction in gestation index and lower litter size, the NOAEL for developmental toxicity is determined to be 25 mg/kg bw/d.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

25 mg/kg bw/day

Study duration:

subacute

Species:

rat

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Additional information

The reproductive toxicity (development) of several salicylates in several animal species have been reviewed in the published literature. MeS and a number of other salicylate esters have been assessed for their safety as cosmetic ingredients (CIR, 2003), as fragrance ingredients (RIFM 2007; Lapczynski, 2007), as food flavouring agents (EPA, 1997; JECFA, 2001; Adams, 2005) and/or (for MeS) as pesticide (EPA, 2005). None of the reviews considered that these salicylates represented a safety concern for humans in the applications assessed.

In a valid GLP Reproduction / Developmental toxicity screen study with 2-ethylhexyl salicylate in rats, the developmental NOAEL was set to 25 mg/kg bw/d (low dose) based on the observation of an increase in incidence of post-implantation loss in combination with prolonged gestation, leading to a lower litter size and reduced gestation index. As no other developmental toxicity studies are available for 2-ethylhexyl salicylate itself, the assessment has been made by read-across primarily from studies on SA and ASA. A read-across justification is provided as attachment to IUCLID section 13 respectively as appendix to the CSR.

The effects of salicylic acid (SA), acetylsalicylic acid or sodium salicylate on organogenesis have been investigated in a large number of studies in several animal species, using a variety of protocols. Many are mechanistic studies, using a single, often high, dose on a restricted number of gestation days. For SA, two studies in rat (Tanaka et al, 1973a and Tanaka et al 1973b) are acceptable, although SA was administered only from GD8 to GD14. To provide data on developmental toxicity in the rabbit, two recent developmental toxicity studies on read-across substance Acetylsalicylic acid (ASA, aspirin) in rats (Gupta et al, 2003) and rabbits (Cappon et al, 2003) have been conducted. These studies complied with current ICH guidelines for pharmaceuticals.

In a pre-natal developmental toxicity study (Tanaka et al., 1973a), salicylic acid was administered to pregnant Wistar rats at levels of 0.06, 0.1, 0.2 and 0.4 % in the diet (30, 50, 100, 200 mg/kg bw/day) on GD 8-14. The high dose of 0.4% caused maternal toxicity, high foetal mortality, growth retardation and a high frequency of complex anomalies including cranioschisis, myeloschisis, pes varus, oligodactyly. At 0.2%, significant foetal growth retardation and a low frequency anomalies. No effect levels were NOAEL (maternal): 0.2% (100 mg/kg bw/day) and NOAEL (development): 0.1% (50 mg/kg bw/day). A parallel study by gavage (Tanaka, 1973b) at 75, 150 and 300 mg/kg bw/day gave similar results, with a NOAEL (maternal): 150 mg/kg/day and a NOAEL (development): 75 mg SA/kg bw/day, that gives for ethylhexyl salicylate 135 mg/kg bw/day. In a clinical segment II study, ASA was administered by oral gavage to pregnant Sprague-Dawley rats at 50, 125 or 250 mg/kg bw/day (equivalent to 38, 96, 192 mg/kg bw as SA or …MeS) during organogenesis (GD6 -17) (Gupta & al, 2003). There was a dose-related reduction in maternal bodyweight gain, significant in the mid and high dose groups. At a dose of 250 mg/kg bw/day, ASA induced increases in early resorptions, increased post-implantation loss, increased variations and malformations. At 125 mg/kg, foetal viability was reduced.

A number of valid supporting studies (not detailed here) in rats report similar results to those described in the studies above. Fritz and Giese (1990), showed a marked increase in embryonic and foetal mortality, delayed ossification and malformations at 180 mg/kg NaS on GD 6-15. Nakatsuka and Fujii (1979) treated SD rats with ASA on GD 7-17. At 200 mg/kg the number of resorptions and malformed survivors were significantly increased. At 100 and 200 mg/kg the average body weights were significantly reduced in a dose-related manner. Schardein et al. (1969) showed ASA to be embryotoxic to rats fed doses of 250 mg/kg bw/day by gavage, or 0.2 or 0.4% (99 or 240 mg/kg bw/day) in the diet on DG 6-15. These doses caused significant reduction in maternal bodyweight gain. At 224 or 250 mg/kg ASA, all pups were resorbed. There were a number of skeletal malformations in the pups at 99 mg/kg bw/day.

ASA was administered by oral gavage to pregnant New Zealand White rabbits at 125, 250 or 350 mg/kg bw/day on GD7 -19 (Cappon & al, 2003). Maternal body weight gain was significantly reduced in the mid and high dose groups from GD7 to GD13. Food consumption was also reduced in these groups. Three high dose does and one mid dose doe died during the study. There were no treatment-related effects on corpora lutea, implantation sites, pre-implantation losses or embryofoetal mortality. There were no treatment-related visceral or external anomalies. Reduction in mean foetal weight at 350 mg/kg bw/day was the only developmental adverse effect reported at this maternally toxic dose. In a supporting study (Schardein et al, 1969), rabbits received ASA at 200 or 250 mg/kg on GD 6-13 or GD 6-18. ASA induced maternal toxicity but no skeletal malformations or other effects on offspring. Based on developmental toxicity studies, the rabbit is seen to be considerably less sensitive than the rat to the developmental toxicity of SA and other salicylates.

Human information are also available from the testing of Aspirin which showed slightly prolonged gestation and labour at daily doses of up to 6120 mg but no developmental effects. Human

Concludingly, a weight of evidence approach assessing data from animal studies and human data on acetylsalicylic acid is done showing that different species show a variation in sensitivity to the developmental toxicity of salicylates, including salicylic acid. The rat seems to be the most sensitive species but salicylates do not induce developmental effects in the rabbit or in humans.

Justification for selection of Effect on developmental toxicity: via oral route:
One study available with information on developmental toxicity

Justification for classification or non-classification

Fertility:

Not classified for effects on reproduction (fertility) according to CLP (Regulation EC No 1272/2008) and/or DSD (Directive 67/548/EEC). Based on a weight of evidence approach, 2 -ethylhexyl salicylate do not adversely affect fertility.

Development:

Not classified for effects on reproduction (development) according to CLP (Regulation EC No 1272/2008) and/or DSD (Directive 67/548/EEC). Based on the weight of evidence approach assessing data from animal studies and human data on acetylsalicylic acid, different species show a variation in sensitivity to the developmental toxicity of salicylates, including salicylic acid. The rat is the most sensitive species, demonstrating effects which might lead to classification. On the other hand, salicylates do not induce developmental effects in the rabbit even at doses causing severe maternal toxicity. An extensive analysis of data on acetylsalicylic acid in human pregnancy indicates that humans are relatively insensitive, allowing the conclusion that salicylic acid should not be considered a developmental toxicant in humans.