p-anisic acid

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Screening Test (according to OECD 422), rats:

NOAEL general toxicity = 500 mg/kg bw/day

NOAEL reproductive toxicity = 500 mg/kg bw/day

NOAEL Offspring = 500 mg/kg bw/day

Read-across from anisaldehyde (CAS 123-11-5)

Link to relevant study records

Reference

Endpoint:

screening for reproductive / developmental toxicity

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Refer to analogue justification provided in IUCLID section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Remarks:

general systemic toxicity

Effect level:

500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no systemic adverse effects noted up to and including the high dose of 500 mg/kg bw/day

Remarks on result:

other:

Remarks:

adaptive, non-adverse effects noted in the liver at 500 mg/kg bw/day; source: CAS 123-11-5, Hatano Institute, 2000, rat

Key result

Dose descriptor:

NOAEL

Remarks:

local effects

Effect level:

20 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

gross pathology

histopathology: non-neoplastic

Remarks on result:

other:

Remarks:

the findings reported for the rat are considered not to be relevant for humans; source: CAS 123-11-5, Hatano Institute, 2000, rat

Key result

Dose descriptor:

NOAEL

Remarks:

reproductive toxicity

Effect level:

500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Remarks on result:

other:

Remarks:

source: CAS 123-11-5, Hatano Institute, 2000, rat

Key result

Dose descriptor:

NOEL

Remarks:

reproductive toxicity

Effect level:

100 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

reproductive performance

Remarks on result:

other:

Remarks:

source: CAS 123-11-5, Hatano Institute, 2000, rat

Key result

Dose descriptor:

NOAEL

Generation:

F1

Effect level:

500 mg/kg bw/day (actual dose received)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: no adverse effects noted up to and including the high dose of 500 mg/kg bw/day

Remarks on result:

other: source: 123-11-5

Key result

Reproductive effects observed:

yes

Lowest effective dose / conc.:

500 mg/kg bw/day (actual dose received)

Treatment related:

yes

Relation to other toxic effects:

reproductive effects as a secondary non-specific consequence of other toxic effects

Dose response relationship:

yes

Relevant for humans:

not specified

Conclusions:

Data from the source substance anisaldehdye (CAS 123-11-5) was selected as key result for reasons of structural similarity and data reliability. The read across approach is justified in the analogue justification (see IUCLID section 13). The target and source substances are considered unlikely to differ in their reproduction toxicity potential. The toxicty to reproduction potential of the target substance is estimated based on an adequate and reliable combined repeated dose toxicity study with the reproduction/developmental toxicity screening test conducted in rats with the surrogate substance anisaldehyde.

In this study, the NOAEL with respect to systemic toxicity was set at 500 mg/kg bw/day, the highest dose level tested; findings in liver seen at this dose level were considered as adaptative rather than degenerative effects under the test conditions used. A Local NOAEL was set at 20 mg/kg bw/day, which was the lowest dose tested. The local NOAEL refers to irritation effects seen at the mid and high dose levels (100 and 500 mg/kg bw/day) in the forestomach of the rats; these effects however are considered of no relevance for humans, due to their localisation. With respect to reproduction toxicity, the NOAEL for the parental animals was set at 100 mg/kg bw/day, referring to reduced reproduction performance noted at 500 mg/kg bw/day. No adverse effects were noted on live born pups, therefore, with respect to developmental toxicity and under the conditions of the present screening test, the NOAEL is set at 500 mg/kg bw/day. The same NOAELs are expected for the target substance.

Effect on fertility: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

500 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

The available information comprises an adequate, reliable (Klimisch 1 and 2) and consistent study, and is thus sufficient to fulfil the standard information requirements set out in Annex VIII, 8.6, of Regulation (EC) No. 1907/2006.

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Toxicity to reproduction: other studies

Additional information

Justification for read-across

There are no data available on the toxicity to reproduction of p-anisic acid. In order to fulfil the standard information requirements set out in Annex VIII - IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances was conducted. In accordance with Article 13 (1) of Regulation (EC) No 1907/2006, "information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI are met.”In particular for human toxicity, information shall be generated whenever possible by means other than vertebrate animal tests, which includes the use of information from structurally related substances (grouping or read-across) “to avoid the need to test every substance for every endpoint”. For each specific endpoint the source substance(s) structurally closest to the target substance is/are chosen for read-across, with due regard to the requirements of adequacy and reliability of the available data. Structural similarities and similarities in properties and/or activities of the source and target substance are the basis of read-across. A detailed justification for the analogue read-across approach is provided in the technical dossier (see IUCLID Section 13).

 

Toxicity to reproduction: oral

CAS 123-11-5

A reliable oral Combined Repeated Dose Toxicity Study with the Reproduction/Developmental Toxicity Screening Test with anisaldehyde (CAS 123-11-5) is available and was performed according to OECD 422 (Hatano Research Institute, 2000) and in compliance with GLP. Groups of 13 male and 13 female Sprague-Dawley rats were exposed to the test substance at dose levels of 20, 100 and 500 mg/kg bw/day by oral gavage once daily for 7 days/week to males for at least 42 days (2 weeks premating, 2 weeks during mating, 2 weeks after the completion of mating period) and to females for at least 40 days (2 weeks premating, throughout mating periods up to 2 weeks, then throughout pregnancy and up to day 4 of lactation); mated females without parturition were dosed until the day corresponding to day 24 of gestation. Control animals (13 per sex and dose) received the concurrent vehicle, corn oil, only. Observations and examinations of the animals included clinical signs, body weight, food consumption, haematology, clinical chemistry, urinalysis, organ weights, gross necropsy, organ weights and histopathology. With respect to reproduction the following parameters were determined: estrous cycling, time to mating, duration of gestation, parturition difficulties, number of corpora lutea and implantation sites, number and sex of pups (stillborn and liveborn), postnatal mortality, presence of gross anomalies/external malformations, pup weights (on days 0 and 4 of lactation), necropsy of pups (scheduled necropsy and deceased animals).

General toxicity: No mortality was observed and except for transient salivation noted in most high dose animals no clinical signs were noted. Body weights and food consumption was marginally increased in mid and high dose males and in high dose females. These findings were not considered adverse. Platelet count was slightly although statistically significantly decreased in high dose males and mid and high dose females. In the absence of any effects on coagulation times (PT and APTT) this finding was considered to be of no toxicological relevance. Red blood cell count was significantly decreased in mid and high dose males. However, as no significant changes in hematocrit value and hemoglobin content, reticulocyte count and the histopathological examination of bone marrow were seen and the spleen did not show any changes related to hematological changes, these changes were considered to have occurred incidentally. Absolute and relative liver weights were increased in high dose males and females. However, histopathology revealed only very slight to slight centrilobular hypertrophy of hepatocytes, which is considered an adaptive rather than an adverse effect. During necropsy black spots or black deposits in the glandular stomach as well as thickening of the forestomach mucosa were noted in a few high dose males and mid and high dose females. Histopathology revealed no changes in the glandular stomach but squamous cell hyperplasia in the forestomach of all high dose animals and also in the forestomach for 3 male and 5 female mid dose animals.

Toxicity to reproduction: All animals mated and the copulation index and time to copulation was not significantly different in the testing groups. There were no statistically significant differences in the number of corpora lutea, number of implantation sites, implantation index, gestation index and gestation length between the control group and the test substance-treated groups. No abnormalities were observed during parturition and lactation in any group. In high dose females a statistically significant decrease in the number of pregnant dams (6 vs 12 in the control) was noted. The respective fertility index was also reduced (46.2% vs 92.3% in the control). No test substance related effects were observed at 100 or 20 mg/kg bw/day. In the high dose group, when calculated for pregnant dams (n = 6), the number of pups born per litter was statistically significantly decreased (9.3 vs 14.0 in the control). When calculated for dams with live pups (n = 5), the number of live born pups (day 0 of lactation) per litter (10.6 vs 13.8 in the control) and the number of live pups (day 4 of lactation) per litter (10.2 vs. 14.8 in the control) was statistically significantly decreased. However, postnatal survival was not affected (viability index 96.0% vs 98.7% in the control). No external malformations were found in all pups born; and also there were no abnormalities in internal organs at autopsy on day 4 of lactation. In addition, no abnormalities were observed at autopsy of dead pups.

In the absence of systemic toxicity, a NOAEL of 500 mg/kg bw /day for systemic toxicity was derived and a NOAEL of 20 mg/kg bw/day for local effects was derived based on stomach irritation noted at 100 mg/kg bw/day and above. The NOAEL for reproductive toxicity was considered to be 100 mg/kg bw/day based on the reduced number of pregnant dams and reduced number of liveborn pups at 500 mg/kg bw/day.

The reduction of pregnancy rate and litter size noted at 500 mg/kg bw/day only, are considered to be secondary non-specific consequences of the rapid metabolism of anisaldehyde to p-anisic acid (Harrison, 2012; Lewis, 2016) which leads to an evident disproportionate increase and an elongation of high p-anisic acid concentrations in plasma. At this dose level, a saturation of the formation of the respective glycine conjugate as detoxifying mechanism has been observed. In the present reproductive toxicity study, dose levels have not been selected taking into account such toxicokinetic data. The disproportionate increase of endogenous p-anisic acid plasma levels based on overwhelmed elimination pathways is assumed to lead to acidosis which may be causative for the adverse effects observed. Effects of metabolic acidosis on sperm quality in animals species including the rat have been published (e.g., Callaghan, 2016; Toth, 1992).

Saturation processes in metabolism and / or excretion are evident at the tested high dose level following bolus administration of the test substance. This type of administration does not reflect the generally protracted exposure of humans that is not expected to lead saturation of metabolism and excretion. These differences in exposure need to be considered for the assessment of relevance of the observed effects to humans (Gelbke, 2008). Accordingly, the relevance of the observed reduction in fertility indices for humans is highly questionable and do not suffice to form a robust rationale for a classification of anisaldehyde as reproductive toxicant.  

 

References

Callaghan, M, et al. 2016: Subacute ruminal acidosis reduces sperm quality in beef bulls. J. Animal Sci. 94(8): 3215-3228

Lewis, E.M. 2016: A 14-Day Percutaneous Study of p-Methoxybenzaldehyde in Rats, with an Oral (Gavage) Study Extension, Including an Evaluation of the Toxicokinetics of p-Methoxybenzaldehyde (study report), Testing laboratory: Charles River Laboratories, Inc. Horsham, PA, USA, Report no: 72608. Owner company: Research Institute for Fragrance Materials, Inc.,Woodcliff Lake, NJ, USA; Report date: Jun 24, 2016

Gelbke, P. 2008: Grundprinzipien für die Ableitung von Grenzwerten. In: Chemische Grenzwerte: Eine Standortbestimmung.Eds. Janich, P, Thieme, P.C., Psarros, N., Verlag Wiley-VCH, Chapter 6: pages 67-72

Harrison, R. 2012: p-Methoxybenzaldehyde: Compoarative In Vitro Metabolism using Mouse, Rat, Rabbit and Human Hepatocytes (study report), Test laboratory: Huntingdon Life Sciences. Huntingdon, UK, Report No CAQ0001. Owner company: Research Institute for Fragrance Materials, Inc.,Woodcliff Lake, NJ, USA; Report date: Oct 02, 2012

Toth, G.P. et al. 1992: Adverse male reproduction effects following subchronic exposure of rats to sodium dichloroacetate. Fundam. Appl. Toxciol. 19(1): 57-63

Mode of Action Analysis / Human Relevance Framework

There is no evidence for species specific effects of the substance. Therefore, the results of the studies are regarded as relevant for humans.

Justification for classification or non-classification

The data on toxicity to reproduction from the source substance, anisaldehyde (CAS 123 -11 -5), indicate adverse effects at 500 mg/kg bw/day (the highest dose tested). However, these effects are attributed to metabolic acidosis following high dose bolus administration of the analogue substance that leads to saturation of metabolic pathways and subsequent metabolic acidosis. As this treatment scenario is not representative of the generally protracted human exposure during which no such saturation of metabolism is expected, the observed effects do not warrant classification of the source substance with respect to reproductive toxicity and by analogy, no classification and labeling according to Regulation (EC) No. 1272/2008 is warranted for the target substance.