Tetrahydro-2-methylfuran

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

Description of key information

There are no studies investigating the effect of methyltetrahydrofuran (MeTHF) on reproduction. A testing proposal has been submitted for an EOGRTS (OECD 443).

Effect on fertility: via oral route

Endpoint conclusion:

no study available (further information necessary)

Quality of whole database:

A new EOGRTS study has been proposed.

Effect on fertility: via inhalation route

Endpoint conclusion:

no study available

Effect on fertility: via dermal route

Endpoint conclusion:

no study available

Effects on developmental toxicity

Description of key information

Met-THF (2-methyltetrahydrofuran) was administered to groups of 24 time-mated female Sprague-Dawley Crl:CD®(SD) IGS BR strain rats at dose levels of 0 (vehicle control), 100, 300 or 1000 mg/kg bw/d on gestation day (GD) 4-19. The test material was formulated in arachis oil and administered at a constant volume of 4 mL/kg bw. Rats were observed daily for mortality and clinical signs. Bodyweights and food consumption were measured at intervals over the study period.

 

Dams were terminated on GD20, subject to gross necropsy and the uterine contents examined. The gravid uterus and placentae were weighed. All foetuses were sexed, weighed, and assessed for external findings. Approximately half of the foetuses from each litter were assessed for visceral findings following fixation in Bouin’s. The remaining foetuses were assessed for skeletal findings following staining with Alizarin Red S. There was no maternal mortality. Signs of reaction to treatment were limited to post-dose salivation and/or ploughing behaviour in a small number of rats at the highest dos level. Findings are considered to represent a reaction to an irritant or unpalatable test material and are not considered to be adverse. Mean bodyweight initial gain was slightly (but significantly) reduced at 300 and 1000 mg/kg bw/d, but rapidly recovered. Overall weight gain at 1000 mg/kg bw/d was slightly (~11%) but significantly lower than controls; this finding is attributable to the significantly lower gravid uterus weight in this group.

 

Litter parameters were unaffected by treatment. Mean foetal weight was marginally (4.5%) but significantly lower at 1000 mg/kg bw/d. Litter weight in this group was also slightly lower than controls. Total placental weight was significantly lower; however mean placental weight was not significantly lower than controls. The nature and incidence of foetal external, visceral and skeletal parameters was unaffected by treatment.

 

At 1000 mg/kg bw/d, the incidence of foetuses showing incomplete nasal ossification was significantly higher than controls and exceeded the historical control range; however the incidences for the control and 300 mg/kg bw/d groups also exceeded the historical control range. While there was some variation from control for some other ossification parameters at 1000 mg/kg bw/d, there was no obvious effect on the overall pattern of ossification and, therefore, this isolated finding, although supported by slightly lower foetal weight, appears most likely to be incidental and unrelated to treatment.

 

Overall the findings observed for foetuses at 1000 mg/kg bw/d are suggestive of a slight effect on foetal growth although survival and offspring development appeared unaffected. Whether this slight retardation of growth is sufficient to preclude this dose level from being a NOAEL is equivocal and, therefore, the dose level of 1000 mg/kg bw/d is considered to represent the developmental NOAEL. The dose level of 1000 mg/kg bw/d resulted in an initial transient lower body weight gain followed by recovery. Lower body weight gain was again apparent from Day 14 of gestation, but this was influenced by a statistically significant lower contribution from the gravid uterus. There were no accompanying effects apparent on food consumption or clinical condition of the animals. Overall, the extent of effects observed were considered to be insufficient to exclude this dose level from being regarded as a maternal NOAEL.

Link to relevant study records

Reference

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27th October 2017 - 14 February 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Version / remarks:

January 2001

Deviations:

no

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.3700 (Prenatal Developmental Toxicity Study)

Version / remarks:

August 1998

Deviations:

no

Qualifier:

according to guideline

Guideline:

other: JMAFF 12 NouSan No 8147

Version / remarks:

November 2000

Deviations:

no

GLP compliance:

yes

Limit test:

no

Specific details on test material used for the study:

Identification : MeTHF
Appearance/Physical State : Clear colorless/liquid
CAS: 90-47-9
Chemical Name: Tetrahydro-2-methylfuran
Alternative Identification : 2-Methyltetrahydrofuran
Purity: 99.98%
Batch : 2-7E25S
Date Received : 07 June 2017
Storage Conditions : Ambient temperature and humidity in darkness; used/formulated in light
Expiry Date : 25 May 2019

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Time-mated females

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River (UK) Limited, Margate, Kent
- Age at study initiation: Not reported
- Weight at study initiation: 187-294 g
- Fasting period before study: None
- Housing: Single housed in solid-floor polypropylene cages with stainless steel mesh lids and softwood flake bedding
- Diet: ad libitum Rodent 2018C Teklad Global diet
- Water: ad libitum mains drinking water

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25
- Humidity (%): 30-70
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: 03-23 November 2017

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on exposure:

The test material was formulated in arachis oil, based on solubility, at a constant volume of 4mL/kg bw

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability and homogeneity of the test item formulations were determined by Envigo. Formulations were shown to be stable for at least eleven days when stored refrigerated. Formulations were therefore prepared in batches up to every eight days, divided into daily aliquots, and stored at approximately 4°C in the dark. Samples were taken of each test item formulation on two occasions and were analysed for test material concentration. The results of the analyses indicate that the prepared formulations were within 96-99% of the nominal concentration.

Details on mating procedure:

Time-mated female Sprague-Dawley Crl:CD(R)(SD) IGS BR strain rats were delivered in two batches containing females prior to Day 3 of gestation. The day that positive evidence of mating was observed was designated Day 0 of gestation (GD0).

Duration of treatment / exposure:

The test material was administered daily, from Day 3 (prior to implantation) to Day 19 of gestation, by gavage.

Frequency of treatment:

Daily

Duration of test:

All animals were terminated on GD20

Dose / conc.:

0 mg/kg bw/day

Remarks:

Vehicle (arachis oil) control

Dose / conc.:

100 mg/kg bw/day

Dose / conc.:

300 mg/kg bw/day

Dose / conc.:

1 000 mg/kg bw/day

No. of animals per sex per dose:

24 time-mated females

Control animals:

yes, concurrent vehicle

Details on study design:

Rats were randomly allocated to treatment groups using a randomidation procedure based on stratified body weight to ensure similarity between the treatment groups. Dose levels were based on the resuts of a 14-day oral range-finding study and a preliminary study in pregnant rats.

Maternal examinations:

CAGE SIDE OBSERVATIONS: Yes
Following arrival, all animals were examined for overt signs of toxicity, ill-health or behavioral changes once daily during the gestation period. Additionally, during the dosing period, observations were recorded immediately before and soon after dosing and one hour post dosing. All observations were recorded.

DETAILED CLINICAL OBSERVATIONS: No

BODY WEIGHT: Yes
Individual body weights were recorded on Day 3 (before the start of treatment) and on Days 4, 5, 8, 11, 14 and 17 of gestation. Body weights were also recorded for animals at terminal kill (Day 20).

FOOD CONSUMPTION: Yes
Food consumption was recorded for each individual animal on Days 3, 5, 8, 11, 14, 17 and 20 of gestation

WATER CONSUMPTION: Yes
Water intake was observed daily by visual inspection of the water bottles for any overt changes.

POST-MORTEM EXAMINATIONS: Yes
All animals were killed by carbon dioxide asphyxiation followed by cervical dislocation on Day 20 of gestation. All animals were subjected to a full external and internal examination and any macroscopic abnormalities were recorded.

Ovaries and uterine content:

The ovaries and uteri of pregnant females were removed, examined and the following data recorded:
i) Number of corpora lutea
ii) Number, position and type of intrauterine implantation
iii) Fetal sex
iv) External fetal appearance
v) Fetal weight
vi) Placental weight
vii) Gravid uterus weight
The uteri of any apparently non-pregnant females were immersed in 0.5% ammonium polysulphide solution to reveal evidence of implantation.

Implantation types were divided into:
Early Death: No visible distinction between placental/decidual tissue and embryonic tissue
Late Death: Separate embryonic/fetal and placental tissue visible
Dead Fetus: A fetus that had died shortly before necropsy. These were included as late deaths for reporting purposes

All implantations and viable fetuses were numbered according to their intrauterine position

Fetal examinations:

The fetuses were killed by subcutaneous injection of sodium pentobarbitone. Fetuses from each litter were divided into two groups and examined for skeletal alterations and soft tissue alterations. Alternate fetuses were identified using an indelible marker and placed in Bouin’s fixative. Fetuses were subsequently transferred to distilled water and examined for visceral anomalies under a low power binocular microscope and then stored in 10% Buffered Formalin. The remaining fetuses were placed into 70% IMS in distilled water. The fetuses were subsequently eviscerated, processed and the skeletons stained with alizarin red S before being transferred to 50% glycerol for examination of skeletal development and anomalies and storage.

Statistics:

The following parameters were analyzed statistically, where appropriate, using the test methods outlined below:

Female body weight change, food consumption and gravid uterus weight: the Shapiro-Wilk normality test and Bartlett’s test for homogeneity of variance and one way analysis of variance, followed by Dunnett’s multiple comparison test or, if unequal variances were observed, an alternative multiple comparison test. All caesarean necropsy parameters and fetal parameters: Kruskal-Wallis non-parametric analysis of variance; and a subsequent pairwise analysis of control values against treated
values using the Mann-Whitney ‘U’ test, where significance was seen. Fetal evaluation parameters, including skeletal or visceral findings: Kruskal-Wallis nonparametric analysis of variance and Mann-Whitney ‘U’ test. Probability values (p) were presented as follows: p<0.01 **; p<0.05 *; p=0.05 (not significant)

Indices:

Not applicable

Historical control data:

Historical control data (updated 2014) for foetal findings are provided in the study report. Specific reference is made to the historical range for nasal ossification (1605 foetuses from 255 litters).

Clinical signs:

effects observed, treatment-related

Description (incidence and severity):

Clinical signs did not indicate any systemic effect of treatment at 100, 300 or 1000 mg/kg bw/d. At 1000 mg/kg bw/d, seven animals were noted to exhibit a ploughing motion with the snout immediately post-dosing and five animals showed increased salivation post-dosing. These signs were considered to reflect either a palatability effect or slight irritancy of the test material and not to be adverse.

Dermal irritation (if dermal study):

not examined

Mortality:

no mortality observed

Description (incidence):

There were no unscheduled deaths on the study.

Body weight and weight changes:

effects observed, treatment-related

Description (incidence and severity):

At 1000 mg/kg bw/d, body weight gain was statistically significantly lower than controls on the first day of treatment, but recovery of body weight gain was apparent the following day. Body weight gains were again lower than control from Day 14 to termination, although only values for Days 14-17 attained statistical significance, and resulted in statistically significant lower cumulative body weight gain from Day 17 of gestation. To a certain extent, these differences in body weight gain during late gestation may reflect a lower contribution from the litter, as gravid uterus weight was statistically significantly lower than control at this dose level. When adjusted for the contribution of the gravid uterus, although final body weight and overall body weight gain from the start of treatment remained lower than controls, differences no longer attained statistical significance.

At 300 mg/kg bw/d, body weight gain was statistically significantly lower than controls on the first day of treatment, but recovery of body weight gain was apparent the following day. There was no subsequent effect on weight gain and overall body weight gain, including when adjusted for the contribution of the gravid uterus, was unaffected by treatment.

At 100 mg/kg bw/d, there was no effect on body weight gain during gestation, including overall body weight gain when adjusted for the contribution of the gravid uterus.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

There was no effect on food consumption during gestation at 100, 300 or 1000 mg/kg bw/d.

Food efficiency:

not examined

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

not examined

Description (incidence and severity):

Daily visual inspection of water bottles did not reveal any overt intergroup differences.

Ophthalmological findings:

not examined

Haematological findings:

not examined

Clinical biochemistry findings:

not examined

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

not examined

Gross pathological findings:

no effects observed

Description (incidence and severity):

Macroscopic necropsy findings observed for adult animals did not indicate any effect of treatment at 100, 300 or 1000 mg/kg bw/d.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

not examined

Histopathological findings: neoplastic:

not examined

Other effects:

no effects observed

Details on results:

There were no unscheduled deaths on the study. Clinical signs did not indicate any systemic effect of treatment at 100, 300 or 1000 mg/kg bw/d. At 1000 mg/kg bw/d, seven animals were noted to exhibit a ploughing motion with the snout immediately post-dosing and five animals showed increased salivation post-dosing. These signs were considered to reflect either a palatability effect or slight irritancy of the test material and not to be adverse.At 1000 mg/kg bw/d, body weight gain was statistically significantly lower than controls on the first day of treatment, but recovery of body weight gain was apparent the following day. Body weight gains were again lower than control from Day 14 to termination, although only values for Days 14-17 attained statistical significance, and resulted in statistically significant lower cumulative body weight gain from Day 17 of gestation. To a certain extent, these differences in body weight gain during late gestation may reflect a lower contribution from the litter, as gravid uterus weight was statistically significantly lower than control at this dose level. When adjusted for the contribution of the gravid uterus, although final body weight and overall body weight gain from the start of treatment remained lower than controls, differences no longer attained statistical significance. At 300 mg/kg bw/d, body weight gain was statistically significantly lower than controls on the first day of treatment, but recovery of body weight gain was apparent the following day. There was no subsequent effect on weight gain and overall body weight gain, including when adjusted for the contribution of the gravid uterus, was unaffected by treatment. At 100 mg/kg bw/d, there was no effect on body weight gain during gestation, including overall body weight gain when adjusted for the contribution of the gravid uterus. There was no effect on food or water consumption in any group. Macroscopic necropsy findings observed for adult animals did not indicate any effect of treatment at 100, 300 or 1000 mg/kg bw/d.

Number of abortions:

no effects observed

Pre- and post-implantation loss:

no effects observed

Total litter losses by resorption:

no effects observed

Early or late resorptions:

no effects observed

Dead fetuses:

no effects observed

Changes in pregnancy duration:

not examined

Changes in number of pregnant:

no effects observed

Other effects:

effects observed, treatment-related

Description (incidence and severity):

At 1000 mg/kg bw/d, fetal weights were slightly lower than control with differences for female and combined weights attaining statistical significance. This resulted in a lower gravid uterus weight and litter weight compared to control, although only differences for the gravid uterus attained statistical significance. Total placental weight was also statistically significantly lower than control at this dosage but, this occurred in the absence of any significant effect on mean placental weight.
There was no effect of maternal treatment on mean fetal, placental and litter weight on Day 20 of gestation at 100 or 300 mg/kg bw/d.

Details on maternal toxic effects:

There was no effect of maternal treatment on litter data, as assessed by pre-implantation loss, number of implantations, subsequent embryofetal survival, live litter size and sex ratio on Day 20 of gestation at 100, 300 or 1000 mg/kg bw/d.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Fetal body weight changes:

effects observed, treatment-related

Description (incidence and severity):

At 1000 mg/kg bw/d, fetal weights were slightly lower than control with differences for female and combined weights attaining statistical significance.

Reduction in number of live offspring:

no effects observed

Changes in sex ratio:

no effects observed

Changes in litter size and weights:

effects observed, treatment-related

Description (incidence and severity):

At 1000 mg/kg bw/d, litter weights was slightly lower than control with the difference attaining statistical significance.

Changes in postnatal survival:

not examined

External malformations:

no effects observed

Description (incidence and severity):

The type, incidence and distribution of external findings at 100, 300 and 1000 mg/kg bw/d did not indicate any obvious effect on fetal development.

Skeletal malformations:

no effects observed

Description (incidence and severity):

The type, incidence and distribution of skeletal findings at 100, 300 and 1000 mg/kg bw/d did not indicate any obvious effect on fetal development.

Visceral malformations:

no effects observed

Description (incidence and severity):

The type, incidence and distribution of visceral findings at 100, 300 and 1000 mg/kg bw/d did not indicate any obvious effect on fetal development

Other effects:

no effects observed

Details on embryotoxic / teratogenic effects:

At 1000 mg/kg bw/d, the incidence of fetuses showing incomplete nasal ossification (15.1%) was statistically significantly higher than control. However, although the incidence of this finding for litters at 1000 mg/kg bw/d exceeded the historical control range (0-6.3%; mean 2.6%), so did the incidences for the control (8.3%) and 300 mg/kg bw/d litters (8.2%). While there was some variation from control for some other ossification parameters at 1000 mg/kg bw/d, there was no obvious effect on the overall pattern of ossification and, therefore, this isolated finding, although supported by slightly lower fetal weight, appears most likely to be incidental and unrelated to maternal treatment.

Key result

Dose descriptor:

NOAEL

Effect level:

1 000 mg/kg bw/day

Based on:

test mat.

Sex:

male/female

Remarks on result:

not determinable due to absence of adverse toxic effects

Key result

Abnormalities:

no effects observed

Key result

Developmental effects observed:

no

Summary of findings

Dose level (mg/kg bw/d)		0	100	300	1000
Mated (#)		24	24	24	24
Not pregnant (#)		0	1	0	1
Litters (#)		24	23	24	23
Salivation (#)		0	0	0	5
Ploughing (#)		0	0	0	7
Bodyweight (g)	GD3	247.1	248.1	250.4	246.3
	GD4	254.1	253.2	255.0	249.9
	GD5	259.1	259.8	260.5	255.0
	GD8	270.2	272.9	272.4	266.0
	GD20	378.7	386.0	379.4	363.3
Bodyweight gain (g)	GD3-4	7.0	5.0	4.6*	3.6**
	GD4-5	5.0	6.7	5.5	5.0
	GD3-17	87.5	91.0	85.5	77.6*
	GD3-20	131.6	137.9	129.0	117.0*
Adjusted weight (g)		294.9	298.5	298.0	287.1
Adjusted weight gain (g)		47.8	50.4	47.6	40.7
Gravid uterus weight (g)		83.8	87.5	81.4	76.3*
Corpora lutea (#)		16.0	16.3	15.6	15.3
Implantations (#)		13.9	14.3	13.6	13.3
Pre-implantation loss (%)		12.6	11.6	12.1	12.8
Post-implantation loss (%)		2.5	0.9	1.2	3.8
Live foetuses (#)		13.6	14.2	13.5	12.9
Foetal weight (g)		3.953	4.013	3.859	3.777*
Litter weight (g)		53.4	56.8	51.8	48.7
Placental weight (g)		0.586	0.532	0.562	0.523
Total placental weight (g)		7.779	7.521	7.569	6.684*
Nasal – incomplete ossification^a		14 (6) 8.3%	6 (3) 3.5%	13 (10) 8.2%	19 (13) 15.1%*

*significantly different to controls (p<0.05); **(p<0.01)

a: foetal incidence (litter incidence) foetal incidence (%)

Conclusions:

Maternal and developmental NOAELs of 1000 mg/kg bw/d can be determined for this study, in the absence of any adverse effects of treatment at the highest dose level.

Executive summary:

Met-THF (2-methyltetrahydrofuran) was administered to groups of 24 time-mated female Sprague-Dawley Crl:CD®(SD) IGS BR strain rats at dose levels of 0 (vehicle control), 100, 300 or 1000 mg/kg bw/d on gestation day (GD) 4-19. The test material was formulated in arachis oil and administered at a constant volume of 4 mL/kg bw. Rats were observed daily for mortality and clinical signs. Bodyweights and food consumption were measured at intervals over the study period.

 

Dams were terminated on GD20, subject to gross necropsy and the uterine contents examined. The gravid uterus and placentae were weighed. All foetuses were sexed, weighed, and assessed for external findings. Approximately half of the foetuses from each litter were assessed for visceral findings following fixation in Bouin’s. The remaining foetuses were assessed for skeletal findings following staining with Alizarin Red S. There was no maternal mortality. Signs of reaction to treatment were limited to post-dose salivation and/or ploughing behaviour in a small number of rats at the highest dos level. Findings are considered to represent a reaction to an irritant or unpalatable test material and are not considered to be adverse. Mean bodyweight initial gain was slightly (but significantly) reduced at 300 and 1000 mg/kg bw/d, but rapidly recovered. Overall weight gain at 1000 mg/kg bw/d was slightly (~11%) but significantly lower than controls; this finding is attributable to the significantly lower gravid uterus weight in this group.

 

Litter parameters were unaffected by treatment. Mean foetal weight was marginally (4.5%) but significantly lower at 1000 mg/kg bw/d. Litter weight in this group was also slightly lower than controls. Total placental weight was significantly lower; however mean placental weight was not significantly lower than controls. The nature and incidence of foetal external, visceral and skeletal parameters was unaffected by treatment.

 

At 1000 mg/kg bw/d, the incidence of foetuses showing incomplete nasal ossification was significantly higher than controls and exceeded the historical control range; however the incidences for the control and 300 mg/kg bw/d groups also exceeded the historical control range. While there was some variation from control for some other ossification parameters at 1000 mg/kg bw/d, there was no obvious effect on the overall pattern of ossification and, therefore, this isolated finding, although supported by slightly lower foetal weight, appears most likely to be incidental and unrelated to treatment.

 

Overall the findings observed for foetuses at 1000 mg/kg bw/d are suggestive of a slight effect on foetal growth although survival and offspring development appeared unaffected. Whether this slight retardation of growth is sufficient to preclude this dose level from being a NOAEL is equivocal and, therefore, the dose level of 1000 mg/kg bw/d is considered to represent the developmental NOAEL. The dose level of 1000 mg/kg bw/d resulted in an initial transient lower body weight gain followed by recovery. Lower body weight gain was again apparent from Day 14 of gestation, but this was influenced by a statistically significant lower contribution from the gravid uterus. There were no accompanying effects apparent on food consumption or clinical condition of the animals. Overall, the extent of effects observed were considered to be insufficient to exclude this dose level from being regarded as a maternal NOAEL.

Effect on developmental toxicity: via oral route

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Quality of whole database:

A GLP, test guideline compliant (OECD 414) rat prenatal development study. A new PNDT study on a second species has been proposed.

Effect on developmental toxicity: via inhalation route

Endpoint conclusion:

no study available

Effect on developmental toxicity: via dermal route

Endpoint conclusion:

no study available

Toxicity to reproduction: other studies

Description of key information

There are no other studies investigating the effect of methyltetrahydrofuran (MeTHF) on reproduction.

Justification for classification or non-classification

Comparison with the CLP criteria

Reproductive toxicity:

Comparison with criteria for Category 1A classification: In accordance with the criteria in the CLP regulation, classification in reproductive toxicity Category 1A is reserved for substances known to be reproductive toxicants in humans. Since there is no evidence of MeTHF having caused reproductive toxicity in humans, classification in Category 1A is not justified.

 

Comparison with criteria for Category 1B classification: In accordance with the criteria in the CLP regulation, classification in reproductive toxicity Category 1B is reserved for substances that are presumed to be reproductive toxicants in humans, and is largely based on data from animal studies where there is clear evidence of an adverse effect on sexual function and fertility in the absence of other toxic effects, or not as a secondary non-specific consequence of other toxic effects. As no reproductive study has been undertaken no conclusion can be made for Category 1B classification.

 

Comparison with criteria for Category 2 classification: In accordance with the criteria in the CLP regulation, classification in reproductive toxicity Category 2 is reserved for substances where there is some evidence from experimental animals of an adverse effect on sexual function and fertility but where the evidence is not sufficiently convincing to place the substance in Category 1. Any effects should be in the absence of other toxic effects, or not as a secondary non-specific consequence of other toxic effects. As no reproductive study has been undertaken no conclusion can be made for Category 2 classification.

 

Developmental toxicity:

Comparison with criteria for Category 1A classification: In accordance with the criteria in the CLP regulation, classification in reproductive toxicity Category 1A is reserved for substances known to be developmental toxicants in humans. Since there is no evidence of MeTHF having caused developmental toxicity in humans, classification in Category 1A is not justified.

 

Comparison with criteria for Category 1B classification: In accordance with the criteria in the CLP regulation, classification in reproductive toxicity Category 1B is reserved for substances that are presumed to be developmental toxicants in humans, and is largely based on data from animal studies where there is clear evidence of an adverse effect on development in the absence of other toxic effects, or not occur as a secondary non-specific consequence of other toxic effects. MeTHF is not a developmental toxicant in rats, with dosing up to the maximum recommended dose for this assay type. There is insufficient evidence of an effect of MeTHF caused developmental toxicity in animals, classification in Category 1B is not justified.

Comparison with criteria for Category 2 classification: In accordance with the criteria in the CLP regulation, classification in reproductive toxicity Category 2 is reserved for substances where there is some evidence from experimental animals of an adverse effect on development but where the evidence is not sufficiently convincing to place the substance in Category 1. Any effects should be in the absence of other toxic effects, or not occur as a secondary non-specific consequence of other toxic effects. The available evidence shows that MeTHF has no effects on fetal developmental. Therefore, classification of MeTHF for developmental toxicity in Category 2 is not justified.