Ethylene diformate

Endpoint summary

Description of key information

Based on read-across from formic acid (CAS No. 64-18-6) and after correction for differences in molecular weight and stoichiometry of full enzymatic hydrolysis):
NOAEC local = 157 mg/m³
NOAEC systemic = 314 mg/m³

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises adequate, reliable (Klimisch score 2) and consistent studies from a reference substance with similar structure and intrinsic properties. Read-across is justified based on structural similarity between the source and target substances, the source substance being a product of the hydrolysis of the target substance (refer to endpoint discussion for further details).
The selected study is thus sufficient 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.

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

The available information comprises an adequate and reliable (Klimisch score 2) study from a reference substance with similar structure and intrinsic properties. Read-across is justified based on structural similarity between the source and target substances, the source substance being a product of the hydrolysis of the target substance (refer to endpoint discussion for further details).
The selected study is thus sufficient 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.

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEC

157 mg/m³

Study duration:

subchronic

Species:

rat

Quality of whole database:

The available information comprises an adequate and reliable (Klimisch score 2) study from a reference substance with similar structure and intrinsic properties. Read-across is justified based on structural similarity between the source and target substances, the source substance being a product of the hydrolysis of the target substance (refer to endpoint discussion for further details).
The selected study is thus sufficient 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.

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Justification for grouping of substances and read-across

There are no data available on the repeated dose toxicity of Ethylene diformate. In order to fulfil the standard information requirements set out in Annex IX, 8.6, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006, read-across from structurally related substances is 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).

Having regard to the general rules for grouping of substances and read-across approach laid down in Annex XI, Item 1.5, of Regulation (EC) No 1907/2006, whereby physicochemical, toxicological and ecotoxicological properties may be predicted from data for reference substance(s) by interpolation to other substances on the basis of structural similarity, ethane-1,2-diol (ethylene glycol) (CAS 107-21-1) and formic acid (CAS 64-18-6) are selected as reference substances for assessment of the repeated dose toxicity of Ethylene diformate.

The read-across is based on the metabolism of Ethylene diformate, in particular on the fact that the substance undergoes enzymatic ester hydrolysis resulting in the formation of ethylene glycol and formic acid. A detailed analogue approach justification is provided in the technical dossier (see IUCLID Section 13).

Overview of repeated dose toxicity

CAS#	Chemical name	Molecular weight	Repeated dose toxicity (oral)	Repeated dose toxicity (inhalation)
629-15-2 (a)	Ethylene diformate	118.09	WoE: RA: CAS 107-21-1	WoE RA: CAS 64-18-6
107-21-1 (b)	Ethane-1,2-diol (Ethylene glycol)	62.07	NOAEL (mouse, m/f) = 2500 (m), 10000 (f) mg/kg bw/day (subchronic)   NOAEL (rat, m/f) = 200 mg/kg bw/day (chronic)	--
64-18-6	Formic acid	46.03	--	NOAEC local (rat, m/f) = 122.4 mg/m³ (subchronic)   NOAEC systemic (rat, m/f) = 244.7 mg/m³ (subchronic)

(a) The substance subject to registration is indicated in bold font.

(b) Reference (read-across) substances are indicated in normal font. Lack of data for a given endpoint is indicated by “--“.

 

Oral

Subchronic

CAS 107-21-1

A study with ethylene glycol in B6C3F1 mice is available and was performed similarly to OECD Guideline 408 in accordance with GLP (National Toxicology Program, 1993). Groups of 10 animals per sex and dose were exposed to 3200 – 50000 ppm in diet (corresponding to calculated doses of 640 – 10000 mg/kg bw/day) for 13 weeks. No mortalities and no clinical toxicity and no test substance-related changes in haematology and urinalysis were observed. No biologically significant changes were apparent in females regarding absolute and relative organ weights and during necropsy. Body weight and body weight gains of male groups that received 12500 and 50000 ppm were significantly reduced. Furthermore, in males of the 25000 and 50000 ppm group, treatment-related lesions were noted in the kidneys and livers at histopathological examination. In these animals, liver hyaline degeneration and nephropathy of the kidneys were observed.

Thus, a NOAEL for female animals of 50000 ppm (10000 mg/kg bw/day) and a NOAEL of 12500 ppm (2500 mg/kg bw/day) for male animals were derived based on liver hyaline degeneration and nephropathy of the kidneys in males.

Chronic

CAS 107-21-1

Ethylene glycol was studied in a two-year feeding study similar to OECD Guideline 452 in rats (DePass, 1986). Groups of 26 male and female Fischer 344 rats received doses of 40, 200 and 1000 mg/kg bw/day via the diet. A concurrent control group, receiving the plain diet was included in the study. In high-dose males, increased mortality and reduced body weight was apparent. No differences in food consumption were observed between treated and control animals. However, high-dose males showed increased water consumption at the 12 months measurement. No changes in haematology and clinical chemistry were observed in female rats; high-dose males showed significantly reduced red blood cells counts, haematocrit and haemoglobin and increased neutrophil counts. Clinical chemistry analysis showed in high-dose males increases in blood urea nitrogen and creatinine. Furthermore, microscopic examinations showed urinary calcium oxalate crystals and increased kidney weights in all high-dose rats. After 12 months, urine samples from high-dose males contained no triple phosphate crystals in contrast to the samples from all other dose groups. Calcium oxalate crystals were found in all groups except for one of the high-dose animals of both sexes. Furthermore, an increased kidney weight in high-dose group animals and reduced liver weights in high-dose males was observed. Histopathology examinations showed that renal lesions were significantly increased in high-dose males including tubular hyperplasia, tubular dilation, peritubular nephritis and calcium oxalate crystalluria. In two males of the high-dose group, granulomatous nephritis and calcium oxalate crystals were present in the urinary bladder. Among females, there was an increased incidence of granulomatous myelitis of the femoral marrow at the highest dose level. At 2 years, females showed significantly increased hemosiderosis of the mesenteric lymph node (high-dose group) and mild fatty metamorphosis of the liver (high- and mid-dose groups). All high-dose males showed chronic nephritis with calcium oxalate crystalluria after 12 months and half of the animals had oxalate crystals in the urinary bladder. At 18 months, all high-dose males had died due to oxalate nephrosis or were sacrificed moribund.

Based on renal toxicity and increased mortality in male animals of the high-dose group, the chronic oral NOAEL for ethylene glycol in rats was found to be 200 mg/kg bw/day and the LOAEL was 1000 mg/kg bw/day.

 

Inhalation

Subchronic

CAS 64-18-6

A study on the subchronic toxicity after inhalation exposure of formic acid is available (National Toxicology Program, 1992). The study was performed similarly to OECD guideline 413 in compliance with GLP. Groups of 10 Fischer 344 rats were whole-body exposed to 8 – 128 ppm (15.3 – 244.7 mg/m³) for 6 h/day, 5 days/week, for 13 weeks. The

In the study, no mortality and no clinical signs were observed. Body weights were increased in all male groups except the high-dose group at the end of the study. Changes in haematological and clinical chemistry parameters were few and generally minimal to mild in magnitude, and therefore deemed not adverse. No statistically significant changes in white blood cell counts at the 13-week time point were observed, however neutrophil counts were mildly to moderate decreased in a not-dose related manner in rats (m, f) of all exposure groups. At 13 weeks, there were minimal but significant increases in mean cell corpuscular haemoglobin concentration in all females. Minimal but significant decreases in mean corpuscular volume in females in 2 exposure groups (16 and 128 ppm) at 13 weeks were associated with increases of similar magnitude in red blood cell counts. There were mild, significant decreases in concentrations of serum albumin in females at Day 3 (32, 64, and 128 ppm) and increases in male rats at 13 weeks (8, 16, and 32 ppm). In all female groups, concentrations of total serum protein were decreased at Day 3. Male and female rats exposed to 16, 32 (female only), 64, and 128 ppm had significant increases in serum alkaline phosphatase at 13 weeks. Examination of organ weights showed somewhat greater liver weights in male rats in all exposure groups and liver-to-body-weight ratios were increased in male rats exposed to 32, 64, and 128 ppm formic acid. Absolute and relative lung weights were decreased in all exposed groups of female rats. In male rats, relative lung weights were decreased in all exposure groups, and absolute weights were decreased in the 64 and 128 ppm groups. During necropsy, no unusual gross lesions were noted. Histopathological changes occurred in the respiratory and olfactory epithelium of the nose and were generally were limited to the 128 ppm exposure groups. Changes in the respiratory epithelium included a minimal squamous metaplasia. A few inflammatory cells were associated with these areas of metaplasia, but inflammation was not a prominent feature of the nasal lesions. In the olfactory epithelium, degenerative changes were minimal to mild and generally limited to the area of the dorsal meatus in the mid-nasal section. There was no evidence of metaplasia in the olfactory epithelium or atrophy of the nerve fibers in the olfactory mucosa. In male and female rats from the control and 32 ppm exposure groups there were minimal to mild inflammatory lesions in the lung. These pulmonary lesions, which were generally less severe in females, were limited to the control and mid-dose groups and corresponded to the slightly greater lung weights observed for these groups of rats.

Thus, a local NOAEC of 64 ppm (122.4 mg/m³ air) was established for male and female rats. The systemic NOAEL for male and female rats was concluded to be 128 ppm (244.7 mg/m³ air) corresponding to the highest concentration tested.

The leading health effect of Ethylene diformate is skin and eye corrosion. The available in vitro data on enzymatic ester hydrolysis of ethylene diformate indicates that the substance is rapidly hydrolysed to ethylene glycol and formic acid (Butler, 2013). Thus, corrosivity is more likely to be related to the hydrolysis product formic acid (Skin corrosive Category 1A according to Annex VI to Regulation (EC) No 1272/2008) rather than to ethylene glycol. Therefore, for the purpose of hazard assessment of Ethylene diformate, the available dose descriptor from the reference substance formic acid is selected as starting point. In order to correct the dose descriptor for differences in molar mass, it is considered that hydrolysis of 1 mole Ethylene diformate (118.09 g) results in the formation of 2 mole formic acid (2 x 46.03 g = 92.06 g). Hence, the mass corrected subchronic NOAECs for Ethylene diformate are estimated to be 157 mg/m³ for local effects (122.4 mg/m³ x [118.09/92.06]), and 314 mg/m³ for systemic effects (244.7 mg/m³ x [118.09/92.06]).

Conclusions for repeated dose toxicity

There are no data available on the repeated dose toxicity of Ethylene diformate.

The substance is classified as corrosive to the skin and eye. In accordance with the introductory text of Annex VII-X of Regulation (EC) No 1907/2006, in vivo testing with corrosive substances at concentration/dose levels causing corrosivity shall be avoided and alternative means of data generation such as read-across from structurally related substance shall be considered first.

Ethylene diformate is anticipated to undergo enzymatic ester hydrolysis within the body resulting in the formation of ethylene glycol and formic acid. Ethylene glycol has been tested in long-term oral (feeding) studies in mice and rats. The subchronic NOAEL in male and female mice was determined to be 2500 and 10000 mg/kg bw/day, respectively. In rats, the chronic NOAEL in males and females was 200 mg/kg bw/day. For formic acid, a subchronic inhalation toxicity study is available indicating local (NOAEC = 122.4 mg/m³) and systemic effects (NOAEC = 244.7 mg/m³).

The leading health effect of Ethylene diformate is corrosivity and this is likely to be related to formic acid rather than to ethylene glycol. Therefore, the available data on the hydrolysis product and formic acid are taken into account for assessment of repeated dose toxicity, in particular by inhalation. The available dose descriptors were selected as starting point for hazard assessment. After correction for differences in molecular weight and considering the stoichiometry of ester hydrolysis, the NOAEC values for Ethylene diformate are 157 and 314 mg/m³ for local and systemic effects, respectively.

Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
Hazard assessment is conducted by means of read-across from structural analogues/surrogates. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substances and overall assessment of quality, duration and dose descriptor level (refer to the endpoint discussion for further details).

Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
Hazard assessment is conducted by means of read-across from structural analogues/surrogates. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substances and overall assessment of quality, duration and dose descriptor level (refer to the endpoint discussion for further details).

Justification for selection of repeated dose toxicity inhalation - local effects endpoint:
Hazard assessment is conducted by means of read-across from structural analogues/surrogates. The selected study is the most adequate and reliable study based on the identified similarities in structure and intrinsic properties between source and target substances and overall assessment of quality, duration and dose descriptor level (refer to the endpoint discussion for further details).

Justification for classification or non-classification

Based on read-across following an analogue approach, the available data on the repeated dose toxicity of Ethylene diformate do not meet the classification criteria according to Regulation (EC) 1272/2008 or according to Directive 67/548/EEC, and are therefore conclusive but not sufficient for classification.