Diphosphoric acid, compound with 1,3,5-triazine-2,4,6-triamine (1:2)

Endpoint summary

Description of key information

No studies are available with diphosphoric acid, compound with 1,3,5 -triazine-2,4,6 -triamine (1:2). However, reliable data are available for the structrual analogue substance 1,3,5 -triazine-2,4,6 -triamine (melamine, CAS 108 -78 -1).

The assessment of repeated dose toxicity is based on repeated dose toxicity studies in rats and mice (similar to OECD 408 and 452) performed with melamine (NTP 1983).

NOAEL rat (13 weeks) = 72 and 84 mg/kg bw/day for males and females, respectively

NOAEL rat (103 weeks) = 126 mg/kg bw/day for males

LOAEL rat (103 weeks) = 262 mg/kg bw/day for females

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Reference 1

Endpoint:

chronic toxicity: oral

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

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Remarks:

rat

Effect level:

2 250 ppm

Based on:

test mat.

Remarks:

corresponds to 126 mg/kg bw/day

Sex:

male

Basis for effect level:

gross pathology

histopathology: neoplastic

histopathology: non-neoplastic

Key result

Dose descriptor:

LOAEL

Remarks:

rat

Effect level:

4 500 ppm

Based on:

test mat.

Remarks:

corresponding to 262 mg/kg bw/day

Sex:

female

Basis for effect level:

histopathology: non-neoplastic

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

4 500 ppm

System:

urinary

Organ:

bladder

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

In the same report a similar study was conducted with mice. Based on hyperplasia and stones in the urinary bladder in male mice up to the lowest dose no NOAEL could be determined. The LOAEL for males was 2250 ppm (corresponding to 327 mg/kg bw/day). In female mice similar effects were observed only in the highest dose and thus the NOAEL for female mice determined to be 2250 ppm (corresponding to 523 mg/kg bw/day). The rat study provides the lowest NOAEL values therefore the rat study is considered for hazard assessment.

Conclusions:

The source substance melamine was administered in the diet to F344 rats or B6C3F1 mice for 103 weeks (chronic) to determine its toxicological profile. The dose levels of melamine in the chronic studies were 2250 and 4500 ppm for rats and mice for each sex. In these studies, compound-related lesions were observed in the urinary tract. Most noticeable was the development of uroliths (urinary bladder stones), which occurred at a greater frequency in males than females of either species. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in repeated dose toxicity potential.

Reference 2

Endpoint:

sub-chronic toxicity: oral

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

Reason / purpose for cross-reference:

read-across source

Key result

Dose descriptor:

NOAEL

Remarks:

rat

Effect level:

750 ppm

Based on:

test mat.

Remarks:

corresponds to 72 and 84 mg/kg bw/day for males and females, respectively

Sex:

male/female

Basis for effect level:

gross pathology

other: formation of urinary bladder stones

Key result

Critical effects observed:

yes

Lowest effective dose / conc.:

1 500 ppm

System:

urinary

Organ:

bladder

Treatment related:

yes

Dose response relationship:

yes

Relevant for humans:

not specified

In the same report a similar study was conducted with mice. Based on urinary bladder lesions in male and female mice a NOAEL of 6000 ppm (corresponding to ca. 1400 mg/kg bw/day) was determined.

The rat study provides the lowest NOAEL values therefore the rat study is considered for hazard assessment.

Conclusions:

The source substance melamine was administered in the diet to F344 rats or B6C3F1 mice for 13 weeks (subchronic) to determine its toxicological profile. The dose levels of melamine in the subchronic studies ranged from 750 to 18,000 ppm for rats, and 6000 to 18,000 ppm for mice. In these studies, compound-related lesions were observed in the urinary tract. Most noticeable was the development of uroliths (urinary bladder stones), which occurred at a greater frequency in males than females of either species. As explained in the analogue justification, it is considered that the target and the source substances are unlikely to lead to differences in repeated dose toxicity potential.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

NOAEL

72 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Quality of whole database:

The available information comprises an adequate and reliable study (Klimisch score 1) from a reference substance with similar structure and intrinsic properties. Read-across is justified based on common functional group(s) and similarities in physical-chemical/ecotoxicological/toxicological properties (refer to analogue justification for further details). The selected study is thus sufficient to fulfil the standard information requirements set out in Annex VIII-IX, 8.7, in accordance with Annex XI, 1.5, of Regulation (EC) No 1907/2006.

System:

urinary

Organ:

bladder

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

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

Mode of Action Analysis / Human Relevance Framework

not applicable

Additional information

There are no data available on repeated dose toxicity with diphosphoric acid, compound with 1,3,5 -triazine-2,4,6 -triamine (CAS 13518 -93 -9). In order to fulfil the standard information requirements set out in Annex VII, 8.3., 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). 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 substances may be predicted as similar provided that their physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity.

A public available carcinogenesis bioassay of melamine is available where melamine was tested in subchronic and chronic repeated dose toxicity studies in rats and mice (NTP, 1983).

Subchronic

Rats

Three separate 13 week studies have been conducted in F344 rats that were 5-6 weeks old at start of experiment. In the first study the rats (12 of either sex) received feed containing 0, 6000, 9000, 12,000, 15,000, or 18,000 ppm melamine. One male receiving the highest dose and one male receiving 6000 ppm died. Dose-related reduction in bodyweight gain was observed. The incidence of stones in the urinary bladder was dose-related and stones were found in all treatment groups among male rats. In the two highest female dose groups 25% or more had stones. Ten animals of either sex from the 18,000 ppm, 6000 ppm and control group were evaluated by histopathology. Diffuse epithelial hyperplasia was found in the urinary bladder in 8/10 males and in 2/10 females in the high-dose group whereas in the low-dose group focal epithelial hyperplasia was observed in only 1/10 males and in none of the females.

In the second study the rats (10 of either sex) received feed containing 0, 750, 1500, 3000, 6000, or 12,000 ppm melamine. This study was designed in order to determine a NOAEL. Reduced body weight gain was observed in the two highest dose groups among males, but not among females. Dose-related increased incidence of stones in the urinary bladder was observed in male rats of all dose groups. None of the female rats had urinary bladder stones. Hyperplasia of the transitional epithelium of the bladder was present in a dose-related manner among males in the three highest dose groups, and only in males with urinary stones. This was accompanied by prominent capillaries and occasional oedema and scattered mast cells in the submucosa. In the female rats there were no evidence of urinary bladder stones or hyperplasia of the bladder epithelium, but dose-related calcerous deposits were observed in the straight segments of the proximal tubules in all dose groups. At Day 65, urine from five rats of either sex in the lowest dose group and in the control group were examined clinically/chemically and microscopically. There were no differences attributed to the presence of melamine, and there were no evidence of melamine crystalluria.

The third 13 week study in rats was performed in order to investigate the effect of ammonium chloride on urinary stone formation in rats receiving 12,000 ppm melamine. The addition of 1 % ammonium chloride to the drinking water had no effect on stone formation.

Based on these results (effects in urinary tract) of the second study a NOAEL of 72 and 84 mg/kg bw/day (750 ppm) for male and female rats, respectively, was determined because the effects found in the lowest dose group were not statistically significant compared to the control group.

Mice

One 13 week study has been conducted in B6C3F1 mice (10 of each sex). They received feed containing 0, 6000, 9000, 12,000, 15,000, or 18,000 ppm melamine. One of the mice receiving feed containing 9000 mg/kg died. Body weight gain was depressed by 9 % or more in all dose groups. The incidence of mice with bladder stones was greater in males than in females, and the incidence increased from 12,000 ppm onwards in a dose related manner.

Based on these results (effects in urinary bladder) a NOAEL of 1400 and 1800 mg/kg bw/day (6000 ppm) for male and female mice, respectively, was determined.

Chronic

Rats

50 male F344 rats were fed diets containing 0, 2250, or 4500 ppm melamine, and 50 female F344 rats were fed diets containing 0, 4500, or 9000 ppm melamine for 103 weeks, starting at 6 weeks of age. Feed consumption and body weight was unaffected by the presence of melamine. Survival of the high-dose group of male rats was significantly reduced compared with the control group. The urinary bladder was the primary site affected in male rats. There was a positive dose-related trend in transition cell carcinomas of the urinary bladder in male rats. The incidence of urinary bladder stones was significantly increased in the high-dose male rats (20%) compared to controls (0 %). A significant association was found between the presence of bladder stones and bladder tumours. Chronic inflammation of the kidney was significantly increased in all dosed female rats, but not in male rats. Due to effects at the urinary bladder in the high-dose (4500 ppm) males and the low-dose (4500 ppm) females a NOAEL for males of 126 mg/kg bw/day (2250 ppm) and a LOAEL for females of 262 mg/kg bw/day (4500 ppm) was determined.

Mice

Groups of 50 male or female B6C3F1 mice were fed diets containing 0, 4500, or 9000 ppm melamine for 103 weeks from six weeks of age. Survival of the high-dose group of male mice was significantly reduced compared with controls. The incidence of urinary stones obtained by gross examination of the urinary bladder was increased markedly in treated males, with 4% incidence in controls, 85% incidence in the low dose group and 93% in the high-dose group. The incidence was 8% in high-dose females. In males, acute and chronic inflammation and epithelial hyperplasia of the urinary bladder was also markedly increased (acute and chronic inflammation: 53% in low-dose and 55% in high dose males compared to 0% in controls; epithelial hyperplasia: 2% controls, 23% low-dose and 30% high-dose males).In female mice only in the high-dose group a small incidence was observed (8% for acute and chronic inflammation and hyperplasia, respectively, compared to 0% in controls and low-dose group). No neoplastic or non-neoplastic lesions were associated with the administration of melamine in mice.

Due to effects at the urinary bladder down to the lowest dose (4500 ppm) for males and only in the high-dose (6000 ppm) females a LOAEL for males of 327 mg/kg bw/day (4500 ppm) and a NOAEL for females of 523 mg/kg bw/day (4500 ppm) was determined.

 

In conclusion, as found in all sub-chronic and chronic studies in mice and rat the target organ was the urinary tract. The lowest observed NOAEL is 72 mg/kg bw/day found in the subchronic study. Recalculating the effect levels to diphoshoric acid, compound with 1,3,5-triazine-2,4,6-triamine 1:2 in respect to the molecular weight (MW diphoshoric acid, compound with 1,3,5-triazine-2,4,6-triamine 1:2 = 430.215 g/mol and MW melamine = 126.1199 g/mol) leads to the following effect level for diphoshoric acid, compound with 1,3,5-triazine-2,4,6-triamine 1:2:

NOAEL = 122.8 mg/kg bw/day.

Based on the above study results with the structural analogue substances melamine (CAS 108-78-1) sufficient evidence is given that the registration substance diphoshoric acid, compound with 1,3,5-triazine-2,4,6-triamine 1:2 (CAS 13518-93-9) is considered to have similar effects after repeated dose exposure.

Justification for classification or non-classification

Reliable data from a structural analogue on repeated dose toxicity indicate that the registered substance does not meet the criteria for classification according to Regulation (EC) No. 1272/2008.