Reaction mass of dimethyl phosphonate and methyl hydrogenphosphonate and phosphonic acid

Endpoint summary

Description of key information

There no data on acute toxicity on phosphonic ester residue available. 
For acute oral toxicity an overall LD50 value was calculated (LD50=1816 mg/kg bw) based on the available information of the  individual components taking into account the requirements of GHS/CLP RegulationNo 1272/2008. For dermal acute toxicity and for acute toxicity via inhalation no studies have to be required because phosphonic ester residue is evaluated to be corrosive.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There is no data on acute toxicity on phosphonic ester residue available

Phosphonic ester residue contains monomethyl phosphonate, phosphonic acid, and Dimethylphosphonate, and salt of pyrophosphoric acid and phosphate which were not further specified ORAL EXPOSURE

Monomethylphosphonate

Marhold (1986) reported LD50(rat, oral) = 1740 mg/kg bw, details were not given.

Phosphonic acid

Acute oral toxicity of phosphonic acid was examined according to OECD TG 401 with female Wistar rats and yield LD50 = 1720 mg/kg bw (details are not given, ECB 2000).

Dimethylphosphonate

NTP, 1985 reported the oral LD50 of dimethyl phosphonate which was determined by acute oral toxicity study conducted with a method similar to OECD guideline 401 with deviations (no GLP study, environmental conditions not reported; body weights not recorded; fasting period too short). The LD50 of dimethyl phosphonate was calculated to be 3040 mg/kg bw in female Fischer 344 rats (95% confidence limits of 2627-3656 mg/kg) and 3283 mg/kg bw in male rats (95% confidence limits of 2729-3949 mg/kg). Clinical signs of toxicity, which have been observed after oral administration of dimethyl phosphonate, were inactivity, weakness, prostration and shallow breathing in rats.

salt Pyrophosphoric acid and phosphate are not further specified

no data available

OVERALL CONCLUSION ON ACUTE ORAL TOXICITY

According to Regulation (EC) No.1272/2008 GHS-CLP the LD50 can be estimated by the formula given in section 3.1.3.6.2.3. because two components of the product are of unknown acute oral toxicity accounting for > 10% of phosphonic ester residue.

Assuming that the product contains approx 30 % phosphonic acid, and approx 11 % Dimethylphosphonate , approx 49 % monomethyl phosphonate, the overall calculated LD50(oral, rat) value for phosphonic ester residue is 1816 mg/kg bw.

However, according to Regulation (EC) 1907/2006 (REACh) ANNEX VIII section 8.5 (Acute Toxicity) a study does not generally need to be conducted if the substance is classified as corrosive to the skin

INHALATION EXOSURE

There are no data available on -phosphonic ester residue to estimate the inhalation toxicity. However, according to Regulation (EC) 1907/2006 (REACh) ANNEX VIII section 8.5 (Acute Toxicity) The study does not generally need to be conducted if the substance is classified as corrosive to the skin

However, the only available data resulted from Dimethylhydrogenphosphit accounting for 11% within phosphonic ester residue. The LC50 (rabbit, inhalation) is >7100 mg/m³,which does not lead to classification

DERMAL EXPOSURE

There are no data available on -phosphonic ester residue to estimate the dermal toxicity. However, according to Regulation (EC) 1907/2006 (REACh) ANNEX VIII section 8.5 (Acute Toxicity) The study does not generally need to be conducted if the substance is classified as corrosive to the skin.

However, the only available data resulted from Dimethylhydrogenphosphit accounting for 11% within phosphonic ester residue. The LD50 (rabbit, dermal) is 681 mg/kg bw which is not taken into account based on severe methologic deficiencies.

Justification for selection of acute toxicity – oral endpoint
There no data on acute toxicity on phosphonic ester residue available. According to Regulation (EC) 1907/2006 (REACh) ANNEX VII section 8.5 (Acute Toxicity) a study does not generally need to be conducted if the substance is classified as corrosive to the skin.
However; according to Regulation (EC) No.1272/2008 GHS-CLP the LD50 can be estimated by the formula given in section 3.1.3.6.2.3. because two components of the product are of unknown acute oral toxicity accounting for > 10% of phosphonic ester residue.
Assuming that the product contains approx 30 % phosphonic acid (LD50=1720 mg/kg bw ), and approx 11 % Dimethylphosphonate (LD50=3040 mg/kg bw), approx 49 % monomethyl phosphonate (LD50= 1740 mg/kg bw), the overall calculated LD50 (oral, rat) value for phosphonic ester residue is 1816 mg/kg bw.

Justification for selection of acute toxicity – inhalation endpoint
There no data on acute toxicity on phosphonic ester residue available. Phosphonic ester residue is evaluated to be corrosive, based on the study result of a mixture component. Consequently, according to ANNEX VII column 2 no study has to be conducted

Justification for selection of acute toxicity – dermal endpoint
There no data on acute toxicity on phosphonic ester residue available. Phosphonic ester residue is evaluated to be corrosive based on the study result of a mixture component. Consequently, according to ANNEX VII column 2 no study has to be conducted

Justification for classification or non-classification

According to Regulation (EC) 1272/ 2008 Phosphonic ester residue is allocated to category 4, H302 = harmfull if swallowed based on the calculated data of acute oral toxicity.