2-phosphonobutane-1,2,4-tricarboxylic acid

Endpoint summary

Description of key information

Bayhibit AM (2-phosphonobutane-1,2,4-tricarboxylic acid) was tested for acute oral (gavage) toxicity in 10 rats by single applications that were well tolerated by all animals. The LD50 found was > 5 mL/kg bw (> 3250 mg/kg bw).

As there are no studies available for acute inhalation and acute dermal toxicity for 2-phosphonobutane-1,2,4-tricarboxylic acid a read-across approach with tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate (Bayhibit AM-Tetra-sodium salt) is proposed.

In aqueous media, 2-phosphono-butane-1,2,4-tricarboxylic acid and tetrasodium hydrogen 2-phosphonatobutane-tricarboxylate dissociate into the corresponding anion (2-phosphonatobutane-tricarboxylate ion) and hydrogen ion (proton) and the sodium ion, respectively. The toxicological properties of 2-phosphonobutane-1,2,4-tricarboxylic acid and its tetrasodium salt are thought to be an effect of the phosphonato-carboxylate ion rather than of the sodium ion or the hydrogen ion (proton), which are normal constituents in body fluids and have no relevant toxic properties in low concentrations.

Therefore a read-across between 2-phosphono-butane-1,2,4-tricarboxylic acid and tetrasodium hydrogen 2-phosphonatobutane-tricarboxylate is justified.

Acute inhalation toxicity was determined for the test substance tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate. The LC50 (inhalation, rat) of tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate is >1979 mg/m³.
A dose level of 1300 mg/kg of the test substance tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate (32.6 % aqueous solution) was examined for acute dermal toxicity resulting in a LD50 (dermal, rat) of > 1300 mg/kg bw.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

NA

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientifically acceptable and sufficient documented

Qualifier:

equivalent or similar to guideline

Guideline:

EU Method B.1 (Acute Toxicity (Oral))

Deviations:

yes

Remarks:

10 rats were used instead of 3 rats.

Principles of method if other than guideline:

10 rats were used instead of 3 rats.

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 160-180 g.

Route of administration:

oral: gavage

Vehicle:

unchanged (no vehicle)

Doses:

One time dosage of undiluted test substance in amount of 5 mL/kg
= 6500 mg/kg (calculation based on density = 1.3 kg/L)
A ca. 50 % solution of Bayhibit AM was used, therefore an amount of ca. 3250 mg/kg of active ingredient was applied.

No. of animals per sex per dose:

10

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Other examinations performed: clinical signs, body weight.

Statistics:

NA

Sex:

male

Dose descriptor:

LD50

Effect level:

> 5 mL/kg bw

Based on:

dissolved

Remarks:

test substance

Remarks on result:

other: A ca. 50% aqueous solution of 2-phosphonobutane-1,2,4-tricarboxylic acid was used (density = 1.3 kg/l)

Sex:

male

Dose descriptor:

LD50

Effect level:

> 3 250 mg/kg bw

Based on:

act. ingr.

Mortality:

No mortality occurred during the study time.

Clinical signs:

other: No clinical signs were observed during the study time.

Interpretation of results:

GHS criteria not met

Conclusions:

LD50 > 5,0 mL/kg bw (equivalent to LD50 > 3250 mg/kg bw active ingredient)

Executive summary:

2-Phosphonobutane-1,2,4-tricarboxylic acid was tested for acute oral toxicity in 10 male rats. A single dosage of 5 mL/kg bw (equivalent to about >3250 mg/kg bw) of active ingredient was administrated by gavage to 10 rats. During 14 days of observation, no mortality and no toxication symptoms were observed. The LD50 was therefore estimated to be > 3250 mg/kg bw (active ingredient (5 mL/kg bw of an aqueous 50% solution).

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

3 250 mg/kg bw

Quality of whole database:

Scientifically acceptable and sufficient documented.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

Not indicated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientifically acceptable and well documented

Reason / purpose for cross-reference:

reference to same study

Reason / purpose for cross-reference:

reference to other study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

Observation period of 7 days (instead of 14 days).

Principles of method if other than guideline:

Observation period of 7 days (instead of 14 days).

GLP compliance:

not specified

Test type:

traditional method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

- Wistar-Albino
- Weight at study initiation: 160-180 g.
- Diet: Standard lab diet, ad libitum
- Water: ad libitum

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

whole body

Vehicle:

water

Details on inhalation exposure:

- System of generating particulates/aerosols: Spray (aerosol) generated by dynamic inhalation apparatus.
- Brief description of analytical method used: A piece of cotton wool was applied with the sprayed test substance (as was inhaled by the rats). The sprayed cotton was dried in an oven (water elution) and weighed by a gravimetric method that gave the weight of the dried substance that was applied. The figure was divided to give a determination of mg test substance in cubic meters (m3) of air.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Remarks on duration:

no

Concentrations:

800, 1479, 1979 mg/m³ air

No. of animals per sex per dose:

5 rats

Control animals:

no

Details on study design:

- Duration of observation period following administration: 7 days
- Other examinations performed: clinical signs, haematological parameters

Statistics:

No data.

Preliminary study:

A concentration of 1780 mg/m³ air, was applied for one hour to 10 male and female rats. No clinical symptoms were observed.

Key result

Sex:

male/female

Dose descriptor:

LC0

Effect level:

1 979 mg/m³ air (analytical)

Exp. duration:

4 h

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 1 979 mg/m³ air (analytical)

Exp. duration:

4 h

Mortality:

No mortality during the time of the study.

Clinical signs:

other: No clinical symptoms appeared during the time of the study.

Body weight:

No data.

Gross pathology:

No data.

Other findings:

Haematological parameters: Erythrocytes, leucocytes, haemoglobin, haematocryte counts. No significant difference was found in the haematological results before and after the test substance application.

No remarks.

Interpretation of results:

GHS criteria not met

Conclusions:

Inhalation of the test substance in concentrations of less than / equal 1979 mg/m³ is harmless. No mortality occurred and no clinical and haematological effects were observed.

Executive summary:

Acute inhalation toxicity was determined for the test substance, tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate. Five male and female rats were exposed for 4 hours to the test substance in analysed concentrations of 800, 1479, 1979 mg/m³ air. After 7 days of observations, no mortality occurred, no clinical symptoms were observed and no significant difference was found in haematological parameters which were examined before and after exposure.

The LC50 can be estimated as >1979 mg/m³. 1979 mg/m³ was the highest concentration that could technically be achieved. Following the mentioned results, the tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate is not to be classified as harmful via inhalation as at the highest achievable concentration (1979 mg/m³) no clinical symptoms were observed and no significant difference was found in haematological parameters which were examined before and after exposure.

Reference 2

Endpoint:

acute toxicity: inhalation

Type of information:

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

Adequacy of study:

key study

Study period:

Not indicated

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: scientifically acceptable and well documented

Justification for type of information:

Please find the Justification attached to Chapter 13.2.

Reason / purpose for cross-reference:

read-across source

Preliminary study:

A concentration of 1780 mg/m³ air, was applied for one hour to 10 male and female rats. No clinical symptoms were observed.

Key result

Sex:

male/female

Dose descriptor:

LC0

Effect level:

1 979 mg/m³ air (analytical)

Exp. duration:

4 h

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 1 979 mg/m³ air (analytical)

Exp. duration:

4 h

Mortality:

No mortality during the time of the study.

Clinical signs:

other: No clinical symptoms appeared during the time of the study.

Body weight:

No data.

Gross pathology:

No data.

Other findings:

Haematological parameters: Erythrocytes, leucocytes, haemoglobin, haematocryte counts. No significant difference was found in the haematological results before and after the test substance application.

No remarks.

Interpretation of results:

GHS criteria not met

Conclusions:

Inhalation of the test substance in concentrations of less than / equal 1979 mg/m³ is harmless. No mortality occurred and no clinical and haematological effects were observed.

Executive summary:

Acute inhalation toxicity was determined for the test substance, tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate. Five male and female rats were exposed for 4 hours to the test substance in analysed concentrations of 800, 1479, 1979 mg/m³ air. After 7 days of observations, no mortality occurred, no clinical symptoms were observed and no significant difference was found in haematological parameters which were examined before and after exposure.

The LC50 can be estimated as >1979 mg/m³. 1979 mg/m³ was the highest concentration that could technically be achieved. Following the mentioned results, the tetrasodium hydrogen 2-phosphonatobutane-1,2,4-tricarboxylate is not to be classified as harmful via inhalation as at the highest achievable concentration (1979 mg/m³) no clinical symptoms were observed and no significant difference was found in haematological parameters which were examined before and after exposure.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

1 979 mg/m³ air

Quality of whole database:

Scientifically acceptable and well documented.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

1 300 mg/kg bw

Quality of whole database:

Scientifically acceptable and well documented.

Additional information

In acute toxicity testing, Bayhibit AM (respectively Bayhibit AM-Tetra-sodium salt) revealed very low acute toxicity (oral, dermal and inhalation route):

Bayhibit AM was tested for acute oral toxicity in 10 male rats. A single dosage of 5 mL/kg bw (equivalent to about > 3250 mg/kg bw) of test substance was administrated by gavage to 10 rats. During 14 days of observation, no mortality and no toxication symptoms were observed. The LD50 was therefore >5 mL/kg bw equivalent > 3250 mg/kg bw (Löser, 1979). Due to the high dosage given in the study which resulted with no clinical effects and for animal welfare reasons, there seems to be no need in repeating the test of 1979.

In conclusion, the LD50 (oral, rat) of Bayhibit AM is >2000 mg/kg bw.

Following the mentioned results, the test substance is not to be classified as acute toxic (oral route).

Acute inhalation toxicity was determined for the test substance, PBTCNa4 (41.4 % aqueous solution) as aerosol generated by a dynamic inhalation apparatus. Five male and female rats were exposed for 4 hours to the test substance in analysed concentrations of 800, 1479, 1979 mg/m³ air.

After 7 days of observations, no mortality occurred, no clinical symptoms were observed and no significant difference was found in haematological parameters which were examined before and after exposure. The LC50 can be estimated as >1979 mg/m³ (Mihail F, Kimmerle G, 1976).

In conclusion, the LC50 (inhalation, rat) of PBTCNa4, applied as aerosol is >1979 mg/m³ (>1.979 mg/L).

Following the mentioned results, PBTCNa4 is not to be classified as harmful via inhalation as at the highest achievable concentration (1979 mg/m³) no clinical symptoms were observed and no significant difference was found in haematological parameters which were examined before and after exposure.

A 32.6 % aqueous solution (1300 mg/kg bw) of PBTCNa4 was examined for acute dermal toxicity. 5 male rats and 5 female rats were observed for 14 days after dermal application of the test substance. No mortality occurred during the study time. The LD50 (rat, oral) was therefore estimated as > 1300 mg/kg based on active ingredient of a 32.6 % aqueous solution of PBTCNa4.

No systemic clinical symptoms or local skin changes were observed. Minor changes were observed in body weight of female rats and no influence was observed in the growing development of the male rats. In a pathological examination of the rats at the end of the study, it was found that one male rat had a brighter (paler) liver with stains and another male rat had in addition a brighter kidney, two female rats, had also a brighter liver (Bomhard E, 1990).

In conclusion, the LD50 (dermal, rat) of PBTCNa4 is >1300 mg/kg bw.

Depending on the high water solubility and the very low log Pow (equivalent to a very low lipophilic character), 2-PBTCNa4 are not likely to penetrate the first skin barrier (stratum corneum). Thus, upon dermal contact, the bioavailability of PBTCNa4 are expected to be low. Additionally PBTCNa4 has an oral LD50 of ca. 8300 mg/kg bw. As no mortality occurred at a dermal dose of 1300 mg/kg bw PBTCNa4, it is assumed, that the effective LD 50 is much higher than this value, but in any case higher than 2000 mg/kg bw.

Following the mentioned results, the PBTCNa4 is not to be classified as acute toxic (dermal route).

Justification for classification or non-classification

In acute toxicity testing, 2-phosphonobutane-1,2,4-tricarboxylic acid revealed a low acute toxicity for the oral route and tetrasodium hydrogen 2-phosphonatobutane-1,2,4- tricarboxylate revealed a low acute toxicity for the dermal and inhalation route.

According to CLP classification criteria (Regulation (EC) No 1272/2008) a classification is not justified.