Tris(2-chloro-1-methylethyl) phosphate

Endpoint summary

Description of key information

Inhalation: LC50: 4.6 mg/L/4h for rat (limit test);
Oral: LD50: 632-4200 mg/kg for rat;
Dermal: LD50: 2,000 mg/kg for rat and rabbit.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Dose descriptor:

LD50

Value:

1 360 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Dose descriptor:

LC50

Value:

4 600 mg/m³

Acute toxicity: via dermal route

Endpoint conclusion

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Additional information

"The inhalation exposure studies in animals were somewhat equivocal and in general lacking in detailed information. One study yielded an LC50 of > 7 mg/L/4hr. A limit test yielded an acute LC50 value of >4.6 mg/L/4hr. No deaths occurred at this concentration. Toxic signs observed in this study, and in 2 further poorly reported studies, included mild lethargy, matted fur, acute bodyweight depression and convulsions. From the studies, it appears that TCPP is more toxic when administered whole body as aerosol than by nose-only exposure. This suggests that some of the systemic toxicity observed when TCPP is administered whole body may result from dermal or oral uptake, rather than inhalation. Therefore, it is concluded that TCPP is of low toxicity via the inhalation route. Studies in rats indicated that TCPP is of moderate toxicity via the oral route of exposure, with LD50 values from the better quality studies ranging from 632 mg/kg up to 4200 mg/kg, with the majority of values determined to be 2000 mg/kg. Common clinical and macroscopic signs of toxicity observed on nearly all studies included depression, ataxia, hunched posture, lethargy, laboured respiration, increased salivation, partially closed eyelids, body tremors, pilo-erection, ptosis, haemorrhagic lungs and dark liver and/or kidneys. A NOAEL of 200 mg/kg can be identified for acute oral toxicity. This is taken from the Stropp 1996 study, in which no clinical signs of toxicity were observed in animals dosed with 200 mg/kg TCPP. In a delayed neurotoxicity study conducted in hens, TCPP showed moderate toxicity. The principle effects were reduced mean body weight and food consumption, feather loss and cessation of laying. There was no evidence of inhibited plasma acetylcholinesterase or brain neurotoxic esterase enzyme levels. Therefore, there is no concern for acute delayed neurotoxicity for TCPP.

Studies in rats and rabbits indicated that TCPP is of low toxicity via the dermal route of exposure with LD50values of >2000mg/kg. "

The following information is taken into account for any hazard / risk assessment:

Hazards identified by Draft EU Risk Assessment in May 2008

-TCPP is of moderate toxicity via the oral route of exposure, with LD50 values from the better quality studies ranging from 632 mg/kg up to 4200 mg/kg, with the majority of values determined to be 2000 mg/kg.

-TCPP is of low toxicity via the inhalation route.

-There is no concern for acute delayed neurotoxicity for TCPP.

-TCPP is of low t oxicity via the dermal route of exposure.

Updated relevant information: none.

Justification for classification or non-classification

Hazards identified by EU Risk Assessment in 2008:

"Based on the results of the acute oral studies, TCPP should be classified with R22, harmful if swallowed. "