Benzyl butyl phthalate

Endpoint summary

Description of key information

Santicizer 160 (benzyl butyl phthalate) has shown no convincing evidence of skin or eye irritation in rabbit tests involving 24-hour application. Only transient effects were observed, not sufficient for classification as a skin or eye irritant. Although details of the two studies are only available in a brief summary report (hence they have been assigned reliability code 4), the data are considered adequate for assessment. A lack of skin irritation was also reported in a human repeat insult patch test and in two mouse ear swelling tests (reliability code 2), which were designed to evaluate skin sensitisation.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

When undiluted Santicizer 160 (0.5 ml) was applied to the intact and abraded skin of six New Zealand albino rabbits for 24 hours, erythema scores of 1 and 2 (by the method of FHSA) were seen in four and two animals respectively, 24 hours after exposure. At 48 hours, an erythema score of 1 was seen in three animals. No erythema was seen when assessed at 4, 72 or 168 hours after removal of the test material. An oedema score of 1 was seen in one animal at the 24 -hour observation point. The irritation scores were the same for intact and abraded sites. The investigators classed the test material as non-irritating when applied to the intact and abraded skin of rabbits (Birch, 1976c). Although details of this study are only available in a brief summary report (hence it has been assigned reliability code 4), the data are considered adequate for assessment.

When undiluted Santicizer 160 (0.1 ml) was placed in the eyes of six New Zealand albino rabbits, and removed after 24 hours (presumably by rinsing), slight discomfort was observed immediately after exposure. After 10 minutes, copious discharge was noted and after 1 hour, copious discharge and slight erythema were reported, giving a mean irritation score of 8 out of a possible 110 (by the method of FHSA). At 24 hours post-exposure, slight erythema and slight-to-moderate discharge were reported, with a mean irritation score of 4.3/110. All effects were on the conjunctivae. Eyes appeared normal when examined 48, 72, 120 and 168 hours after removal of the test material, giving an overall irritation score of 1.43 (average of scores assessed at 24, 48 and 72 hours post-exposure). The investigators classed the test material as slightly irritating to the eyes of rabbits, but noted that it would not be classed as an eye irritant under FHSA (Birch, 1976d). Again, details of this study are only available in a brief summary report (reliability code 4), but the data are considered adequate for assessment.

In two skin sensitisation studies in AKR and Balb/c mice using the mouse ear swelling test, the application of Santicizer 160 (30 µl at up to 110 mg/ml) to the ears during the induction and sensitisation phases was without effect on ear thickness, indicating that it was not irritating to mouse skin (Little, 1983b,c).

Santicizer 160 showed no skin irritation potential in humans when tested for skin sensitisation using a repeated insult patch test method. During the induction phase, 200 healthy volunteers were exposed to 0.2 ml of the undiluted test material applied to an occlusive patch for 24 hours on fifteen separate occasions and the skin was assessed for irritation after each induction exposure. No evidence of irritation (or sensitisation) was observed by the investigators or reported by any of the volunteers during the study (Shelanski, 1980).

No data are available on the potential of benzyl butyl phthalate to cause irritation of the respiratory tract.

Justification for classification or non-classification

The available studies on Santicizer 160 (benzyl butyl phthalate) are considered adequate for concluding that the compound does not need to be classified for skin or eye irritation, under the EU CLP regulations.