Zinc bis(dibutyldithiocarbamate)

Endpoint summary

Description of key information

Available GLP-compliant skin irritation study and three independent eye irritation studies with rabbits suggest that zinc bis(dibutyldithiocarbamate) (ZDBC) is not irritating to skin and eyes. However, as the substance is already classified on Annex I of EU Directive 67/548/EEC as skin and eye irritant, this shall be taken into account by performing the risk assessment. 

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Eye irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

One GLP-compliant study on skin irritation with zinc bis(dibutyldithiocarbamate) (ZDBC), performed in accordance with Draize method, was available for assessment (Monsanto Company, 1982c). A mass of ca. 0.5 g of the test material, moistened with physiological saline, was applied to each of two preliminary shaved intact and two abraded sites of 3 male and 3 female New Zealand White rabbits for 24 hours under occlusive dressing. The initial observation for skin irritation was made approximately one hour after the removal of the wrappings. Dermal irritation was scored by the method of Draize (1944), and results were recorded on the first and third days after topical application. The Primary Irritation Index was calculated by averaging the mean scores at 24 and 72 hours.

Only one out of six animals had a slight erythema (score 1) at the intact test site 24 hr post-application, which resolved at 72 hours examination. The overall PII for both intact and abraded skin sites was 0.1 on the scale from 0.0 to 8.0. Based on the results of the test, zinc bis(dibutyldithiocarbamate) was concluded to be not irritating to rabbit skin.

Three independent eye irritation studies with zinc bis(dibutyldithiocarbamate) were available for assessment. Out of these studies, the most recent one, performed under GLP and in accordance with the method of Draize, was chosen as a key study (Monsanto Company, 1982d). A volume of 0.1 ml of test material was instilled into the conjunctival sac of the right eye of each out of 3 male and 3 female New Zealand White rabbits. Observations for signs of irritation were conducted on the first, second, and third days after dosing. The untreated eye of each animal served as a negative control. The cornea and iris score were 0 at all time points in all animals. One rabbit had a conjunctivae score 4 and another a conjunctivae score 2 at 24 hr examination. In both cases irritation was resolved at 48 hr examination. Also only minor signs of irritation, resolved within 72 hours, were observed in other two studies. Based on these results, zinc bis(dibutyldithiocarbamate) is concluded to be not irritating to rabbit eye.

However, although the results of the available studies suggest that zinc bis(dibutyldithiocarbamate) does not possess skin and eye irritating properties, the substance is already included in Annex I of EU Directive 67/548/EEC as irritating to skin, eyes and respiratory tract (Xi, R36/37/38). Therefore, using a precautionary principle, this classification shall be taken into account at the performance of risk assessment.

Effects on skin irritation/corrosion: irritating

Effects on eye irritation: irritating

Effects on respiratory irritation: irritating

Justification for classification or non-classification

Zinc bis(dibutyldithiocarbamate) (ZDBC) is included in Annex I of EU Directive 67/548/EEC as skin, eye and respiratory tract irritant (Xi, R36/37/38). In accordance with EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008, it should be classified as Category 2, H315 (causes skin irritation), H319 (causes serious eye irritation) and STOT - single exposure, Category 3, H335 (may cause respiratory irritation).