National Toxicology Program

National Toxicology Program
https://ntp.niehs.nih.gov/go/17366

IMM87038: NTP Assessment of Contact Hypersensitivity to Isobutyraldehyde Fluid (CASRN 78-84-2) in Female B6C3F1 Mice

The following abstract presents results of a study conducted by a contract laboratory for the National Toxicology Program (NTP). The findings have not been peer reviewed and were not evaluated in accordance with the levels of evidence criteria established by the NTP on March 2009 (see http://ntp.niehs.nih.gov/ntp/htdocs/levels/09-3566%20NTP-ITOX-R1.pdf). The findings and conclusions for this study should not be construed to represent the views of the NTP or the US Government.

SUMMARY

Isobutyraldehyde (IBA) was selected for evaluation as a sensitizing agent for contact hypersensitivity in guinea pigs and mice. Isobutyraldehyde is used as an intermediate for rubber antioxidants and accelerators; in the synthesis of amino acids, pantothenic acid, cellulose esters, perfumes, flavors, plasticizers, resins and gasoline additives; in the manufacture of brake fluid and butyl esters; and as a solvent for the manufacture of artificial leather, coated paper, textiles, plastics, resins, rubber chemicals and organic chemicals.

The objective of this study was to determine the sensitizing potential of isobutyraldehyde when applied dermally to female B6C3F1 mice.

Isobutyraldehyde was tested on female B6C3F1 mice. The doses of isobutyraldehyde ranged from 3% to 30% in a solution of 4 parts acetone to one part olive oil (4:1) for sensitization and 30% for challenge. Mice received 20 ┬Ál by direct dermal application for 5 consecutive days to a prepared site. DNFB (1-fluoro-2,4-dinitrobenzene) (98%) was used as a positive control at a concentration of 0.5%. Measurement of the contact hypersensitivity was accomplished by the radioisotopic assay and the mouse ear swelling test (MEST).

No statistically significant dose-dependent contact hypersensitivity response to isobutyraldehyde was demonstrated in mice when the site of sensitization was prepared using shaving and dermabrasion with or without adjuvant.




Summary of Irritancy and Contact Hypersensitivity Results
Type of Response Day of
Assay
Method Used Adjuvant Dose Response
(P<0.05)*
Positive Response
(P<0.05)
Irritation
Radioisotopic
assay
No No No
Contact
Hypersensitivity
Day +1 MEST
No
Yes
No
No
No
No

Day +2 Radioisotopic
Incorporation
No
Yes
No
No
No
No

Day +2 MEST
No
Yes
No
No
No
No
Abbreviations: MEST - Mouse Ear Swelling Test

The studies were conducted at the Medical College of Virginia Immunotoxicology Laboratory under NTP Contract No. ES 55094. The in-life phase of the studies was conducted between 30 July 1987 and 4 April 1990. The animals were housed in the animal facility of the Strauss Building. To the best of our knowledge, no significant deviations from Good Laboratory Practices occurred that affected the quality of the data and the ability to interpret the data with respect to the sensitizing potential of isobutyraldehyde.

NTP is located at the National Institute of Environmental Health Sciences, part of the National Institutes of Health.