Sub-chronic dermal exposure to aircraft engine oils impacts the reproductive organ weights and alters hematological profiles of Sprague Dawley rats

There is little data available for the toxicity of used aircraft engine oils relative to their unused (new) versions. This study was conducted to determine if grade 3 (G3) and 4 (G4) aircraft engine oils in their new states (G3-N and G4-N) and their used versions (G3-U and G4-U) have the potential to induce toxicity via dermal application. Male and female Sprague Dawley rats were dermally exposed to water (control), new and used versions of G3 and G4 oils to determine the oil sub-chronic toxicity potentials. A volume of 300 μL of undiluted oil was applied to the pad of the Hill Top Chamber System©. Then the chamber was attached to a fur-free test site located at the back of the rat for 6 h/day for 5 consecutive days/week for 21 days (15 total exposures). Recovery rats also received similar treatments and were kept for 14 days post-exposure to screen for reversibility, persistence, or delayed occurrence of toxic effects. Both G3 and G4 oils had a significant impact on the weight of male and female reproductive organs: testes weights for recovery rats exposed to G3-N significantly decreased (12%) relative to controls; G3-N and G3-U decreased uterus weights by 23% and 29%, respectively; G4-N decreased uterus weights by 32% but were resolved at the end of the recovery period; G4-N increased the weight of the adrenals and spleen for females by 34% and 27%, respectively, during the recovery period. G3 and G4 induced more changes in female blood indices than in those for males. Of all versions of oils, G4-N induced the most changes in profiles of female blood. G4-N significantly decreased the white blood cells, lymphocytes, neutrophils, eosinophils and increased the mean platelet volumes. Interestingly, males were not affected by exposure to G4-N oil. While G3-N decreased the white blood cells and lymphocytes for females it slightly increased those for males. In summary, G3 and G4 oils impacted the weights for male and reproductive organs. This study highlights the health risks that aircraft maintenance workers may be exposed to if precautions are not taken to minimize exposure to these oils.