Chronic inhalation study in rats exposed to car exhaust originating from fuel with and without ferrocene additive

Gasoline engine exhaust deriving from the combustion of commercial fuel with 30 ppm ferrocene additive was compared to exhaust from the same fuel without ferrocene. Rats inhaled the exhaust after dilution of 1 : 20 and 1 : 40 for 18 hrs/day, 5 days/week for up to 24 months plus an additional exposure of 6 months to clean air. The high exposure concentration was the highest exhaust concentration technically feasible in an inhalation study as the limiting factor was the relative humidity of the exposure atmosphere. The exhaust was characterized by particle mass, size distribution and measurement of aliphatic hydrocarbons, polycyclic aromatic hydrocarbons, aldehydes and other components (phenols, ammonia, iron, patinum, NO-X, CO). At defined intervals, parameters of clinical chemistry, hematology, and broncho-alveolar lavage were measured as well as lung clearance and particle retention. Histopathological investigations were done in 20 animals per group after 12 months and in 200 animals per group after 30 months. In none of the investigations conducted, could differences in the toxic effects of the exhausts, deriving from fuel without or with ferrocene, be detected. The only exposure-related alterations which could be found were a loss in the iron concentration in the cell pellt of the BALF and slight alterations in the nasal cavity.