Is the central nervous system yet another target organ for ultrafine particles?
Do UFP emitted from internal combustion engines cause adverse health effects? We still need to know more, but results from our controlled clinical and animal studies using ultrafine elemental carbon particles permit some preliminary conclusions: The high deposition of inhaled UFP (0.007-0.1 m) in the human respiratory tract as predicted by ICRP (1994) could be confirmed; moreover, deposition was even higher during exercise and in asthmatics. Unlike larger fine particles, UFP seem to escape phagocytosis by alveolar macrophages and are translocated to extrapulmonary organs, as was determined in rodents using ultrafine 13C particles, although such translocation was only minimal with ultrafine iridium particles. Cardiovascular effects in humans and animals and mild pulmonary inflammation in animals were also found following ultrafine carbon particle exposures. Although health effects data and understanding of mechanisms are still limited, there are intriguing data from other disciplines, i
