Toxicologists discover traces of diesel exhaust in the body

provided by Netherlands Organization for Scientific Research

oxicologists at Nijmegen University have discovered substances in the bodies of test subjects caused by diesel exhaust and which can act as bio-markers. Such markers are necessary to determine health risks in the workplace. Until now, the risk of lung cancer from inhaling diesel soot particles has been assessed on the basis of cases of lung cancer in related occupational groups, for example drivers. The research was funded by the NWO's Technology Foundation STW.

The Dutch toxicologists discovered that office staff, unloaders and drivers at an indoor transport company were exposed to almost the same extent as a result of ineffective ventilation of the office building. This shows how unreliable risk assessments based on occupational groups can be. To improve health conditions at work, it is necessary in many cases to test individual employees.

The diesel residues identified are products created by the degradation of 1-nitropyrene, one of the organic substances that attach themselves to the core of particles of carbon in the diesel soot. In the human body, the organic compounds and the carbon core disintegrate and are then metabolized. Toxicologists are able to detect the degradation product of 1-nitropyrene amongst the numerous metabolites in the urine and blood at an amount of at least 4.10-10 milligrams. To determine the damage caused by smoking, it is sufficient to have a detection limit thousands of times higher.

The Nijmegen research team have already developed a method of determining the concentration of 1-nitropyrene in air. Measuring the decomposition products of this substance in the body now makes it possible to take account of individual differences in uptake, conversion, and excretion. Major differences in the individual uptake of the harmful substances are possible, even when subjects are exposed to the same quantities. This is because the quantity of air inhaled, hygiene when dealing with dusty objects and metabolism differ in each individual.

Air samples taken in Vienna have shown that between 12 and 30 percent of the larger particles contained in air consist of soot particles from diesel exhaust fumes. The WHO has designated such particles as "suspected of causing cancer," and companies are therefore required to minimize exposure of their employees to diesel exhaust fumes. Using bio-markers can be of assistance in doing so. Previous research has shown that the risk of lung cancer from exposure to high concentrations of diesel soot is somewhere between a quarter to a fifth of the risk resulting from smoking.

Further information: Dr. Yvette van Bekkum, phone +31-412-666-151, fax +31-24-354-1802, email or; or Dr. Paul Scheepers (KUN), phone +31-24-361-6878, fax +31-24-354-1802, email