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 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. 
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