English Abstract 1,3-Butadiene is mainly emitted to the air. The most
important sources in the outdoor air is traffic. Indoors cigarette smoking
is the most important source. Because of the genotoxic and carcinogenic
properties of 1,3-butadiene and its metabolites a non-threshold
extrapolation method was used for establishing toxicological limit values.
It was indicatively calculated that an ambient concentration of 0.03 to
0.15 mug.m-3 corresponds to a lifetime cancer risk of 1 x 10-6 (negligible
risk level, the maximum permissible is a factor 100 higher). The all-year
average 1,3-butadiene concentration in the Netherlands was estimated at 0.4
mug.m-3. Much higher levels have been measured in the seventies in urban
areas related to traffic activities (<2.2 to 158 mug.m-3). According the
model calculations the all-year average contribution to the 1,3-butadiene
concentration in busy streets by traffic has been estimated to be 2 mug.m-3.
Indoor air 1,3-butadiene concentrations may reach levels of approximately 3
mug.m-3 and up. On the basis of very limited exposure data, the estimated
1,3-butadiene concentration in ambient air seems to be below the "maximum
permissible" risk level. Therefore, the cancer risk due to 1,3-butadiene in
ambient air is within acceptable limits. However, in busy streets in inner
cities the exposure concentrations are estimated to be close to the 'maximum
permissible" risk level. On the other hand the 1,3-butadiene concentrations
resulting from traffic emissions have dropped in the last decades and are
expected to decrease further in the next few years since over 95% of the
gasoline powered new cars sold in the Netherlands are equipped with a
catalytic converter. No data are available on the occurrence of
1,3-butadiene in indoor air in the Netherlands. Literature data indicate
that in smoke-filled rooms the concentrations are in the range of "maximum
permissible" risk level. It is advocated to limit the gap-filling to a
survey into the concentration of 1,3-butadiene in indoor and outdoor air in
inner city streets.
