Health risk assessment of residents living on harbour sludge

A modelled approach for the assessment of exposure and health risks in a case of soil pollution with an unknown but probably large number of potential contaminants is presented. In 1983 the Steendijkpolder, a housing estate of about 800 houses, an agglomeration of schools and a tennis hall was built directly on a 4-m-thick layer of harbour sludge. The sludge originated from around 20 harbour basins in Rotterdam and the industrial area around the Nieuwe Waterweg. In the soil organic solvents, PAH's, aldrin, dieldrin, isodrin, telodrin and several heavy metals were found to be present as contaminants. Not all contaminants, including a number of halogenated compounds, were identified. The investigation of the other relevant environmental compartments in this situation, e.g. drinking-water, indoor-air and home grown vegetables showed that soil ingestion was the predominant route of intake of contaminants. Therefore the exposure of infants (age: 2-3 years) was calculated. The calculated intake of PAH by soil ingestion was around half the average intake of PAH in the daily diet. The extra exposure to drins (a group of cyclodiene insecticides) due to soil ingestion and inhaled contaminated indoor air was calculated to exceed twice the Acceptable Daily Intake (ADI) of dieldrin. The calculated maximal intake of Pb by soil ingestion exceeded the average intake of Pb in the daily diet by around 1.4 times. The maximal intake by soil ingestion of the other identified contaminants was relatively low. It was concluded that with the present knowledge the calculated exposure would not result in observable health damage.