Evaluation of PCB fluxes in the environment

In addition, PCB flows in the year 2000 have been calculated for two scenarios: with and without additional policy measures. Sources of PCB emissions have been inventoried extensively in the Netherlands and the surrounding countries. Over the period 1980-1990 there has been a major decline in PCB emissions to the air, water and soil. Today the main influx of PCBs to the Netherlands is from other countries, viz. transboundary influx via the major rivers and via atmospheric deposition. PCB concentrations in the major rivers have also clearly decreased over the period 1980-1990. It is noteworthy, however, that this decline has not subsequently continued. Since 1989 PCB concentrations in nationally administered Dutch waterways have fluctuated around a virtually constant level. This level exceeds the current statutory limit value for PCBs. A similar pattern holds for the coastal waters of the Netherlands. The scarce monitoring data available for soil indicate that wide-scale transgression of the target value for PCBs is unlikely.

Expectations are that, under the terms of current policy, the main PCB flows will continue to decrease during the period 1990-2000. An accelerated decline could be achieved if additional measures were taken in neighbouring countries. The most effective approach to reducing foreign PCB emissions to the atmosphere would be to tackle (unintentional) emissions from a variety of industrial processes. A clean-up of upstream river sediments would reduce the PCB influx via the major rivers. Because a substantial proportion of PCBs ultimately enters the North Sea via these rivers, upstream clean-up would also have a positive impact on the Dutch input of PCBs to the marine ecosystem. Further tightening-up of policy in the Netherlands, including accelerated collection of fluorescent lighting ballasts and capacitors, will have scarcely any effect on the situation in the year 2000, because of the relatively small share of these sources in aggregate PCB flows.

The present report provides an inventory of PCB flows in the abiotic environment. On its own, though, this inventory does not answer the key question of whether the PCB concentrations currently observed in the Netherlands imply a risk for the human population or for ecosystems. It is therefore recommended that a supplementary risk assessment be carried out, as an important follow-up to this study. This is fully in line with scheduled Dutch policy to re-evaluate the environmental quality standards for PCBs on the basis of new insights in the environmental chemistry and toxicology of this group of substances.