Abstract

RIVM has derived environmental risk limits (ERLs) for three organotin compounds: dibutyltin, tributyltin and triphenyltin. These are the most widely used organotin compounds. Dibutyltin has several uses, for example in the plastic PVC and in printer toner. Tributyltin and triphenyltin are mainly used for wood conservation and as antifouling. Triphenyltin was also used as plant protection product for potatoes. The use as antifouling has been banned within Europe since 2003, and there is no authorisation anymore for the use of triphenyltin as plant protection product.

Intervention values for soil
The environmental risk limits have been derived because they are needed to determine intervention values for soil and groundwater. In case an intervention value is exceeded, the (polluted) soil will be considered for remediation. For this purpose, ERLs for groundwater and soil are required. ERLs for soil were not available and have been derived for this report. ERLs for water were already derived within other frameworks and have been adopted. ERLs for surface water and sediment are also reported in this report because they are related to soil and groundwater. In this way a complete overview of the available ERLs for each compound is given

The derived environmental risk limits for soil and groundwater
One of the derived ERLs is the Serious Risk Concentration (SRC). At this concentration, harmful effects for soil organisms are expected. The determined SRCs for soil are 28; 0.052 and 0.24 milligram per kilogram dry weight soil for dibutyltin, tributyltin and triphenyltin respectively. For groundwater, the SRCs are respectively 50; 0.046 and 0.40 microgram per liter.

Direct and indirect effects
The SRC is based on the annual average concentrations in soil, water and sediment. For this report, two routes of exposure have been examined: direct exposure of water or soil organisms, and indirect exposure of birds or mammals consuming water or soil organisms (food chain). Indirect exposure of humans where it concerns intervention values is evaluated in a separate report (Brand et al., 2012).