Presenter:  Dave Bull Golder Associates (NZ)

Presentation title:  Bioavailability in site-specific human health risk assessment

The Moanataiari subdivision, Thames, was gradually reclaimed from the Firth of Thames between the 1870s and 1970s, principally using wastes from historic mining activities around the Thames township.  Due to this geological heritage, arsenic (and sometimes lead) concentrations in Moanataiari soils generally exceed the Soil Contaminant Standard for residential use. However, the generic SCS may be over-protective at many sites because they must be applicable to a range of different situations.  One site-specific factor that is relevant to assessment of health risks at Moanataiari is (oral) bioavailability: the fraction of a contaminant that is absorbed into the body following soil ingestion.     This presentation will show how Relative Bioaccessibility Leaching Protocol (RBALP) data for Moanataiari soils was incorporated into a site-specific human health risk assessment. Taking bioavailability into account, estimated health risks are substantially less than indicated by the Soil Contaminant Standard. Approximately one-third of the properties appear to present minimal health risks providing excavation controls are in place, which means that expensive and disruptive remediation can be avoided.

Event: WasteMINZ Conference 2013

Date: Tuesday 22 October 2013