Radon Measurements in Ghana: Health Risk Assessment at the Lake Bosomtwi Basin

Abstract

The need to assess the risk of exposure to radon and its daughters stems from the reality that radon
is a potential carcinogenic. We report Radon-222 risk assessment, from measurements on soil and
sediments taken from six towns along the Lake Bosomtwi basin at two levels of 10cm and 20 cm.
The current and future prospects of Lake Bosomtwi, the largest natural lake in Ghana, make this
assessment imperative, since radon forms half of natural background radiation. Spatial Analyser
Decision Assistant (SADA) algorithms were used to model the measured radon concentrations under
two land-use scenarios, namely residential and recreational. Setting the data under a targeted
risk of 1E-6,we found that the external exposure was below that of the maximum concentrations to
the measurements. This indicates that the radon levels around those towns as of the time of the
measurements is low and below limits which can cause carcinogenic threats. The mean risk associated
with the sampled locations was found to be 9E-11 at the recreational areas and 2E-8 at the
residential centres. To confirm the authenticity of the point risk analysis, geospatial modelling
based on inverse distance interpolation schemes were performed. The results tally closely with that
of the measured point risk analysis with and error margin o f 2% and 1.3 % for both land use scenarios
at 10 cm and 20 cm depth respectively.

Journal of the Ghana Science Association Vol. 9 (2) 2007: pp. 85-94