Download as a PDF - CiteSeerX

THE USE OF FISH TO DETERMINE IMPACTS OF
DIFFUSE POLLUTION ON RIVERS AND HUMAN HEALTH
RGM Heath, HH du Preez and B Genthe
Pulles Howard & de Lange Inc, P. O. Box 861, Auckland Park, Johannesburg, South
Africa, E-mail: ralphh@phd.co.za
INTRODUCTION
Modern agriculture, industrialization and urbanization have negatively affected
environmental quality and specifically aquatic systems (Förstner and Wittmann,
1983). In South Africa, the pollution of freshwater aquatic systems can be linked to
point source discharges (waste water treatment works and industrial effluents) and
diffuse surface run-off (agricultural, mining, informal settlements and urban). As a
result of these anthropogenic activities, innocent people as well as other life forms
may be exposed to harmful contaminants that may be released without adequate
consideration of human health and the environmental effects (Tchounwou et al.,
1996).
Effects on human health as a result of exposure to surface water contaminants
can occur through contact recreation, drinking water and the consumption of
contaminated food for example, fish and shellfish (USEPA, 1991). People consuming
fish or shellfish are potentially at risk as these organisms have the potential to
bioaccumulate harmful contaminants from the aquatic environment (USEPA, 1991;
Bevelhimer, 1995). The contaminants that have been bioaccumulated by the fish
or shellfish pose carcinogenic, genotoxic and non-carcinogenic health risks to
consumers (Reinert et al., 1991; USEPA, 1991). It must be stressed, however, that the
consumption of fish is generally beneficial as it provides a good source of protein,
vitamins, omega fatty acids and basic minerals (USEPA, 1997), as well as many
others benefits. It is evident that the consumption of fish is beneficial to humans, but
if these fish are contaminated they pose a health risk to consumers.
As a result of the potential health risk associated with the consumption of chemically
contaminated non-commercially caught fish, the United States of America has been
issuing fish consumption advisories and bans that are designed to reduce the risk to
fish consumers (USEPA, 1995a, 1999).
The results of metal surveys in South Africa linking human health and consumption
of fish have indicated that in highly industrialised catchments and those with mining
activities (mainly gold and coal), that the metals in the fish tissues are at levels that
could cause human health risks under different exposure scenarios (Heath, 1999;
Heath et al., 2004a,b). Similarly studies undertaken on biocides from diffuse pollution
sources such as intensive agriculture, forestry and where malaria control is practiced
have indicated that the levels of pesticides recorded in the fish could possible cause
human health risks under different exposure scenarios (Bouwman et al., 1990; Heath,
1999; Heath and Claassen, 1999).
From the preceding it is evident that possible human health risks due to the
consumption of contaminated fish from South African freshwater systems have
received little attention. This is an unacceptable situation as pollutants from various
153