GENERAL INFORMATION
In South Africa water and waste water is coming under tough scrutiny as new
legislation is going to be enforced by Government to assess our most valuable
and scarce natural resource, not only in terms of chemical pollution but also in
terms of biological impact on the environment.
Until recently, environmental water was considered to be generally suitable for
human use if free from disease-causing organisms and specific chemical
contaminants. However, rapid industrialization, population growth and the
widespread use of plastics and pharmaceuticals have changed this situation.
Synergistic and antagonistic effects, chronic toxicity, mutagenesis and the
presence of agents that interfere with normal physiological control mechanisms
are now commonplace events. Therefore, traditional chemical analysis no
longer provides the safe, cost-effective answers it once did. The best option
at present appears to lie in using integrated suites of chemical and biological
tests, tailored to identify specific problem situations.
CURRENT ECO-TOXICITY TEST
We can only begin to understand the extent of present and potential future
damage to our water resources if we have relevant biological response systems.
There are several such biological systems already in place that can monitor
toxic effect(s) - their common requirement is a "bio-sensor organ", that is the
biological target upon which the toxic impact is measured. Each type of test
with its specific bio-sensor indicates a different focus of interest and
concern: the fish test is meaningful for the assessment of the aquatic
environment of rivers and streams and so are the daphnia and algae tests; the
bacterial luminescence tests looks at toxic effects of water on the microbial
environment.We can only begin to understand the extent of present and potential
future damage to our water resources if we have relevant biological response
systems. There are several such biological systems already in place that can
monitor toxic effect(s) – their common requirement is a "bio-sensor organ", that
is the biological target upon which the toxic impact is measured. Each type of
test with its specific bio-sensor indicates a different focus of interest and
concern: the fish test is meaningful for the assessment of the aquatic
environment of rivers and streams and so are the daphnia and algae tests; the
bacterial luminescence tests looks at toxic effects of water on the microbial
environment.
However there are other considerations to be taken into account when choosing a
toxicity test for a specific investigation: these are considerations of
relevance to the problem solving, considerations of accuracy, of numbers of
tests that can be done within a certain time, and of course of
costs.
Toxicity per se is only meaningful if measured as a response of live forms, i.e.
bacteria, algae, insects, fish, humans. The "Weaver Test" makes use of human
cells to assess possible damage to their energy pathway; this damage is
translated into a color reaction via an enzyme system (modified MTT test), the
intensity of which is measured and calculated through instrumentation and
computation - the result is objective and scientific.
The "Weaver Test" took 8 years to develop. It lends itself to mass screening,
for instance contour probing of polluted water sources or monitoring during
cleaning-up operations of polluting industries. It is a micro-test, using very
small amounts of test sample, at the same time it is highly sensitive to many
pollutants in detecting parts per million. The important feature of this human
cell test (HCT) is that the bio-sensor organ is well understood and controlled.
The effectiveness of the HC test has been demonstrated in a large field study
over 12 months on the East Rand comprising about 40 000 individual
measurements.
The cost of the test is low compared to currently applied tests.
Other toxicity test systems involving human cells are still in the developmental
stage and at present mostly of academic interest.
Below are listed major advances of the Human Cell Test ("Weaver Test")
compared to other toxicity tests using bio-indicator systems: The test
is
accurate: providing a correlation between biological and chemical
toxicity. The use of standard 96 well plates allows for multiple tests of the
same samples to obtain accurate mean values compared to appropriate
controls.
objective: assessing cell damage by computer analysis of
spectrophotometer readings.
suitable: for mass screening because of comparative low cost per unit.
distinguishes between salt overload and real toxicity, it also allows for
the possibility of detecting certain toxins in parts per billion.
allows for concentration and dilution of small sample volumes; it is
useful in the laboratory for "what… if… analysis"
flexible as the system has potential for further developed (e.g.
adaptation to air pollution).
can assists with the selection of sites to prioritize possible remediation
and law enforcement.
Whenever the Human Cell test identifies a problem, it is a warning sign of
potential risk to human and animal health either of immediate effect or longer
term. It is necessary to take action now!
In conclusion, the Human Cell Test provides a
bridge between chemical
analysis and environmental reality in that it adds significantly to the
understanding of the potential impact of physical and chemical pollutants in
water. This is a new
management tool that can greatly assist
environmental, safety and health officers as well as engineers, who are
concerned with the provision of clean water as well as the inevitable task of
removing harmful pollutants from industrial effluents.
For further information, please
contact
us!