Toxicity Reduction Evaluations (TRE)
are often required when an effluent, sediment or other environmental sample is determined to exhibit unacceptable acute
or chronic toxicity. Determining the
cause of toxicity can be difficult because 1) multiple potential toxicants may
be present, 2) little or no toxicity data exist for many compounds, 3) toxicity is frequently variable, and 4) the sample matrix may greatly modify
toxicity. By working closely with site personnel and engineers we have assisted numerous
facilities identify the causative toxicant(s) so that appropriate treatment
and/or management options could be instituted and toxicity reduced or
eliminated.
A Toxicity Identification Evaluation (TIE)
is generally performed as part of the TRE to identify causative toxicants. In the TIE process samples are manipulated in
such a way that toxicity is predictably increased or decreased dependent on the
causative toxicant(s). For example,
chelator addition is used to reduce metal toxicity, solid-phase extraction is
used to remove acid, base and neutral organic compounds and pH control is used
to modify toxicity of pH-dependent toxicants such as ammonia and metals. However, the EPA TRE/TIE procedures do not
address all potential toxicants (e.g. ion imbalance, biological pathogens) and
additional procedures are constantly being developed and published in the
scientific literature. We can tailor a
TIE which incorporates identification methods appropriate for the specific situation and thus provides the most economical and expeditious solution to the
toxicity problem.
