 | Vol. 5 No. 4 Spring 1998 |
| A Newsletter About New Jersey's Water Quality Programs |
 | Unsuccessful Toxicity Identification Evaluations can be traced to human error, where studies were inappropriately designed, conducted, or interpreted. |
Identifying and correcting toxicity problems is a three step process. (1) A chronic WET test is performed on a discharger's effluent. Chronic WET testing measures the effects of pollutants on the growth, reproduction, and survival of aquatic organisms over a seven-day period. It is an invaluable tool for assessing toxicity problems in wastewater prior to discharge to our waterbodies. (2) Once a toxicity problem has been discovered through WET testing, a Toxicity Identification Evaluation (TIE) needs to be conducted. This evaluation helps pinpoint the specific component(s) causing the toxicity condition. (3) After the problem has been identified, a Toxicity Reduction Evaluation (TRE) is performed to determine methods for reducing/eliminating the toxic source.
A common example of how the above process is applied involves the use of flocculants in wastewater treatment. Flocculants are chemicals used to help suspended particles in wastewater stick together to form larger clumps which can be settled in clarifier tanks. On occasion, flocculants can create toxicity problems in wastewater effluent. The problem would first show up through WET testing. Then, a TIE would point to the flocculant as the constituent causing the toxicity problem. A TRE would then identify possible solutions, such as switching to a different flocculant.
At the heart of conducting a successful toxicity identification and elimination program is the TIE. In several articles published in the January 1997 issue of Society of Environmental Toxicology and Chemistry Newsletter, TIE success is discussed. The articles state, that in experienced labs, the success/accuracy rate of TIEs is very high - usually 80-90 percent. Unsuccessful TIEs can usually be traced to human error, where studies were inappropriately designed, conducted, or interpreted. As a result, one of the most important decisions a permittee with toxicity problems needs to make is selecting the right consultant. The right consultant is a professional with very specific knowledge and experience, including a solid understanding of toxicology, chemistry, and bioavailability.
With this information in mind, the process of contracting a consultant for conducting a TIE should include an evaluation of experience in performing toxicity identifications and an assessment of how successful those evaluations have been. These qualifications are important considerations and can often determine a study's success or failure.
For more information on toxicity problems in wastewater discharges, contact Betty Boros-Russo of the Office of Quality Assurance, at (609) 292-3950.