Whole effluent toxicity testing—usefulness, level of protection, and risk assessment

Abstract

The general status of whole effluent toxicity (WET) tests is assessed relative to their generally accepted purpose of identifying, characterizing, and eliminating toxic effects of effluents on aquatic resources. Although WET tests are useful, they are not perfect tools (no perfect tools exist). Imperfections include the innate variability of these tests, due both to biotic and anthropogenic factors; the reality of species differences both between the laboratory and the field and within the field; and differences between the laboratory and the receiving environment. Whole effluent toxicity tests may be overprotective (because of their conservative nature, the absence of environmental and ecological processes that could ameliorate exposure, and sensitivity to noncontaminant effects), underprotective (because the most sensitive species cannot be tested, multiple stresses tend to be present in the receiving environment, and failure to account for food chain effects or all possible endpoints), or offer an uncertain level of protection (intermittent doses and mixtures in the environment, adaptations, and hormesis). The implication of hormesis and inverted U‐shaped dose responses for WET testing are reviewed in particular detail. Comparisons to field conditions indicate that WET tests are not reliable predictors of effects or lack of effects in the receiving environment. Whole effluent toxicity tests are only the first stage in a risk assessment and as such identify hazard, not risk. Identification of risk requires discarding the concept of independent applicability. The appropriate use of WET tests is identified in the context of their advantages and disadvantages.

Performance Evaluation and Design of RO Desalination Plant: Case Study

“…In waterfront areas, desalination of saline water is progressively investigated and used as a strategy to supplement different wellsprings of water supply [10]- [13]. There are three major techniques for desalination [14]: thermal desalination (involves phase change); membrane desalination (Reverse Osmosis, Forward Osmosis, and Membrane Distillation) and ion exchange desalination [15]- [20]. Water desalination by the system of reverse osmosis has turned out to be the most reduced vitality expending strategy concurring to numerous studies [17]- [22].…”

Toxic effects of combined stressors on Daphnia pulex: Interactions between diazinon, 4‐nonylphenol, and wastewater effluent

“…In addition to survival, methods have been developed to assess aggregate toxicity on the growth and reproduction of aquatic organisms (e.g., US Environmental Protection Agency whole-effluent toxicity test methods [29]). In addition to survival, methods have been developed to assess aggregate toxicity on the growth and reproduction of aquatic organisms (e.g., US Environmental Protection Agency whole-effluent toxicity test methods [29]).…”

Application of a direct toxicity assessment approach to assess the hazard of potential pesticide exposure at selected sites on the Crocodile and Magalies rivers, South Africa

“…synergistic, antagonistic and additive effects) (Dorn 1996, Sarakinos et al 2000, Smolders et al 2003, Martins et al 2007). However, no single toxicity test has proven to be suitable to assess all adverse ecological effects because individual organisms differ in susceptibility to different chemicals (Rand et al 1995, Chapman 2000, Fernandez-Alba et al 2001, DWAF 2003. Consequently, several different bioassays at different levels of biological complexity and trophic levels need to be used simultaneously to adequately assess if a potential hazard is posed (Jergentz et al 2004).…”