Water Environmental Risk Research Articles

Evaluation of environmental waters using the comet assay in Tilapia rendalli

Testing for environmental pollutants is an ever-growing concern. Various tests in organisms have been utilized for the detection and identification of toxic substances in the air, water and soil. In the present study, we utilized the comet assay in Tilapia rendalli to conduct an environmental assessment of Lake Igapó II, a lake located in the metropolitan area of Londrina, PR-Brazil. The results demonstrated that samples from Lake Igapó II had a significantly greater number of comets, mainly in classes 2 and 3. The results suggest a genotoxicity of the aquatic environment at Lake Igapó II and that the comet assay in T. rendalli provides adequate sensitivity to be utilized as a tool in the monitoring of water pollution and environmental risk assessment.

Environmental risk increase due to heavy metal contamination caused by a copper mining activity in Southern Brazil.

The Camaquã Copper Mines (CCM) were the main sulphide deposit in Southern Brazil and have been in operation from last century to 1996. To evaluate water contamination and environmental risk increase by heavy metals from mining operations, two points on the João Dias Creek were sampled (Station 1, background area and Station 2, contaminated area). Mining activity increased the natural weakly heavy metal fluxes by approximately 5424 kg. (approximately 60%) of the total metal flux, 1542 kg. (approximately 49%) of dissolved and 3881 kg (approximately 66%) of particulate metal flux. Total metal flux of anthropic origin was mostly due to Fe followed by Cu > Zn > Mn whereas Cd, As and Pb fluxes were negligible. The potential human health hazards and risk assessment related to daily intake of water from João Dias Creek are mostly due to Mn and should be of concern for the contaminated area. The ingestion of water from station 2 represents incremental risks of 130% and 59% respectively, considering the non-carcinogenic and the carcinogenic effects. The real increase of human health hazards may be greater than those related to the total concentrations since Mn and As dissolved concentrations were 5.5 and 2.0 higher than acceptable, respectively.

Bioassay standardization for water quality monitoring in Mexico

In Mexico, bioassays for water toxicity testing can be useful tools for water quality control programs and environmental risk evaluation. However, since many bioassays have not been standardized, their application and acceptance in pollution monitoring and control sectors are limited. In an effort to overcome this limitation, the Mexican Institute of Water Technology (MIWT) agreed to participate in an international laboratory network (WaterTox), sponsored by the International Development Research Centre (IDRC). The Centre seeks to evaluate the analytical repeatability and reproducibility of six bioassays (Allium, Hydra, Daphnia magna, and Panagrellus assays; lettuce seed germination and Fluctuation tests) and to determine their sensitivity patterns and the manner in which they are complementary or redundant in a core test battery. In addition, the Mexican team added the Vibrio fischeri Microtox toxicity test to the evaluation. A series of 24 blind samples were analyzed over a 1-year period. Results indicated that precision, or repeatability, was acceptable for most bioassays. For blind sample replicates, the overall coefficient of variation was less than 22%, except for the Muta-ChromoPlate test (60%) and the nematode assay (greater than 100%). While most toxic samples were detected by D. magna and Hydra attenuata assays, those that produced little effect on these two organisms affected lettuce and onion root elongation. The complementary nature of these tests provides a wide spectrum of toxicant detection, in contrast to the Microtox test which showed a more limited and redundant sensitivity pattern when compared against a battery comprised of the four inexpensive bioassays. © 2000 John Wiley & Sons, Inc. Environ Toxicol 15: 322–330, 2000