Abstract—Chironomids belong to the group of benthic insects that could reflect aquatic environment degradation. A 96-hour toxicity test for Cu, Cd and Pb in chironomids was investigated and the LC50 obtained were 1.37 μg/mL for copper, 73.09 μg/mL for cadmium, and 38.47 μg/mL for lead. The three metals exhibited an increase in accumulation with increasing concentration of test solution. Among the three metals, Pb yielded the highest concentration in organisms. The result suggests that some Pb may have accumulated in physiologically inert sites in the body of organisms. However, from the LC50 obtained, it shows that cadmium is the least toxic. The organisms used in this study might have the ability to synthesize metallothionein, a metal-binding protein which could reduce the toxicological capability of Cd. A multiplemetal system was also employed to monitor metal accumulation in chironomids. It was found that there was a reduction in the amount of metals absorbed by the organisms when compared to organisms exposed to a single metal system.

Index Terms—Accumulation, biological indicator, chironomids (or Chironomus sp.), median lethal concentration, metals.

C. C. Lagrana is with College of Science, Tarlac State University, TarlacCity, Philippines (e-mail: clairechem@yahoo.com).
D. C. Apodaca, was with Mines and Geosciences Bureau in Quezon City and with School of Graduate Studies, Mapua Institute of Technology, Manila, Philippines (e-mail: dcapodaca@yahoo.com).
C. P. David is with National Institute of Geological Science, University of the Philippines, Diliman, Quezon City, Philippines (e-mail: cp.david@yahoo.com).

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Cite: Claire C. Lagrana, Dahlia C. Apodaca, and Carlos Primo C. David, "Chironomids as Biological Indicators of Metal Contamination in Aquatic Environment," International Journal of Environmental Science and Development vol. 2, no. 4, pp. 306-310, 2011.