By Dhel Nazario
A group of scientists has urged for the extensive monitoring of Laguna de Bay after their study found the presence of potentially harmful pollutants in the lake.
According to the Department of Science and Technology (DOST), a group of scientists from the University of the Philippines (UP) studied Laguna de Bay and selected tributaries for one year and found that although most of the pollutants are still within the limits of the water quality standards as set forth by law, the detection of antibiotics, steroid hormones, and protozoa is a cause for the conduct of further studies to gather more comprehensive data.
“The study, which established lower concentrations of pollutants when compared to other parts of the world, is a good start for more in-depth studies,” said Dr. Mylene G. Cayetano, a professor from the UP Institute of Environmental Science and Meteorology who led the third team of scientists that studied the presence of heavy metals in the fishes of Laguna de Bay.
The Philippine Council for Industry, Energy and Emerging Technology Research and Development (PCIEERD) of the DOST, in collaboration with the Laguna Lake Development Authority (LLDA), commissioned the UP scientists’ study, the Program Synergistic Capacity Advancement in the Management of Laguna Lake (SCALE).
SCALE’s Project 1 was led by Dr. Maria B. Espino of the Water Research and Management Laboratory of the UP Diliman Institute of Chemistry. It studied the lake’s level of steroid hormones.
SCALE’s Project 2 was led by Dr. Windell L. Rivera of the Pathogen-Host-Environment Interactions Research Laboratory of the UP Diliman Natural Sciences Research Institute. It studied microbial source tracking in Laguna Lake and selected tributaries.
The study revealed that based on the presence of fecal bacteria Escherichia coli and Bacteroides species, domestic sources contribute the most fecal contamination, particularly human origin in most river tributaries. Among the animal sources, swine and duck feces are abundant in the rivers of Sapang Baho in Cainta, Rizal and in Pila, Laguna.
The presence of these intestinal protozoan parasites may pose a threat to water safety and human health since Laguna Lake serves as a catch basin. Consistently, Bagumbayan River has been marked the most contaminated among the sampling stations.
SCALE’s project 3 was led by Dr. Cayetano. It studied trace metals and organics in commodity fishes of the lake: method optimization, extent of contamination, and health risk due to fish intake.
The study noted that the mean arsenic content in bangus samples remains high in both dry and wet season, and higher than in tilapia. The daily human intake of lead and cadmium in tilapia and bangus does not exceed the guideline limits set by the World Health Organization, and the Food and Agriculture Organization.
For safety, the study recommended the daily human consumption of bangus from Pila and Biñan at 875 grams and 800 grams, respectively, for mean arsenic content.