The appearance of white worms bodes ill for the Seven Lakes of San Pablo, Laguna. The worms, called by local fishermen "puting bulate," are found in the guts of Nile tilapia caught in the Seven Lakes. The worms have alerted researchers to the presence of heavy metals pollutants in the lakes, said Vachel Paller in a policy briefing paper for the National Research Council of the Philippines (NRCP), Department of Science and Technology.

Icamina, P. (2018, March 27). Heavy pollutants plague Seven Lakes. Malaya Business Insight, p. A4.