A study conducted by Michelle Grace Paraso of the University of the Philippines Los Baños (UPLB) College of Veterinary Medicine found that a majority of the male common carp in the lake have shrunken testes compared with those of the normal male carp. This indicated that they have been "feminized". This feminization shows that the carp was exposed to certain types of pollutants, particularly estrogen. Paraso's study, which was funded by the Department of Science and Technology-National Research Council of the Philippines (DOST-NRCP), evaluated carp as fish biomarker in determining the contamination of Laguna de Bay in four sites: Sta Cruz and Paete, Laguna (East Bay) and Muntinlupa City (West Bay).

Ronda, R. A. (2016, October 13). Carp in Laguna lake emasculated by pollution. The Philippine Star, p. B8.