LAKE TITICACA, PERU - Tucked between snow-capped mountains, it was once worshipped by the Incas, who proclaimed the deep blue waters the birthplace of the sun.

These days the shores of South America's largest lake are littered with dead frogs, discarded paint buckets and bags of soggy trash. Less visible threats lurk in the water itself: toxic levels of lead and mercury.

The steady deterioration of the prized tourist destination has caused a rash of health problems among the 1.3 million people in Peru and Bolivia living near Lake Titicaca's polluted banks.