By FRANKLIN BRICENO and FRANK BAJAKSANTA ROSA DE CAJACAY, Peru (AP) â¿¿ It began with a loud pop like a tire bursting. A toxic cocktail of copper concentrate laced with a periodic-table's mix of volatile compounds then shot skyward. The pipeline that carries slurry at high pressure from Peru's most productive mine 188 miles (302 kilometers) to its desert coast had sprung a leak at a pumping station in this village of poor farmers. It was 9:15 a.m. Abraham Balabarca, who was building a house nearby, ran to the station with others to try and halt the flow. But the door was chained and bolted. The security guard had no key. By the time someone pried open the lock with a crowbar, the town was shrouded in a toxic cloud. In the next days, about 350 villagers would be treated for headaches, respiratory tract bleeding, nausea and vomiting, according to the mayor's office. At least 69 were children. Three weeks after the leak spilled 45 tons of slurry into the town of Cajacay, spreading toxic dust that left 42 people hospitalized for up to 11 days, the copper mine's owner, Antamina, has said little about the accident, and been silent about the slurry's chemistry. Environmental protection has traditionally been lax in Peru, where mining has been the engine of a decade of average 7 percent annual growth that has made the Andean nation a darling of investors. But an anti-mining backlash has been growing in the country. In the past three months, eight Peruvian civilians have been killed in anti-mining protests that have dominated the country's political agenda, prompting the resignation of two prime ministers. Immediately after the July 25 spill, many in this community of 410 pitched in at the request of Antamina's director of community relations to help stop the slurry from reaching a nearby river. They isolated the mucky mixture using absorbent cloth provided by Antamina, using no protective gear, or masks or gloves. Balabarca said it stank like a common insecticide.