United Farm Workers Union leader Cesar Chavez has lost 15 pounds in the first eight days of an indefinite fast to protest "the scourge" of pesticides that he says is causing cancer in children of farmworkers.

The labor leader's son, Paul Chavez, said he does not know how long his 61-year-old father intends to continue the water-only fast that he began at midnight July 17.The younger Chavez said his father plans to spend most of the fast in seclusion at the union's 40 Acres facility in Delano, although he attended mass Monday night with other farmworkers.

Dolores Huerta, a UFW officer and spokeswoman who has known Chavez since the 1960s when he came to national attention in battles to organize farmworkers, said he has dropped from 169 pounds to 154 pounds.