Erin Brockovich, the tenacious eco-crusader made famous by Hollywood, is back in the news: She says that many former Beverly Hills High School students have been stricken with cancer because of exposure to toxic fumes from an active oil field on school property. Brockovich and her boss, attorney Ed Masry, yesterday filed 25 personal injury claims for damages against the city of Beverly Hills and its school district — and they say that hundreds more claims could be forthcoming. They also plan to go after three oil companies and two government entities. The duo argues that contamination on the campus has led to 280 cases of thyroid cancer, Hodgkin’s disease, and non-Hodgkin’s lymphoma since the 1970s, giving the school a cancer rate 20 to 30 times higher than the national average. The school district and the South Coast Air Quality Management District, which monitors air pollution in the region, dispute Brockovich and Masry’s findings.