In March, voters in California’s Mendocino County approved the nation’s first ban on growing genetically engineered crops. On November 2, residents of four more California counties will vote on similar measures. The LA Times (registration required) reports on the battle between farmers defending their right to grow the crops and environmental activists hoping to stir up opposition to GE foods one county and state at a time.

While few farmers in the relevant counties–Butte, Marin, Humboldt, and San Luis Obispo–grow GE crops yet, many fear such a ban could reduce their ability to stay competitive in the long run. The arguments on both sides are those used since the introduction of the first GE crops. Farmers see benefits such as increased crop production, less pesticide use, and reductions in diesel use and air pollution on the horizon. Opponents of GE crops argue the plants could harm the environment, and that wind-blown pollen could contaminate organic crops. Their biggest concern is that GE foods have not been proven safe. According to the LA Times, “Without their consent, consumers are being forced to participate in the largest uncontrolled biological experiment in the history of humankind,” said Scott Wolf, a leader of Citizens for a GE-Free Butte.

It’s worth noting that crop plants developed through traditional breeding can also be dangerous and are monitored for safety only voluntarily. For instance, at least traditionally developed potato varieties have been introduced and subsequently withdrawn from the market due to elevated toxin levels (in 1970 and again in 1995).

The battle in California is interesting because it seems to represent a shift in tactics for U.S. opponents to GE foods. Despite several years of high profile protests by such groups, bioengineered plants such as corn or soy are now ingredients in as much as 70 percent of the nation’s processed foods. By gathering local support and effecting cultivation bans one county at a time, anti-GE groups may finally begin to make some headway.