A sixteenth-century Swiss chemist named Paracelsus gave us the most basic rule of toxicology: “The dose makes the poison.” Practically every substance on earth (including water and Vitamin C) can kill you if it’s concentrated enough in your stomach or your bloodstream. It’s such a simple idea. Unless you’re California Attorney General Bill Lockyer, in which case five centuries of common sense goes out the window.

On August 26, 2005 Lockyer filed lawsuits against McDonald’s, Burger King, Wendy’s, KFC, Frito-Lay, Procter & Gamble, Heinz, and the makers of Cape Cod and Kettle brand snacks. Why? French fries and potato chips contain acrylamide, a chemical formed when starchy foods (including potatoes) are cooked at high temperatures.

Citing Proposition 65 (California’s “toxics right-to-know” law), Lockyer says Americans need a warning label on foods that contain acrylamide, even though it’s perfectly harmless at the low levels found in fries and chips. Acrylamide is also found in sautéed and roasted asparagus, spinach, and beets. You can find it in 750 different foods including olives, breads, coffee, banana chips, tomato sauce, gingerbread, prune juice, breakfast cereal, and fruit preserves.

Unless we all stop eating breakfast cereal, give up toast, and swear off spinach (not exactly a recipe for good health), harmless amounts of acrylamide will be a fact of life. It’s always been there, and we typically get a daily dose that’s 10,000 times smaller than the weight-adjusted amount that gives cancer to lab rats. Not surprisingly, human studies from Harvard University, the British Journal of Cancer and elsewhere have shown no negative health effects from dietary acrylamide.

It turns out that in order to be in any real danger from acrylamide, a person of average weight would have to eat over 62 pounds of chips or 182 pounds of fries, every day, for his or her entire life. Is anyone really being served by issuing government-mandated warnings about this?

Proposition 65 requires companies to warn people about exposure to an ever-growing list of toxins, even in harmless quantities. Anglers have to contend with warning labels on every rod and reel because of tiny amounts of lead. Never mind that there have been no reports of people actually eating fishing equipment. The mere threat of a lawsuit forced sporting goods manufacturers to knuckle under.

Lawyers who specialize in Proposition 65 lawsuits have targeted manufacturers for failing to adequately warn the public about the harmful nature of brass darts, video-game joysticks, billiard chalk, Christmas lights, hammers, and picture frames. The Civil Justice Association of California reports that one such attorney filed 400 lawsuits against candle makers, claiming their products emitted toxic fumes when burned.

As silly as these examples are, they’re no more absurd than the scams being foisted on food companies and restaurants. Last year the Environmental Working Group (known in some circles as the “Environmental Worrying Group”) sued 50 salmon farms, grocery chains, and fish processors for their failure to frighten us about trace amounts of chemicals — called PCBs — in farmed salmon. The FDA said there was no public health concern, but Prop 65 allowed the suits to proceed.

Your doctor may counsel you to get a healthy dose of the Omega-3 fatty acids found in fish, but California’s warning-sign requirement aims to keep you away from it.

The U.S. Food and Drug Administration underlined this conflict — between the health risks and benefits that a food can offer — in an August 12, 2005 letter to Lockyer. “Proposition 65 warnings,” the FDA wrote, are made “without any scientific basis as to the possible harm caused by the particular foods in questions, or as to the amounts of such foods that would be required to cause this harm.”

In other words, the dose makes the poison. This applies equally to acrylamide in French fries and potato chips. And ignoring Paracelsus doesn’t make for good public policy.