At one end of the spectrum, the rules phasing out lead additives from gasoline are widely viewed as a model of efficiency, flexibility and solid science.

Ever since 1970, when the Environmental Protection Agency mandated the removal of lead additives from gasoline, the oil companies had sought other octane-producing additives to replace lead.

Once the leading source of fuel, its low octane rating required lead additives.

A side effect of the lead additives was protection of the valve seats from erosion.

Because of the environmental impact of lead additives, the octane rating is increased today by refining out the impurities that cause knocking.

So, the sale of gasoline with lead additives was greatly reduced in the 1980s.

When the Great Lakes Chemical Corporation bought control of the world's biggest maker of lead additives for gasoline six years ago, the product itself was almost an afterthought.

Recognition of these risks has led to evidence-based programmes of prevention, such as elimination of lead additives in petrol.

A catalytic converter for an automobile can be poisoned if the vehicle is operated on gasoline containing lead additives.

The company that makes the lead additives that are trickled into our petrol has another answer to the problem.