Scientifically, genetic drift means the gradual modification of the genome of a species as a result of inbreeding, outbreeding or random mutation, without reference to the agents of transformation. More recently it has also come to mean the pollution of one genetic strain by another, notably cross-pollination between crops which have been genetically engineered and those that have not. This effect – whose scope it is claimed was unanticipated by regulators, companies, or farmers, though not by environmentalists – is that insects, birds, and the wind spreading "biotech" pollen to fields planted with conventional or organic crops miles away. This has led to problems for farmers who choose to grow not GM crops, because they have been unable to sell their contaminated harvest in the more lucrative markets for non-GM and organic produce.
The question of liability is being contested by both sides. Insurance companies covering crop losses say their policies will not cover genetic drift. That reflects not only the novelty of the problem but also a sense that studies are still lacking on the scope of drift – how far pollen can travel, for instance, and how big farmers' losses might be.
Genetic contamination from genetically engineered corn has become a major problem in the USA, where in 2001 it accounts for as much as a quarter of all corn grown. Virtually all commercial seeds have at least trace levels of genetically modified proteins, just five years after the introduction of the crops. Organic farmers fear that, given the unpredictability of pollination, they can never guarantee a biotech-free crop.
In 1998, cross-pollination was suspected of carrying a genetically engineered variety of corn to an organic farm in Texas. The contamination was not discovered until the corn had been processed and shipped to Europe as organic tortilla chips. When testing revealed traces of biotech corn, the shipment of 87,000 bags was recalled, costing the company more than $150,000.
In 2001, a US judge last month ruled in favour of Monsanto in its demand that a Canadian farmer pay for the company's genetically engineered canola plants found growing on his field. He claims his crop was contaminated after pollen blew onto his property from nearby farms. Similar lawsuits have been filed against US farmers, but the Canadian case was the first to go to trial.
Aventis CropScience, meanwhile, is the target of several lawsuits over the mingling of its StarLink corn with other varieties. StarLink, engineered to produce a protein toxic to insect larvae, was approved in 1998 only for animal use out of concern it could cause allergic reactions in people. It was later detected in taco shells, forcing a recall of more than 300 corn-based products and an ongoing and costly attempt to contain StarLink still in the market. A class-action federal lawsuit argued that cross-pollination by StarLink has hurt farmers' ability to export corn and to sell it to food processors. With cross-pollination possible and even likely, Aventis itself has acknowledged the StarLink problem could persist for years, even though the seed was planted on less than 0.02 percent of cropland in 2000.