PARIS -- A year and a half after the Chernobyl nuclear accident spewed radioactive isotopes across Europe, traces of contamination continue to crop up in Europe's food chain, and increasingly the fallout is political as well.

There has been contamination most recently in the wild mushrooms that are considered delicacies in France and Germany, and English lambs grazing in highland pastures are still showing elevated radiation levels. As the ripple effect of Chernobyl persists, the situation has become more urgent this month in Europe because emergency limits on radiation content of food are about to expire. Moreover, there are wide differences among major European countries over which standards to apply permanently.

Along with projections and extrapolations based on assumptions about the food market after a nuclear accident, the politicians are also considering public perception and the potential danger of disrupting their agricultural markets with limits that may be too strict.

Until now, the European Community nations have been following the emergency limits they agreed to in the hectic days just after Chernobyl. Those limits allowed no more than 370 becquerels of radioactive cesium in a kilogram of milk or baby food, and no more than 600 becquerels per kilogram in other foodstuffs.

The United States also has adopted the 370 level for imported food.

But the three nations of the E.C. that have big nuclear power programs -- the United Kingdom, France and Spain -- are pushing for a relaxation of the standards, which expire Saturday. They argue for a 5,000 becquerel limit on major foods, a number derived by a group of scientists commissioned by the E.C. itself.

West Germany, home to the Green Party political and environmental movement, is insisting on keeping the emergency measures permanently. The European Commission, the executive body of the E.C., has recommended a compromise level of 1,250 becquerels. In fact, there is enough room in the scientists' extrapolations for politicians to make a case for all three numbers.

The emergency measures of May 1986 applied only to foods imported into the E.C. countries. The member nations have been free to do as they please with foods produced within their own borders.

In Britain, for example, many lambs grazing on rocky pastures in the highlands and eating the sparse grass down to the roots continue to show elevated levels of radioactive cesium. Rather than risking devastation of its lamb industry by applying the stringent 600 becquerel limit, Britain has been allowing lamb onto the market if it registers under 1,000 becquerels per kilogram.

"If you take a lot of food off the market because it is so-called 'contaminated,' you have the problem of disposal and food shortages," said Janet Griffey, a spokeswoman for the British Ministry of Agriculture. "We eat a lot of lamb. The scientists have recommended a maxiumum 5,000 becquerels for cesium. We want everybody to base their levels on scientific evidence."

In France and West Germany, the food in question is wild mushrooms. Certain types of wild mushrooms, pushing up from the humus of dead leaves that fell in the autumn after Chernobyl, are showing more contamination this year than last. Individual specimens of one mushroom, the yellow boletus, have registered 2,400 becquerels per kilogram, according to a non-government French group called the Independent Regional Committee for Information about Radioactivity, known as CRII-RAD.

Among the most contaminated types, said Christian Courbon, an expert at CRII-RAD, are boletus badius, boletus chrysenteron and craterellus cornucopioides, which the French call "Trompette de la Mort" -- Trumpet of Death, an edible and delicious mushroom, despite its name.

"If you eat mushrooms one time, you won't fall down dead on the spot," said Courbon. But the level of contamination, he said, "is not insignificant."

The popular girolles and cepes from Perigod and Bordeaux are mostly uncontaminated, he added, as is the morille conique shown on a 4-franc postal stamp issued by the French government in September.

The French health ministry has dismissed any suggestion that eating wild mushrooms is dangerous. Mushrooms are considered a minor foodstuff, consumed infrequently, and it would take tens of kilograms of mushrooms to accumulate a dangerous dosage.

But the West German environmental authorities have issued an official warning to their citizens to limit their consumption of the fungi. Levels of between 3,000 and 6,000 becquerels per kilogram have been found in some West German wild mushrooms, although the average of the specimens measured is under the 600 becquerel limit. The West Germans have also been warned about eating a lot of wild game or fish from some German lakes where melting snow waters have brought contamination.

The unit of measure for radiation, the becquerel, represents the breakdown of one atom per second, which is accompanied by the emission of an alpha, beta and gamma rays.

In determining maximum permissible levels of radiation in food, the E.C.'s scientific group began with the accepted international safety standard for the cumulative radiation dose a person may receive per year. That number is 0.5 rem or 500 millirems, and it originated with the International Commission on Radiological Protection, the world authority in the field, and has been adopted into the standards of all United Nations bodies and Euratom.

Working backward, the E.C. scientists tried to set a becquerel limit on food contamination that would prevent an individual from accumulating a 500 millirem dose over a year's time. For example, according to the World Health Organization, a person would have to eat 100 kilograms (220 pounds) of meat registering 4,000 becquerels per kilogram over the year in order to hit the 500 millirem standard. An average person eats between 400 and 500 kilograms of food per year.

But instead of assuming that 100 percent of the food that a person ate after a nuclear accident would be contaminated up to the becquerel limit, the scientists decided to make the assumption that only 10 percent of a person's diet would be that contaminated.

Assuming a 10 percent contamination, the numbers work out to a 5,000 becquerel per kilogram limit on major foods -- those that are consumed regularly.

West Germany quarrels with the assumption that only 10 percent of the food would be contaminated to the bequerel limit after an accident. Its environmental authorities are assuming 100 percent contamination -- leading them to the emergency figures, 10 times more severe than the E.C. scientists' proposal.

"We want to protect our people," said Marlene Muehe, a spokeswoman for the Ministry of the Environment in Bonn. "For security, for safety, for health we want to make the limits very strong. We the politicians want to be sure, to have security for our people. It's a political decision, what level you want to have."

Britain is on the other side of the argument. The emergency E.C. limits "were pulled out of the air after the accident without any scientific basis whatsoever," said John Dunster, former director of Britain's National Radiation Protection Board and a member of the E.C. group that proposed the 5,000 becquerel limit, of which he says, "We think there is a strong safety factor there."

The new, permanent measures will apply not just to imports into the E.C. but to all exports and home-grown products, in short, everything that enters the food market. Hence the political stalemate over the decision.

The emergency measures have already been extended twice because of a lack of agreement on permanent becquerel limits. The E.C. foreign ministers are scheduled to meet again this week to give it another try.

Robin Herman is a free-lance writer based in Paris.