A U.S. Environmental Protection Agency official said here today that radiation in Warsaw poses no health hazard and probably had not reached a dangerous level at any time since the Chernobyl nuclear accident.

Richard Hopper, an EPA radiation specialist, said tests he conducted after arriving here today showed that radioactive traces in Warsaw's air were about twice normal levels, but far below the amount considered hazardous. He said that he had not tested water or food.

Hopper said he believed there was no reason for the State Department to continue a recommendation announced yesterday that women of child-bearing age and children should not visit here. He added that no U.S. diplomatic personnel or dependents would be evacuated and that those he had tested showed no sign of harmful contamination.

The official's evaluation came as the Polish authorities appeared to extend safety measures to prevent the consumption of contaminated substances.

Although there was no public announcement, shop managers said they had been told not to sell locally made soft drinks or butter until May 15. Farmers have been told not to graze cows until that date.

The government previously announced a ban on the sale of fresh milk and distributed an iodine solution to children under age 16 as a radiation antidote. The new measures were the first sign of official concern that drinking water, which is used in local soft drinks, might be unhealthy to consume.

A commission of Polish government experts repeatedly has reported this week that increased radiation levels in Poland following the Chernobyl accident posed no immediate health danger. However, the experts said they expected some increase in cancer rates over the next two to three decades.

Western diplomats here said that scientists consider radiation hazardous when it reaches a level sufficient to cause illness or increase the risk of cancer for a large percentage of people exposed to it. At the same time, any significant increase in radiation levels can lead to a long-term statistical increase in the cancer rate of a large population, they said.

Hopper said that the radiation level in Warsaw today was so low that it could be measured only in microroentgen, a quantity thousands of times smaller than that of harmful radioactive doses. He said that the current readings indicated that dangerous quantities of radiation never had been present in the air here.

The U.S. official was dispatched to Poland with monitoring equipment because of dissatisfaction among American and other western diplomats over information provided by authorities about radiation levels.

The uncertainty has led about 50 dependents of western diplomats, including Canadians, French, West Germans and British, to leave Poland in recent days. The State Department offered yesterday to pay the travel expenses of dependents of American employes here wishing to leave, but none chose to do so, a spokesman said.

Diplomats here said the EPA testing and State Department offer to cover travel expenses were put into effect primarily to ease anxiety among Americans here and not because it was believed that a serious health risk might exist.

At the same time, several western diplomats said the testing and travel advisories by U.S. and British authorities were a way of expressing dissatisfaction with Polish authorities for not releasing detailed information about radiation levels.