The FDA is waiting on test results on the effects of pasteurization on the virus in cow’s milk, but to date, it’s seen nothing that would change the assessment that commercial milk is safe.

The Food and Drug Administration said Tuesday that fragments of the bird flu virus had been detected in some samples of pasteurized milk in the U.S. While the agency maintains that the milk is safe to drink, it notes that it is still waiting on the results of studies to confirm this.

The findings come less than a month after an outbreak of the H5N1 strain of bird flu was found, for the first time, in herds of dairy cows in several states. It has since been detected in herds in eight states.

The FDA has been working with the Centers for Disease Control and Prevention and the U.S. Department of Agriculture to investigate the outbreak.

The fragments of the virus were found while testing samples of pasteurized milk, the FDA said. The testing method, called PCR testing, looks for bits of genetic material; a positive result doesn’t mean that live, infectious virus has been found.