The U.S. Food and Drug Administration said on Tuesday that it had found bird flu virus particles in some samples of pasteurized milk, but said commercial milk supply remains safe.
The FDA said that because the milk is pasteurized, it remains safe for human consumption as the process kills harmful bacteria and viruses by heating milk to a specific temperature.
"Based on available information, pasteurization is likely to inactivate the virus, however the process is not expected to remove the presence of viral particles," the FDA said.
The agency said it has been evaluating milk from affected animals, in the processing system and on the shelves. It said it is completing a large, representative national sample to understand the extent of the findings.
The FDA said it is further assessing any positive findings through egg inoculation tests, which it described as a gold standard for determining viable virus.
The agency said it has seen nothing that would change its assessment that the commercial milk supply is safe, adding that results from multiple studies will be made available in the next few days to weeks.
"Sound science is critical to informing public health decisions like those made by the FDA related to food safety and we take this current situation and the safety of the milk supply very seriously," the agency said.
There are confirmed cases of bird flu in dairy cattle in eight U.S. states, according to the U.S. Department of Agriculture.
The Centers for Disease Control and Prevention said one associated human case has been linked with the outbreak in dairy cows. The case was reported in Texas on April 1.
