In a survey of nearly 2,000 dairy farms in the United States, the Food and Drug Administration has found that less than one percent of the total samples contained illegal drug residue, reports the Associated Press.
The investigation began after a number of public health groups expressed concerns about the possibility of milk being contaminated by animal antibiotics, particularly from dairy farms “that had repeatedly tried to sell older cows for slaughter with illegal levels of antibiotic residue in their tissue.”
Farms that had previously tested positive made up approximately half the samples in the recent study, with the other half coming from a control group.
Out of 2,000 farms tested, 11 farms with previous violations tested positive for illegal residue, and four farms from the control group also tested positive.
"Overall this is very encouraging and reinforces the idea that the milk supply is safe," said the FDA's William Flynn.
The agency will continue its efforts to further reduce the level of antibiotic contamination.