The Department of Agriculture confirmed that it was lead toxicity that killed two cows on a dairy farm in Silvermines in February and that subsequent tests were carried out on 20 other herds.
Sampling and testing of bulk tank milk identified two herds as being in excess of the maximum residue limit.
Those two, along with the farm that lost two cows, had their milk supply restricted to allow an investigation into finding the source of the lead.
Two of the three herds have since had restrictions lifted.
History of high lead levels
An inter-agency meeting was due to take place this week involving the Department of Agriculture, Tipperary County Council, the Environmental Protection Agency, the Food Safety Authority of Ireland, the Heath Services Executive and Teagasc to try and locate the source of the lead. However, it has been postponed until next month.
Lead has been a problem in the Silvermines area for years due to the history of mining.
No human health risk
The Department also added that it is satisfied that there was no human health risk.
Sean Keating, director of Water Services at Tipperary County Council, told the Irish Farmers Journal it was well known that there was higher than average levels of lead in the area.
He added that the he understands the meeting will establish a protocol for the investigation of incidents of animal disease and decide if new recommendations are required.