Silvermines area deemed 'safe for farming' after investigation into lead poisoning

The disused Magcobar Quarry outside Silvermines. Pic: Fergal Shanahan.
The disused Magcobar Quarry outside Silvermines. Pic: Fergal Shanahan.

Martin Ryan and Ciaran Moran

Ongoing monitoring of lead levels in soil, water supplies, animal tissue and farm produce in the Silvermines area of North Tipperary has been recommended by an inter-agency group following an investigation into animal deaths on farms in the area.

Seven state and semi-state bodies were requested by the Department of Agriculture to appoint experts to carry out the investigation after two dairy cows died from lead poisoning on a farm near Silvermines in early 2017 and bulk tank milk supplies from the herd was found to contain lead above the maximum safety level.

Restrictions were temporarily placed on milk supplies from the herd. Slightly elevated lead levels were also found in supplies from two other farms in the immediate area.

The Silvermines area has a natural geological occurrence of lead that has been released in to the environment over time both by natural processes and a long history of mining spanning over a thousand years.

Although the last mine closed in 1993, years of mining activity left a legacy of open-pits, mine shafts, large waste dumps, tailings and derelict structures, much of which has now been remediated.

In 1999, following a lead poisoning incident in cattle in the Silvermines area, an Inter-Agency Group (IAG) was established composed of different public agencies, to examine the risk to public health, animal health and the environment.

In early 2017, two dairy cows died from lead poisoning on a farm in the Silvermines area of County Tipperary. Bulk tank milk from this herd was found to contain lead above the maximum level (ML) permitted in milk (0.02 mg/kg) resulting in a restriction on milk supply to safeguard the food-chain.

Two further dairy herds in the Silvermines area with lead levels in milk above the ML were also identified and restricted at that time.

Follow-up investigations undertaken in all three herds to establish the source of the lead and the pathway of exposure supported a working hypothesis of an environmental source to which cattle had been exposed by winter feeding on 2016-17 ensiled grass that had been contaminated with lead-enriched soil and/or river sediments.

The IAG in their report published on Friday concluded that "the Silvermines area is a safe place in which to grow up, live, work and produce food, provided that farmers, the local community and relevant agencies continue to implement active management measures on an on-going basis".

The recommendations added that "in order to do this, strategies for communication will need to be implemented in a low-key but sustained way in the longer term".

Among the recommendations is that the area of interest in respect of monitoring activities should be based on the 1999 study area but extended by approximately 1km to the east of Silvermines village, informed by currently available information on the levels of total heavy metals in soil.

Indo Farming