Arsenic and DDT residues at cattle dip yards

Summary

Soil at many cattle tick dip sites is contaminated due to past use of arsenic and DDT. Arsenic was used as the tickicide in the dip solution up until 1955 when the ticks became resistant to it. DDT, an organochlorine (OC) was then used until it too became ineffective in 1962. Since 1962 other much less persistent tickicides have been used to dip cattle. The use of DDT was banned in 1985.

Arsenic and DDT can still be found at high levels in the soil beside many dip baths today because they are very persistent compounds.

There are 1,648 dip sites scattered throughout the far North Coast of NSW, with a few dotted along the Qld border. Of these 1648 dips, 254 have been demolished over the years with 29 of those sites having residences built over them. To assist in the recognition of these old dip sites, whether they remain standing, are dilapidated or have been destroyed, a register of known cattle dip sites in that region is maintained by the NSW DPI. This information is shared with all relevant Local Government councils.

Topics include:

• Where is the contamination?
• Why do residues remain?
• Can the residues spread?
• Residue uptake by plants and animals
• Reducing the risk of organochlorine chemicals in beef
• Human health risks
• Is the NORM program working?