Wednesday, July 6, 2022

Top medical officer questions beetle safety

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The head of public health in Auckland has added her voice to concerns over dung beetle release, calling for a closer look at their human health impact. In a written response to The New Zealand Farmers Weekly, the Auckland regional senior chief medical officer Dr Denise Barnfather expressed misgivings about the unanswered questions surrounding dung beetles’ potential to transfer diseases. However, her concerns are not being echoed on a national level by the Ministry of Health. The ministry is relying on Environmental Protection Authority (EPA) assessment of the beetles’ risk. “Any risks from release, including those to humans, are considered as part of the release process led by EPA. The ministry has not provided any formal submission. The ministry is aware of Denise Barnfather’s concerns and believes the appropriate forum to address these is through the EPA,” ministry director of public health Dr Mark Jacobs said.  Concerns about the EPA assessment of beetle risk have already been raised by Dr Grant Guilford, of Auckland University. They were dismissed by the authority’s researchers. Barnfather’s concerns centre on the beetles’ ability to transfer pathogens into rural water supplies and their possible impact on bacterial loading within soils. The Auckland region has 260 rural bore water supplies. Nationally about 10% of the population is estimated to have home-based water supplies that could be exposed to beetle contamination. Barnfather believes the biggest potential risk posed by the beetles is through spreading gastrointestinal illness in the population, particularly notifiable diseases including campylobacter, cryptosporidium and salmonella. New Zealand already records high rates of gastrointestinal diseases. Barnfather questions the wisdom of releasing other potential disease carriers into the New Zealand environment.

She is concerned the beetles’ ability to fly some distance will make containment of such contagious diseases by health authorities more difficult.

While caged trials are under way on the beetles there are no human-health impacts being studied.

The first trial just completed has studied impacts on pasture production and water run-off and the second is on livestock parasite populations.

A background document obtained by Farmers Weekly outlines the trials and acknowledges public-health risks are addressed only “to a minor degree”.

Landcare Research notes in the trial outline it did not consider human health a major issue from a science perspective but that it was an emotive area and not surprisingly some stakeholders are concerned.

Landcare also maintains dung beetles are no more likely to transmit diseases to people than flies, earthworms or other beetles.

Chief executive Dr Richard Gordon said Australian experience indicated no reported cases of disease transmission by dung beetle.

“On the contrary, there is evidence for reduction in disease transmission risk by removing dung from soil surface, reducing run-off into water, wind-blown dung etc,” he said.

The Dung Beetle Release Strategy Group has cited work by an Australian entomologist. He stated while transmission of pathogens to food and water might be theoretically possible, the risk would be small and generally insignificant.

But Barnfather is concerned at the reliance on the Australian experience with the beetles. She noted domestic water supply infection via the beetles was less of an issue in Australia, where distance between farms and rural communities was much greater.

She has misgivings if the beetles are to be freely released based on current trial work.

“There are mostly unanswered questions about the level of risk posed by dung beetles on people’s health.

“A risk assessment that adequately addresses public health risk must be about actively seeking, identifying and acknowledging risk and uncertainty and determining how best to address such risk and uncertainty.”

Related stories: Public health issue ‘hasn’t been studied’Beetles effective in AustraliaEPA backs dung beetle decisionExperts dump on dung beetle

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