Science

Waste to Energy needs rethink

The proposal for a Waste to Energy (WTE) incineration plant being considered for the Kaipara District has been the subject of recent articles by various local experts in the Mahurangi Matters. The international trend is now strongly towards recycling (The Circular Economy) and away from WTE processes, as I have described in a science column a couple of years ago. This ongoing coverage has elevated local community awareness and concern about emissions from WTE processes. Waste to Energy plants that do not have high-quality scrubbing of output gases are particularly dangerous, as international reviews of WTE plants have shown (Environmental Research Letters, 2020). Perfect scrubbing of incineration gases is difficult and expensive, and makes the capital intensive WTE process financially less viable. The gases emitted by incineration of waste include climate changing carbon emissions, but also carcinogenic organic incineration products, dioxins and furans (www. zerowaste.co.nz). Dioxins and furans are not manufactured for any industrial purpose but are the products of incineration and related processes. While dioxin and furan contamination has been found in the air, soil and food, they are mainly distributed across landscapes through the air. Eating food contaminated by dioxins and furans is the primary source of exposure of these carcinogens to humans and animals. A leading source of exposure to these incineration toxins is if you work near or live close to a WTE plant. These dangerous gases have serious health impacts for the human body and are especially dangerous for unborn children. When they are ingested by farm animals, they contaminate dairy foods and meat. And when washed off the land into streams, they pollute the fresh and marine waterways and the species that exist in them. Contamination of the soil and plants by these airborne gases is a serious problem for other plant-based foods and perhaps even our wines. Dioxins and furans and their effects on human health have been reviewed by the World Health Organisation (www. who.int) and by the USA Environmental Protection Agency (https://archive.epa. gov). Dioxins are a group of chemically related compounds that are persistent environmental pollutants (POPs). Dioxins are found throughout the world in the environment, and they accumulate in the food chain, mainly in the fatty tissue of animals. More than 90 per cent of human exposure is through food, mainly meat and dairy products, fish and shellfish. Many national authorities have programmes in place to monitor levels in the food supply. Dioxins are highly toxic and can cause reproductive and developmental problems, damage to the immune system and interfere with hormones, and can cause cancer. While all humans are already exposed to background levels of dioxins and furans, these are not high enough at this stage to cause extensive health impacts. However, it is essential that these background levels are not increased to a level that would become a problem to broader community health.

The World Health Organization (2016) recommends strict control of industrial processes, including Waste to Energy processes, that would add to the existing threshold level.

The way forward for waste management in NZ is via The Circular Economy and the NZ Sustainable Business Council, which I urge readers to consult at the link https://sustainable.org.nz/circular-economydirectory/

Controversial crossing on August agenda

A controversial decision to install a raised zebra crossing outside Leigh General Store will be re-examined by the Rodney Local Board at its next monthly meeting, on August 16 in Kumeu. More than 70 residents wrote to Auckland Transport about the planned crossing, with most saying it should be placed nearer the school, 80 metres further back along Hauraki Road. However, AT decided to proceed with its original plan, infuriating many people in the process (MM, Jul 17). At the July local board meeting, Kumeu member Geoff Upson said due to the huge opposition to the plans, including from the school, he would like to see the issue on next month’s agenda. Chair Brent Bailey agreed, and said relevant AT staff would be present to discuss the proposed crossing, funding for which comes from the board’s transport targeted rated.