Fears over tainted region groundwater
A chemical cocktail has been found in Waikato’s groundwater including banned firefighter foam, bee harming insecticide, pesticides and pharmaceuticals.
The new study by the Waikato Regional Council and GNS Science was carried out to provide the council a baseline understanding of how widespread organic contaminants are in the region’s groundwater.
It detected PFOS firefighting foam at three of the 57 groundwater sites sampled.
PFOS was banned from use in firefighting foams in New Zealand in 2011.
The chemicals pose a serious health risk.
The insecticide imidachloprid was detected at six of the sites. Imidachloprid is currently listed on the European Union surface water watchlist and also poses a risk to bees and other pollinating insects.
The insecticide is part of a class of neonicotinoid pesticides which can impact bees if not used correctly.
It has been available for use in New Zealand for more than 20 years.
The Environmental Protection Agency is currently investigating its usage.
The study measured 47 sites across Waikato from Land, Air and Water’s State of the Environment monitoring system, along with 10 targeted sites close to contaminant sources as well as a waste-water site as a comparison.
The study detected contaminants at 91 per cent of the 47 sites with 73 different chemicals detected. Forty-eight different pesticides were detected, 11 pharmaceuticals, 10 industrial chemicals 3 preservatives/food additives and one personal care product.
When asked if the results posed a risk to human health, Waikato Regional Council senior scientist Jonathan Caldwell said there was a limited amount of international information available on human and animal toxicity for most of the compounds measured in the study.
‘‘For the selected few compounds with a New Zealand drinking water standard associated with them, there were no exceedances identified,’’ he said.
Twenty-eight chemicals were found in concentrations above European Union admissible levels for pesticides at one or more of the sites.
‘‘There were also cases where we detected multiple compounds at low concentrations individually, but with a significant concentration when combined. There is no information on combined toxicity for these compounds.’’
The study was presented to the council’s Environmental and Services Performance committee.
Caldwell said some results were really positive.
‘‘Most of the compounds we tested for were not detected. Of the 723 compounds we tested for, we detected 73 at most of the ‘state of the environment monitoring sites’ we sampled. The flip side is that for those compounds we did detect, there were some high concentrations or multiple compound occurrences.’’
He said the most common chemical the study found was the herbicide chloridazon-desphenylmethyl. It was detected at 47 per cent of the sites.
The study said the concentrations of the chemicals were comparable to those found in overseas’ groundwaters and were found with a large range of concentrations.
At the 10 targeted sites, pesticide concentrations were consistently lower than the 47 sites, but higher for all other EOC categories.
Pesticides were found across the region with 18 different compounds overlapping between land uses, with a wider range and higher concentrations found in horticultural areas in North Waikato. Industrial compounds and pesticides were detected at variable quantities at the 10 targeted sites where land uses ranged from waste-water treatment sites to urban locations. Pharmaceuticals and personal care products were only detected at urban and waste-water treatment sites.