Something in our water

Caffeine, artificial sweeteners, ibuprofen and chemicals used to make plastic bottles are flowing through New Zealand’s groundwater.

A four-yearly groundwater pesticide survey carried out by the Crown research institute ESR for regional councils has for the first time monitored wells for emerging organic contaminants (EOCs), believed by some to affect human health and aquatic ecosystems.

ESR principal scientist Murray Close told Stuff while their existence in groundwater had come as a surprise, the narrow range of compounds tested for had been found in such minimal amounts they were unlikely to affect human health.

However, it was less clear if they might have an effect on aquatic species, he said. The survey also tested for glyphosate – the active ingredient in the weedkiller Roundup – for the first time.

Of 135 wells tested, its presence was only found in one well in North Otago, with a concentration of 2.1 parts per billion, more than 400 times lower than the World Health Organisation’s recommended health-based value.

Close said that well had serviced market garden operations and showed evidence of ‘‘poor well-head protection’’, with contamination likely from containers stored near it.

Overall, pesticides showed up in 68 wells out of 279 sampled, with 28 wells having two or more pesticides detected.

‘‘The level of pesticides was fairly similar [to four years ago] and slightly decreasing. There were no pesticides measured above drinking water standards, and most were about 200 times below.’’

The wells registering pesticides were mainly in Mid- and South Canterbury, parts of Otago and Southland, Nelson and Marlborough, and in the Waikato.

The emerging contaminants included chemicals in personal care products, pharmaceuticals and food preservatives, and more specifically caffeine, pain relief compounds, contraceptive pills and sunscreens, Close said.

Of 121 wells sampled across the country, excluding the Waikato, Hawke’s Bay and West Coast regions, 85 contained a total of 227 such contaminants.

Bisphenol-A – used to make plastic bottles and containers – was the most commonly detected, in 40 wells, while two ultra-violet filter compounds used in sunscreens were the next most common with 33 and 24 detections.

The artificial sweetener Sucralose was found in 18 wells and was also detected in the highest concentration of

655 parts per trillion (or nanograms per litre) in a Taranaki well.

‘‘From a human health point of view, I don’t think they are a concern because we already either use them in our sunscreens or take them for headaches or put them in our coffee.’’

One well in the Manawatu contained

175 nanograms per litre of Ibuprofen However, Close said if there was one nanogram per litre of paracetamol in the groundwater, it would require drinking the equivalent of 200 Olympicsized swimming pools to receive the dose of a 500mg paracetamol tablet, he said.

‘‘These compounds are commonly used by humans in big doses. What we are not sure about is any impacts on other ecosystems, the groundwater protozoa and crustacea. We don’t really know at what levels these are sensitive.

‘‘Even though they are at a low concentration, the fact we did find EOCs in

70 per cent of wells was a surprise to me. And we only analysed for a suite of

30 compounds – there are up to 1000 you can test for.’’

Victoria University of Wellington freshwater ecologist Dr Mike Joy told

Stuff the survey’s detection of dieldrin some 40 years after it was banned showed how New Zealand should ‘‘err on the side of caution’’ when it came to setting acceptable limits for emerging contaminants.