Explained: What you need to know about arsenic and drinking water

Inorganic arsenic is widespread in our environment, but concentrations may be higher near geothermal systems or gold deposits, in industrial facilities, or in places such as sheep bottoms, orchards, and vineyards where it has been used as a pesticide in the past.

Could it pose a health hazard?

Ingesting large amounts of arsenic over a few hours or days can cause poisoning; however, this condition is extremely rare.

Since it enters our bodies through water and food, we are more likely to hear that it is a potential health hazard in the long run.

If we drink water containing high levels of arsenic for a long time, our risk of developing various types of cancer, as well as heart and skin problems, may increase.

“Arsenic is toxic in relatively low doses and therefore the amount people ingest should be kept to a practical minimum,” a Waikato Regional Council (WRC) spokesman said. reporterHe added that it is not practical to remove all arsenic from public drinking water.

What do we consider a high level?

According to our current drinking water standards, the “maximum acceptable value” (MAV) in drinking water is 0.01 milligrams per liter (mg/l).

According to a study conducted by the United States National Academy of Sciences, constantly drinking this level of water corresponds to a 1 in 1000 chance of developing cancer in your lifetime.

So how much arsenic has been detected in the Waikato River?

This week, two drinking water suppliers who treat the Waikato River water reported their latest sampling results were just above that threshold.

Watercare, which services Auckland supplies, reported a result of 0.011/mg/l, while Hamilton City Council recorded results of 0.0113mg/l and 0.0115mg/l.

Health officials say people don’t need to panic.

“Drinking water with slightly elevated levels for a short period is unlikely to affect people’s health,” said Dr William Rainger, regional clinical director for the National Public Health Service.

Where did arsenic come from?

WRC said reporter The results of further sampling would soon be released, but it was possible that scientists at the council would not be able to pinpoint the source.

But arsenic has long been found in the Waikato River, and much of it comes from geothermal sources.

In the case of Lake Taupō, arsenic levels at the outlet are already well above the drinking water standard.

Meanwhile, the upper reaches of the Waikato River around Wairakei and Ohaaki are receiving some of the arsenic discharged from geothermal energy companies.

Another potential source may be arsenic accumulated in sediments in hydro lakes along the Waikato River.

Massey University environmental chemist Dr Nick Kim said such fluctuations had been observed for a long time.

“There is no danger of it becoming acutely toxic: this is about long-term averages, not spikes.”

What can you do if you don’t want arsenic in your water?

Arsenic cannot be removed from water by boiling; It actually increases concentrations.

Rainger says the levels are low enough to not need to be removed at home.

But if you draw water from your own well, it’s a good idea to install purification filters and have them tested to make sure arsenic levels are within safe limits.

The cost of obtaining a sample is usually less than $100.

Jamie Morton specializes in science and environmental reporting. he joined reporter In 2011, he writes about everything from conservation and climate change to natural hazards and new technology.

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