Study of hormones in Bay of Plenty sewage

An analysis of the Bay of Plenty’s municipal sewage has shown that human hormones are not likely to be present in large enough numbers to alter the genetic make-up of creatures living nearby.

Environment Bay of Plenty commissioned the ground-breaking research to check the levels of natural and synthetic hormones – the latter mostly from birth control pills – in the region’s sewage. In certain concentrations, these hormones can cause reproductive and developmental abnormalities in humans and animals.

Ian Noble, chairman of the council’s regulation and monitoring committee, says the results should reassure the community. They show that hormones are unlikely to be causing any problems, he says.

Research laboratory AgriQuality had to develop a method specifically for the analysis because so little research has been carried out on the subject in New Zealand. “Because it was so new, we didn’t know what we’d find,” Mr Noble says.

But New Zealand is not alone in being confronted with these questions. “Other countries have also identified considerable research gaps that need to be filled.” The chemical industry, including Tasman pulp and paper mill, has also carried out research programmes over the last five years.

For the study, AgriQuality tested four Bay of Plenty sewage treatment plants, in Tauranga, Mount Maunganui, Te Puke and Whakatane, for four different types of male and female sex hormones.

When compared to overseas research, it found that hormone levels are “in the common range”, says Environment Bay of Plenty manager environmental investigations, John McIntosh. Each plant produced a similar result. None of the results was at the high end of the overseas studies.

One hormone, called estrone, was at a borderline concentration “where it could just possibly have effects on fish”, he says. However, once the treated sewage was discharged into the environment, the hormones would immediately dilute down to far below that level.

The results also revealed larger quantities of naturally excreted hormones than of the synthetic hormones from birth control pills.

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