Trout from Lake Opuha is safe for eating, Environment Canterbury says.





Trout from Lake Opuha is safe for eating, Environment Canterbury (ECan) says.

The regional authority on Friday released test results it said indicated "even a frequent eater of trout" would be safe from DDT levels in the fish.

The South Canterbury Anglers Club raised concerns in October that DDT levels in fish in the lake were unknown.

An ECan spokesperson said in a statement trout flesh DDT concentrations were within health guidelines for frequent consumption.

READ MORE:

*South Canterbury Anglers Club raises fresh Opuha DDT claims

* Renewed allegations of contamination in Opihi catchment

Although the spokesperson said DDT levels in trout liver samples were higher, they could be eaten "in moderation".

DDT levels from fish flesh sampled in 2015 were lower than specimens taken for an earlier study in 2011, the spokesperson said.

The 2011 study examined all internal trout organs, but only the trouts' livers were tested in the latest round of tests.

ECan also released final results from an inter-laboratory study of DDT levels in Lake Opuha's sediment.

The Opihi Catchment Environment Protection Society (OCEPS) had publicly presented test results in July suggesting elevated levels of the banned pesticide DDT in the lake's sediment.

The group had suggested a hidden dump of toxic chemicals lay beneath the lakebed.

ECan also released University of Canterbury environmental chemist Dr Sally Gaw's independent comment on sediment test results produced by four laboratories, taken under a joint sampling protocol with OCEPS.

The commentary covered test results from Hill Laboratories in New Zealand, state-owned enterprise AsureQuality's laboratories, Australian laboratory ALS and South Canterbury chemist Dr Nick Wall.

Gaw said the results Wall produced "are considered to be anomalous and have not been considered further".

"For eight of the 14 samples, the results from the Wall laboratory are two to three orders of magnitude higher than those of the other laboratories."

Gaw's commentary stated the lakebed samples showed "no obvious concentration gradient", and suggested concentrations of DDT in the lakebed were more "consistent with the site of the dam being constructed over farmland that had been previously treated with DDT" than a "point source", such as the chemical dump OCEPS had claimed existed.

Community and Public Health South Canterbury medical officer of health Dr Daniel Williams said the results were reassuring.

Gaw's recommendations included further sediment sampling if the lakebed was exposed again.

ECan released the results on behalf of a group including OCEPS, dam company Opuha Water Ltd, Te Runanga o Arowhenua, Fish & Game, Timaru District Council and Community and Public Health.

What is DDT?

Dichlorodiphenyltrichloroethane (DDT) is an organochlorine pesticide and Persistent Organic Pollutant (POP).

The weight of evidence concerning human impacts indicates an association between high levels of exposure to POPs over a long time and birth defects, fertility problems, greater susceptibility to disease, diminished intelligence, and some types of cancers.

Their use in New Zealand was phased out in the 1960s and 1970s.

Source: Ministry for the Environment