Mapping New Zealand’s chemical romance

New Zealand relies on chemicals for agriculture, horticulture, and industry but mystery surrounds the volume, where they are used, and the extent of land contaminated by them.

The Environmental Protection Agency (EPA) chief executive, Dr Allan Freeth, wants to create a chemical map of New Zealand to capture usage of hazardous substances in order to manage them more effectively and protect the environment.

“I have to be honest and say we really don't know what's out there.”

Freeth said keeping track of more than 150,000 substances administered by the EPA is difficult. The agency knows what types of substances come into the country, but doesn't gather data on volumes used. He believes visually mapping their use could provide a snapshot of the country’s chemical landscape.

“We can look at geographical distribution across New Zealand and we can see effectively what volumes are being used and correlate those to toxicity and hazard classifications and we can start wrapping those around waterways, we can map them around farm land or whatever.”

A visual guide of the substances the EPA are most concerned about could aid in their management and make decision-making easier.

“I'm a sort of picture conceptual person. I would sit down, and start reading stuff and say, ‘Well show me what that picture looks like’. That picture helps to communicate.

“What we want to do as we develop these models - and it's probably more likely to be a chemical atlas by the time we've finished - is to be able to go out to industry, politicians and communities and say this is what New Zealand looks like for the 30 top pesticides. This is what it looks like for the top chemical cleaners.”

Freeth expects the final output of the two-year mapping project will be a mix of geographic maps and diagrams illustrating chemical usage and toxicity. He estimates the project will cost between $200,000 and $1 million.

Chemicals will be mapped in order of risk. The EPA has a list of 300 chemicals which cause concern globally, 30 of which they consider high-risk. Among them are the herbicides paraquat and mecoprop and the pesticide chlopyrifos.

"A lot of this stuff is highly emotional. It’s very easy to retreat into your shell and think this is really bad and even the suggested presence of these chemicals should be banned or outlawed."

The usage picture given by a chemical map may prompt high-risk chemicals to be reassessed. This could lead to a ban or additional controls placed on their use.

Freeth said Australia, Canada, the United States and the European Union have chemical reassessment programmes underway but “at the moment we all feel like we are facing Mount Everest”.

He estimated Canada is spending $200 to $300 million on reassessments. New Zealand’s EPA has a reassessment budget of $1 to $2 million.

Getting the data

The biggest challenge to completing the chemical map is getting the data. Freeth said the EPA will survey industry associations such as Horticulture New Zealand and Federated Farmers as well as going into the field to find out what is being used.

Territorial Authorities include information on property information reports about past and current land use. The Hazardous Activities and Industries List (HAIL) identifies the activities and industries considered likely to cause land contamination.

Almost 20,000 sites nationwide were identified as HAIL land, but regional councils told the Ministry for the Environment they estimate the real number could be three times higher.

The Ministry for the Environment’s land report, released last week, points out currently there is no integrated dataset showing the extent of contaminated land, saying there are significant gaps in knowledge.

Massey University soil chemist Professor Chris Anderson said there is a challenge to understanding where chemicals have been used and where they are stored.

“There’s not a lot of it [data] around. It’s a mess and half of the data you can find as far as stock piles are concerned, you’ve got to question the validity of it half the time. We’ve got massive legacy issues. We’ve still got piles of aldrin and dieldren and DDT and stuff sitting in sheds in all parts of the country.”

As well as the issue of old chemicals being stored Anderson said understanding past land use was an important part of assessing whether soil could be contaminated.

Some chemicals which normally break down in soil when used in isolation don’t break down the same way when other substances are present.

“If you go to an old orchard site and you’ve got a legacy of copper or arsenic, or an old sheep dip site you’ve got arsenic, that is a fundamental element, you can’t do anything with it, you can’t break it down.

“There’s what’s called a co-contaminant effect, especially where you interact things like DDT. What happens is the copper or the arsenic will actually prevent the growth of micro-organisms, so you don’t get the degradation of the organochlorine you would expect.”

DDT (Dichlorodiphenyltrichloroethane) was banned in New Zealand in 1989. Residue can make its way into the human food chain through meat and milk from animals that graze on contaminated land.

Illustrating conversations

Anderson said it can be hard to have rational conversations about chemical use and a chemical map could help.

“We do struggle. A lot of this stuff is highly emotional. It’s very easy to retreat into your shell and think this is really bad and even the suggested presence of these chemicals should be banned or outlawed.”

He said sharing visuals or videos on Twitter, Facebook or YouTube can help reach people.

“That’s what people engage with now, so coming up with clever visuals that present and bring to life some of these stories is really crucial.”

Freeth feels the same way which is why he suggested the project to the EPA.

“People get a picture really quickly right? If you have to sit down and go through a scientific paper or analysis of how many litres of glyphosate or paraquat and it's toxicity and where it's used, your mind starts to cloud over.”

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