Chemical contaminants in the environment
Did you know there are over 30,000 chemicals approved for use across Aotearoa New Zealand?
Who approves and regulates the use of these chemicals? How do we know what happens to these chemicals when they get into the environment? Are our regulations sufficient to stop contamination of waterways, land and oceans?
The Parliamentary Commissioner for the Environment set out to answer these questions in the report Knowing what’s out there: Regulating the environmental fate of chemicals.
The rules about how a chemical can be used shouldn’t be static – we need to be able to adapt as new information comes to light. Restrictions should be based on the latest science and informed by New Zealand-specific data on use and impact
Rt Hon Simon Upton, Parliamentary Commissioner for the Environment
Knowing what’s out there report cover
Details from the cover of the Parliamentary Commissioner for the Environment report Knowing what’s out there: Regulating the environmental fate of chemicals.
A PDF of the report can be downloaded here.
Photos on cover: Autosampler vials, Matthew Bates, Flickr; culvert drain, Megan Martin; maize field, pxhere.com.
To give a sense of how the regulatory framework works in practice, the report included four case studies of chemical substances. The case studies illustrate the way the regulatory system intervenes – or does not – to limit the impact of these chemicals on the environment. The four chemicals are:
neonicotinoids – a class of insecticide
the herbicide terbuthylazine
the metal zinc
Who decides what chemicals can be used in New Zealand and how they can be used?
Overview of national-level regulatory authorities
An overview of national-level regulators in Aotearoa New Zealand.
Four main regulators play a role in chemical management in New Zealand. The Environmental Protection Authority (EPA) is the key agency responsible for the management of any environmental risks associated with the use of hazardous substances. This means that, before a chemical can be used in New Zealand, the risks have to be assessed by the EPA. These include risks to human health and the environment. Not all chemicals get approved, and some can be banned later following a reassessment based on new evidence.
Nature of science
Science is not a fixed body of facts. Science knowledge keeps growing as we do more science and have better technology. The reassessment of chemicals in the environment can mean that once approved chemicals can be heavily regulated or banned due to new evidence. The changing of explanations in science is a strength, not a weakness – it demonstrates how scientists and other experts build on or shift from prior ideas.
Organochlorines are an example of how regulation has changed as new evidence has come to light. The pesticide DDT was regularly used in homes and on farms, but new evidence resulted in a ban on use in the mid 1970s. Polychlorinated biphenyls, organochlorines used in electric transformers and as a plasticiser in plastic products (among other uses), were banned in 1994.
While the EPA approves the use of chemicals (as individual substances or under a group standard), other agencies have a role to play too. For example, the Ministry for Primary Industrie s (MPI) approves and registers agricultural compounds (such as pesticides and veterinary medicines), and Medsafe approves use of human medicines. From all agencies involved in the management of chemicals, the EPA is the only one looking at the potential impacts of chemicals on the environment.
If risks are identified during the assessment of a chemical, the EPA can restrict its use to limit the potential for harm. For example, once approved, some chemicals can only be used by people who have been trained how to use them. The EPA can also determine how a chemical is used by setting application rates (how much of a chemical can be used over specific time periods or areas) and buffe r zones and prescribing label statements that give clear instructions about the risks.
What are chemical contaminants?
Chemicals are not inherently bad. Many – like medicines – help society. Not all chemicals have the same properties, and once in the environment, not all have the same level of persistence, mobility, bioavailability and toxicity. Decisions to approve, regulate or ban a chemical’s use involve judgements about what level of risk is acceptable in relation to the advantages it offers and condition s for how and where it will be used.
Problems arise when chemicals enter environments where they are not usually present or in quantities above naturally occurring levels. They become contaminants when they have the potential to cause problems for living things. Organisms can be mildly or severely affected by exposure to certain chemicals, and some can die. These contaminants can be natural (such as mineral compounds or human or animal waste) or human made (such as plastics and pharmaceuticals).
Dye affects the Oruarangi Stream
The banks and water of the Oruarangi Stream were adversely affected when over 1,000 litres of methyl violet dye leaked from an industrial storage tank. Freshwater and marine life died as a result of a dye spill.
The report focuses on the impact of chemicals in receiving environments – where they are most likely to end up – such as freshwater ecosystems, coastal environments and soil.
How do chemicals get into our environment in the first place?
There are multiple ways in which chemicals enter the environment, including:
direct application onto the land such as by spraying pesticides on lawns or crops
leaching out of landfills (when they’re not properly lined), storage facilities, manufactured items or from naturally occurring sources
they can be carried in run-off from roofs and roads into stormwater drains reaching waterways after a rain event
discharge of treated sewage from wastewater treatment plants that may still contain traces of some chemicals.
What happens to chemicals in the environment?
Properties and processes that influence if and how chemicals reach the environment
This figure illustrates the physical and chemical properties that influence what happens to chemicals in the environment and the biological and ecological processes that can result in toxicity to living things.
Diagram adapted from the National Research Council, 2014.
Once a chemical is in the environment, its physical and chemical properties will influence where it ends up and whether it will have any toxic effects on organisms and ecosystems exposed to it. Based on these properties and observational work, scientists have developed tools to measure:
persistence – how long a chemical remains in the environment
mobility – how far a chemical can move from its source to, within or through a receiving environment
bioavailability – how much is likely to be available to organisms to take up
toxicity – how a chemical can harm an organism.
The persistence of a chemical in the environment will depend on how easily it degrades. Key environmental factors affecting the rate of a chemical’s degradation include exposure to:
photolysis (light)
hydrolysis (water)
biodegradation (microbial activity).
Mobility is affected by interactions with other chemicals or non-biological factors such as pH (acidity), temperature, dissolved organic matter or salinity. A chemical can be transported through different pathways, including soil, water or air, meaning living things can be exposed to chemicals through different routes.
In the environment, only a portion of the total amount of a chemical is potentially available to be absorbed or taken up by an organism. This is referred to as bioavailability.
Assessing chemical toxicity
There are a range of methods to assess the toxicity of chemicals to living things. Some are used to predict or determine both the effect and impact of chemicals on individual organisms at a cellular level, while others focus on impacts on populations and ecosystems.
Do we know what chemicals end up in the environment and where?
Monitoring of chemicals and the many related compounds in New Zealand is very patchy. Fewer than 200 chemicals – of the roughly 30,000 approved for use – are routinely monitored by national (state of the environment reporting) or regional monitoring programmes.
Report findings and recommendations to fix the identified problems
The report Knowing what’s out there: Regulating the environmental fate of chemicals makes several recommendations to help the government keep a better track of what chemicals are reaching the environment.
Nature of science
There are many questions that science and its methods cannot directly answer such as ethical, moral, aesthetic, social and metaphysical questions. Science can provide information to inform the debate, but it alone cannot provide the answers. Not all questions can be investigated in a scientific manner. When considering chemical use and impacts on the environment, many different points of view come into play. For example, in Aotearoa New Zealand, tangata whenua play a key role in looking after the environment. For Māori, tikanga, the responsibilities of kaitiakitanga and mauri will be at the forefront when they consider the environmental impacts of chemicals and contamination and future regulation or pathways.
The Commissioner recommended that the quantities of chemicals imported, manufactured, sold and used be fed back to the regulatory system so regulators know where they have been used.
We cannot monitor every single chemical in New Zealand, but we should monitor the riskiest chemicals. These should be prioritised based on their scale of use, potential harm and environmental presence. The design of any framework should involve Māori.
Once identified, actual levels of the riskiest chemicals for environmental contamination should be monitored and compared against appropriate guidelines and limits. Ideally, the results would be reported back so rules for the chemical can be adjusted if needed. This would help make sure we have New Zealand-specific data for the chemicals we’re most worried about.
Framework to target chemicals
A framework to target chemicals at the most risk of causing environmental contamination.
This image is from Knowing what’s out there: Regulating the environmental fate of chemicals report. The overview section available in te reo Māori from page 13.
The best way to prioritise which chemicals to monitor is to consider those that are present in the environment at a large scale and are known to be harmful to the environment and human beings.
Related content
The environmental fate of chemicals – a context for learning uses this report and three of its case studies. The PLD article provides pedagogical information, curriculum links and inquiry questions.
Organochlorines are harmful because they do not break down easily. This means they stay in the environment and our bodies for a long time. They can be concentrated in the food chain so the animals at the top of the food chain such as humans will have the highest levels. There are 12 organochlorines listed as (persistent organic pollutants).
To build knowledge about contamination and toxicity, take a look at Soil contamination, Keeping it clean, Estuaries and farmland run-off, How harmful are microplastics? and Environmental toxicity after Rena.
Learn about Disinfecting wastewater and understand how scientists research adverse impacts on the quality of drinking water, recreational water and wastewater and the measures taken to manage them in ESR Water Management Group.
Read about how contaminated sites are cleaned up in Treatments for acid mine drainage, Cleaning up the oil spill and Restoring mauri after the Rena disaster. Understand the importance of mauri to determine environmental impacts and solutions in situations like the Rena grounding and hear Dr Kepa Morgan talk about the model he has developed to incorporate mauri into decision making.
Ahi Pepe and tikanga looks at how students and educators embedded tikanga into a citizen science project.
For solutions and actions to better protect the environment from contamination, go to Waitī – freshwater environments, Urban solutions for water quality or Managing nutrients.
Environmental issues are suited to inquiry investigations. This PLD interactive guides you through the process.
See how different schools have used action to support learning in Students help restore mauri to the Oruarangi Stream and Down the drain.
Activity ideas
In the Nutrient pollution activities, students consider point source pollution and non-point source pollution of water.
In the activity Groundwater contamination, students build an aquifer model to look at point source and non-point source pollution.
In the web quest activity Site clean-up, groups of students use the web links provided to study the clean-up of sites contaminated by hazardous waste.
Useful links
Per-fluoroalkyl and poly-fluoroalkyl compounds (PFAs) are used in many r products. However, the use of PFAs in firefighting foams has caused contamination issues. Read about these compounds and how they’re being dealt with by Fire and Emergency New Zealand.
Hear an interview with environmental toxicologist Dr Louis Tremblay. He is looking into the risk new chemicals pose on the health of ecosystems in Aotearoa.
Acknowledgement
This resource has been created from the FAQ PDF and other resources from the Parliamentary Commissioner for the Environment, with support from the office of the Parliamentary Commissioner for the Environment.
Parliamentary Commissioner for the Environment logo
The Parliamentary Commissioner for the Environment is one of three Officers of Parliament that work in an independent watchdog capacity, helping Parliament hold to account the government of the day.
