The environmental fate of chemicals – a context for learning

There are over 150,000 substances approved for use in Aotearoa New Zealand that contain an estimated 30,000 chemicals.

We use chemicals on a daily basis – they’re all around us. Chemicals are not inherently bad. Many – like medicines or fertilisers – provide some benefit to society. When chemicals are used in the way that they are approved for and the approval process has taken into account their likely environmental fate, the chemicals we find in the environment should be at acceptable levels. Questions arise when chemicals migrate from the intended application to the environment.

When chemicals enter environments where they are not usually present or in quantities above naturally occurring levels, they can cause problems for living things. The article Chemical contamination in the environment summarises the Parliamentary Commissioner for the Environment report, which questions the adequacy of the information on which we base important environmental decisions.

Many natural systems and problems are complex. Complexity concepts and dynamics have not been part of a traditional science curriculum but should be considered as an important new element, given the complex nature of many urgent issues that face us.

Enduring competencies for designing science learning pathways, NZCER 2022

Exploring socio-scientific issues and the nature of science

The use, impacts and fate (end point) of chemicals in the environment is a socio-scientific issue. Addressing socio-scientific issues in the classroom can provide a context for developing understanding of science knowledge, scientific processes and the nature of science. It also shows how science is socially and culturally embedded as it highlights the intricate relations between science, technology and society – including the cultural, social, economic, political, ethical and environmental implications.

Socio-scientific issues are complex and require scaffolding to be an effective learning tool in the classroom. Often an inquiry-based approach is utilised when exploring socio-scientific issues. For complex issues such as the environmental fate of chemicals, the teacher may not necessarily be an expert but will be a facilitator of the process of inquiry. Providing the opportunities to elicit students’ prior knowledge about the issue will often uncover misconceptions as well as different levels of knowledge and students’ beliefs and values in relation to the issue. By engaging in an inquiry process, the students can develop new understandings, often raising further questions driven by their own learning journeys and curiosity – much like practising scientists. Inquiries can also be scaffolded to support ākonga to identify, articulate and justify their own views about complex issues.

In any issue, ākonga need to sort out what parts of the issue require a scientific lens and what parts require other lenses.

For example, when exploring an issue, ākonga need to identify and understand:

• what scientific knowledge is relevant
• how reliable the knowledge is
• how the knowledge was gathered
• the limits of the knowledge
• how much confidence we can have in that knowledge
• te ao Māori perspectives, including relevant local mātauranga Māori
• additional cultural, social and ethical considerations – local, national and/or global.

The Hub has articles on three case studies featured in the report Knowing what’s out there: Regulating the environmental fate of chemicals:

• Zinc – used in industrial, household, human and animal health products.
• Tetracycline antibiotics – in New Zealand they are mainly used to treat farm and companion animals.
• Neonicotinoid insecticides – used on food crops and for household uses.

These articles provide information on why and how we use the various products in Aotearoa, their chemical structures, pathways into the environment and key concerns and impacts.

Science concepts, mātauranga Māori and curriculum links

Science and mātauranga Māori concepts that underpin each of the case studies include:

• ecosystem interactions and potential impacts on non-target organisms
• properties and processes that affect chemical transport, including solubility and adsorption
• persistence, degradation or transformation of chemicals released in the environment
• cellular resistance mechanisms
• what constitutes a toxin and a toxic dose
• people are an interconnected part of an ecosystem
• acknowledging relationships between all living organisms impacts the practices of being ethical and responsible.

The case studies support science learning primarily in the Material World strand:

• Structure of matter: chemical processes; structure and bonding.
• Chemistry and society: groups of substances and how they are used; meeting needs, resolving (or creating) issues and development of new technologies.

They also support learning about Earth systems and interacting systems in the Planet Earth and Beyond strand and learning about human actions on ecosystems in the Living World strand.

When young people are confronted with real-life events, opportunities, and challenges, or issues of concern and interest to them, they know how and when to draw on their science knowledge and skills, or their mātauranga Māori knowledge and skills, to act in the world. They are prepared to act responsibly and ethically on these issues with an awareness of the interconnectedness of things and events in both the natural and social world.

Enduring competencies for designing science learning pathways, NZCER 2022

The environmental fate of chemicals – questions to consider

Simon Upton, Parliamentary Commissioner for the Environment, writes, “We need to ask the right questions about the things that matter.” Questions can help guide an inquiry approach to learning about chemicals we use, their fate, regulations about their use and why this matters.

• Zinc is a naturally occurring chemical – how does it become an environmental issue?
• Neonicotinoids were developed to reduce harm to non-target vertebrates – why is there growing concern about their use?
• Do the advantages of antibiotics outweigh what appear to be low to medium environmental risks?
• What are some physicochemical properties that influence what happens to chemicals in the environment?
• What are some soil/water processes that influence what happens to chemicals in the environment?
• What causes a substance that is beneficial in one setting to become a toxin in another setting?
• What are the unintended consequences of useing substances such as insecticides or antibiotics?
• Should we have national guidelines or guidelines for smaller, more localised areas?
• Are there ethical considerations to examine?
• What are the rights and responsibilities of those who use and/or regulate the use of a particular chemical substance? Who decides on these rights?
• Do the benefits of using a chemical product outweigh the potential harm? What are the alternatives?
• Are international guidelines adequate for protecting endemic taonga species?