Tackling Microplastic Pollution Through Behavioural Nudges: A Case Study on Corner Trimming of Milk Packet
Introduction
Have you ever noticed how we open milk packets at home? A seemingly trivial activity — snipping or tearing off the corners — is so deeply ingrained in our daily routines that we seldom stop to think about its consequences. Yet, this small act carries a large environmental footprint.
In this article, we explore why this innocuous habit poses a serious threat to the environment, how it has caught the attention of policymakers, the scale of its impact, and how insights from behavioral economics can help us design more effective interventions.
In India, packaged milk is a daily staple. On average, a household consumes 3 to 4 milk packets every day. According to the MyGov platform, more than one-third of branded plastic waste generated daily from households comes from dairy product packaging. These milk packets are made from low-density polyethylene (LDPE), a form of plastic that, when improperly disposed of, exacerbates the problem of microplastic pollution.
When corners of these packets are cut or torn off, the small fragments are often too tiny to be captured in traditional recycling processes. They eventually disintegrate into microplastics — plastic particles less than 5 mm in size — that persist in the environment for centuries. A recent survey in Bengaluru revealed that nearly 5 million such fragments enter the waste stream daily, highlighting the magnitude of this seemingly minor behavior.
Recognizing the need to address this issue, the Government of India included it in its comprehensive list of 75 individual LiFE (Lifestyle for Environment) actions. Listed as Action Plan No. 44, it urges citizens to "cut the packaging bags used for milk, buttermilk, etc. only partially to avoid plastic bits from mixing into biodegradable waste." This effort is part of the broader LiFE initiative, introduced by Prime Minister Narendra Modi at COP26 in Glasgow, which calls for “mindful and deliberate consumption” over “mindless and destructive consumption.”
But what makes changing this small behavior so challenging? And how can behavioral economics provide answers?
The Hidden Dangers of Microplastics
While plastic waste is visible to the eye, microplastics—the tiny fragments often less than five millimetres in size—pose a far more insidious threat. Emerging from the breakdown of larger plastics or habits like corner trimming of milk packets, microplastics have wide-ranging impacts on human health, the environment, and the economy.
For human health, microplastics present several risks. Their abrasive texture can irritate the digestive tract, and chemicals associated with plastics may disrupt hormonal regulation, potentially affecting growth and reproduction. Inflammatory responses linked to microplastic ingestion have been associated with cardiovascular and autoimmune diseases. Although research is ongoing, there are concerns about organ damage and even increased cancer risk from long-term exposure.
Environmentally, microplastics infiltrate oceans, rivers, and agricultural land, disrupting ecosystems by harming marine life and altering habitats. Wildlife often ingest these particles, leading to malnutrition and death. Through bioaccumulation and biomagnification, microplastics concentrate toxins up the food chain, affecting both wildlife and humans. On land, they contaminate soils and clog urban drainage systems, exacerbating the risk of floods.
Economically, the impact is substantial. Coastal tourism suffers as plastic debris tarnishes beaches; fisheries are jeopardized by declining aquatic health; and governments face growing costs in cleaning up polluted environments. These hidden costs underscore that the effects of microplastic pollution ripple far beyond the immediate environment, affecting economies and communities worldwide.
Diagnosing the Behavioural Barriers
Understanding why individuals continue to engage in environmentally harmful habits, even when they are aware of the consequences, requires a close look at behavioural barriers. Several cognitive biases and heuristics explain why corner trimming of milk packets persists despite awareness campaigns and policy efforts.
The first barrier is habitual behaviour, governed by what behavioural economists call System 1 thinking. This refers to our fast, automatic mental processes that bypass deliberate thought. Over time, tearing off the corner of a milk packet has become a reflexive act—one that is rarely questioned or reconsidered. Breaking this habit requires conscious effort, which many individuals resist due to behavioural inertia and the status quo bias. People often prefer to stick with their current routines because maintaining the status quo demands less cognitive energy than changing it. In behavioural terms, individuals develop an "endowment effect" toward their habits, valuing them simply because they are familiar and effort-free.
The second major barrier is temporal discounting reinforced by present bias. Behavioural economics suggests that people often prioritize immediate rewards over long-term consequences, even when the latter are severe. Biting or trimming plastic corners might offer a small, immediate benefit: a quick opening of the milk packet or even mild sensory satisfaction akin to oral stimulation. However, the adverse environmental impacts—microplastic pollution, ecosystem damage—are distant, abstract, and therefore heavily discounted in people's mental calculus. The human tendency toward immediate gratification further entrenches the practice, as the short-term ease of access far outweighs the long-term ecological costs in people's decision-making processes.
Social norms and peer influence represent another powerful barrier. Behaviour is rarely formed in isolation; it is shaped and reinforced by what we observe around us. If individuals see others trimming packet corners casually—family members, friends, neighbours—they are more likely to imitate this behaviour. Peer pressure and the innate human desire to conform to perceived social norms make deviation seem unnecessary or even awkward. A personal example illustrates this vividly: despite trying to avoid corner trimming, one might find family members mocking the attempt, reinforcing the idea that careful behaviour is somehow excessive or unnecessary.
Anchoring also plays a significant role. Once a behaviour is established as the "normal" or "default" way of doing something, it becomes a strong mental reference point that is difficult to shift. For most people, corner trimming has always been the way to open milk packets—it is deeply anchored in their consumer experience. As one participant in our discussion remarked, "I never even thought about it until you mentioned it," highlighting how anchoring can make alternative behaviours seem unnatural or unnecessary.
Lack of awareness compounds these behavioural biases. Many consumers are simply unaware of the environmental risks associated with microplastics, or the role that small plastic fragments from milk packets play in exacerbating the problem. This ignorance leads to riskier behaviours because the perceived threat is low or nonexistent. Furthermore, overconfidence bias can exacerbate the issue: some individuals mistakenly believe they already know enough about plastic waste, or assume that the environmental impact of their single action is negligible. Combined with low risk perception, where dangers are downplayed because no immediate harm is visible, these cognitive distortions significantly lower the motivation to adopt more sustainable behaviours.
Finally, loss aversion—one of the cornerstones of behavioural economics—plays a subtle but influential role. People tend to perceive the act of giving up convenience or familiar routines as a "loss," and losses loom larger than equivalent gains in human psychology. Giving up the quick tear or bite of a packet corner feels like losing ease, time, and effort. Rather than framing careful cutting as a gain for the environment, the mind frames it as a personal inconvenience, further reducing willingness to change.
Together, these behavioural barriers—habitual inertia, present bias, social norms, anchoring, lack of awareness, and loss aversion—paint a clear picture of why a seemingly minor action persists, even when the stakes are so high. Understanding these barriers is the first step toward designing interventions that not only inform but also reshape consumer behaviour at scale.
Designing Behavioural Solutions
Once the behavioural barriers have been diagnosed, the next step is to design interventions that address these barriers systematically. Here are six key behavioural solutions tailored to the problem of milk packet corner trimming:
One of the most powerful interventions is to make the desired behaviour the default option. Milk packets can be redesigned with perforated lines, allowing consumers to open the packets partially and easily without needing to cut or bite off corners. By embedding perforations, the act of partially cutting becomes automatic, aligning with the psychological concept of default bias—where people are more likely to stick with pre-set options that require minimal effort. Additionally, this approach taps into anchoring, by setting partial cutting as the "standard" or "normal" way of opening milk packets, making consumers less likely to deviate.
Another strategy involves using negative reinforcement to deter harmful behaviour. Manufacturers could coat the edges or corners of milk packets with scented or foul-tasting deterrents. If consumers attempt to bite into the plastic, they would encounter an unpleasant experience, creating an aversion to the behaviour over time. This technique leverages negative reinforcement principles, where the removal of an unpleasant outcome (i.e., avoiding the foul taste) motivates behavioural change. Over time, consumers would instinctively avoid biting or tearing packet corners altogether.
Visual cues and emotional framing can also play a crucial role in behaviour change. By placing impactful imagery—such as pictures of marine life like turtles entangled in plastic—on milk packets, manufacturers can evoke strong emotional responses. Accompanying the visuals with phrases like "Thank you for saving one life today" taps into the principle of reciprocity, making consumers feel appreciated for taking environmentally responsible actions. Emotional appeals like these build a personal connection to the larger environmental cause, bridging the psychological distance that often weakens motivation for sustainable behaviour.
Influencing social norms is equally critical to shifting entrenched habits. Public campaigns can share statistics showing how many people in a given community have adopted partial cutting, creating a sense of collective action. Launching a social movement, such as the hashtag campaign #cutmilkpacketproperly, could further build momentum, making the responsible behaviour appear not only common but expected. Using descriptive norms—the idea that "most people like you are doing this"—is a proven behavioural lever to encourage conformity and promote widespread adoption.
Additionally, positive reinforcement strategies can be deployed to reward desired behaviours. A Milk Packet Recycling Rewards program could be introduced, offering points, discounts, or small incentives for consumers who return intact milk packets for recycling. By partnering with delivery services or NGOs, collection could be made convenient and accessible. Furthermore, adding positive labelling—for instance, attaching special coupon codes labelled as "Responsible Consumer" to intact returns—can strengthen people's self-identity as environmentally conscious individuals, increasing the likelihood of consistent long-term behaviour.
Finally, choice architecture can be redesigned at the manufacturing stage itself by innovating with biodegradable or edible opening tabs. These specially designed tabs would eliminate the need for consumers to cut or bite the packets altogether. Factories could pre-cut these tabs to make opening easier and safer, thereby making partial cutting the effortless default. This solution not only leverages prospect theory (where individuals prefer choices framed as low-risk and beneficial) but also aligns with default bias and anchoring, creating a strong foundation for new behavioural norms to take root.
Together, these behavioural interventions—spanning defaults, deterrents, emotional framing, social norm activation, positive reinforcement, and choice architecture—provide a comprehensive roadmap for addressing the microplastics problem linked to milk packet consumption. When systematically applied, they can shift daily habits at scale, creating a cleaner environment and a healthier future for all.
Conclusion: Small Changes, Big Impact
Microplastic pollution is one of the gravest, yet most overlooked environmental challenges of our time. What makes it even more insidious is that much of it originates from everyday behaviors that seem inconsequential — like cutting the corners off a milk packet.
By diagnosing the behavioral barriers — habitual behavior, temporal discounting, social norms, anchoring, and lack of awareness — we can design interventions that nudge individuals towards better choices. Public awareness campaigns, changing default packaging designs, introducing clear warning labels, and leveraging positive social norms are just some of the tools that can drive change.
The fight against plastic pollution doesn't always require grand gestures. Sometimes, it begins with the smallest actions — and the smallest pieces of plastic.
