What you Don’t Know Can Hurt You: Taking the Precautionary Approach to Microplastics and Nanoplastics

Anastasia Telesetsky
Living in the Plastocene
8 min readFeb 26, 2021


by Anastasia Telesetsky, Susanne M. Brander, and Scott Coffin

Microplastics permeate the world. Putting on a freshly-washed fleece jacket and driving to the corner store, you are an unwitting “emitter” as your fleece and tires shed plastic into the environment. Researchers calculate that indoor air has even more microplastics than outdoor air, with most of it in the form of plastic fibers. When you pick up a bottle of soda and a packet of chips for a snack at said corner store, you unwittingly are releasing and potentially ingesting or inhaling staggering amounts of microplastic ranging from 14–2,000 particles when you open the bottle and 14,000–75,000 particles when you open the chip bag. These plastics enter the environment and the surrounding air. An as yet-be-calculated amount also enters you. Is this cause for concern? Probably, but we don’t know. Given our knowledge of hazards but our insufficient data on risk, it is time for government decision-makers to take a precautionary approach, especially considering that microplastics are “forever” particles.

What We Know and Don’t Know About Microplastics and Nanoplastics

Microplastics, which are typically defined as solid polymeric particles smaller than 5 millimeters, often occur from plastic degrading, but may also be formed intentionally as either pre-production pellets or additives in products.

With over 168 studies and 6,000 measurements, toxicologists have exhaustively documented that microplastics impact freshwater and marine ecosystems, and are rapidly documenting impacts for terrestrial ecosystems. Ingestion of plastic occurs across food webs and affects swimming distance and speed and other types of movement important for survival in larval fish. Microplastics may be difficult or impossible to egest, accumulating in guts and preventing nutrient uptake from food, resulting in reduced growth and mortality. Increasing concentrations of microplastics impact respiration and immune responses. Microplastic debris also stress corals by depriving the organisms of light and may allow for pathogens to get an unhealthy foothold.

But what about humans? Microplastics are in the aquatic and terrestrial food chain but there is not enough information about the implication of consuming these microplastics on seafood or agricultural safety. Furthermore, research suggests that most of the microplastics we encounter and internalize are inhaled rather than eaten. Chronic inhalation of high quantities of microplastics (such as in occupational settings) is associated with lung cancer, however it is unknown how lower exposures affect health. Plastics have become part of us, giving new meaning to the saying “You are what you eat.” In humans, it appears that exposure to plastic begins before birth and continues into the early weeks of life, with polymers now documented in placenta tissue . Thousands of microplastic fragments are estimated to be shed daily from polypropylene baby bottles.

Microplastics eventually become nanoplastics and we have even less information about the potential impacts of these pieces of debris that are far too small to be seen with a standard microscope. But just because they are too small to notice doesn’t mean they are harmless. In fact, recent research indicates that at a molecular level, microplastic and nanoplastic exposure can lead to certain genes responsible for inflammation and oxidative stress to be more active, causing damage to cells and potentially tissues too.

The challenge for creating meaningful policy in this area is that scientists do not fully understand the extent of the risk of continued exposure via ingestion and inhalation of microplastics. A critical roadblock to determining risk has been analytically characterizing the most hazardous microplastic particles in the environment, which are smaller than 20 microns. If researchers are right that only 0.1% of microplastics ingested through foods are likely to reach human organs or pass through the blood-brain barrier because most microplastics are larger than 20 microns and would be excreted, should the average person really be concerned about their exposure over their lifetime?

We know there are hazards for living systems associated with microplastics and we know that there is plenty of human exposure to microplastics with children receiving daily exposures of 17 micrograms per day from PET microplastics, but what exactly are the risks? Some studies suggest more inhaled airborne particles could exacerbate asthma, chronic bronchitis and other pulmonary problems. What is the impact on our organs from plastics that are smaller than 20 microns? We don’t know and won’t know for years to come because the studies needed to determine thresholds for acceptable exposure (assuming there is a safe level of plastics) take numerous dedicated teams of knowledgeable researchers collecting data in a standardized and repeatable way. For example, it has taken decades to understand the effects caused by chemicals such as endocrine disruptors (e.g. polybrominated diphenyl ethers PBDE), which mimic or interfere with hormones. During that time, such chemicals can do considerable, irreversible harm. Between 2001 and 2016, researchers estimate that in utero exposure to PBDE substances may have been responsible for the collective loss of 162 million IQ points. Good science takes time, however we don’t need to wait to make wise decisions.

What We Can Do About Managing Microplastics and Nanoplastics

One policy approach would be denial based on asserting that what we don’t know will not hurt us yet. This approach seems unwise in terms of data emerging about potential serious respiratory impacts of polystyrene microplastics. Such a strategy proved perilous for other toxic substances such as PFAS, which causes between €52–84 billion in health-care costs annually for European Union nations alone.

The pervasiveness of microplastics and nanoplastics presents a wicked problem that seems to defy regulation. How can one create a policy capable of responding to the scale of the issue? Governments can start by applying a precautionary approach in designing policies. While governments have inadequate information about long-term risks, governments in applying the precautionary principle should take proactive steps to limit production of new sources of microplastics that may have cumulative impacts on human wellbeing and ecological health when added to the existing mass of microplastics.

Lacking incontrovertible evidence regarding health effects of microplastics, the State of California decided to push the science forward instead of waiting for industry to take action. In 2018, California adopted Section 116376 of the Health and Safety Code mandating the State Water Resources Control Board (SWRCB) to advance the state of science of microplastics in drinking water. The SWRCB is responsible for defining potential plastic contaminants, adopting a methodology to test drinking water for microplastics, testing for at least 4 years for the presence of microplastics in drinking water, and then evaluating the human health effects to determine if there are safe levels.

Law has never been a fully satisfactory tool when dealing with dispersed, non-point source pollutants like carbon dioxide or mercury, but it is one of a limited number of social tools we have for changing systems. From a legal perspective there are two subjects for regulation: intentional microplastics such as microbeads added to products such as cosmetics and paints, and unintentional microplastics such as fibers from a fleece jacket or your child’s bottle.

Law offers two options for action. Governments can regulate products upstream during production or consumption or downstream during disposal. In terms of actual microplastic regulation, the majority of countries regulating microplastics have focused on banning the introduction of intentional microplastics, particularly microbeads in the cosmetic industry (see e.g. United States’ Microbead-Free Waters Act, Canada’s Microbeads in Toiletries Regulations, England’s Environmental Protection (Microbeads) Regulations 2017, Ireland’s Microbeads (Prohibition) Act). As of fall 2020, ten countries (Canada, China, England, France, India, Italy, New Zealand, Thailand, Sweden, and the U.S.) have some form of ban on microbeads in particular products. In response to the European Chemical Agencies’ 2019 declaration that there was no known safe threshold level for discharges of intentional microplastics (), the European Union has proposed a ban that will go into effect in 2022 but like other efforts also limited in what products it would cover. This precautionary approach to the discharge of microplastics was also recently adopted by the San Francisco Bay Regional Monitoring Program in a precedent-setting decision.

Intentionally introduced microplastics are, however, only a small part of a much larger plastic production challenge. Plastic production in a business-as-usual growth model is expected to increase exponentially, with the United States generating the most plastic waste in the world and the third most plastic pollution. As in so many sectors of American life, we need systemic change; ultimately, this is the cheapest, and most effective solution to reducing plastic waste. Instead of hiding waste plastics through downcycling of items like plastic bottles into roads or fleeces in hopes of catching up with the production of new plastics flooding into the market, governments need to invest in regulations designed to create conditions for a circular economy.

Circular Economy: Photo Credit- https://www.government.nl/topics/circular-economy/from-a-linear-to-a-circular-economy

At a very minimum, these circular economy regulations would eliminate existing subsidies for fossil fuel production and redeploy these subsidies to enhance public research to commercialize technologies that will not create hazardous exposures to humans and ecosystems. The global oil industry and its products are subsidized somewhere between $4.9 trillion and $5.3 trillion a year so redistributing some of this money to other industries would offer new economic opportunities. Such an approach would not only reduce plastic pollution but would help to reduce our global carbon budget, ultimately reducing the impact on climate as well.

Due to the global nature of the plastic issue as evidenced in waste plastics contaminating villages across Southeast Asia, a circular economy model would be most effective if adopted internationally and universally, with fees placed at the initial stages of production (i.e. raw fossil-fuel derived plastic resin)- thereby increasing the value embedded within any used plastic and improving the likelihood of reuse. Is this possible? Maybe, but States will need political will to remain committed to drafting, adopting and ratifying a Global Plastics Treaty. Industry is understandably not enthusiastic about any shift because the largest plastic producers do not have an alternative vision for a substitute to the single-use plastics economy that has produced a legacy of macro and microplastic waste.

Perhaps more ambitiously, circular economy regulations could shift the burden of health and safety studies so that entities wishing to continue production of fossil-fuel derived plastic feedstocks would need to carry the burden of proving that their polymers and additives do not pose long-term risks when subject to different environmental conditions. Right now the burden sits squarely on the consumer awash in his or her sea of plastic goods.

Through informing legislators, the public will need to decide for itself how to weigh short-term consumer convenience against long-term impacts that have yet to be fully understood. Truly applying the precautionary approach would urge action beyond existing microbead bans — the very tippy top of the plastic iceberg. Local attempts at introducing circularity in the United States have not fared well. In California, legislators in 2019–2020 proposed the California Circular Economy and Plastic Pollution Reduction Act (SB-54 and AB-1080) to reduce single-use packaging, utensils, and other foodwares by 75% and ensure that new packaging for any products sold in California by 2032 would be reusable, recyclable, or compostable by 2032. The bills were subject to intensive lobbying from the plastic industry and failed to gain sufficient votes to pass. New bills have been introduced in the current legislative system to focus on producer responsibility. (e.g. SB-38 and SB-54 2020–2021) Sustainably achieving a global circular economy will depend on participation from California as the fifth largest economy in the world and the largest state economy in the United States. Future attempts to introduce a basic circular economy in the state may fare better but, as with so many Anthropocene environmental challenges, critical time for implementing environmentally sound and economically viable policies may have already been lost.