From iodized salt to sugar: How microplastics infiltrate India’s most basic food staples and why one should be concerned

However, recent research uncovered an even more alarming finding: higher concentrations of microplastics were detected in iodized salt. These microplastics appeared as multicoloured thin fibres and films.

The study tested ten varieties of commonly used salts, including table salt, rock salt, sea salt, and local raw salt, as well as five sugar samples purchased both online and from local markets. Except for two salt samples and one sugar sample, all others were branded. Of the ten salt samples tested, three were packaged iodized salts, three were rock salt samples (including two organic brands), two were sea salts, and two were local brands.

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What’s there in the salt?

Salt, an integral part of most food items, plays an essential role in maintaining various ion levels in the human body and also acts as a preservative. Additionally, salt finds applications in diverse industries, including cosmetics, personal care products, and pharmaceuticals. It is extracted from various sources, such as saline lakes, saline rocks, and saline wells.

The study found that the abundance of microplastics (pieces per kilogram of dry weight) varied across different salt samples, ranging from 6.71 to 89.15 pieces per kilogram of dry weight.

The highest concentration was found in an iodized salt sample (89.15 pieces per kilogram of dry weight), while the lowest concentration in an organic rock salt sample (6.70 pieces per kilogram of dry weight). Among the samples, packaged iodized salt brands exhibited higher contamination levels compared to the others. Overall, high concentrations of microplastics were found in iodized salt samples, whereas rock salt samples generally had lower microplastic content, with the exception of one inorganic sample.

How shape, size and colour of microplastic matters

The colour, size, and shape of microplastics are crucial in understanding their environmental and health impacts. Different colours indicate their origins, with black plastics often linked to food packaging and transparent ones to disposable bags.

Colours also reveal their degradation through photoaging, affecting aquatic life, as certain fish prefer ingesting red, green, and yellow microplastics. Size matters too; smaller microplastics (0.1-1 mm) are more easily transported and ingested, posing greater risks to both humans and animals.

The shape, such as fibres from clothing, influences how microplastics spread in air, water, and soil, highlighting their contamination potential. The primary types of microplastics identified in the three iodized salt samples were films and fibres. Fibrous forms were the predominant shape observed in tested local salt samples, accounting for 91.11 percent of all shapes among the two samples. The four types of microplastics found in the rock salt samples were fibres, pellets, films, and fragments.

In the iodized salt samples, a total of five colours were identified. White was the most common, constituting almost 38.53 percent, followed by transparent at 33.02 percent, blue at 14.67 percent, red at 8.25 percent, and black at 5.5 percent.

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The sugar story

The study revealed varying levels of microplastic contamination in different sugar samples. Among the five tested sugar samples, the highest concentration of microplastics was found in the range of 68.25 pieces per kilogram to 11.85 pieces per kilogram.

The majority of microplastics were in the 0.1-0.3 mm size range. Fibers were the predominant type of microplastic found in the sugar samples, constituting 95.65 percent of the total. This was followed by pellets and films. A total of seven colours of microplastics were identified in the sugar samples, including transparent ones.

Mr Ravi Agarwal, Founder Director, Toxics Link in a statement said, “The objective of our study was to add to the existing scientific database on microplastics so that the global plastic treaty addresses this issue in a concrete and focused manner. The aim is also to trigger policy action and attract the attention of researchers for possible technological interventions to reduce the exposure risks to microplastics.”

Where does microplastic come from? 

Researchers suggest several potential sources for microplastic contamination in iodized salt:

• Additional Processing: Iodized salt undergoes more processing steps compared to raw or unrefined salt. These additional steps often involve treating the salt with various substances, such as potassium iodide, to enrich it with iodine. During these processes, the salt may come into contact with equipment and environments that have higher levels of microplastic contamination.
• Packaging and Transportation: After iodization, salt is typically packaged in plastic materials for distribution. During packaging and transportation, the salt can pick up microplastics from these plastic containers and other handling materials made of or lined with plastic.
• Source and Refinement: The source of the salt can also impact its microplastic content. Raw salt is often minimally processed, involving basic extraction, washing, and drying. In contrast, iodized salt generally comes from sources that undergo extensive processing and refinement, which could include multiple stages where microplastic contamination might occur.
• Environmental Exposure: Throughout the processing chain, iodized salt may be exposed to environments with high concentrations of microplastics. Facilities that process and package iodized salt might not be exclusively dedicated to salt production and could handle other materials that contribute to microplastic contamination.

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Health risks from cardiovascular issues to inflation of brain 

“The study is critically significant as microplastics (MPs) are being discovered in various parts of the human body, including the lungs, blood, and digestive system,” the study said. This raises significant health concerns due to their potential toxicological impact and ability to contribute to inflammation and other health issues.

“Although the precise health effects of these small particles and their associated chemicals have yet to be fully proven, the pervasive presence of MPs underscores the urgent need for comprehensive research into their long-term health implications,” said the study.

While the exact health impacts of these tiny particles and their associated chemicals are not yet fully understood, their widespread presence highlights the urgent need for extensive research into their long-term effects. Emerging studies suggest that microplastics may increase the risk of conditions such as oxidative stress, which can cause cell damage, inflammation, and cardiovascular disease.

Animal studies have also connected microplastics to fertility issues, various cancers, disruption of the endocrine and immune systems, and impaired cognitive functions like learning and memory. In one of the most recent studies—a preprint paper still under peer review and posted online by the National Institutes of Health—researchers discovered a particularly alarming accumulation of microplastics in brain tissue samples.

An autopsy examination of livers, kidneys, and brains revealed the presence of microplastics in all these organs, with 91 of the brain samples showing significantly higher concentrations—about 10 to 20 times more than the other organs. Among 24 brain samples collected in early 2024, microplastics made up approximately 0.5 percent of the tissue’s weight on average. The study described the brain as “one of the most plastic-polluted tissues yet sampled.”

Other health risks of microplastics

• Microplastics can disrupt hormones and are associated with increased risk of chronic diseases like diabetes, obesity and heart disease.
• Chemicals added to plastics like BPA and phthalates are endocrine disruptors that mimic hormones and interfere with their normal functions.
• Sharp-edged microplastics are more likely to rupture cell walls and cause cell death.
• Microplastics have been found in human placenta, breast milk, stool, and blood, indicating they are being absorbed into the body.

Exposure levels

• An average person may consume over 50,000 microplastic particles per year from food alone.
• Exposure increases to 90,000 particles per year for those who drink bottled water regularly.
• In the US, an adult may consume 11,000 ± 29,000 microplastic particles annually, with a maximum of 3.8 million particles.

What the government said? 

The Food Safety and Standards Authority of India (FSSAI) in a statement said that while the report underscores the global prevalence of microplastics, it also emphasises the need for more robust data to fully understand the implications for human health and safety, particularly in the Indian context.

“As the food safety regulator of the country, FSSAI is committed to ensuring that Indian consumers have access to safe and healthy food. While global studies have highlighted the presence of microplastics in various foods, it is imperative to generate reliable data specific to India,” it said in a statement. In response to it, FSSAI launched a project to tackle the growing concern of microplastic contamination in food.

FSSAI said that recognising microplastic pollution as an emerging threat that requires immediate attention, the project – “Micro-and Nano-Plastics as Emerging Food Contaminants: Establishing Validated Methodologies and Understanding the Prevalence in Different Food Matrices” – was started in March this year to develop and validate analytical methods for detecting micro and nano-plastics in various food products, as well as assess their prevalence and exposure levels in India.

The primary objectives of the project include developing standard protocols for micro/nano-plastic analysis, conducting intra- and inter-laboratory comparisons, and generating critical data on microplastic exposure levels among consumers.

“This project will help understand the extent of microplastic contamination in Indian food and guide the formulation of effective regulations and safety standards to protect public health. The findings from this project will not only inform regulatory actions but also contribute to the global understanding of microplastic contamination, making Indian research an integral part of the global effort to combat this environmental challenge,” said the FSSAI in statement.

This study is being implemented in collaboration with leading research institutions across the country, including the CSIR-Indian Institute of Toxicology Research (Lucknow), ICAR-Central Institute of Fisheries Technology (Kochi), and the Birla Institute of Technology and Science (Pilani).

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Recommendations from the study

Toxic link highlights the urgent need to address microplastics (MPs) in food and their presence in the human body through coordinated actions:

• Standardisation of Testing: Establish consistent testing protocols and unified terminology for detecting MPs in food, particularly in salt, to improve comparability across studies.
• In-Depth Research: Investigate the sources of microplastic contamination, including packaging materials, and study how MPs are absorbed and accumulate in the human body.
• Risk Assessment and Regulation: Conduct comprehensive risk assessments to establish safe limits for MPs in food products and enforce strict regulatory standards.
• Industry Action: Encourage manufacturers to adopt better processing techniques, filtration methods, and alternative packaging to reduce MP contamination.
• Public Awareness: Educate consumers about the risks of MPs in food and guide them on minimising exposure by choosing products from brands with stringent microplastic management practices.

Microplastics in food, a growing concern

Apart from Salt and Sugar, microplastics have infiltrated various food items, raising significant concerns about human exposure. Here are key findings on different food products contaminated with MPs:

• Seafood: MPs have been detected in various marine organisms, including fish, shellfish, and canned seafood, across multiple regions globally. Studies have found MPs in popular brands of canned seafood and various shrimp species, with high contamination levels in freshwater fish from Thailand and canned sardines and sprats from 13 countries.
• Fruits and Vegetables: MPs have been recently discovered in fruits like apples, pears, and tomatoes, as well as vegetables such as broccoli, lettuce, carrots, and potatoes, in markets from Italy and Turkey.
• Cereals: A study from Indonesia in 2022 identified MPs, including PVC and PE, in rice, highlighting contamination in staple foods.
• Beverages: MPs have been found in beverages like beer, tea, milk, soft drinks, energy drinks, and wine. Studies from multiple countries, including Switzerland, Germany, and Italy, reported varying levels of MPs in these drinks.
• Honey: Research has shown MPs in honey from countries like Switzerland and Ecuador, with common polymers being PE, PP, and polyacrylamide.
• Meat: MPs have been detected on the surface of poultry meat, indicating potential ingestion through meat consumption.
• Drinking Water: MPs have been found in both bottled and tap water, with studies reporting contamination in India, China, Nepal, and globally. Bottled water was found to contain MPs in 93 percent of samples tested.