Unbeknownst to many, microplastics do not originate solely in the ocean. In fact, most microplastic accumulation primarily occurs on land and then moves to the waterways. Oceans have been polluted between 83,000 to 236,000 tons of microplastics yearly. Agricultural soils of all kinds, including agricultural soils, have 107,000 to 730,000 tons of microplastics dumped into the soil each year through processed sewage, mulches, slow-release fertilizers, and even seed coatings.¹

During the last few years, there have been ongoing discussions about what defines a microplastic. Microplastics are plastic particles ranging in size from 5 mm to 1 nm. Primary microplastics are intentionally manufactured in smaller sizes for use in consumer cosmetics and biomedical products. Secondary microplastics are plastic waste particles that break down from larger plastic materials. Secondary microplastics brought about by degradation of larger discarded plastics are the subject of this article.

Only 1% of total microplastics are due to seed coatings.² However, with a rather forceful kick from the European Chemicals Agency (ECHA), seed manufacturers are being required to eliminate microplastics that are generated due to seed coatings by October 2028. The rest of the world is not far behind. In fact, France has pulled implementation ahead to January 1, 2027. California has already proposed legislation that would eliminate 75% of plastic waste by 2030. While this does not yet affect seed coatings, history suggests that a broader set of regulations will germinate from this legislation.

Certain seed coatings are exempt from the October 2028 regulation:³
• Liquids: Must not form films upon drying.
• Natural origin coatings: No chemical modifications allowed. Even the simplest chemical modification might cause eventual microplastic formation. Commercially used natural polymers can contain additives, processing aids, or impurities that could hinder biodegradation or contribute to microplastic pollution.
• Water soluble coatings: Must have a solubility of ≤ 2 g/l.
• Biodegradable: Not to be confused with compostable materials.
• Coatings with no carbon atoms in the molecular chain structure

Manufacturers have embraced the challenge of eliminating microplastics from seed coatings. Even though seed coatings are 1% of the problem, producers across the globe are determined to become ZERO percent contributors to microplastic pollution.

The first step has been to make the microplastic coating fragments that detach from seeds as biodegradable as possible. Degradation rates vary, and no standard has yet been set. The lowest degradation rate so far is ≤ 48 days obtained from some commercially available polymeric coating mixtures. Biodegradable plastic formulations degraded completely in 32 days. Coatings selectively doped with certain plant growth promoting bacterium (Bacillus subtilis) degraded in ≤24 days.⁴ A good start, but still not enough.

A Seed Coating Primer

The first question in eliminating a problem material is to determine whether the material is really needed. Seed coatings are critically important for:
• Promoting germination and robust growth
• Providing resistance to pests and fungal infections
• Improving drought tolerance through osmopriming⁵ (for germination in low-moisture soils)
• Facilitating mechanical planting
• Increasing overall yield

While there are significant advantages for coated seeds (higher germination percentage, healthier roots and shoots as well as stronger established plants), there are also disadvantages (limited shelf life of treated seed, pesticide breakdown, incomplete crop protection, and surplus cannot be repurposed for grain). However, when weighing the risks, the ability to feed the world trumps any disadvantage. Eliminating seed coatings is not practical, so improvements to guard against microplastic formation and pollution must be the conclusion.

There are three basic methods of seed protection: film coating, encrustation, and seed pelleting.⁶

Film coating involves applying thin layers of coating solution (a total of less than 10% seed weight) onto the seed surface (Figure 1). For precise control over thickness and composition, a rotating drum or fluidized bed apparatus is used. Film coating allows the seed to maintain the original size and shape. In addition to resistance to environmental stressors, these seeds are well suited for mechanical planting and precision field applications.

FIGURE 1. Schematic of various protective film coating layers applied to seeds.⁷

Seed encrusting forms a protective matrix around seeds that is 100–500% seed weight. This allows for targeted delivery and sustained release of active ingredients throughout germination and early growth for pest and disease resistance, even in adverse soil conditions. A film is not formed. Many organic farmers take advantage of seeds treated with this technique.

Pelleting agglomerates seeds into uniform spherical pellets by coating them with a mixture of binding agents and additives that is >500% seed weight. This technique is especially good for small seed crops and precision planting. The enhanced seed-to-soil contact leads to good moisture retention, better germination rates, and uniform stand establishment.

Commercial Seed Film Coating Materials

Traditional seed film coatings are manufactured from polyethylene glycol (PEG), polyvinyl alcohol (PVOH) or chitosan (a glucosamine polymer).

Polyethylene Glycol is effective for improving seed germination and seedling establishment of sorghum under adverse moisture conditions. Osmopriming strengthens the antioxidant system further by increasing the osmotic adjustment of the seed resulting in increased stress tolerance.⁸

Lignan-modified PEG has a high molecular weight, takes a little longer to dissolve, and is less easily converted into water. The high-viscosity solutions do not transport oxygen, leading to no absorption by the seed, eliminating genetic or physical damage. Coating with 5-lignin PEG improved the germination percentage of maize seeds from 86.6% to 93.3%.⁹

Polyvinyl alcohol seed film coatings are extremely useful because water solubility and mechanical strength can be controlled. These coatings are used as a binder for adhering layers to the seed surface. Seed physical properties are improved and the delivery of active ingredients can be controlled. PVOH coatings decrease dusting and improve germination.¹⁰

Chitosan is one of the truly natural seed treatments and growth enhancers. This glucosamine polymer is developed from a sugar that comes from the outer skeleton of shellfish like crab, lobster, and shrimp. The material bonds to seeds via hydrophobic or cation-π interaction. Chitosan is a cationic source in an aqueous solution. Free amine groups form crosslinked polymer networks with dicarboxylic acids to improve mechanical properties.¹¹

Unlike other polymeric materials used for film seed coatings, Chitosan influences the biochemistry and molecular biology of the plant cell. The targeted plasma membrane and nuclear chromatin causes changes in cell membranes, chromatin, DNA, calcium, MAP kinase, oxidative burst, reactive oxygen species, cellulose pathogenesis-related genes, and phytoalexins. It is an ecofriendly biopesticide that boosts the innate ability of plants to fight fungal infections.¹² In addition, it allows for an innate immunity response in developing roots that destroys parasitic cyst nematodes without harming beneficial nematodes and organisms.

The Future

Sometimes the additives used in current seed coating formulations can lead to microplastic free products. Acting as rheology modifiers, film formers, and stabilizers, these biodegradable materials help to create porous films and coatings, enabling early seed germination.

One example is a microfibrillated cellulose viscous material that under high shear can be sprayed onto seeds. Under high shear, the fibrils break apart, lowering viscosity and allowing for consistent coating. After application, when high-shear conditions are removed, the fibrils reconnect forming solid films while still allowing for complete drying of the coating. These additives assist with germination, reducing or eliminating seed dusting and enabling longer shelf-life stability of liquid formulations.¹³

Seed coatings themselves are undergoing a metamorphosis as well. Petroleum-based polymers cannot always be made biodegradable and, at the same time, fully functional. The ideal would be to develop completely natural coatings that leave no residue, disappear without a trace, and retain critical seed protection and nutrient properties. Supramolecular engineered proteins have been developed over the past 15 years. They perform as well as synthetic polymer-based coatings but decompose naturally. This serves two purposes: mitigating soil degradation and eliminating microplastic pollution in farm fields.¹⁴

Thinking even further outside the box, these supramolecular engineered proteins might be the foundation for producing plant-based protein products to replace traditional single-use and even multiple-use carbon-chain plastics without the threat of microplastic pollution.

References

1. Petersen, K. S. There is an Alarming Amount of Microplastics in Farm Soil–and Our Food Supply. Environmental Health News. January 27, 2021.
2. Nielson, A.. The Seed Sector’s Battle Against Microplastics. Seed World. April 29, 2024
3. Verney, C.; DeGassert, G. Microplastic Seet Coatings the Perform Better than Conventional Ones: Myth or Reality? Agropages AgNews. June 14, 2024.
4. Accinelli, C. et al. Degradation of Microplastic Seed Film-Coating Fragments in Soil. Chemosphere. V 226. July 29, 2019. Pages 645-650.
5. Harish, D., et al. Effect of hydropriming and Osmopriming on the Germination of Seedling Vigor in East Indian Sandalwood (Santalum album L.). Forests. V 14, P. 1076. 2023.
6. Sharma, S. Enhanced Crop Potential: Exploring Seed Coating Techniques and Applications. LinkedIn. May 14, 2024.
7. King Quenson Group. A Farmer Friendly Technique for Producing Crops. King Quenson News. September 3, 2023.
8. Zang, Fei, et al. Seed Priming with PEG Induces Physiological Changes in Sorghum Seedling Under Suboptimal Soil Moisture Environments. National Institute of Health. October 15, 2015.
9. Yahong, G., et al. Preparation of Lignin Polyethylene Glycol Film-Forming Agent and Its Application in Chlorantraniliprole 5% Flowable Concentrate for Seed Coating. Industrial Crops and Products. V. 182. P 114877. August 2022.
10. Agriculture | Coating for Seeds, Fertilizers & FilmsPolyvinyl Alcohol. https://www.kuraray-poval.com/applications/agriculture (accessed September 10, 2024).
11. Chitosan. https://en.wikipedia.org/wiki/Chitosan (accessed September 10, 2024).
12. Hadwiger, L. A. Multiple Effects of Chitosan on Plant Systems: Solid Science or Hype. Plant Science. V. 208, 42-49. July 2013.
13. Electrolyte Tolerant Film Forming Agent for Seed Coatings. Borregaard https://www.borregaard.com/markets/agriculture/applications/seed-coating/products/film-forming-agent/ (accessed September 10, 2024).
14. Natural Alternatives to Microplastics Developed for the Seed Coating Industry. Environment Times. February 1, 2022. https://www.environmenttimes.co.uk/news/item/995-natural-alternatives-to-microplastics-developed-for-seed-coating-industry (accessed September 10, 2024).

In George Pilcher’s 2024 state of the paint industry article, he explains that supply chain issues still have not fully recovered from the challenges wrought by COVID-19.¹ Initially, it appeared that 2023 was going to be a year when the pandemic-related supply chain problems stabilized. Unfortunately, in the second half of 2023, new challenges evolved and spread, upending much of the progress brought about by adding manufacturing capacity closer to home, adjusting inventory levels to accommodate availability, and decreasing lead times.

This time, shutdowns related to COVID-19 were not the culprit. Rather, a more insidious set of circumstances were and are at work to stymie the almost-reestablished post-COVID supply chain: Houthi forces and La Niña.

COVID-related issues caught everyone off-guard without measures in place to shore up long-held just-in-time delivery practices. During COVID, just-in-time began to be replaced with just-in-case deliveries. Reshoring became very popular. Many companies’ manufacturing processes returned from Asia to be closer to customers in the United States, Mexico, Central, and South America. Unfortunately, as the supply chain stabilized in 2023, some importers went back to just-in-time deliveries, completely negating one important lesson learned during COVID.

In 2023, many ships that had been built during the pandemic were placed into service. Freight rates dropped due to vessel overcapacity, causing shipping prices to tumble. Shippers and customers started to relax, transportation costs came down, and prices fell to more reasonable levels—albeit not necessarily to pre-COVID rates.

Then in late 2023, tensions exploded in the Middle East. The instability in the region is the most obvious problem affecting supply chains in all markets. Any shipper that depended upon the Suez Canal or the Red Sea had massive logistical headaches. During normal operations, 15% of world trade passes through the Red Sea². However, starting in the first 11 days of January 2024, Egypt reported a 40% drop in revenue from transit fees as reported by the Suez Canal Authority’s Admiral Osama Mournier Mohamed Rabie.²

As the Israeli-Palestinian conflict escalated, Houthi forces began to attack cargo ships in the Suez Canal and the Red Sea. Commercial ships are huge, but they are poorly equipped to absorb missile and drone attacks. Any ships navigating the Red Sea had to depend on the U.S.-led Maritime Coalition for protection. The Bab-el-Mandel Strait into the Red Sea from the Asia side was essentially shut down: ships that were lined up for miles were often hijacked while waiting to get through.²

The inability to navigate the Suez Canal was a major catastrophe. Recall that in 2021, the Ever Given, a container vessel operated by Evergreen Marine, got stuck in the canal and that halted traffic for a week. The blockage stopped 369 ships from passing through the canal and delayed an estimated $9.6 billion worth of trade each day.⁴ The effects of that comparatively small delay impacted supply chains for up to nine months.

In the 2000s and 2010s, Somali pirates were a threat. Today, drones, drone strikes, and waterborne IEDs are a bigger problem. Clearly, the ongoing Middle East issues are going to have a much larger impact on supply chains than a one-week stoppage because of a stuck ship.

Now, through lessons learned from the complications related to COVID-19, initial response times were shortened. Major shippers such as Maersk and Hapag-Lloyd immediately rerouted ships around South Africa to protect the containers—lengthening transportation time by at least 25% and increasing costs exponentially.³ But at least shipments were not brought to a halt or otherwise destroyed.

On top of that, all the new ships languishing in ports after the pandemic were suddenly needed to shore up the longer routes and shipping times. Freight rates rose dramatically, but the consolation was that COVID rates were still five times higher than the new rate increases.

As if the Middle East didn’t pose enough significant challenges for container-vessel transit and supply chain disruption, there was another major issue brought about by La Niña in North America. The lack of rainfall during the wet season in 2023 caused severe drought conditions, dropping the depth of Gatun Lake to dangerous levels. The Panama Canal reduced traffic due to this historic drought, which saw water levels fall to the lowest since 1965. In addition to impacting the drinking water available for that region, the lake did not have enough water to spill over into the Panama Canal. It became “too dry”—rather, too shallow—to permit the usual number of shipping vessels to traverse the canal without an advanced reservation.

For ships that needed to move from the Atlantic to the Pacific side, reservations were (and still are) as difficult to obtain as an uber-exclusive 5-star restaurant in New York City. Ships without reservations must resort to an auction for a passage slot. The opening bid was $55,000 over the regular tariff—one confirmed bid was $4 million! Bloomberg reported that in November 2023 alone, shipping companies have paid $223 million above transit costs just to get a slot.⁵ And they still must wait for days before passage is finally allowed. However, the wake of these large ships causes water to spill out of the canal if they are too close together, which further lowers the water level. In November 2023, as conditions worsened, the Panama Canal Authority reduced daily transits to 24 from the normal of 34–36, and further reduced them in 18 in January. This continued into the third quarter of 2024.⁵

Fortunately, the Panama Canal Authority anticipates much higher rainfall during the 2024 May to December rainy season because of the weather shift to El Niño. The refilling of Gatun Lake has allowed for an additional booking slot beginning August 5, 2024. Drafting regulations have been eased, allowing for additional ships to pass at the same time. A proper rainy season could lead to normal operations by fall 2024.⁶

What does this all mean for the coatings industry?

On the plus side, because of the lessons learned during COVID, there is now some level of stabilization and predictability. PVC resin prices held steady in June remaining below 2023 levels.⁷ On the other hand, the hurricane season is expected to be especially active in the Gulf region where many PVC manufacturers are located. Hurricane Beryl already made an early appearance in Texas.

Another plus is that industries tangential to the coatings industry have also made significant supply chain modifications that will benefit our products. For example, GE Appliances (a subsidiary of China-based Haier Smart Home) in Louisville, KY, remade their supply chain more flexible after coping with product shortages during the pandemic.⁸ Admittedly, they began the process in 2017. The pandemic forced the acceleration of those plans as they struggled with over and under stocking of major appliances.

The largest change GE Appliances made was to bring manufacturing from Asia to the United States, which added 4,000 manufacturing jobs. For the company, this change cut shipping costs, reduced transit delays, allowed better control of production, strategically located inventory levels, and generated consumer goodwill with the new jobs. For the tangential industries such as coatings and metals, these manufacturing sites turned into new, large domestic customers.

In addition, GE Appliances balanced inventory by tracking customer orders delivered on time and in full–thereby prioritizing existing orders. The cascading effect was that because many appliances are painted scheduling those needs were also better managed. Pretreatment and paint suppliers were better prepared to provide products as needed, instead of way ahead, too far behind, or as an emergency.

Although the situation in the Panama Canal will most likely resolve itself later this year, there are still going to be significant challenges within the supply chain. Ocean shipping costs will remain very high as long as the Middle East remains unstable and hostilities keep the Suez Canal a shipping nightmare. Increased lead time will continue for core commodities well past any cessation of hostilities.

Pressures due to ongoing freight and raw material pricing will continue to drive cost pressures this year.⁹ Section 301 tariffs that went into effect on August 1 will impact just about all commodities — although this can be mitigated by bringing manufacturing back onshore.

Another pressure on the coatings industry is the price of crude oil. Many raw materials used in oil and acrylic paints are derived from petroleum. A $10 rise in crude oil equals a 3% rise in paint manufacturing cost.⁹ A gallon of top shelf house paint sold for approximately $30 in 2017. That same gallon of paint at the same store is now at least $60. (I can vouch for this as I keep receipts!)

Resiliency, flexibility, and excellent planning will be the attributes that help meet the challenges of ultimately stabilizing the supply chain for coatings and tangential industries this year and into 2025.

Cynthia A. Gosselin, Ph.D., is director at The ChemQuest Group, ChemQuest Technology Institute, and ChemQuest Powder Coating Research. Email: cgosselin@chemquest.com.

References

1. Pilcher, G. The State of the U.S. Paint and Coatings Market 2023-2025: Slow and “Steady as She Goes.” CoatingsTech. 2024, September/October.
2. Hunnicutt, T. etal. US Strikes Houthi Anti-Ship Missiles, Shipping Disruptions Grow. Reuters Business. January 19, 2024
3. Neuman, S. As Houthi Attacks on Ships Escalate, Experts Look to COVID Supply Chain Lessons. NPR, Jan 20, 2024.
4. 2021 Suez Canal Obstruction. https://en.wikipedia.org/wiki/2021_Suez_Canal_obstruction (accessed July 31, 2024).
5. Panama Canal Warns of “Indefinite Delays” as it Offers Special Auction Slot. The Maritime Executive, Nov 23, 2023.
6. Panama Canal Traffic to Increase as Drought Conditions Ease. Oil & Gas Journal. https://www.ogj.com/, June 28, 2024.
7. Border States website. Border States Supply Chain Update—July 2024. Border States. https://solutions.borderstates.com/news/border-states-supply-chain-update-july-2024/ (accessed July 31, 2024).
8. Young, L. Supply-Chain Overhaul Boosts GE Appliances’ Sales. Wall Street Journal, Heard on the Street, July 8, 2024; p B10.
9. On the Job with Behr (blog). 2024 Paint Industry Outlook: Exploring Headwinds & Tailwinds in a Dynamic Marketplace. Behr Pro website. Published February 2024. https://www.behr.com/pro/onthejob/blog/2024-paint-industry-outlook/ (accessed July 31, 2024).