Burning cargo ship off Kerala coast poses serious toxic threat, sparks concerns

A massive cargo fire on board a container vessel drifting in the Arabian Sea has sparked serious concerns after it emerged that the ship was carrying a hazardous mix of industrial chemicals.

The vessel, WAN HAI 503, which caught fire on June 8 while en route from Colombo to Mumbai, was carrying more than 800 tonnes of dangerous goods, according to a cargo disclosure released by the Directorate General of Shipping (DGS).

Hazardous mix of chemicals

The ship, flagged under Singapore, was approximately 144 km off the coast of Kozhikode when the fire broke out. While the majority of the 22-member crew have been rescued, the situation onboard remains volatile as several containers were reportedly damaged in the blaze, and some may have fallen into the sea. The release of the cargo manifest has confirmed fears that the ship's hold included a wide range of flammable, corrosive, toxic and environmentally hazardous substances.

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The cargo manifest of WAN HAI 503, released by the Directorate General of Shipping, reveals that the vessel was carrying a highly hazardous mix of industrial chemicals, with several substances posing grave risks to human health and the marine environment. Leading the list is Butyl Acrylate Monomer, with over 132 tonnes on board, a volatile and highly flammable liquid that can cause severe irritation and harm aquatic ecosystems. This is followed by Tetrahydrofuran (THF), of which 10 tonnes were being transported — a dangerous solvent known for its explosiveness and ability to form peroxides when exposed to air. The vessel also contained 6.6 tonnes of lithium-ion batteries, which are highly prone to combustion under heat or impact and can trigger thermal runaway fires.

Another major concern is the 55 tonnes of Methacrylic Acid, a corrosive and flammable substance that poses serious inhalation and contact hazards. Sodium Hydroxide, or caustic soda, was present in 28 tonnes, capable of causing chemical burns and reacting violently with water. Additionally, 9.7 tonnes of Acetone, 1.4 tonnes of Formic Acid, 3.8 tonnes of Ethyl Acetate, and 1.9 tonnes of Isopropyl Alcohol were listed — all flammable solvents with toxic vapours and environmental risks.

Rounding off the list is 26 tonnes of Titanium Dioxide, a pigment component not immediately flammable but considered a possible carcinogen in powdered form and dangerous in bulk if dispersed in marine ecosystems. This combination of chemicals underlines the severity of the threat posed by the fire on board and the potential for lasting damage if these materials leak into the Arabian Sea.

Adequate safeguards in place?

The Directorate General of Shipping’s decision to publicly release the cargo details has helped clarify the risks involved, but it has also raised questions about whether sufficient safeguards were in place during the ship’s voyage. The complexity of the substances listed in the manifest has underlined the urgent need for an independent environmental risk assessment and a long-term monitoring plan for the waters off the Kerala coast.

Among the chemicals listed are substantial quantities of butyl acrylate monomer, methacrylic acid, sodium hydroxide, titanium dioxide, tetrahydrofuran, and lithium-ion batteries. Each of these substances, commonly used in various industrial processes, poses significant environmental and safety risks if released into the marine ecosystem.

Butyl acrylate monomer, present in the largest volume, is a volatile and flammable liquid often used in the manufacture of plastics and coatings. It is known to release toxic vapours and cause severe irritation upon exposure. Methacrylic acid, another major component of the cargo, is both corrosive and combustible, raising the stakes in a scenario where firefighting crews are attempting to suppress flames under uncertain conditions. Sodium hydroxide, or caustic soda, can cause severe burns and is highly reactive with water, while tetrahydrofuran is a solvent that is not only highly flammable but can also form explosive compounds when exposed to air over time.

Challenge to emergency response

The presence of lithium-ion batteries adds another layer of complexity to the emergency response. These batteries, widely used in consumer electronics, are particularly notorious for undergoing thermal runaway—where the heat generated during combustion causes them to reignite, even after being extinguished. If containers with these batteries have been breached or fallen overboard, they present a risk not only to the vessel but to nearby ships and marine life.

Although not all substances onboard are classified as flammable, many still pose risks through environmental contamination. Titanium dioxide, for instance, is widely used in pigment manufacturing and may appear benign, but in powder form, it is considered a potential carcinogen and can pose inhalation risks. Chemicals such as acetone, isopropyl alcohol, ethyl acetate, and formic acid—also part of the cargo—are highly volatile and can spread through air and water quickly.

Fishing activities suspended

In the aftermath of the fire, fisherfolk, already under pressure from the seasonal trawling ban and erratic monsoon conditions, have suspended normal fishing activities amid fears of contamination. While authorities have yet to confirm any direct spill into the coastal waters, the potential impact on marine biodiversity and livelihoods is significant.

The Indian Coast Guard and Navy are leading operations to monitor and contain the situation. However, officials admit that firefighting has been hampered by the nature of the cargo. Traditional fire suppression methods such as water-based extinguishing are unsuitable for many of the materials onboard, as some react violently with water or create harmful runoff. Teams have been relying on satellite imagery and aerial reconnaissance to assess the damage and identify drifting containers.

Environmental concerns

This is the second maritime emergency to strike Kerala’s waters in as many weeks. On May 25, another cargo vessel suffered a mishap near the Kochi coast, causing fears of environmental fallout when containers were lost overboard. The back-to-back incidents have renewed calls for stronger regulatory oversight of hazardous cargo movements along India’s coastline.

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Environmental groups have pointed to past shipping disasters, such as the X-Press Pearl spill off Sri Lanka in 2021, as examples of how chemical fires at sea can lead to prolonged ecological damage. The ongoing fire aboard WAN HAI 503, with its complex and hazardous cargo, is now being viewed as a potential parallel that could test India’s maritime preparedness and disaster response mechanisms.

As firefighting and salvage efforts continue, there is still no official estimate on the number of containers lost or the precise scale of the environmental risk. What is certain is that the fire aboard WAN HAI 503 is no longer just a shipboard emergency—it is a chemical hazard with potential consequences for marine life, coastal livelihoods, and environmental safety in one of India’s most ecologically sensitive maritime zones.

Toxic substances in cargo ship

These are among the toxic substances listed in the ship’s cargo manifest. In total, the released document details 157 hazardous items on board.

1. Butyl Acrylate Monomer

• Quantity: 132.94 tonnes

• Hazard: Highly flammable liquid and vapour. Can cause severe respiratory, skin, and eye irritation. Vapours may form explosive mixtures with air. Harmful to aquatic life.

• UN No: 2348 | Class 3 (Flammable Liquids)

2. Tetrahydrofuran (THF)

• Quantity: 10 tonnes

• Hazard: Extremely flammable and volatile. Can form explosive peroxides when exposed to air. Poses inhalation risks.

• UN No: 2056 | Class 3

3. Lithium-ion Batteries (contained in equipment)

• Quantity: 6.6 tonnes

• Hazard: Fire and explosion risk under heat, physical damage, or water exposure. Capable of thermal runaway and reignition. Difficult to extinguish once ignited.

• UN No: 3481 | Class 9 (Miscellaneous Dangerous Goods)

4. Methacrylic Acid

• Quantity: 55 tonnes

• Hazard: Corrosive and combustible. Causes burns and severe eye damage. Vapours are irritating and flammable.

• UN No: 2531 | Class 8 (Corrosive Substances)

5. Sodium Hydroxide (Solid)

• Quantity: 28 tonnes

• Hazard: Strongly corrosive. Causes severe burns to the skin and eyes. Dangerous if dissolved in water—produces heat and caustic solution.

• UN No: 1823 | Class 8

6. Acetone

• Quantity: 9.7 tonnes

• Hazard: Highly flammable. Vapours can cause dizziness, drowsiness, and irritation. Explosive in confined spaces.

• UN No: 1090 | Class 3

7. Formic Acid

• Quantity: 1.4 tonnes

• Hazard: Corrosive, with strong irritating fumes. Harmful if inhaled, swallowed or in contact with skin. Can cause burns.

• UN No: 1779 | Class 8

8. Ethyl Acetate

• Quantity: 3.8 tonnes

• Hazard: Flammable solvent. Vapour can cause headaches and nausea. Can contribute to ozone formation and smog.

• UN No: 1173 | Class 3

9. Isopropyl Alcohol (2-Propanol)

• Quantity: 1.9 tonnes

• Hazard: Flammable. Vapours may cause eye and respiratory irritation and central nervous system effects.

• UN No: 1219 | Class 3

10. Titanium Dioxide (Solid)

• Quantity: 26 tonnes

• Hazard: Not flammable or acutely toxic, but airborne dust is a suspected carcinogen. Environmental concern if released in bulk.

• UN No: Not classified as a dangerous good under most transport codes but included due to bulk.

A UN number (UN No.) is a four-digit identifier assigned by the United Nations Committee of Experts on the Transport of Dangerous Goods to hazardous materials for international transport.