When reports of toxic metals in fish being sold in Guwahati markets surfaced in January, the Assam government initiated an investigation to verify the findings. The results, based on a study conducted by the Pahle India Foundation and reported by Down To Earth indicated that lead and arsenic were present in Bhangon (Labeo bata), a commonly consumed freshwater fish.
While the immediate focus remains on testing and verification, the episode has brought to light a deeper and more troubling structural problem: Assam’s food safety system lacks any field-level mechanism to test heavy metals in fish, even as it maintains a robust and rapid system to detect formalin within minutes.
Formalin contamination has long been recognised as a serious issue in the state, particularly in relation to imported fish. To address this, the Food Safety Department has a Standard Operating Procedure (SOP) that allows Food Safety Officers and District Fishery Development Officers to inspect markets using rapid test kits. These kits can detect formalin in two to three minutes, enabling officials to seize contaminated fish and initiate legal action under the Food Safety and Standards Act, 2006.
Heavy metals such as lead and arsenic, however, present an entirely different challenge. Unlike formalin—which is deliberately added by traders as a preservative—heavy metals are environmental pollutants.
Fish accumulate them gradually through contaminated water, sediments, and the aquatic food chain. In Guwahati, wetlands such as Deepor Beel, which receive untreated sewage and industrial effluents, are widely believed to be potential sources of contamination.
Despite posing a far more serious long-term public health threat, there is no equivalent SOP or rapid testing mechanism for heavy metals. This regulatory gap has major implications for enforcement and consumer protection.
“If they smell formalin, they can act immediately. If they suspect lead or arsenic, they have no choice but to collect samples and send them to a laboratory,” a food safety official explained.
The testing process can take days or even weeks. By the time results are available, the fish would already have been sold and consumed. There is no recall system, no immediate public warning, and no way to prevent further exposure at the market level.
In effect, heavy metal testing functions largely as a post-exposure exercise rather than a preventive safeguard.
Under the Food Safety and Standards (Contaminants, Toxins, and Residues) Regulations, 2011, the maximum permissible limit for lead in fish is 0.3 mg per kg, while for arsenic it is 1.1 mg per kg. The preliminary summary of the Pahle India Foundation study shows that all tested samples of Bhangon exceeded the permissible limit for lead, and in every lead-contaminated sample, arsenic levels were also unsafe. Other affected species reportedly include Naro, a freshwater catfish, and Bariola.
This is particularly alarming because Bhangon is among the most affordable and widely consumed fish species in Assam and is a dietary staple in many lower-income households. The risk, therefore, is not confined to a niche consumer group but potentially affects a large section of the population.
Health experts warn that heavy metals are especially dangerous because of their ability to bioaccumulate in the body. They are not destroyed by cooking and cannot be easily eliminated. Lead accumulates in bones and kidneys, causing permanent neurological damage, reduced cognitive ability in children, and kidney disease in adults.
Arsenic is a proven carcinogen and has been linked to skin lesions, cardiovascular disease, and cancers of the bladder, lung, and skin.
Pregnant women and children are particularly vulnerable. Lead and arsenic can cross the placenta, affecting foetal brain development and increasing the risk of developmental delays and low birth weight. Regular consumption of contaminated fish, even in small quantities, can therefore have severe and irreversible long-term consequences.
At present, samples are typically sent to facilities such as the State Public Health Laboratory in Bamunimaidam, Guwahati.
However, heavy metal analysis requires sophisticated equipment like Atomic Absorption Spectroscopy (AAS) or Inductively Coupled Plasma Mass Spectrometry (ICP-MS), both of which are expensive, technically demanding, and time-consuming. This raises serious questions about the state’s laboratory capacity, testing frequency, and the largely reactive nature of monitoring.
The existence of a strong SOP for formalin demonstrates that the government can establish rapid, decentralised enforcement systems when contamination is visible, market-based, and directly attributable to trader behaviour. The absence of a comparable system for heavy metals exposes a regulatory blind spot—one tied not to individual misconduct, but to broader environmental degradation.
Put simply, Assam’s food safety regime is designed to catch fast poisons, not slow ones.
Experts argue that addressing this gap does not require alarmism, but sustained policy reform. This includes developing a dedicated SOP for heavy metal monitoring in freshwater fish, conducting routine sampling in high-risk wetlands, issuing consumer advisories, and strengthening coordination between food safety authorities, fisheries departments, and pollution control agencies.
Environmental scientists also stress the importance of tackling pollution at its source, including stricter enforcement of effluent standards, improved sewage treatment infrastructure, and protection of wetlands that function as natural filters.
Without parallel action on environmental contamination, food safety interventions alone will remain limited in their impact.
Until such systems are put in place, consumers remain exposed—not because the danger is unknown, but because the tools to prevent it are still missing.
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