Bioaccumulation refers to the buildup of substances, such as pesticides or chemicals, within an organism over time. This occurs when an organism absorbs a substance at a rate that exceeds its elimination through catabolism and excretion. As a result, if the biological half-life of a toxic substance is longer, the risk of chronic poisoning increases, even when the environmental levels of the toxin are low.

Biomagnification, also referred to as biological magnification or bioamplification, is the process by which the concentration of a particular toxin, such as pesticides, increases at each successive level of the food chain, resulting in higher levels of accumulation in the tissues of tolerant organisms. This phenomenon can occur due to various reasons, including the persistence of the toxin, which prevents it from being broken down by environmental processes, the energetics of the food chain, where the concentration of the toxin increases as it moves up the food chain, and the low or non-existent rate of internal degradation or excretion of the substance, primarily as a result of its water-insolubility.

Example: India’s study by the Central Water Commission found toxic heavy metals exceeding limits in more than 40 rivers, including the national river Ganga with 5 metals. Contaminated soils increase toxic metal concentration in crops, posing a severe threat to health and environment due to their toxicity, non-biodegradability, and bioaccumulation.

Process involved:

Toxic substances like pesticides and pollutants are absorbed by plants and consumed by primary consumers in low concentrations. As the toxins cannot be excreted, they get absorbed by secondary consumers, and the process repeats as they are consumed by higher-level consumers. This results in the concentration of toxins remaining in the tissues of animals at each trophic level, with top-level animals having the highest concentration.

Causes of Bioaccumulation/Biomagnification:

Organic Contaminants

Microplastics/Plastic Pollution

Mining

Toxic Gases

Air Pollution

Contaminants in food

Effects

On Human Health:

Seafood consumption has been associated with certain types of cancer due to the accumulation of mercury and Polycyclic Aromatic Hydrocarbons in the tissues of marine organisms. Moreover, consuming plants or aquatic animals that have absorbed heavy metals and toxic substances can lead to long-term effects such as kidney failure, respiratory disorders, brain damage, birth defects, and heart diseases.

On aquatic animals:

The consumption and accumulation of metals in the tissues of marine organisms can have a negative impact on their reproduction and development. Seabirds that consume heavy toxic metals may produce eggs with soft, thin shells that easily break during incubation. Water bodies contaminated with toxic chemicals such as Selenium and Mercury can also affect the reproductive process of fish, among other adverse effects.

Disruption of Food Chain:

The accumulation of substances that cause biomagnification can disrupt the natural food chain, which is vital for the survival of all animals in a given biosphere. If a group of organisms dies due to toxic substances, the natural flow of the food chains becomes disrupted, and this may have long-term effects that may not be immediately noticeable.

Destruction of Coral Reefs:

Cyanide used in leaching gold and fishing is the main cause of the destruction of coral reefs, which affects the lives of many aquatic animals that depend on the coral habitats for their survival.

Effective solutions for this environmental issue:

• It is essential to restrict the dumping of all forms of waste in rivers, as well as prevent the washing of clothes and animals in these bodies of water. This will help to reduce the inflow of harmful chemicals from soaps and detergents. Additionally, the disposal of hazardous fishing nets should be minimised to prevent further damage to aquatic ecosystems. It is crucial to educate people and raise awareness about the potential side effects of such actions to promote responsible environmental practices.
• To eliminate heavy metals at the source, industries such as coal plants should reduce their reliance on toxic substances like lead, arsenic, and mercury by developing innovative strategies to eliminate emissions. Additionally, wellsprings and preservation techniques can help reduce the concentration of these toxic substances in products like petroleum.
• It is crucial for institutions to take a proactive role in promoting safer practices, particularly in the healthcare and home improvement sectors. For instance, the use of mercury-containing items in the healthcare industry should be phased out in favor of more secure alternatives. Similarly, in the home improvement sector, products such as PVC plumbing materials, lead paints, and wood treated with CCA and ACZA, which contain heavy metals like mercury and arsenic, should be restricted to minimize health risks for individuals and the environment.

Measures already in place:

The Central Pollution Control Board (CPCB) is expanding its manual water quality monitoring network and establishing real-time monitoring stations along rivers such as the Ganga to ensure continuous monitoring of water quality. The government is also taking steps to strengthen compliance mechanisms to prevent untreated industrial effluent from being discharged into the environment. To promote self-monitoring and transparency, 17 categories of polluting industries have installed online effluent monitoring systems and are sharing data with SPCB/CPCB. Additionally, the government is improving the performance of existing sewage treatment plants and adopting non-conventional technologies in synergy with conventional methods to improve water quality. Inspection of all 726 grossly polluting industries in the Ganga basin has been carried out, and action has been taken against 611 non-compliant industries. Furthermore, the government has launched numerous mass awareness programs and conducted training in various priority areas.