Arsenic Contamination in Food Chain


    In News

    • As per a study by Bihar Pollution Control Board, the arsenic contamination has found its way into the food chain– mainly rice, wheat and potato.
      • Arsenic contamination in groundwater has been a growing concern in several parts of the country. 

    Arsenic (As)

    • Arsenic is a naturally occurring trace element that occurs in many minerals, usually in combination with sulfur and metals.
      • It can also exist as a pure elemental crystal. 
      • It is a metalloid and has various allotropes.
      • Only the gray form, which has a metallic appearance, is important to industry.
    • Arsenic has been recognized as a toxic element and is considered a human health hazard.
    • It can occur in both organic and inorganic form.
      • Inorganic arsenic compounds (such as those found in water) are highly toxic 
      • The organic arsenic compounds (such as those found in seafood) are less harmful to health.
    • It is now recognized that at least 140 million people in 50 countries have been drinking water containing arsenic at levels above the WHO provisional guideline value of 10 μg/L.

    Permissible Limits

    • The World Health Organization’s provisional guideline value for arsenic in drinking water is 0.01 mg/l (10 μg/l).
    • The permissible limit of arsenic in India in the absence of an alternative source is 0.05 mg/l (50 μg/l).

    Health hazards due to Arsenic

    • Acute effects:
      • The immediate symptoms of acute arsenic poisoning include vomiting, abdominal pain and diarrhoea
      • These are followed by numbness and tingling of the extremities, muscle cramping and death, in extreme cases.
    • Long-term effects:
      • Affects Skin and can lead to Skin Cancer
        • The first symptoms of long-term exposure to high levels of inorganic arsenic are usually observed in the skin, and include 
          • pigmentation changes, skin lesions and hard patches on the palms and soles of the feet (hyperkeratosis).
        • These occur after a minimum exposure of approximately 5 years and may be a precursor to skin cancer.
      • Bladder and Skin Cancer
        • The International Agency for Research on Cancer (IARC) has classified arsenic and arsenic compounds as carcinogenic to humans.
          • It has also stated that arsenic in drinking-water is carcinogenic to humans.
      • Developmental Effects, Diabetes, Pulmonary disease & Cardiovascular disease
        • Arsenic-induced myocardial infarction, in particular, can be a significant cause of excess mortality.
        • In Taiwan, arsenic exposure has been linked to “Blackfoot disease”.
          • It is a severe disease of blood vessels leading to gangrene.
      • Adverse Pregnancy Outcomes, Infant Mortality and Child Health
        • Exposure in utero and in early childhood has been linked to an increase in mortality in young adults due to 
          • multiple cancers, 
          • lung disease, 
          • heart attacks, and 
          • kidney failure. 
        • Numerous studies have demonstrated negative impacts of arsenic exposure on cognitive development, intelligence, and memory.

    Sources of Arsenic and exposure

    • Drinking water and food: 
      • The greatest threat to public health from arsenic originates from contaminated groundwater. 
      • Inorganic arsenic is naturally present at high levels in the groundwater of a number of countries, including Argentina, Bangladesh, Chile, China, India, Mexico, and the USA. 
      • Drinking-water, crops irrigated with contaminated water and food prepared with contaminated water are the sources of exposure.
      • Fish, shellfish, meat, poultry, dairy products and cereals can also be dietary sources of arsenic.
    • Industrial processes: 
      • Arsenic is used industrially as an alloying agent, as well as in the processing of glass, pigments, textiles, paper, metal adhesives, wood preservatives and ammunition.
    • Tobacco and smoking: 
      • A person who smokes tobacco can also be exposed to the natural inorganic arsenic content of tobacco. 
        • It is because tobacco plants can actively take up arsenic naturally present in the soil.
    • Earth’s crust: 
      • Arsenic is a natural component of the earth’s crust and is widely distributed throughout the environment in the air, water and land. 
      • It is highly toxic in its inorganic form.
    • Volcanic action: 
      • Around 1/3rd of the arsenic in the Earth’s atmosphere is of natural origin. 
      • Volcanic action is the most important natural source

    Arsenic Contamination: Status in India

    • Increasing Area under Arsenic Contamination:
      • The number of arsenic-affected habitations in India has increased by 145% in the last five years (2015-20).
      • India had 1,800 arsenic-affected habitations in 2015. 
      • This increased to 4,421 habitations as of September 2020.
    • Affected Regions: 
      • The occurrence of Arsenic in groundwater was first reported in 1980 in West Bengal in India.
      • Maximum number of the arsenic-affected habitations are in the Ganga and Brahmaputra alluvial plains.
        • They are distributed across Assam, Bihar, West Bengal, Punjab, and Uttar Pradesh (UP).
    • States Performance:
      • Assam had the highest share of As contaminated habitations (1,853), followed by West Bengal (1,383).
      • However, Karnataka which had nine habitations in 2015, had none in 2020.
    • Menace in Bihar and West Bengal:
      • Out of its 38 districts, 22 were reported to have arsenic in drinking water above the WHO provisional guide value of 10 μg /L.
      • The recent major cause of concern is the presence of arsenic in the food chain in Bihar through irrigation water. 
      • Three common eatables – rice, wheat and potato – have elevated levels of arsenic that increases the disease burden in exposed persons.”
        • Arsenic content in food items was higher than that in drinking water. 
        • The concentration was higher in cooked rice compared to raw rice.

    Source: Vikaspedia


    Solutions to mitigate the Challenges

    • Muktoshri: Arsenic Resistant Rice
      • It has been developed jointly by 
        • the Rice Research Station at Chinsurah, coming under West Bengal’s Agriculture Department and 
        • the National Botanical Research Institute, Lucknow.
      • The research and development in agri-engineering can  help in reducing the Arsenic content in food.
      • Similar research can be extended to other crops.
    • Water Treatment Methods
      • There are multiple Arsenic removal techniques available world wide like oxidation, coagulation-flocculation, and membrane techniques.
    • Other Simpler Methods
      • Uses of surface water sources
      • Exploring and harnessing alternate arsenic free aquifer
      • Adopting rainwater harvesting/ watershed management practices.

    Government Schemes for mitigating such challenges

    •  Jal Jeevan Mission (JJM):
      • JJM was started in 2019 by the Ministry of Jal Shakti.
      • Aim: To provide piped water supply to every household by 2024.
      • Priority has been given to such quality-affected habitations through Community Water Purification Plants (CWPP).
        • The CWPP will meet drinking and cooking needs- until potable water supply through tap connection is provided.
      • Under JJM, upto 2% of the allocation to states/ UTs can be utilised for Water Quality Monitoring & Surveillance activities (WQM&S).
    • A new Sub-programme under National Rural Drinking Water Programme (NRDWP) viz. National Water Quality Sub-Mission (NWQSM) 
      • It was started by the Ministry of Drinking Water and Sanitation (now the Ministry of Jal Shakti) in 2017.
      • Aim: To address the urgent need for providing clean drinking water in about 28000 Arsenic & Fluoride affected habitations.
      • The NWQSM aims to cover all rural populations in Arsenic/Fluoride affected habitats by March 2021.
      • NRDWP is a Centrally Sponsored Scheme with 50:50 fund sharing between the Centre and the States.


    Way Ahead

    • To combat Arsenic Pollution, focussing only on drinking water will not be sufficient, rather the focus should also be on irrigation water.
    • The strengthened canal system may reduce the farmers’ dependence on groundwater.
    • Differences in the sampling frame, mitigations and public education / awareness interventions by various agencies can go a long way in ensuring the safe potable drinking water and food to millions of Indians.

    Source: DTE