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

 
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