Is arsenic a threat to the Bangladeshi livelihoods?
Arsenic poisoning is a global health issue affecting millions of people worldwide. It naturally occurs with ubiquitous distribution throughout the earth's crust, groundwater, air and food products. This metalloid propagates into the environment through weathering and mining processes, volcanic activity, arsenic ores with gold, lead, cobalt, nickel and zinc. Chronic arsenic toxicity occurs through contaminated drinking water, erosion of land sources and contaminated wells and aquifers.
Acute arsenic toxicity manifests with gastroenteritis followed by hypotension and vesicle damage. Doses under 5 mg results (within minutes to hours after ingestion) in garlic breath odor, nausea, vomiting, diarrhoea, abdominal and chest pain, loss of balance, tachycardia, fever and renal failure (1 to 12 hours after exposure). 4 to 48 hours after exposure, port wine hue urine, reddish stained conjunctiva, jaundice, liver and spleen tenderness, heart block, asystole and weakened mees' lines. Arsenic poisoning also causes dehydration and volume loss and electrocardiogram (ECG) abnormalities.
Chronic exposure to arsenic results in multiple dermatologic signs such as prominently diffuse or spotted hyperpigmentation (raindrop appearance), palmer-planter hyperkeratosis, eczematoid lesions, warts, alopecia, basal cell carcinoma, squamous cell carcinoma, hyperkeratosis, skin cancer (especially in palms, soles, and abdomen), non-specific abdominal pain, gangrene of the extremities (blackfoot disease), lung and bladder cancer etc.
Arsenic is especially common in the rocks of the Himalayas, from where the Ganges and other great rivers carry it to the heavily populated plains of South and Southeast Asia. Most of the world's arsenic is locked up in mineral compounds underground, but mining and coal burning have released many tons into the environment. Rice, legumes and vegetables grown in the fertile lands of Bangladesh are the common foods of the Bangladeshis. Moreover, Bangladesh is a riverine country.
Recent scientific evidence suggests that rice is the efficient scavenger of arsenic as it takes up 10-20 times as much as other cereal grains — because it is the only grain traditionally grown in fields that are under water. Flooding makes soil conditions anaerobic, which causes arsenic to convert from bound and stable forms into more mobile ones.
On the other hand, arsenic has a similar chemical structure of phosphate and silicon, which allows it to sneak through the same pathways that plants use to absorb these important nutrients. Once inside, it becomes embedded in the roots, shoots, leaves and — particularly important for human health — the seeds. It accumulates most in the husk, the outer covering of the seed that is left intact in brown rice. Thus, there is a well-balanced arsenic cycle in the Bangladeshi lifespan.
Notably, Bangladesh has high rates of exposure (with an estimated 27 million individuals) through drinking water with contamination levels greater than 50 parts per billion (ppb), where the World Health Organisation labels safe arsenic drinking levels at less than 10 ppb. Therefore, how arsenic is threatening the Bangladeshi livelihoods from generation to generation is a burning question now-a-days.
The writer is an Assistant Professor of Pharmacy at the Bangabandhu Sheikh Mujibur Rahman Science and Technology University, Gopalganj, Bangladesh.