18 May 2022


Major cities have drinking water contamination by Arsenic

Mahnoor Baloch BSES 8th semester


Worldwide pollution is increasing due to various natural and anthropogenic activities, leading to contamination of terrestrial and aquatic ecosystems with organic and inorganic contaminants.

Some of heavy metals like copper (Cu), cobalt (Co) and zinc (Zn) are essentially required for normal body growth and functions of living organisms, while the high concentrations of other metals like cadmium (Cd), chromium (Cr), manganese (Mn), and lead (Pb) are considered highly toxic for human and aquatic life.

The pollution of groundwater by arsenic and fluoride have been identified in many developed and developing countries. These two elements are recognized worldwide as the most serious inorganic contaminants in drinking water. In recent years, a high concentration of Arsenic has been detected in groundwater from a number of regions across the world. This problem has increased greatly in recent years in many regions of Southeast Asia including Bangladesh, India, Nepal, Myanmar, Pakistan, Vietnam, Cambodia, and China.

The detection of arsenic in ground waters of various countries throughout the globe has threatened the use of groundwater as major source of drinking water. Many anthropogenic activities and natural biological action, and geochemical reactions mobilize arsenic into ground waters. Most arsenic problems in the environment are the result of mobilization under natural conditions but mining activities, combustion of fossil fuels, use of arsenic pesticides, herbicides, and crop desiccants and use of arsenic additives to livestock feed create additional impacts.

Pakistan’s current population is expected to grow to about 221 million by the year 2025. This increase in population will have a direct influence on the water resource of Pakistan. The demand for domestic, industry and agriculture use will increase which will put further stress on the existing water resource. The per capita water availability in Pakistan has dropped from 5600m3 in 1953 to about 1000m3 in 2006. Pakistan has now essentially exhausted its available water resources and is on the verge of becoming a water deficit country. Pakistan Strategic Country Environmental Assessment Report 2006 showed that 80% of Punjab province freshwater resources are based upon groundwater. Anthropogenic activities have affected the quality of water in Lahore, Karachi, Peshawar, Faisalabad, Sialkot, Gujrat, Kasur and Rawalpindi. In some areas of  Pakistan, the presence of arsenic in subsurface aquifers and drinking water systems has become a potentially serious human health hazard.

A majority of shallow subsurface aquifers and tube wells are contaminated with arsenic at levels which are above the recommended arsenic level as set by Pak EPA. Arsenic is capable of causing serious adverse health effects, including human mortality.  Arsenic mobility and retention in surface water and groundwater are of great importance because of its toxic effects.

Human exposure to arsenic can take place via ingestion, inhalation or skin adsorption. Ingestion is the predominant form of arsenic intake. Long term exposure to arsenic is capable of causing strong adverse effects on health and drinking water is now recognized as the major source of human intake of arsenic in its most toxic (inorganic) forms. Numerous studies review the effect of long-term exposure to arsenic on people’s health. Inorganic As exposure at chronic levels adversely impacts on human health, causing skin disorders. diabetes mellitus, cardiovascular disease, neurological complications, reproductive disorders, respiratory effects as well as various types of cancers including skin, lung, bladder, and kidney. The presence of arsenic does not affect taste, odors and/or visible appearance of water therefore it is difficult to detect without complex analytical techniques and hence it may present a significant hazard to community health.

A study was carried out to determine the possible source of Arsenic contaminated groundwater in the Kalalanwala area of Pakistan. Results showed that all groundwater samples contained high levels of Arsenic (32-1900 mg/L) which was in excess of WHO drinking water standards. Similarly, study carried out in Muzaffargarh District of south-western Punjab, central Pakistan revealed that concentrations of As exceeded the World Health Organization provisional guideline value, and United States Environmental Protection Agency (USEPA) Maximum Contaminant Level (MCL), of 10µg/L in 58% of samples and reached up to 906 µg/L.

There is an urgent need to carry out detailed studies to ensure that accurate and reliable data is available for immediate actions. Further research is needed to improve field testing and monitoring of drinking water sources, and to develop and introduce new treatment options for chronic Metal toxicity and to generate new sources of safe drinking water