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Caution sounded on drinking water risks

Caution sounded on drinking water risks

RESEARCHERS at the University of Dar es salaam (UDSM) in collaboration with their counterparts from the Swedish KTH institute of Technology have recorded high levels of arsenic concentration in drinking water which if not attended, the users will suffer grave consequences in the near future.

At a presentation during a research week at the University of Dar es salaam (UDSM), Professor Felix Mtalo, a researcher and an engineer, describes arsenic as basically a chemical element that is poisonous, a metallic element that forms a number of poisonous compounds in the human body.

Arsenic is found in nature at low levels, mostly in compounds with oxygen, chlorine and sulfur. It is known to occur with gold ore deposits. He explained that arsenic has been known from time immemorial to be lying dormant and that it has no negative effects if it remains unexposed to air where it is oxidised by oxygen.

When exposed to oxygen through human or natural activity, arsenic gets oxidized. It easily flows and dissolves into basic water sources like wells and streams and that eventually causes incurable diseases like skin cancer when taken by humans through drinking water sources.

The World Health Organisation has recommended maximum levels in drinking water sources of 10 parts per billion (ppb). The study found the standard to be exceeded in tested water samples from gold mining areas, especially around Musoma and Tarime districts in Lake Zone.

“We found out that water, especially in Musoma and Tarime districts in Mara Region, recorded high dangerous arsenic amounts of up to 300 microgrammes arsenic per litre while in Geita the level was up to 70 microgrammes compared to the WHO recommended standard values of below 10 micro-grams per litre. This means people are drinking water polluted by heavy metals and the danger is eminent if strict measures are not taken,” he explained.

The professor suggested that immediately needed measures to rescue human health from incurable health complications include the government reviewing the Tanzanian drinking water standard on arsenic removal.

He also suggests that with changing precipitation due to changes in climatic conditions where East African countries are expecting more rainfalls, mining activities must be carefully carried out to avoid solubility of more arsenic flowing, further affecting water sources that human beings and animals are relying for domestic and other uses.

According to him, the spreading of arsenic into water is more aggravated by small scale miners than multinational, big scale miners.

“Small scale miners are using poor tools and methods in mining that exposes arsenic containing ores to oxygen and thus dissolving in water sources and thus affecting a big number of users,” he pointed out, adding: “Shallow wells and water streams users are at high risks. Large water bodies like Lake Victoria do not record high values yet, due to the dilution effect. However, over a long time, the heavy metal will find its way into the food chain through fish which will be consumed by humans.”

He elaborated further that open cast mines are more at risk for they oxidize arsenic and they easily mix with water sources compared to the closed ones as there is no oxygen.

With all that, still there is hope as the UDSM and the KTH Royal College of Technology are working hand in hand to researching and come up with a lasting and affordable solution for arsenic removal in drinking water using locally available materials, thanks to the funding from Swedish International Development Cooperation Agency (SIDA).

The university don also revealed that it is not affordable for average citizens and authorities to access arsenic testing technology as the cost is high. For field testing, there is a possibility of using a colour code for comparison purposes. It will show a range.

The exact concentration can only be determined by sophisticated equipment and methods. According to him, water to be secured can be pumped through a membrane. This method is expensive and demands high pressure to pump water through (nanofiltration) which will require a lot of power.

Reached for comment, Minister for Water and Irrigation, Prof Makame Mbarawa said that the government’s priority was to create an environment for enabling Tanzanians countrywide access safe and secure water.

He said that apart from the country having specific water testing laboratory in almost all regions, still there are efforts put in place to ensure that international and local standards are complied with. “We have TBS (Tanzania Bureau of standards), EWURA (Energy and Water Utilities Regulatory Authority) and WHO standards that are to keenly observed.”

The minister said that even though the report hasn’t reached his desk, he promised still technical measures will be put in place which may include special water treatment to combat the metal effect. “I urge all Tanzanians not to perform mining and farming activities near water sources so as to avoid polluting and contaminating water and destroying water sources,” called Prof Mbarawa.

Arsenic poisonous consequences have affected populations in Bangladesh, India and Nepal where thousands of deaths have been reported and inhospitable skin cancers and lesions are affecting humanity in these countries.

On crops contamination, Professor Mtalo said: “Our irrigation water is not yet so polluted.. The accumulation in plants takes time and it will definitely depend on the growth rate and age of the crop as well as the concentration of the arsenic in the irrigation water. Rice has been one example and samples from far east Bangladesh, Assam and Mongolia have been shown to contain high arsenic concentrations and this is another form of human ingestion of Arsenic.”

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