Why is 'uranium' bad for the human body?

The presence of uranium in groundwater beyond the permissible limits was observed in about 409 samples against 14,377 samples tested in 18 states, the Jal Shakti Ministry said.

Punjab is the most affected state in India, where 29% of wells have been observed to have a uranium concentration above the 30 parts per billion (ppb) limit, the Groundwater Yearbook 2021-22 reveals.

Out of the total of 329 samples that were tested for uranium concentration, 96 were found to be beyond the permissible limit of the Bureau of Indian Standards (BIS) in Punjab. In India, Punjab has the highest uranium value at 532 parts per billion (ppb). Haryana followed with 14.4% of the samples, while Uttar Pradesh with 9.2% of the samples exceeding the BIS allowable limit.

According to India's National Compilation of Dynamic Groundwater Resources, 2022, “The stage of groundwater extraction is very high in the states of Haryana, Punjab, Rajasthan, etc.”

It added: “(In Punjab) Of the total 150 blocks assessed and three urban areas (total 153) taken for study, 114 blocks and three urban areas (total 117) have been categorized as over-exploited, four blocks as critical, 15 blocks as semi-critical and 17 blocks as safe”.

According to the Department of Atomic Energy, hydrogeological and stable isotope tracer investigations conducted in groundwater around the Tummalapalle uranium mining project have confirmed that there is no association between the uranium mining industry and elevated levels of uranium in groundwater.

What is uranium?

Uranium is a naturally occurring radioactive substance. It is part of the rocks, earth, air and water and is found in nature in the form of minerals, but never as metal.

Uranium is a gray metallic chemical element of the actinide series, its chemical symbol is "U" and its atomic number is 92. It has the highest atomic weight of all the elements found in nature and is, about 70% denser than lead.

It is slightly radioactive and is located in the earth's crust in its natural state in a mixture of three isotopes: 0.02% U-234 (considered trace level), 0.7% U-235 and 99.28% U-238.

In soil, it is found in typical concentrations of a few parts per million (ppm). Certain rocks contain uranium concentrations high enough to be mined.

Effects of uranium on human health

Uranium is radioactive. Humans have been mining it from underground for centuries to use it in everything from pottery to the atomic bomb.

Natural and enriched uranium have the same chemical effects on the body. The health effects of natural uranium and depleted uranium are due to the chemical effects of these substances and not radiation.

Uranium mainly affects the kidneys. Kidney damage has been seen in humans and animals that inhaled or ingested uranium compounds. However, kidney damage has not been consistently observed in soldiers who have had uranium metal fragments in their bodies for years. Ingestion of water-soluble uranium compounds will cause kidney effects at lower doses than exposure to insoluble uranium compounds.

Workers who inhaled uranium hexafluoride suffered respiratory irritation and fluid buildup in the lungs. However, these effects were attributed to irritation caused by the Hexafluorosilicic acid and not by the uranium.

Because uranium is broken down by alpha particles, external exposure to uranium is not as dangerous as exposure to other radioactive elements because the skin will block the alpha particles.

However, ingesting high concentrations of uranium can cause serious health effects, such as bone or liver cancer. Inhalation of large concentrations of uranium can cause lung cancer due to exposure to alpha particles.

Uranium is also a toxic chemical, which means that ingesting uranium can cause kidney damage due to its chemical properties much sooner than its radioactive properties would cause bone or liver cancers.

How does the uranium leave your body?

Most of the uranium that is ingested and inhaled is not absorbed into the body and is eliminated in the faeces. The uranium that is absorbed leaves the body in the urine. Some of the uranium that is inhaled can remain in the lungs for a long time.

The uranium that is absorbed is deposited throughout the body; the highest levels are found in the bones, liver, and kidneys. 66% of the uranium in the body is found in the bones. It can remain in the bones for a long time; the half-life of uranium in bone is 70–200 days (this is the time it takes for half of the uranium to leave the bone). Most of the uranium that is not in bone leaves the body in 1–2 weeks.

How likely is uranium to cause cancer?

In humans and animals exposed to high levels of uranium, no higher-than-normal rates of cancer were observed.

The Committee on the Biological Effects of Ionizing Radiation stated that eating food or drinking water with normal amounts of uranium is unlikely to cause cancer.

Uranium can change into other radioactive substances, such as radium, which can cause cancer if you are exposed to enough of them over a long period of time.

Cases of lung cancer and other cancers have been reported in studies of uranium miners; however, the miners also smoked and were exposed to other cancer-causing substances such as radon and silica dust.

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