Nitrate-contaminated water causes prostate cancer, says new study

Scientists at Barcelona Institute for Global Health (ISGlobal) have proposed that people who drink nitrate-contaminated tap water or bottled water for a long period of time are likely to develop prostate cancer.

Prostate cancer is one of the most common cancers in men. American Cancer Society reports that there are over 3.1 million prostate cancer patients in the US alone. Moreover, about 22 percent of all men diagnosed with cancer in Spain also suffer from this disease. 

The researchers conducted their study in Spain and found evidence suggesting an association between nitrate in water and prostate cancer. They also found a link between trihalomethane (THM) contamination and bladder cancer.

Unfortunately, we may never know (unless some chemical tests are performed) if our drinking water is heavily polluted by nitrate because our senses cannot taste, smell, or spot nitrate in water.

Sources of nitrate pollution

Fertilizers used in farmlands to increase the yield and the manure from livestock farming that is left untreated contain large amounts of nitrate. During the rainy season, this nitrate seeps into freshwater bodies like rivers and ponds and even into aquifers. Apart from this, nitrate could also get into our environment from explosives, medicines, and food preservatives.

On the other side, THM contamination is the result of reactions between water disinfectants like chlorine and other organic and inorganic chemicals that are already in the water. Basically, it is formed as a by-product of using water disinfectants. 

Unlike nitrate, which enters the human body only when a person drinks contaminated water, THM can make its way also via the skin. So your body is exposed to THM even when you are bathing, washing dishes, or swimming in contaminated water.

The link between nitrate pollution and prostate cancer

The ISGlobal team studied the nitrate and THM contamination in the drinking water consumed by 697 prostate cancer patients since they were 18 years old. They performed a similar analysis for 927 healthy men and then compared their findings. 

During their study, the authors ran tests on both tap water and commonly available bottled water in the areas where the patients and members of the control group spent their lives. They also collected data from the respective municipalities, water suppliers, and packaged drinking water brands.

The findings were surprising; people who drank water with nitrate levels above 14 mg per day were at a three times greater risk of developing aggressive prostate cancer tumors than those who drank water with only 6 mg nitrate. 

The results strongly suggest that “the higher the nitrate intake, the greater the association with prostate cancer.” However, this is only one of the first pieces of evidence of this association, and therefore, further studies are required to confirm these findings.

Fighting prostate cancer with fruits and fiber

Apart from water intake, the researchers also collected information about the diet that the study participants followed throughout their life. Interestingly, this information revealed that participants who regularly ate fruits and vegetables rich in fiber and vitamin C didn’t have to face the negative health consequences of drinking nitrate-contaminated water. 

“In participants with lower intakes of fiber (≤11 g/day), higher nitrate intake increased the likelihood of prostate cancer by a factor of 2.3. However, in those with higher intakes of fiber (>11 g/day), higher nitrate intake was not associated with an increased likelihood of prostate cancer,” the researchers note in the press release.

Nitrates give rise to toxic and carcinogenic chemicals like nitrosamines in the human body, and these toxicants are mainly responsible for causing health issues such as prostate cancer.

According to the study authors, regular intake of fiber and vitamin C-rich fruits and vegetables is effective against nitrate-driven prostate cancer as vitamin C promotes anti-tumor activity, fiber inhibits the action of toxic chemicals in the digestive system, and the antioxidants in fruits and vegetables prevent nitrosamine activity. 

However, they didn’t mention anything related to the effect of diet on THM-driven health issues.

The researchers hope that future studies will shed more light on the link between nitrate, cancer, and diet and help us devise new ways to prevent nitrate pollution in the environment.

The study is published in the journal Environmental Health Perspectives.