Introduction: Water is the source of life and is an indispensable living substance for us. The safety of drinking water is closely related to our health. Recent studies have shown that if the nitrate content in drinking water is too high, it may increase the risk of colorectal cancer in the human body. Therefore, we need to be vigilant about the nitrate content of drinking water in daily life!
Globally, agricultural intensification has led to an increase in nitrate content in water sources, which in turn has led to nitrate contamination of drinking water. Although nitrates in our diets also play an important role, such as nitrites can be further reduced to nitric oxide and other reaction products that are toxic to pathogenic bacteria and other harmful microorganisms, excess nitrate content can produce N-nitroso compounds or expose cells to oxidative stress, which in turn can lead to adverse health consequences [1].
Recent epidemiological evidence suggests a link between nitrate ingested through drinking water and an increased risk of cancer. If you drink drinking water with excessive nitrate content for a long time, it may lead to a significant increase in the risk of cancer. A study published in the Australian and New Zealand Journal of Public Health showed that people who drank excessive nitrate levels had a 16 percent increased risk of rectal cancer, a 27 percent increased risk of colon cancer, and a 39 percent increased risk of colorectal cancer. The above research data is enough to show that drinking drinking water with excessive nitrate content will really cause great harm to the body, resulting in a great increase in the risk of certain diseases.
Figure 1 Research results (Source: [1])
The study, which analysed the link between nitrate levels and cancer risk in drinking water across New Zealand, estimated that as many as 800,000 New Zealanders (17 per cent) were likely to drink water with excessive nitrate levels, putting them at risk of cancer, based on internationally published data.
Fig. 2 Association between exposure to drinking water with excessive nitrate content and cancer risk (Source: [1])
In order to accurately assess the potential harm to the human body caused by drinking water with excessive nitrate content, the researchers also conducted a comparative analysis of nitrate and other factors that may lead to colorectal cancer, including alcohol consumption, smoking, exercise, obesity and other factors, and listed the corresponding population attribution score (PAF). They found that drinking water with an excess of nitrate in PAF was 3.3 per cent, which in New Zealand would result in 100.3 cases of colorectal cancer caused by nitrates each year. Although drinking water with a nitrate content exceeding the PAF is lower than that of obesity and alcohol consumption, it is higher than the impact of processed meat and smoking.
Table 1 Population attribution scores for known risk factors for colorectal cancer in New Zealand
Table source:[1]
In summary, from the results of this study, the excessive nitrate content in drinking water is related to the increased risk of colorectal cancer.
In fact, research on the possibility of carcinogenicity in excess of nitrate content in drinking water has long been carried out. In 2018, a study published in the International Journal of Cancer titled "Nitratein drinking water and colorectal cancer risk: A nationwide population-basedcohort study" suggested that excessively high nitrates in drinking water are likely to contribute to an increased risk of colorectal cancer. The higher the amount of nitrate in drinking water, the higher the risk of colorectal cancer.
Figure 3 Research results (Source: [2])
In the study, the researchers calculated individual nitrate exposure in 2.7 million adults based on drinking water quality analysis from public waterworks and private wells between 1978 and 2011, using a Cox proportional risk model to analyze the association between nitrate exposure and colorectal cancer risk. The researchers found that people exposed to drinking water with higher nitrate content (above 9.3 mg/L) had a 15 percent increased risk of colorectal cancer compared to people who were not exposed to drinking water with higher nitrate levels (less than 1.3 mg/L).
Both studies have shown a high correlation between excessive nitrate levels in drinking water and colorectal cancer risk, and excessive nitrate levels in drinking water are likely to have adverse health consequences. It is hoped that the above research can attract people's attention, be vigilant about the quality of daily drinking water, and do not drink unhygienic and unhealthy water casually.
Written by | Muzijiu
Typography | Muzijiu
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Resources:
[1] Chambers T, Douwes J, Mannetje A, et al. Nitrate in drinking water and cancer risk: the biological mechanism, epidemiological evidence and future research. Aust N Z J Public Health. 2022 Mar 3. doi:10.1111/1753-6405.13222. Epub ahead of print. PMID: 35238441.
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