Cancer rates higher in cold, wet climates

Rain may cause a cancer-causing gas to be released from soil. [Photo: Getty]

Hot, sunny climes are known to increase our risk of skin cancer.

And now research suggests living in cold, wet areas may also trigger malignant tumours.

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Scientists from the West Chester University of Pennsylvania looked at cancer rates across 15 US states.

They found areas with high rainfall and cold temperatures had significantly higher incidences of the disease.

Although unclear exactly why this occurs, rain and moisture in the air may act as “carriers” for cancer-causing substances, the scientists claim.

Cancer is responsible for a quarter of all deaths in the US, the scientists wrote in the journal Environmental Engineering Science.

In the UK, half of people born after 1960 will develop the disease at some point in their life, Cancer Research UK statistics show.

Although common throughout the US, cases are “clustered towards the east coast”, which has been put down to “racial, ethnic, behavioural, social, economic and lifestyle factors”.

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To learn more about the effect of weather, the scientists analysed cancer registries from 15 states. Chosen at random, these included Arizona, California, New York, Texas and Utah.

In the first study of its kind, they then looked at the average rainfall and temperature of each state.

Results suggest a chilly climate raises the risk of total invasive cancer, when the disease spreads beyond where it developed into surrounding, healthy tissue.

It was also linked to breast, lung, colorectal, prostate and ovarian cancer.

Rainfall was associated with all the above, aside from ovarian cancer, the results show.

This remained true after the scientists adjusted for age and income.

Although chilly climes were linked to lung cancer, the disease was actually found to be most common in dry, hot regions.

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When it comes to the link between cold, wet weather and cancer, some point the finger at soil.

Soil is generally more acidic in the eastern US, the scientists wrote. This is thought to be due to rain washing away alkaline elements like calcium, magnesium and potassium.

Acidic soil and chilly weather may allow “ammonia-oxidising microorganisms” to thrive in soil. These convert ammonia to nitrites, which then become nitrous oxide.

Once released into the atmosphere, nitrous oxide is a known cancer-causing gas. It may also leach into underground water supplies, contaminating food and drink.

While excessive UV exposure is known to cause cancer, a lack of the “sunshine supplement” vitamin D may also trigger the disease.

Research even suggests working to maintain our body temperature in cold weather leads to “internal stress”, which could be damaging.

The scientists stress further research is required to understand how climate and rainfall may be linked to cancer.