Animals living in cities may be more likely to get cancer – just like humans, a study suggests.
Light, chemical and noise pollution, food high in sugars, and viruses have all been found to increase the chances of humans getting cancer.
Now researchers suggest the same factors could be raising the risk of cancers in wild animals living in cities such as birds, squirrels, rats, mice and hedgehogs.
Researchers led by Giradeau Mathieu writing in Proceedings B of the Royal Society said: ‘Wild animal populations can be compared to prehistoric human populations, in which fossil data indicate a low prevalence of cancer.
‘It is clear that the characteristics of a modern lifestyle and the urbanising environment have brought along a change in cancer prevalence in humans, but so far little attention has been given to similar changes in wild animals.
The authors write: ‘It has only recently been proposed that human activities might increase the cancer rate in wild populations’.
Obesity is linked to 10 per cent of cancers in humans.
Feeding animals such as squirrels food such as bread – which is not a natural part of their diet – is leading to obesity although it will need more research to pinpoint the link, the authors suggest.
The researchers write ‘we suggest tourist fed small mammals such as squirrels in urban parks are a good place to start looking for links between anthropogenic food, obesity and cancer in wildlife.’
The authors say that further evidence that city life is bad for animals has been found in gulls and laboratory rats, both of which show more mutations living near major motorways or steel mills.
POLLUTION LEVELS ILLEGAL IN MOST UK MONITORING ZONES
The UK’s air pollution was labelled a ‘national embarrassment’ in September.
Figures for 2017 showed 37 out of 43 air quality zones across the UK had illegal levels of nitrogen dioxide pollution, the same number as the previous year.
Annual average levels of the pollutant from exhaust fumes fell in most places, figures from the Government and environmental law charity ClientEarth revealed.
But levels are still more than double the legal limit in Greater London and also well over the limit in areas including South Wales, West Midlands, Glasgow and Greater Manchester.
Brighton, Worthing and Littlehampton in West Sussex – an area declared as legal in the previous year – crept up to just below the threshold again, the statistics show.
The UK has been breaching EU pollution limits for nitrogen dioxide, much of which comes from diesel vehicles, since the rules came into effect in 2010.
Air pollution causes an estimated 40,000 premature deaths a year in the UK and is linked to health problems from childhood illnesses to heart disease and even dementia.
Pollution at sea is thought to be compromising the immune systems of sea turtles and sea lions making them more susceptible to cancer causing viruses.
Domestic cats living in cities are more likely to suffer the feline equivalent of the HIV infection, weakening their immune systems, and this makes them more likely to get cancer, the researchers state.
Cities can also lead to habitat fragmentation, which leads to greater inbreeding from populations due to barriers such as roads.
Light pollution has been found to increase cancer in humans.
Known as ALAN, artificial light at night, is also likely to trigger cancer in animals. The authors suggest that further research should look at the effects of light on birds – as the increased hormone levels due to higher light exposure have been linked to higher cancer rates.
SOURCE: Daily Mail, by COLIN FERNANDEZ