Are humans causing cancer in wild animals?

As humans, we know that some of our activities can cause cancer to develop in our bodies. Smoking, poor diets, pollution, chemicals used as additives in food and personal hygiene products, and even too much sun are some of the things that contribute to an increased risk of cancer.

But, are human activities also causing cancer in wild animals? Are we oncogenic -- a species that causes cancer in other species?

Researchers from Arizona State University's School of Life Sciences think so and are urgently calling for research into this topic. In a paper published online today in "Nature Ecology & Evolution," Mathieu Giraudeau and Tuul Sepp, both postdoctoral researchers in the lab of ASU life sciences professor Kevin McGraw, say that humans are changing the environment in a way that causes cancer in wild animal populations.

"We know that some viruses can cause cancer in humans by changing the environment that they live in -- in their case, human cells -- to make it more suitable for themselves," said Sepp. "Basically, we are doing the same thing. We are changing the environment to be more suitable for ourselves, while these changes are having a negative impact on many species on many different levels, including the probability of developing cancer."

In the paper, Giraudeau and Sepp and a team of international researchers, point out many pathways and previous scientific studies that show where human activities are already taking a toll on animals. These include chemical and physical pollution in our oceans and waterways, accidental release of radiation into the atmosphere from nuclear plants, and the accumulation of microplastics in both land- and water-based environments. In addition, exposure to pesticides and herbicides on farmlands, artificial light pollution, loss of genetic diversity and animals eating human food are known to cause health problems.

"Cancer in wild populations is a completely ignored topic and we wanted to stimulate research on this question," shared Giraudeau. "We recently published several theoretical papers on this topic, but this time, we wanted to highlight the fact that our species can strongly influence the prevalence of cancer in many other species of our planet.

"Cancer has been found in all species where scientists have looked for it and human activities are known to strongly influence cancer rate in humans. So, this human impact on wild environments might strongly influence the prevalence of cancer in wild populations with additional consequences on ecosystem functioning," he said.

Even something such as artificial light and light pollution, as well as food meant for humans, are negatively affecting wild animals.

Sepp said: "It is already known in human studies that obesity and nutrient deficiency can cause cancer, but these issues have been mostly overlooked in wild animals. At the same time, more and more wild species are in contact with anthropogenic food sources. In humans, it's also known that light at night can cause hormonal changes and lead to cancer. Wild animals living close to cities and roads face the same problem -- there is no darkness anymore. For example, in birds, their hormones -- the same that are linked to cancer in humans -- are affected by light at night. So, the next step would be to study if it also affects their probability of developing tumors."

While these scientists are urgently calling for studies on cancer and its causes in wild animal populations, they realize that this is no easy subject to study.

"The next step is definitely to go into the field and measure cancer rate in wild populations," said Giraudeau. "We are now trying to develop some biomarkers to be able to study this. I think it would be interesting to measure cancer prevalence in wild animals in human-impacted environments and also in more preserved areas for the same species."

If humans are the cause of cancer in wild animals, then many species may be more threatened than people realize. Yet Tuul said, there is reason to hold out hope.

"To me, the saddest thing is that we already know what to do. We should not destroy the habitats of wild animals, pollute the environment, and feed wild animals human food," shared Sepp. "The fact that everybody already knows what to do, but we are not doing it, makes it seem even more hopeless.

"But I see hope in education. Our kids are learning a lot more about conservation issues than our parents did. So, there is hope that the decision-makers of the future will be more mindful of the anthropogenic effects on the environment."

Global warming: Humans responsible for 60% loss of sea ice, study shows

That human activity is a cause of global warming and changing temperatures is a fact that cannot be debated, but until now, scientists had little clue as to what was the extent of damage due to human intervention.

That human activity is a cause of global warming and changing temperatures is a fact that cannot be debated, but until now, scientists had little clue as to what was the extent of damage due to human intervention. A paper published in Nature, based on model simulations of different climate conditions, shows that humans may be responsible for 50-70% change in climate conditions, leading to melting of ice at the Arctic sea. Although the study absolved humans for air flow changes, 70% of which, it said, is due to natural variability, it pointed that 60% of sea ice decline since 1979 was caused by summer-time changes in atmospheric circulation.

While the study is expected to change how we observe climate change, it will also get us to alter our future predictions. With Arctic ice depleting fast—in January it was 1.26 million square kilometres, which was 8.6% below the 1981–2010 average—global warming would need coordinated action from governments. Policy turns in the US—Republicans have presented a bill in the Congress to do away with the country’s Environmental Protection Agency—will end up harming the environment. With global warming accompanying industrialisation, countries would need a concerted approach to tackle its ill-effects.

Global warming making oceans sick, spreading disease in humans and animals, scientists warn

Global warming is making the oceans sicker than ever before, spreading disease among animals and humans and threatening food security across the planet, a major scientific report said.

The findings, based on peer-reviewed research, were compiled by 80 scientists from 12 countries, experts said at the International Union for Conservation of Nature (IUCN) World Conservation Congress in Hawaii.

"We all know that the oceans sustain this planet. We all know that the oceans provide every second breath we take," IUCN director general Inger Andersen said at the meeting, which has drawn 9,000 leaders and environmentalists to Honolulu.

"And yet we are making the oceans sick."

The report, Explaining Ocean Warming, is the "most comprehensive, most systematic study we have ever undertaken on the consequence of this warming on the ocean", co-lead author Dan Laffoley said.

The world's waters have absorbed more than 93 per cent of the enhanced heating from climate change since the 1970s, curbing the heat felt on land, but drastically altering the rhythm of life in the ocean, he said.

Mr Laffoley, marine vice chair of the World Commission on Protected Areas at IUCN, said "the ocean has been shielding us and the consequences of this are absolutely massive".

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Warming likely to change turtle sex ratio

The study included every major marine ecosystem, containing everything from microbes to whales, including the deep ocean.

It documents evidence of jellyfish, seabirds and plankton shifting toward the cooler poles by up to 10 degrees latitude.

Mr Laffoley said the movement in the marine environment was "1.5 to five times as fast as anything we are seeing on the ground."

"We are changing the seasons in the ocean."

The higher temperatures will probably change the sex ratio of turtles in the future, because females are more likely to be born in warmer temperatures.

The heat also means microbes dominate larger areas of the ocean.

"When you look overall, you see a comprehensive and worrying set of consequences," Mr Laffoley said.

Evidence warming causing plant, animal disease

ore than 25 per cent of the report's information is new, published in peer-reviewed journals since 2014, including studies showing global warming is affecting weather patterns and making storms more common.

The study includes evidence ocean warming "is causing increased disease in plant and animal populations", it said.

Pathogens such as cholera-bearing bacteria and toxic algal blooms that can cause neurological illnesses such as ciguatera poisoning spread more easily in warm water, with direct impact on human health.

"We are no longer the casual observers in the room," Mr Laffoley said.

"What we have done is unwittingly put ourselves in the test tube where the experiment is being undertaken."

Coral reefs killed off at unprecedented rate

 

Meanwhile, the hotter oceans have killed off coral reefs at an unprecedented rate, reducing fish species by eliminating their habitats.

The loss of reefs cuts down on the abundance of certain fish, with implications for food security.

"In South-East Asia, harvests from marine fisheries are expected to fall by between 10 per cent and 30 per cent by 2050, relative to 1970-2000, as the distributions of fish species shift," the report said.

The report highlights the need for swift action on renewable energies, experts said.

"We need to cut greenhouse gases," director of the global marine and polar program at IUCN Carl Gustaf Lundin said.

"There is no doubt in all our minds that we are the cause of this.

"We know what the solutions are. We need to get on with it."

AFP

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