Part 1: A conservation geneticist’s call to keep studying cancer in wildlife
Part 1 of 4: Environmental contaminants
The idea that cancer could cause human extinction may sound absurd. Until recently the same could have been said for most wildlife populations. However, over the past few decades, scientists have gained an improved, and occasionally shocking, perspective about the prevalence and impact of cancer in certain endangered species.
Cancer can affect animal populations by directly or indirectly leading to population declines. It can reduce reproductive success and alter population dynamics.
Some wildlife is experiencing an increase in cancer prevalence due to four main factors: pollution, viruses, genetic predisposition, and contagious cancers. Scientific discoveries regarding these factors may lead to healthier wild populations as well as healthier environments and lives for humans.
Follow this four-part series to learn more about the four main factors contributing to cancer in wildlife and why I want to use genetics to save endangered species.
Pollution, a chemical or substance in the environment, can be harmful because they act as a mutagen, an agent that causes changes (mutations) in the genetic code of living organisms. These environmental contaminants can cause cancer. For example, many of us are familiar with the warnings that various tobacco products cause lung cancer. However, for some human communities and many wild populations, the warning signs of pollution are non-existent and cannot be avoided, leading to an increase in cancer risk.
From small fish to large beluga whales, it is well established that cancer is showing up in a variety of marine animals likely due to contamination of marine water.
Ongoing research has shown that beluga whales, specifically ones in the St. Lawrence river estuary (Canada), live in waters with high levels of chemicals. These chemicals are released from burning coal, oil, gasoline, trash, tobacco, wood, or other organic substances and can cause cancer. Cancer is the second leading cause of death in this population of beluga whales. This may be the reason why the average age at death is much younger for these whales than other populations.
Fortunately, there has been a decline in the belugas’ cancerous tumors after the implementation of stricter regulation of the disposal of some toxic chemicals into the estuary.
Green sea turtles living in polluted water around the world are more likely to have skin tumors (called Fibropapillomatosis). Several other factors, such as viruses (more to come regarding viruses in the next Cancer in Wildlife Series blog post) and sun light, have also been associated with the development of this type of cancer. The incidence of these tumors has increased 10-fold over the past decade, but luckily affected turtles can be treated. First, turtles can undergo surgical removal of the tumor and then chemotherapy and treatment with the anticancer drug. Continuing research on treatment as well as preventative measures is necessary for the persistence of healthy sea turtles populations worldwide.
Thanks for reading and stay tuned for the next in my series about cancer in wildlife when I discuss viruses…those little buggers.