Algal blooms posing risks to human health are becoming more frequent

To beat the summer heat, people are rushing to nearby lakes only to find a thick green film coating the water’s surface. 

Harmful algal blooms are popping up more frequently across the U.S., and new research suggests that they may cause serious lifelong health problems.

Like the algal blooms that have killed sea lions and dolphins across the Southern California coast, the cyanobacterial algal blooms found in fresh waterways throughout the state produce toxins while growing.

The blooms are “alarming because it does not take a huge amount of these toxins to affect human health,” especially for people with medical conditions such as chronic liver or kidney disease, polycystic ovarian syndrome, obesity, or type 2 diabetes, Saurabh Chatterjee, a professor of environmental and occupational health at UC Irvine, said. 

Cyanobacterial algal blooms

The cyanobacterial algal blooms are made of bacteria, not algae, even though their blueish-green color and name may suggest otherwise, Chatterjee said. They are a kind of bacteria that researchers have identified in freshwater lakes, brackish water, and estuaries. 

These blooms are showing up in new places and more frequently due to rising temperatures and runoff, he said.

The ashes from wildfires or the fertilizer from farming enrich the soil with nutrients, and heavy rain then pushes those nutrients into bodies of water where they feed the algae, especially by the coasts, he said.

While it grows, the cyanobacteria release a toxin called microcystin that hurts animals, such as the fish living in a pond or someone’s dog running along the edge of an impacted lake, Chatterjee said. 

Health risks in humans

The blooms “ultimately affect us because many households in this country get access to drinking water from the lakes,” he said, adding that people can be exposed to cyanobacteria by jumping in contaminated water or eating an oyster that had ingested some bacteria. 

“There is no foolproof method to completely eliminate microcystins from drinking water at this point of time, but there are a number of studies being carried out in association with EPA as well as the state’s environmental health department to make sure that we do not have signs of bacterial toxins,” he said.

Though people with underlying conditions are more likely to develop diseases after being exposed to the harmful algal blooms, Chatterjee said that anyone could be impacted.

“Low doses of these toxins can actually alter the reproductive pathways in a fashion that affects not only the female reproductive system but also the male reproductive system,” he said. Research suggests that microcystin causes irregular menstrual cycles and infertility related to ovulatory disorders.

Though an individual may appear healthy following an exposure, Chatterjee said that cyanobacteria can weaken one’s immune system by harming one’s gut microbiome, making it harder to fight off an illness in the future.

Prevention

The only public health measure people can take is advising recreational parks to close a body of water when there is a bloom, Chatterjee said. 

“However, you cannot do anything for the fish because you cannot tell the fish ‘Don't come into the lake and swim’ because they are there,” he added.

Chatterjee said that removing algae from a lake is only a short-term solution. “There is absolutely no strategy to counter the long-term effects because, with climate change, this is going to come back year after year.”

He suggested that one solution could be preventing runoff from entering bodies of water, but that “for the heat, we can't do anything unless and until we have a roadmap of the changing climate.”

People should wait six months before visiting a place where there have been blooms and contact a physician if they are experiencing symptoms from an exposure, but “you can only treat the symptoms. You cannot treat the cause because you are already exposed to it,” he said.