A toxin from blue-green algae poisoned a child playing in a southern Iowa lake this summer. The same toxin has been blamed for the deaths of six dogs in Texas, North Carolina and Georgia.

So how do you keep children and pets safe while swimming and playing in Iowa lakes and ponds?

The best information comes from the Iowa Department of Natural Resources, which maintains details on water quality at more than 75 beaches.

The DNR tests 39 state park beaches for microcystins, the toxic byproduct of blue-green algae, as well as E. coli, an indicator of fecal bacteria from people and animals. It also posts water quality results from dozens of private lakes.

When water quality slips below state standards, the DNR issues an advisory and posts “Swimming is Not Recommended” signs at state beaches.

However, a Des Moines Register report Tuesday revealed that the state uses less restrictive standards for blue-green algae toxins than those recommended by the federal Environmental Protection Agency.

More:Iowa uses less restrictive standards than EPA guidance for blue-green algae toxins

The EPA recommends that states limit water recreation when microcystins reach 8 micrograms per liter. The state allows 20 micrograms per liter before issuing a swim advisory.

Even when state swimming advisories are not in place, parents and pet owners should be wary if the water looks "green and scummy," said Mary Skopec, executive director of Iowa Lakeside Laboratory in Milford.

Children and pets are more at risk of microcystin poisoning because of their small size — and because they're likely to play near the shore where toxins are concentrated, Skopec said.

Toxic blue-green algae can carry an odd smell as well, experts say.

"We know that dogs like to find things that don't smell the best and roll around and eat that," she said.

And if dogs have gotten into blue-green algae, Skopec said owners should quickly rinse them off with clean water and dry them. Otherwise, pets will lick their fur to dry it, getting continued exposure to microcystin cells, she said.

People who accidentally swallow water containing microcystin can develop gastrointestinal symptoms, such as nausea, vomiting and diarrhea, the Iowa Department of Public Health says.

Other symptoms can include cough, runny eyes and nose, sore throat, and asthma-like symptoms. Skin rashes also can develop. In severe cases, liver failure can occur.

"It can be very scary, which is why we want to be especially careful of children's exposure," Skopec said.

The Iowa Environmental Council and other groups want the state to adopt EPA's guidance on microcystin levels.

"Because of the low body weight of children, their susceptibility is higher, which is why EPA recommended a lower level for advisories," Skopec said. "You can see a severe reaction in a relatively short amount of time."

"We want families to be able to recreate in water in ways that lower the risks," she said.

Donnelle Eller covers agriculture, the environment and energy for the Register. Reach her at deller@registermedia.com or 515-284-8457.