A matter of safety

Pool chlorine levels may be increased to prevent illness, but possible exposure raises concern

The city of Minneapolis’ recent recommendation to increase chlorine levels in wading and swimming pools is drawing praise from the state health department and nearby cities, but at least one parent is worried about children’s exposure to the chemical.

City officials say the increase is necessary to prevent water-borne illnesses, particularly intestinal bacteria such as E. coli and salmonella. There are no known cases of water-borne illness outbreaks in any of the 140 city pools, but Carl Samaroo of the city’s Environmental Health Division said it would be unwise to wait until an outbreak occurs. The Minneapolis Park and Recreation Board, which operates about 50 wading pools and two swimming pools, is reviewing the recommendation.

Below state standards The current standard for chlorine in swimming pools is .5 parts per million (ppm), and 1 ppm for wading pools–the same as the state minimum. Minneapolis proposes an increase in chlorine to 2 ppm in swimming pools and 3 ppm in wading pools–both of which are under the state maximum standards.

The state health department approves of the city’s recommendation, on which the city council has yet to vote.

"Under the kind of conditions you might see in a wading pool in the summertime, with sunlight and a lot of people swimming in the pool and therefore a high bacterial load, that is actually going to drive the chlorination levels down as the chlorine in effect gets used up by killing bacteria," said Buddy Ferguson of the Minnesota Dept. of Health. "There are concerns about what happens in a wading pool, especially if you have young children and they might be swallowing the water. There have been cases where, for example, E. coli has been transmitted that way–so it is a very prudent step they are taking, and one that we support."

Chlorine works by attacking the cell walls of microorganisms and bacteria and destroying enzymes within the cells, which renders the organic material harmless.

Nearby cities already operate pools with a higher level of chlorine to prevent levels from dipping too low. In St. Louis Park, the chlorine levels are between 1.5 and 2 ppm, and range from 1 to 1.5 ppm in Richfield. The wading pool in St. Louis Park has chlorine levels between 2 and 3 ppm.

"Chlorine on the heavier side is better than chlorine on the lighter side," said Craig Panning of the parks and recreation department of St. Louis Park. "It is more critical in wading pools because the smaller amount of water warms up quicker. Warmer water tends to breed bacteria easier, and the sun has the effect of burning out the chlorine. Plus, the more bodies in the pool–contaminating the water as they enter–the less chlorine."

Questions about by-products But Jackie Hunt Christensen, co-director of the food and health program for the Whittier-based Institute for Agriculture and Trade Policy, said she is not sure she wants to take her 5-year-old and 10-year-old boys to the park pools near her Nokomis home if more chlorine is added.

"Most standards have been around for awhile and they are created for adults," she said. "It’s very different for little kids who are closer to the surface of the water and probably drink the water as they are splashing around. And kids spend a lot of time in the pool in the summer."

Hunt Christensen said she worries about children breathing in the by-products of the chlorine process, such as chloroform. She would like to see the city test the levels of chloroform at the water’s surface to ensure they are safe for children. She would also like to see research into chlorine alternatives, such as ozone or ionization.

The ozonation process, which removes organic and inorganic contaminants and does not produce any carcinogenic by-products, was used at the 1996 Summer Olympics in Atlanta.

"Because kids breathe more air per unit of body weight, and drink more pool water, and are lower to the ground, and put their hands in their mouths, and their systems aren’t fully developed–these are all reasons why we should proceed with caution," Hunt Christensen said.

The U.S. Environmental Protection Agency (EPA) has determined that chloroform is a probable human carcinogen, but studies have focused on chloroform and other by-products that are ingested (through drinking water), not inhaled or absorbed through the skin. Scientists at EPA said the agency doesn’t regulate swimming pools for trihalomethanes, which includes chloroform.

Limited studies In fact, chlorine levels in swimming pools have received hardly any attention from scientists. The Southwest Journal found no studies being conducted to determine children’s exposure to or risk from chlorine or chlorine by-products from swimming or wading pools, and only one study on 11 adult males exposed to chloroform when swimming in indoor pools. The 1994 study said swimming is an important source of exposure to chloroform. Other studies have noted that people breathe in chlorine by-products when bathing in chlorinated water.

Park Board Commissioner Ed Solomon will watch for signs in children if chlorine levels are increased.

My concern is "from past experience," he said. "Too much chlorine and you get burning in your eyes. And the wading pools have the closest connection with kids. We are at a point where we can investigate why we need to do this. They are finding more fecal matter in wading pools. But part of what we can do is educational — people have to understand what happens to it when it goes in a wading pool. It can end up in another kid’s mouth.

"I guess my feeling is if we don’t have to [increase the chlorine levels] and if there is no danger, we won’t," Solomon said.