Research linking swimming in chlorinated pools to cancer and other medical conditions continues to make headlines. The latest such studies come from the Centre for Research in Environmental Epidemiology in Barcelona, Spain. They indicate, among other things, that swimming in a pool with chlorine may increase the risk of developing cancer and damage lungs. The studies, published this week in the journal Environmental Health Perspectives, also identified more than 100 chemical byproducts in pools that use chlorine as a disinfectant. But lead scientists in the studies are quick to admit that their research sample was small, and they stress that more research is necessary before drawing sweeping conclusions.

Here is a rundown of findings by the center's researchers: • In one study, scientists collected blood, urine and exhaled air samples from 49 non-smoking adults before and after they swam for 40 minutes in an indoor chlorinated pool. Researchers found that, after swimming, concentrations of four biomarkers (used as indicators of specific biological states) suggested toxicity from disinfection byproducts that can lead to cancer.

• A second study measured short-term changes in respiration to explore potential lung damage from swimming in chlorinated pools. Among 48 people who swam for 40 minutes, researchers found a slightly higher level of one particular biomarker that indicates cell damage in the lungs.

• A third study examined the health differences found in people who swam in public swimming pools disinfected with chlorine and those disinfected with bromine. While researchers discovered similar levels of disinfection byproducts in both types of pools, some of those byproducts have not previously been reported in either swimming pool water or drinking water, according to researchers.

Despite the results, CREAL's co-director Manolis Kogevinas says that nobody should stop swimming. Rather, facility operators and swimmers need "to encourage the reduction of chemicals in swimming pools to ensure disinfection" - thereby further increasing the positive health effects of swimming. He also suggests that facility operators pursue diligent pool-water management and enforce the shower-before-swimming rule, thus allowing swimmers to wash off much of the organic material that reacts with chlorine to produce toxic byproducts.

Alfred Bernard, a toxicologist at Catholic University of Louvain in Brussels, Belgium, told the chloramines are a major risk factor for rising rates of asthma, airway irritation and allergic diseases among swimmers - especially in babies and young children.