Living near the Salton Sea reduces lung growth in children

Children who live within 11 kilometers of the Salton Sea, a drying body of water with high concentrations of salt and contaminants in California’s Imperial Valley, have slower lung function between the ages of 10 and 12 than children who live farther away. Its impact is equivalent to that of people living within 500 meters of a freeway and can affect respiratory health in adulthood. The study, partially funded by the National Institutes of Health, was recently published jama network open.

The Salton Sea is a salt lake near the United States–Mexico border that was formed in 1905 when the Colorado River was dammed by an irrigation canal. Today, the lake is shrinking due to drought, heat and diversion of water, exposing large areas of dry lake bed that release dust into the air in the form of fine particles. This type of pollution is known to increase the risk of lung, heart, immune and neurological problems.

Local surveys have tracked respiratory problems, including the incidence of asthma, but the Keck School of Medicine of USC-led group is the first to directly look at changes in lung capacity. Their findings on lung function patterns over time could have implications beyond the Imperial Valley, as drought and rising temperatures cause other lakes, such as the Great Salt Lake in Utah and the Aral Sea in Central Asia, to shrink and emit dust.

“Our findings are worrying because they may have long-term health implications. Research shows that if lung growth is reduced during a critical developmental period such as adolescence, it may increase the risk of respiratory, cardiovascular and metabolic diseases later in life,” said Fangqi Guo, PhD, a postdoctoral research associate in population and public health sciences at the Keck School of Medicine and first author of the study.

Lung function typically increases during adolescence, then peaks in young adulthood. More research is needed to understand what happens when growth is disrupted, but ongoing problems with lung capacity may have lasting health consequences.

Dust exposure and lung function

The Keck School of Medicine team worked with Comite Civico del Valle, a long-standing local community organization, to recruit children for the first long-term health study in the region. Researchers followed 369 children for about two years, whose average age was 10 years when the study began.

Lung function was measured in two ways: forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). FVC measures how much air the lungs can expel after taking a deep breath and FEV1 measures how fast that air can be expelled from the lungs. Overall, these measures help show whether air is flowing normally through the lungs.

The researchers also calculated the distance between each child’s home and the Salton Sea and obtained data on increased levels of fine particle pollution and dust from local air quality monitors. In their analysis, they controlled for the effects of age, sex, ethnicity, socioeconomic status, height, body mass index, and respiratory health at the beginning of the study.

Children who lived within 11 kilometers of the Salton Sea had 52.18 ml less per year increase in FVC and 38.7 ml less per year increase in FEV1 than children who lived further away. More hours of exposure to high dust levels were also associated with lower growth of FVC and FEV1, especially for children living close to the sea.

protecting long term health

These findings add to previous research from the group that showed more than 1 in 5 children in the area have asthma, almost three times the national average. Those findings suggest that if trends are not reversed, this population could face lung, heart and metabolic problems later in life.

Shohreh F., associate professor of population and public health sciences at the Keck School of Medicine and co-senior author of the study. Farzan, PhD, said, “We don’t yet know whether these changes are permanent. Some of the harm may be mitigated if environmental exposures are reduced, because children’s lungs are still developing.”

California officials are already working to address the environmental and health consequences of the drying lake through a 10-year plan called the Salton Sea Management Program. Researchers say more widespread action is needed in California and around the world to protect children’s health as hot, dry conditions get worse.

After this, the team will continue to monitor the children to see if the effects on lung function persist into adolescence and adulthood. They are also studying which components of the dust are most harmful as part of a broader investigation of air pollution in the Imperial Valley, including dust from the Salton Sea, wind-blown desert dust, diesel emissions and other sources.

About this research

In addition to Guo and Farzan, the study’s other authors are Sandra P. Eckel from the Department of Population and Public Health Sciences, Keck School of Medicine of USC, University of Southern California; Jill E. Johnston, Elizabeth M. Kamai and Dayane Duenas Barahona from the University of California, Irvine; Luis Olmedo, Esther Bejarano and Christian Torres from Comite Civico del Valle, Brawley, California; and Christopher Zuidema and Edmund Seto from the University of Washington, Seattle, Washington.

This work was supported by the National Institute of Environmental Health Sciences (NIEHS) Southern California Environmental Health Sciences Center (5P30ES007048-21S1; 5P30ES007048-22S1) and the Keck School of Medicine of USC 2017-2018 Dean’s Pilot Funding Program. Funding for extended enrollment and longitudinal follow-up of the cohort was provided by NIEHS (R01ES029598; 3R01ES029598-04S1).