SAN FRANCISCO -- A new study by the University of California, Berkeley, suggests that elemental sulfur, the most heavily used pesticide in California, may harm the respiratory health of children living near farms that use the pesticide.

Published this week in the journal Environmental Health Perspectives, the study establishes associations between elemental sulfur use and reduced lung function, more asthma-related symptoms and higher asthma medication use in children living about a half-mile, namely 800 meters, or less from recent elemental sulfur applications compared to unexposed children.

The research was conducted at the agricultural community in Salinas Valley, south of San Francisco Bay.

Generally considered to be safe for the environment and human health by the US Environmental Protection Agency (EPA), elemental sulfur is allowed for use on conventional and organic crops to control fungus and other pests. It is the most heavily used agricultural pesticide in California and Europe, according to a news release from UC Berkeley. In California alone, more than 21 million kilograms of elemental sulfur were applied in agriculture in 2013.

However, previous studies have shown that elemental sulfur is a respiratory irritant to exposed farm workers. The chemical's effect on residential populations, especially children, living near treated fields has not previously been studied despite its widespread use and potential to drift from the fields where it is applied.

In the first study to link agricultural use of sulfur with poorer respiratory health in children living nearby, Rachel Raanan, a UC Berkeley postdoctoral fellow and the study's lead author, and her colleagues examined lung function and asthma-related respiratory symptoms in hundreds of children living near fields where sulfur had been applied, leading to the discovery of several associations between poorer respiratory health and nearby elemental sulfur use.

Among them, a 10-fold increase in the estimated amount of elemental sulfur used within 1 kilometer of a child's residence during the year prior to pulmonary evaluation was associated with a 3.5-fold increased odds in asthma medication usage and a two-fold increased odds of respiratory symptoms such as wheezing and shortness of breath; and each 10-fold increase in the amount of sulfur applied in the previous 12 months within a one-kilometer radius of the home was associated with an average decrease of 143 milliliters per second (mL/s) in the maximal amount of air that the seven-year-old children could forcefully exhale in one second.

 For comparison, the research has shown that exposure to maternal cigarette smoke is associated with a decrease of 101 mL/s after five years of exposure.

The study's authors call for more research to confirm these findings and possible changes in regulations and application methods to limit impacts of sulfur use on respiratory health.  (Xinhua)