Sulfur is a natural element that can be used in strawberries, grapes and other crops to protect fruit from powdery mildew, a fungal disease that results in damaged fruit, reported Eilis O'Neil on Reveal, a podcast produced by the Center for Investigative Reporting and PRX.
Because sulfur is natural, it can be used by organic and conventional farmers alike. And it is inexpensive.
"Farmers use tons of it," O'Neill said. "It's the most used pesticide in California and it's widely used in the rest of the country."
However, it is an irritant. People who accidentally breath it in can have irrigated eyes, sore throats or difficulty breathing.
"There's something about sulfur that makes people (react more strongly) every time that they're exposed to sulfur ... kind of like if you are allergic to a bee sting. So every subsequent time that you are stung, your body responds in a more severe way," Blecker said.
Brenda Eskenazi, a public health researcher at UC Berkeley, also appeared on the podcast. She said she had seen case reports about an increase in asthma symptoms in children who live near fields where sulfur was sprayed. Eskenazi and her colleagues followed the health of more than 500 children in the Salinas Valley from pre-birth to 7 years old.
"Kids that lived closer to where sulfur was applied had more asthma problems and also poorer lung function," Eskenazi said.
Blecker said that sulfur must be closely regulated.
"Anything that we do to reduce the offsite movement of pesticides is good, (such as) monitoring wind speed and direction," Blecker said. "A lot of grape growers do night applications because they are trying to just minimize the exposure to people because there's more people out during the day. If you're spraying in a situation where grapes are only on one side of you, it's best to be spraying into the vineyard."