A recent UC Davis study found that as Central Valley residents go about their day, they regularly breathe in pesticides, including one that has been banned in California and another whose effects on people is unclear.

The study, which was conducted in 2022 with the help of Central Valley residents, found that seven of 31 adults and one out of 11 children were exposed to detectable amounts of pesticides, including chlorpyrifos, which was banned by the state in 2020 after research showed it had a harmful neurodevelopmental effect on children.

The researchers recruited volunteers to wear backpacks with air-collection tubes for at least eight hours a day. They found that the residents were exposed to five other pesticides including 1,3-dichloropropene, also known as 1,3-D, a pesticide used to eradicate parasitic worms that has been banned in more than 20 countries, and penthiopyrad, a fungicide used to prevent mold and mildew that has not yet been studied for its effect on mammals, so the human impact is unknown.

It concluded that pesticide monitoring should be expanded because residents’ personal exposure included compounds not regularly measured in routine monitoring and that the pesticides should undergo additional toxicity testing.

“It really highlights the need that we research the health impact of all these different pesticides that are being used because people are being exposed to a range of pesticides,” said Deborah Bennett, a scientist, UC Davis professor and lead author of the study, which was published Sept. 10 in the Journal of Exposure Science and Environmental Epidemiology.

Bennett said she was surprised to find detectable amounts of chlorpyrifos because farmers were supposed to have stopped applying the pesticide. It was commonly used on alfalfa, almonds, citrus, cotton, grapes and walnuts. Before it was banned, more than 900,000 pounds of chlorpyrifos were used in 2017 — more than in any other state. The primary manufacturer of the pesticide announced in 2020 that it would stop producing it due to reduced demand.

It could be that a farmer was using the last of their reserves, or the individuals who tested for chlorpyrifos might have been exposed at home with products that use the pesticide, Bennett said, but researchers were ultimately unable to determine the cause.

Leia Bailey, deputy director of communications and outreach for the state Department of Pesticide Regulation, said the agency did not have enough information to investigate the findings independently, but the department continues to enforce the ban on chlorpyrifos and maintains four air monitoring stations in areas where pesticides are used.

She added that a preliminary review of the pesticide levels cited in the study found that they were “significantly below health screening levels.” Still, Bailey said, studies like this one complement the department’s work to inform their regulatory efforts.

“Community-focused studies like this are key inputs to inform our continuous evaluation of pesticides,” Bailey said.

She added that the department requires mammalian toxicology data for all pesticide evaluations, including penthiopyrad.

Jane Sellen, co-director of the Californians for Pesticide Reform and co-author of the study, said she wasn’t surprised by the “toxic soup” of pesticides that they found through the study.

“There’s not nearly enough pesticide monitoring happening in the state,” Sellen said.

They recruited volunteers for the study in farmworking communities, and found that people were eager to participate because they wanted to know what they were being exposed to, she said. The volunteers were told to go about their regular day and wear the backpacks wherever they went, including to the grocery store, work and school. She said exposure to or illness from pesticides does not get reported as frequently as it occurs because people are afraid of being retaliated against or deported, as many farmworkers are in the U.S. without authorization.

When the researchers were recruiting volunteers, the Tulare County Agricultural Commissioner Tom Tucker issued an advisory warning farmers to be “on the lookout for people trespassing onto orchards and farms” during or immediately after pesticide applications. The advisory asked residents to call Tucker’s office or the county sheriff.

“We are concerned these individuals may attempt to enter a field or orchard during a pesticide application or immediately thereafter to utilize their air monitoring equipment in an attempt to detect pesticide spraying,” the advisory stated.

The advisory, issued June 22, 2021, cited fliers that sought volunteers to wear backpacks. But those behind the study never asked participants to trespass or go near where pesticides were being applied, Sellen said.

The state Environmental Protection Agency and Tucker later issued a joint statement clarifying the advisory and described the study as a project supported by the Air Resources Board and consistent with the Legislature’s intent to support community-led air monitoring.

“The last thing we would ever do is send anyone into harm’s way,” she said. “It was really disheartening and disappointing that [the agricultural community] was threatened by the idea of monitoring air quality in these communities.”

The communities, which were not named in the study, were in Kern, Fresno and Tulare counties, which have the highest pesticide applications in the state.

A San Fernando Valley resident is the first person in L.A. County to die this year from West Nile virus, a mosquito-transmitted illness that can cause lethal inflammation in the brain.

The L.A. County Department of Public Health reported on Thursday that the patient died from neurological illness caused by severe West Nile. So far in 2024, there have been 14 confirmed cases of the virus in the county and 63 in the state, according to state and county public health departments.

“To the family and friends grieving the loss of a loved one due to West Nile virus, we extend our heartfelt condolences,” said Muntu Davis, L.A. County health officer. “This tragic loss highlights the serious health risks posed by mosquito-borne diseases, such as West Nile virus, dengue, and others.”

West Nile virus is the most common mosquito-borne disease that harms residents in L.A. County. The disease lives in infected birds and is transmitted to humans via mosquito bites.

Davis recommended Angelenos take simple steps to protect themselves from mosquito bites. This includes using insect repellent, getting rid of items that hold standing water around the home — such as flowerpots and bird baths — and using screens on doors and windows to keep mosquitoes out.

Most people who are infected will not experience any symptoms, but 1 in 5 will suffer a fever with symptoms including:

• headache
• body ache
• joint pain
• vomiting
• diarrhea
• rash

About 1 in 150 people will experience more severe symptoms such as high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness and paralysis, according to the World Health Organization. The Department of Public Health recommends anyone with severe symptoms call their doctor immediately.

In serious cases, the virus can cause inflammation of the brain or spinal cord, leading to permanent neurological damage or death. People older than 50 and those with health problems are at greater risk of complications, according to the Public Health Department.

The disease was first found in Africa before being discovered in the U.S. in 1999 and California in 2003. Since then the state has reported more than 300 deaths and 7,500 cases.

This year, there have also been deaths reported in Santa Clara County, Contra Costa County and Fresno County. Orange County reported its first case of West Nile in August, but so far there have been no deaths.

A respiratory virus that in rare cases can cause polio-like paralysis in children is on the rise in California and across the nation, according to wastewater analyses.

Enterovirus D68 was detected in 207 out of 268 samples taken from wastewater sites across the nation in the last 10 days, says the nonprofit WastewaterSCAN.

In the same time period, EV-D68 was detected at a medium level at 17 wastewater sites in California, including facilities in Los Angeles, San Diego, San Francisco, Sacramento and San Jose. Because humans shed viruses in waste, wastewater sampling is used to measure the prevalence of infection in a community.

Most people who contract EV-D68 will experience slight respiratory symptoms or none at all, according to the Centers for Disease Control and Prevention. Nevertheless, its spread is troubling because the virus can lead to a rare and debilitating neurological condition called acute flaccid myelitis, or AFM.

AFM attacks motor neurons in the spinal cord’s gray matter, which controls movement. This causes muscles and reflexes to weaken and, in severe cases, can lead to paralysis and death, according to the CDC.

Around 90% of cases occur in children, and there is no known treatment.

Dr. Robert Kim-Farley, an epidemiologist and infectious diseases expert with the UCLA Fielding School of Public Health, told The Times that the best way to avoid contracting EV-D68 is to practice common respiratory hygiene.

“This is covering your coughs and sneezes, it’s washing hands,” he said, “If you’ve been around someone who’s coughing and sneezing … make sure that you haven’t touched contaminated surfaces that they’ve been touching or shared cups or utensils.”

This year, the CDC has confirmed 13 cases of AFM, including one in California, as of Sept. 3.

The largest known outbreak of the illness took place in 2018, when 238 cases were confirmed across the country. Cases also spiked in 2014 and 2016.

Most cases of EV-D68 will be mild and feel like a common cold. However, children with asthma are at higher risk of experiencing more severe symptoms, according to the CDC.

Here are some common symptoms of EV-D68:

• Runny nose
• Sneezing
• Cough
• Body aches
• Wheezing and difficulty breathing

If the virus progresses to cause AFM, symptoms include:

• Arm or leg weakness
• Difficulty swallowing or slurred speech
• Difficulty moving the eyes and drooping in the eyelids and face

Kim-Farley recommends people seek medical care if they develop any evidence of paralysis or weakness in the limbs or muscles after having had a respiratory or fever-inducing illness one to two weeks prior.

The paralysis caused by AFM is very similar to that caused by polio — which, like EV-D68, is also an enterovirus.

Polio was eradicated in the Unites States in 1979, thanks to a widespread vaccination campaign, according to the CDC. Unfortunately, there is no vaccine for EV-D68.

“Even though [EV-D68] is not vaccine-preventable, it’s always a good opportunity to realize there are other diseases that cause paralysis, like polio, that are vaccine-preventable” and against which children can be inoculated, Kim-Farley said.

He also recommended getting the latest COVID-19 vaccine.