Science
Mosquito season is upon us. So why are Southern California officials releasing more of them?
Jennifer Castellon shook, tapped and blew on a box to shoo out more than 1,000 mosquitoes in a quiet, upscale Inland Empire neighborhood.
The insects had a job to do, and the pest scientist wanted every last one out.
Aggressive and impactful reporting on climate change, the environment, health and science.
Their task? Find lady mosquitoes and mate.
But these were no ordinary mosquitoes. Technicians had zapped the insects, all males, with radiation in a nearby lab to make them sterile. If they achieve their amorous quest, there will be fewer baby mosquitoes than there would be if nature ran its course. That means fewer mouths to feed — mouths that thirst for human blood.
“I believe, fingers crossed, that we can drop the population size,” said Solomon Birhanie, scientific director for the West Valley Mosquito and Vector Control District, which released the mosquitoes in several San Bernardino County neighborhoods this month.
Sterilized male Aedes mosquitoes are released from a box in Rancho Cucamonga.
(Myung J. Chun / Los Angeles Times)
Controlling mosquitoes with mosquitoes
Mosquito control agencies in Southern California are desperate to tamp down an invasive mosquito — called Aedes aegypti — that has exploded in recent years. Itchy, unhappy residents are demanding it. And the mosquitoes known for fierce ankle biting aren’t just putting a damper on outdoor hangouts — they also spread disease.
The low-flying, day-biting mosquitoes can lay eggs in tiny water sources. A bottle cap is fair game. And they might lay a few, say, in a plant tray and others, perhaps, in a drain. Tackling the invaders isn’t easy when it can be hard to even locate all the reproduction spots. So public health agencies increasingly are trying to use the insects’ own biology against them by releasing sterilized males.
The West Valley district, which covers six cities in San Bernardino County, rolled out the first program of this kind in California last year. Now they’re expanding it. Next month, a vector district covering a large swath of Los Angeles County will launch its own pilot, followed by Orange County in the near future. Other districts are considering using the sterile insect technique, as the method is known, or watching early adopters closely.
On the plus side, it’s an approach that doesn’t rely on pesticides, which mosquitoes become resistant to, but it requires significant resources and triggers conspiracy theories.
“People are complaining that they can’t go into their backyard or barbecue in the summer,” Birhanie said at his Ontario lab. “So we needed something to strengthen our Aedes control.” Of particular concern is the Aedes aegypti, which love to bite people — often multiple times in rapid succession.
Releasing sterilized male insects to combat pests is a proven scientific technique, but using it to control invasive mosquitoes is relatively new.
Vector control experts often point to the success of a decades-long effort in California to fight Mediterranean fruit flies by dropping enormous quantities of sterile males from small planes. That program, run by the U.S. Department of Agriculture and the California Department of Food and Agriculture, costs about $16 million a year. That’s nearly four times West Valley’s annual budget.
So rather than try to tackle every nook and cranny of the district, encompassing roughly 650,000 residents, West Valley decided to use a more targeted approach. If a problem area reaches a certain threshold — over 50 mosquitoes counted in an overnight trap — it becomes a candidate.
1
2
3
4
5
1. Solomon Birhanie inspects a container of mosquito larvae in the lab at the West Valley Mosquito and Vector Control District in Ontario. 2. Birhanie and his team raise mosquitoes in the lab, separating them by sex, because only the males, which don’t bite humans, will eventually be released. 3. Mosquito eggs in the West Valley lab. 4. The lab can grow about 10,000 mosquitoes at a time. 5. Before the male mosquitoes are released, an X-ray machine sterilizes them. If the zapped males mate with a female, her eggs won’t hatch. (Allen J. Schaben / Los Angeles Times)
And it’s still a big lift. About 10,000 mosquitoes are reared at a time at West Valley’s facility, about half of which will be males. The males are separated out, packed into cups and placed into an X-ray machine that looks like a small refrigerator. The sterilizing process isn’t that different from microwaving a frozen dinner. Zap them on a particular setting for four to five minutes and they’re good to go.
Equipment purchased for the program costs roughly $200,000, said Brian Reisinger, spokesperson for the district. He said it was too early to pin down a cost estimate for the program, which is expanding.
Some districts serving more people are going bigger.
The Greater Los Angeles County Vector Control District plans to unleash up to 60,000 mosquitoes a week in two neighborhoods in Sunland-Tujunga from mid-May through November.
With the sterile-insect program, “the biggest hurdle we’re up against really is scalability,” said Susanne Kluh, general manager of the L.A. County district, which is responsible for nearly 6 million residents across 36 cities.
In part to save money, Kluh’s district has partnered with the Orange County Mosquito and Vector Control District. They’re sharing equipment and collaborating on studies, but L.A. County’s releases will move forward first, said Brian Brannon, spokesperson for the O.C. district. Orange County expects to release its “ankle biter fighters,” as Brannon called them, in Mission Viejo this fall or next spring.
So far, the L.A. County district has shelled out about $255,000 for its pilot, while O.C. has spent around $160,000. It’s a relatively small portion of their annual budgets: L.A. at nearly $25 million and O.C. at $17 million. But the area they’re targeting is modest.
Mosquito control experts tout sterilization for being environmentally friendly because it doesn’t involve spraying chemicals, and it may have a longer-lasting effectiveness than pesticides. It can also be done now. Other methods involving genetically modified mosquitoes and ones infected with bacteria are stuck in an approval process that spans federal and state agencies. One technique, involving the bacteria Wolbachia was recently approved by the Environmental Protection Agency and is now heading to the California Department of Pesticide Regulation to review, said Jeremy Wittie, general manager for the Coachella Valley Mosquito and Vector Control District.
“Using pesticides or insecticides, resistance crops up very quickly,” said Nathan Grubaugh, associate professor of epidemiology at the Yale School of Public Health.
Vector control experts hope the fact that the sterilization technique doesn’t involve genetic modification will tamp down conspiracy theories that have cropped up around mosquito releases. One erroneous claim is that a Bill Gates-backed effort to release mosquitoes was tied to malaria cases in Florida and Texas. Reputable outlets debunked the conspiracy theory, pointing out that Gates’ foundation didn’t fund the Florida project and that the type of mosquito released (Aedes) does not transmit malaria.
To get ahead of concerns, districts carrying out the releases say they’ve engaged in extensive outreach and education campaigns. Residents’ desire to rid themselves of a scourge may overcome any anxieties.
“I think if you have the choice of getting eaten alive by ankle biters or having a DayGlo male X-rayed mosquito come by looking for a female to not have babies with, you’d probably go for the latter,” Brannon said. (“DayGlo” is a riff on the fluorescent pigment product of the same name — the sterilized mosquitoes were dusted with bright colors to help identify them.)
Sterilized male mosquitoes buzz around vector ecologist Jennifer Castellon as they are released in Rancho Cucamonga earlier this month.
(Myung J. Chun / Los Angeles Times)
Disease at our doorstep
As the climate warms and some regions become wetter, dengue is expanding to areas it’s never been seen before — and surging in areas where it’s established. Florida has seen alarming spikes in the viral infection in recent years, and Brazil and Puerto Rico are currently battling severe outbreaks. While most people infected with dengue have no symptoms, it can cause severe body aches and fever and, in rare cases, death. Its alias, “breakbone fever,” provides a grim glimpse into what it can feel like.
In October of last year, the city of Pasadena announced the Golden State’s first documented locally transmitted case of dengue, describing it as “extremely rare” in a news release. That same month, a second case was confirmed in Long Beach. Local transmission means the patient hadn’t traveled to a region where dengue is common; they may have been bitten by a mosquito carrying the disease in their own neighborhood.
Surging dengue abroad means there’s more opportunity for travelers to bring it home. However, Grubaugh said it doesn’t seem that California is imminently poised for a “Florida-like situation,” where there were nearly 1,000 cases in 2022, including 60 that were locally acquired. Southern California in particular lacks heavy rainfall that mosquitoes like, he said. But some vector experts believe more locally acquired cases are inevitable.
Ale Macias releases sterilized male mosquitoes in Upland this month.
(Myung J. Chun / Los Angeles Times)
Set them free
In mid-April, a caravan of staffers from the West Valley district traveled to five mosquito “hot spots” in Chino, Upland and Rancho Cucamonga — where data showed mosquito levels were particularly high — to release their first batches of sterilized male mosquitoes for the year. Peak Aedes season is months away, typically August to October in the district, and Birhanie said that’s the point. The goal is to force down the numbers to prevent an itchy tsunami later.
Males don’t bite, so the releases won’t lead to more inflamed welts. But residents might notice more insects in the air. Sterilized males released by West Valley will outnumber females in the wild by at least 100 to 1 to increase their chances of beating out unaltered males, spokeperson Reisinger said.
“They’re not going to be contributing to the biting pressure; they’re just going to be looking for love,” as Reisinger put it.
Eggs produced by a female after a romp with a sterile male don’t hatch. And female mosquitoes typically mate only once, meaning all her eggs are spoiled, so to speak. Vector experts say the process drives down the population over time.
Interestingly, the hot spots were fairly spread out across the district, indicative of the bloodsuckers’ widespread presence and adaptive nature. A picturesque foothills community in Upland was “especially interesting” because of its relatively high elevation, Birhanie said.
It was once inhabited primarily by another invasive mosquito that prefers colder, mountainous climates. Construction and deforestation in the area has literally paved the way for its humidity- and heat-loving brethren to move in.
Another neighborhood, in Rancho Cucamonga, posed a mystery. For the last two years, mosquito levels were consistently high. Door-to-door inspections, confoundingly, didn’t reveal the source.
“That’s one of the things about invasive Aedes mosquitoes — you can’t find them,” he said.
Next steps
Some vector control experts want to see a regional approach to sterile mosquito releases, similar to the state Medfly program.
Jason Farned, district manager for the San Gabriel Valley Mosquito and Vector Control District, believes a widespread effort “would be much more effective” and thinks that will come in time.
There are no talks underway to make it happen, and it’s not yet clear how it would work. Vector control agencies are set up to serve their local communities.
Fears of a bad mosquito year ahead are bubbling as the weather warms. Rain — which there was plenty of this spring — can quickly transform into real estate for mosquito reproduction.
When the swarms come, mosquito haters can take typical precautions: dump standing water and wear repellent. And they can root for the sterile males to get lucky.
Science
After bold pledge, EPA shelves microplastics testing in U.S. drinking water
For the next five years, the Environmental Protection Agency has indicated it will not require public water utilities to test for microplastics or pharmaceuticals in drinking water, according to a proposed rule published in the Federal Register.
On Friday, the EPA submitted a list of chemicals it plans to test for under the Unregulated Contaminant Monitoring Rule, a mandatory testing program used to collect information about concerning chemicals in drinking water that could be harming human health. It did not include microplastics or pharmaceuticals.
The omissions come after announcements by EPA Administrator Lee Zeldin earlier this year that his agency was designating microplastics and pharmaceuticals priority contaminants for testing.
“This is a direct response to the concern of millions of Americans who have long demanded answers about what they and their families are drinking every day,” he said at an April news conference with Health and Human Secretary Robert F. Kennedy Jr. at EPA headquarters.
Zeldin’s announcement was seen at the time as a move to placate the increasingly disgruntled Make America Healthy Again contingent of Trump supporters.
Now the agency says it has no validated or standardized method to test for the plastic particles in drinking water, and wouldn’t be able to develop one before December, when testing is required to begin.
Among the 33 chemicals the EPA will require water utilities to test for are seven PFAS, or forever chemicals, and three pesticide residues.
It will be five years before the EPA proposes another list.
The EPA did not respond to a request for comment.
The agency noted in its proposed rule that it will collaborate with other federal agencies to “evaluate risks and exposures” of microplastics for future monitoring.
Environmentalists reacted with frustration and resignation. They pointed out that the European Union has developed methods to test for the tiny plastic particles, which have been found in people’s blood, brains and lung tissue. California has one in the works.
“The California water board has spent a lot of time and money on how to measure in drinking water,” said Judith Enck, a former EPA regional administrator and president of the anti-plastic environmental group Beyond Plastics. “EPA should give them a call.”
California was required by a 2018 state law to establish a protocol for local water utilities to test for the particles in drinking water. The state has not yet begun reporting its results, but protocols were established in 2021. Blair Robertson, a spokesman for the State Water Resources Control Board, said it’s not “a fully validated, end-to-end regulatory method” yet.
At the April meeting, Zeldin announced that he would place microplastics on what is known as the Contaminant Candidate List, which acts as a preliminary “watch list” of unregulated, priority contaminants in drinking water. Like the mandatory monitoring list, it is updated only every five years. The most recent list was published on April 2 — the day he made his announcement.
“Americans have been ignored as they sound the alarm about plastics in their drinking water,” Zeldin said during the announcement. “That ends today by placing microplastics on the contaminant candidate list for the first time ever. EPA will follow the science, will pursue answers and will hold ourselves to the highest standards to protect the health of Americans.”
There appears to be no clear association between these two lists, although the contaminant list is supposed to inform the monitoring list. Seventy-five chemicals and four chemical groups (microplastics, pharmaceuticals, PFAS chemicals, and disinfection byproducts) were listed on the 2026 contaminant list. Only seven of those chemicals were also on the proposed monitoring list (as well as seven PFAS chemicals).
When Zeldin announced microplastics as “‘a priority contaminant for regulation,’ and called it ‘a historic action on microplastics,’ he made it seem like the administration was going to take microplastics seriously,” said Mary Grant, water policy director for the environmental group Food & Water Watch.
“By not including them, they made it clear they don’t actually have plans to immediately address this crisis by getting the real-world monitoring data that we need right now to really start correcting ourselves,” she said.
Craig Davis, senior director of plastics chemistry at the American Chemistry Council — the nation’s largest trade group for chemical companies — said that while his organization supports microplastic research, it also agrees with the EPA’s decision not to include them in the monitoring list.
“National drinking water monitoring should be based on validated, standardized methods that can produce reliable and comparable data,” said Davis in a statement. He said “limited” national monitoring resources should be focused where data can produce “actionable public health information.”
The public has 60 days to comment once the plan is published in the Federal Register.
Science
Hospital visits for smoke inhalation spiked during Boyle Heights warehouse fire
The number of Angelenos who went to the hospital with throat pain and concerns about smoke inhalation spiked as a fire burned through the massive Lineage cold storage warehouse in Boyle Heights this month, The Times has learned.
The blaze burned for eight days beginning June 17 and involved solar panels, insulation foam and other industrial materials.
During that time, more than three times as many people went to emergency departments within 10 miles of the warehouse mentioning the fire or smoke inhalation compared with the two weeks prior, according to data from the Los Angeles County Department of Public Health obtained through a public records request.
The agency also noted a near doubling of patients mentioning throat pain within five miles of the fire June 21 — 1.9 times the baseline levels.
Usually, fewer than 50 people go to the emergency room each day for throat pain, and fewer than 20 people for smoke inhalation, the department said.
The hospitalization data was tracked through the department’s syndromic surveillance project, which monitors trends in what people report when they come to emergency departments in L.A. County, as well as diagnosis codes noted by providers. The system is not as comprehensive as full patient health records, and clinicians may not always include key words about “fire,” “smoke” or other circumstantial information in their diagnoses, the public health department said.
As such, it “cannot capture the true number of [emergency department] visits related to symptoms from the fire and likely underestimates the true burden of fire related symptoms,” the department said.
Perhaps unexpectedly, the department said it did not note a substantial increase in asthma, acute respiratory symptoms or chronic obstructive pulmonary disease-related emergency department visits during the fire.
But even these preliminary findings are concerning, experts said. The fire is believed to have started on the solar array on the roof of the 500,000 square-foot building, which housed 85 million pounds of frozen food. It then reached an ammonia line, prompting two brief shelter-in-place orders for nearby residents.
Over the next week, the fire continued to burn through dense insulation foam within the building’s walls and other unknown industrial materials, blanketing much of L.A. in acrid smoke. Residents in downtown L.A., northeast L.A., Burbank, the San Gabriel Valley and many other parts of the city and county reported seeing and smelling the fumes.
The South Coast Air Quality Management District issued multiple warnings about unhealthy levels of PM 2.5, or fine particulate matter. The city and county opened two smoke respite shelters in the immediate area so that people could breath cleaner air.
It is still unclear what exactly was in the smoke that people breathed in. Industrial fires release far more materials than the burned wood smoke that is emitted during wildfires.
“The makeup of the smoke can include toxic chemicals, fine particles and other serious risks to lung health depending on fire conditions and what is burned,” Will Barrett, assistant vice president for nationwide clean air policy at the American Lung Assn., said as the fire was burning. Children and elderly people are particularly at risk.
David Eisenman, director of the UCLA Center for Public Health and Disasters, said urban industrial fires also can represent a hazard that standard PM 2.5 warnings don’t always address. Those advisories are “blunt instruments” that don’t adequately capture emissions from burning man-made goods — or convey that the source of pollution may include burning batteries or toxic refrigerants, he said.
The fact that initial numbers don’t show a spike in asthma attacks is “somewhat reassuring,” Eisenman said. But “people may have gone to their primary care doctors, which this would not capture. This data deserves follow up.”
The air district and the U.S. Environmental Protection Agency deployed air monitors to assess particulate matter, airborne toxic metals and other harmful compounds during the early days of the blaze. The air district said it didn’t find significant levels of air toxics during the first two days of the fire, although it did record significantly elevated concentrations of particulate matter within the plume downwind.
Some of the measurements it took with mobile monitors, which are five-minute snapshots, also showed increased bromine and chlorine, which often are found when buildings burn and were at levels “below short-term health-based exposure thresholds,” the air district said. It began continuous PM 2.5. monitoring at two nearby elementary schools on the third day.
The L.A. Fire Department said it detected low-levels of toxic hydrogen fluoride on the second day of the fire, which can be a byproduct of burning lithium-ion batteries.
Lineage, the tenant-operator of the warehouse, said no concentrations of ammonia were detected in the air at any time.
“There’s no doubt this fire has had a huge impact on the local community, and we are committed to showing up in every way we can,” company officials wrote in a statement last week. They said Lineage worked closely with the Fire Department during the blaze and delivered masks, air purifiers and other supplies to the community, and will work to ensure the fastest cleanup possible.
The long-term health effects of the fire and its smoke probably won’t be known unless researchers conduct a follow-up study, said Eisenman of UCLA.
For example, there may have been delayed pulmonary effects from the hydrogen fluoride and burning insulation foam that — when combined with the elevated PM 2.5 levels in a dense urban environment — produced health effects that didn’t show up in the emergency room data.
“They will show up in increased primary care office visits and exacerbations of chronic disease over the next few weeks,” he said. “So from a public health standpoint, this fire is not over.”
Science
Water from Boyle Heights warehouse fire carries foam into L.A. River, sparks testing
LOS ANGELES — All the water unleashed onto the warehouse fire in Boyle Heights — some of it 480 gallons at a time by helicopter — had to end up somewhere.
That somewhere is the Los Angeles River.
Los Angeles Fire Department crews ripped through 50-foot walls filled with foam insulation to get to the building’s steel skeleton and its storage racks.
Charred chunks of foam have been floating from the burn site, partially blocking storm drains. Now organizers from East Yard Communities for Environmental Justice are teaming up with scientists from UCLA and Columbia University to find out more about what’s in the runoff.
“The community here is really interested in knowing, ‘Are there any contaminants that are potentially making their way down to the L.A. River?’” said Yoshira “Yoshi” Ornelas Van Horne, UCLA assistant professor in environmental health sciences. “We really can’t answer that unless we actually have measures and samples analyzed.”
Water samples collected directly from the warehouse fire runoff have been shipped to Columbia‘s Multi-Element Trace Analysis Laboratory in New York, which has a spectrometer that can identify trace levels of elements. The lab also has relationships with researchers in Southern California.
1. Emmanuel Carrera Ruedas, left, and Casey Cooper prep containers to take water samples from the L.A. River. 2. Casey Cooper holds a water sample. (Christina House / Los Angeles Times)
The data will then come back to UCLA for analysis. For now, the scientists and community advocates only have the money to test for copper, lead and arsenic, Ornelas Van Horne said. Residents have expressed interest in testing for more contaminants.
As the water from the firefighting efforts trickles through the warehouse in rivulets, it forms a stream at the corner of S. Indiana and Noakes streets, that gushed into the storm drain. On a recent visit, the water traversed a smoky 10-foot canyon of charred foam and twisted wall panels on its way to the drain.
From there, the water flows to the L.A. River. Despite the fact that its concrete design is intended to whisk water out of the city as fast as possible, life stubbornly persists in the river and nearby. Recreational swimming is not permitted, yet anglers fishing for tilapia, largemouth bass and carp are a common sight along the rocky sides of the soft-bottom areas.
The L.A. River, and all it carries with it, meets the ocean in Long Beach.
The L.A. County Public Works Department said it has deployed three containment booms — floating barriers — on the L.A. River, and is continuing to monitor the water as it makes its way to the ocean.
Emmanuel Carrera Ruedas takes a water sample.
(Christina House / Los Angeles Times)
Before it gets there, the river passes through the Dominguez wetlands, where Public Works is removing some number of dead fish. The wetland has absorbed toxic runoff from a warehouse fire before, resulting in a fish die-off.
“For so long, the L.A. River has been used as a dumping ground for all kinds of chemicals,” said Emmanuel Carrera Ruedas, a community scientist and member of East Yard Communities for Environmental Justice.
Pollution has plagued the L.A. River, but it does have allies. In the 1980s, the Friends of the LA River pushed to address street runoff and trash that had made the water body infamous. Significant progress from advocacy and government initiatives improved water conditions, but these efforts have not been equally distributed.
Carrera said the samples represent “proof of what’s actually going on, and accountability, too, for the city, of not just what’s happening in our air, but what’s actually happening in our waterways.”
The first samples for the project were taken last Friday, the second day of the fire.
They were the first of 20 samples the research groups have agreed to test at no cost to see if any exceed regulatory standards and could pose a risk to people nearby.
The warehouse fire represents the latest environmental disaster for people in Boyle Heights and East L.A. Just four weeks ago, a telecommunications crew accidentally struck one of the many oil pipelines beneath the L.A. area, spilling 25,000 gallons of crude oil near Eastern and Cesar Chavez avenues — including into storm drains feeding to the L.A. River.
“I think it really is difficult to see disaster after disaster hit the communities here, with not a lot of talk about how we can move through these disasters together,” said Casey Cooper, a volunteer community scientist involved in the sampling. They were inspired, they said, by the response of neighbors, and how people were supporting one another.
Results from the laboratory analysis could be back to Ornelas Van Horne within a month.
-
Lifestyle20 minutes agoGreetings from London, where Banksy’s flag man is a warning cry
-
Education23 minutes ago
This Little Robot Cleans Windows
-
Technology28 minutes agoComcast’s split could make or break Peacock
-
World35 minutes agoState Department congratulates Keiko Fujimori as Peru’s president-elect following razor-thin vote count
-
Politics38 minutes agoMamdani ripped for claiming victory over capitalism after NYC’s multi-billion dollar taxpayer funded bailout
-
Health43 minutes agoAmerican vaccines that transformed public health over 250 years: ‘Outweighs harm’
-
Sports50 minutes agoEx-NFL reporter Dianna Russini interaction with police officer to dodge traffic ticket comes to light
-
Business58 minutes agoJoby Aviation creates a joint venture with Toyota to build air taxis