The chemicals used in standard flea treatments are polluting waterways and having a drastic effect on wildlife in the UK, killing songbird chicks.

Vets usually advise owners to treat their pets every month or so, even if they do not have fleas, but scientists are now urgently calling for the government to reassess the environmental risk of pesticides used in the treatments and to restrict them.

The Guardian has spoken to experts to find out what pet owners can do to prevent a flea infestation while minimising the impact on the environment of regular treatment.

What are topical flea treatments made of and how do they work? Topical flea treatments, often referred to as spot-on products, are capsules of liquid that contain insecticides. They are typically applied at the back of a pet’s neck so they do not lick them off, according to Elizabeth Mullineaux, president of the British Veterinary Association. The insecticides are distributed through the grease glands of the coat and into the pet’s hair, making it toxic to fleas for one to three months. While there are a range of flea treatments, the two most common are imidacloprid (a neonicotinoid) and fipronil. Both chemicals are banned from outdoor agricultureto prevent the pollution of waterways. While some are available over the counter, flea treatments are often sold as part of pet healthcare plans by vets.

What impact are they having on wildlife and the environment? Research at the University of Sussex has found that pesticides used in regular flea treatments are in 98% of English rivers, often at levels far higher than those deemed safe. Some of this is from treated dogs swimming, but much goes down the drain from households, (eg from shampooing dogs, washing bedding, stroking and washing hands) and then enters rivers, according to Dave Goulson, professor of biology at Sussex, who co-authored the study and supervised the research. Recent research also found that 100% of blue tit and great tit nests are contaminated with pesticides from pet flea treatment, as the birds collect fur from dogs and cats to insulate their nests. The study, funded by the charity Songbird Survival, found that nestling mortality is associated with higher levels of the pesticides. “Other products used in flea treatments have not raised the same environmental concerns as fipronil and imidacloprid but we don’t necessarily have all the environmental data to say they’re absolutely environmentally safe,” said Mullineaux.

So how can pet owners reduce causing damage to wildlife? The most important thing owners should consider is whether their pets need topical treatment and, if so, how often and when, and if there are alternatives, say experts. Mullineaux said: “Speak to your vet about the best way to use the products for your pet, and your circumstances and risk level. For example, the sorts of questions we might ask you are how much a pet goes outside, if you have other pets, if anyone in the household is particularly medically vulnerable, and what your pet’s lifestyle is like – whether it swims or goes for doggy daycare, or whether you need to wash and groom it a lot. “We strongly encourage vets and owners to take a risk-based approach to prescribing or recommending these medicines, reflecting an animal’s exposure to parasites.” If spot-on products are considered the only appropriate form of treatment, you should brush your pet indoors or in a sheltered area where you can gather the hair afterwards and dispose of it in a sealed bag. “What we don’t want is the hair blowing away and birds collecting it up as nesting material. I think a lot of us have probably thought that was kind of quite a nice thing for birds to do but clearly it really isn’t if the hair is contaminated with chemicals,” said Millineaux. It is also important to take care of packaging material, particularly from spot-on products. “I’ve heard horror stories of people washing out the little containers, which obviously do contaminate water,” added Millineaux. “What we want to be doing is not washing them out but disposing them of them in something like a seal bag and following any manufacturers guidelines.” Washing is discouraged for several days after treatments, owing to the risk of product getting into waterways.

Plants to Avoid and Why

Most plants are a pleasure to grow. Fortunately, there are only a few to avoid. Here’s how invasive plants and plants that have been treated cause problems.

Image Scotch broom currently infests millions of acres throughout California. Photo: UC ANR

Invasive plants: bad for our environment, economy, and health

Thanks to Marin’s gentle climate, we can grow plants from all over the world. Most are not a problem. But sometimes a plant gets out of hand and causes trouble.

Pampas grass is a familiar invasive plant in Marin. Photo: Marie Narlock

What are some invasive plants in Marin?

Scotch broom (Cytisus scoparius)

French broom (Genista monspessulana)

English ivy or Algerian ivy (Hedera helix or H. canariensis)

Periwinkle (Vinca major)

Pampas grass (Cortaderia selloana)

Iceplant (Carpobrotus edulis)

Fountain grass (Pennisetum setaceum)

Feather needlegrass (Nasella (Stipa) tenuissima)

What are invasive plants?

Iceplant smothers native plants out of existence. Photo: Wikipedia Commons

• They are non-native.

• They reproduce and spread quickly.

• They cause harm to the environment, economy, or human health.

How did they get here?

• Some invasive plants arrived accidentally with European settlers.

• Some were introduced by nurseries.

• Some have proliferated due to climate change.

• Some are still sold in nurseries!

What problems do invasive plants cause?

Mexican feather grass spreads like wildfire. Photo: UC ANR

• Habitat loss

• Reduction in biodiversity

• Crop decimation

• Clogged waterways

• Soil degradation

• Erosion

• Wildlife and human disease transmission

• Threats to fisheries

• Threats to cattle

• Increased fire vulnerability

• Reduced land values for farms and ranches

• Increased management expenses for farms and ranches

How can you help?

Periwinkle’s flowers look sweet, but the plant is invasive. Photo: Wikipedia Commons

• Do NOT plant invasive plants.

• Eliminate invasive plants wherever possible.

• Visit PlantRight to see which plants are considered high priority invasive plants – and what to plant instead.

• Join environmental groups that eradicate invasive plants.

Avoid buying treated plants

Some retail nurseries and the growers that supply them use pesticides. These pesticides can cause harm far beyond the original target, and this harm can endure for a long time. Unfortunately, it is not always obvious which plants have been treated.

“Neonics” make the environment sick

Plants treated with neonicotinoids can harm pollinators and other important wildlife. Photo: James Wheeler, Pexels

• Neonicotinoids (aka “neonics”) are a group of chemicals. They are the most widely used insecticides in the world.

• Neonics are systemic. This means the chemical invades a plant’s vascular system, tissue, and even its nectar and pollen.

• Target pests are often sucking insects like aphids and beetles, but these chemicals also harm honeybees, bumblebees, butterflies, and other pollinators.

• Neonics threaten biodiversity and interrupt the natural food web by harming non-target wildlife.

• Some neonics harm natural enemies that would otherwise keep the balance of “good bugs and bad bugs” in check.

• Some neonics can remain active for up to three years.

How to avoid plants treated with neonicotinoids

Read plant labels carefully; support nurseries that offer neonicotinoid-free plants. Photo: Visually, Pexels

Read labels carefully. Look beyond the friendly name on the bottle. Acetamaprid, imidacloprid, dinotefuran, clothianidin, and thiamethoxam are all neonicotinoids.

Support nurseries and retail outlets that have a “no neonicotinoid” policy.

Buy from local growers, often at farmers’ markets, who can attest that their plants are free of pesticides.

Look for “neonic-free” plant tags.

Buy organic plants.

Ask your local nurseryman to carry neonic-free plants and to voice your request to their corporate headquarters.

Remove flowers. If you fear you may have purchased a treated plant, remove all flowers the first year after purchasing. This may seem unthinkable, but it can be an effective way to minimize impact on pollinators.

KNOW YOUR INVASIVE BROOM…

Important step forward in delivering on election commitment to safeguarding bees, butterflies and the wider environment

A complete ban on use of bee-killing neonicotinoid pesticides has moved a step closer today (Saturday 21 December), as the government sets out its plans to deliver a key election pledge.

Despite being banned from general use in the UK, the last government authorised the use of neonicotinoids every year for the last four years in England via a process known as emergency authorisation.

Neonicotinoids are extremely toxic to pollinators. Even at doses that are not directly fatal to bees they can cause cognitive problems impacting foraging abilities and the productivity of hives. The chemicals can also persist in the soil creating a further risk to bees.

Bees and other pollinators are crucial to the agricultural economy with the economic benefits of pollination to crop production in the UK estimated at £500 million annually.

The Government has set out its next steps, including identifying legislative options that would legally prevent the future use of three specific neonicotinoids – clothianidin, imidacloprid and thiamethoxam – entirely, taking full account of the importance of pollinators.

Environment Minister Emma Hardy said:

“We are delivering on our promise to ban toxic bee-killing pesticides and ending the long-term decline of our wildlife.

“A healthy environment is vital to our food and economic security. Protecting bees by stopping the use of damaging neonicotinoids is an important step in supporting the long-term health of our environment and waterways, and our farming sector.”

The move comes ahead of the publication of a new UK National Action Plan (NAP), which will set how pesticides can be used sustainably.

Ensuring that our food production is sustainable is key to the long-term health of the agricultural sector, as well as the nation’s food security. The Government’s Plan for Change is built on the strong foundation of a stable economy.

The Government commitment to farmers remains steadfast and we are fully committed to supporting farmers to protect their crops in more sustainable ways. There has already been progress in this space, including research into new virus-resistant varieties of sugar beet and new alternative pesticide sprays, and we will continue to support this work.

The announcement today builds on the swift action the Government has taken to recover nature more widely. This includes committing to a rapid review of the Environmental Improvement Plan and new delivery plans to meet targets on air quality, the circular economy and water. In the first few months of this government, legislation was introduced to put failing water companies under special measures to curb pollution in our waterways and a Flood Resilience Taskforce was introduced to speed up the creation of nature-based solutions, like planting trees to protect communities against the impact of extreme weather.

NOTES TO EDITORS:

Unbeknownst to Morrissey at the time, the decision to nix the proposed ban was based in part on a scant replication of her research conducted by the giant pesticide company Bayer Crop Science — with full support from federal officials in Canada’s Pest Management Regulatory Agency (PMRA), at Environment and Climate Change Canada, and at Agriculture and Agri-Food Canada.

Water sampling data collected on the Prairies by Christy Morrissey, a Canadian ecologist and University of Saskatchewan professor, helped form the basis for a national ban, proposed in 2016, on imidacloprid and two other related neonicotinoid pesticides used on corn, soybeans, potatoes and other crops.

The federal pesticide regulator collaborated with an agrochemical giant to undermine research by a prominent Canadian scientist to stave off an impending ban of a class of pesticides harmful to human brains and sperm and deadly to bees, insects and birds , Canada’s National Observer has found.

Used both as a seed treatment and sprayed on fields while crops are growing, neonics leach into soil, snowmelt and runoff then wash out of fields and into streams and wetlands, where they kill insects – including pollinators – and can contaminate water supplies. Those ecological harms have led to stringent restrictions or bans on neonic use in the E.U. and some U.S. states, and a partial ban in Quebec.

Critics were furious, slamming the decision as inadequate to tackle the chemicals’ environmental risk, which the PMRA had noted in the 2016 document proposing the ban was “not sustainable.”

Morrissey was stunned. “I couldn’t understand how the government flip-flopped from the ban,” she told Canada’s National Observer. “We had all the data, and the levels we found all exceed the levels of concern. I didn’t understand how they got to their decision.”

Elsewhere in Canada, neonics remain widely used by farmers, albeit with a few new restrictions.

The imidacloprid revelations come on the heels of several recent investigations by Canada’s National Observer into the regulator’s transparency and independence from industry that have left critics skeptical of its ability to protect Canadians and the environment from harmful pesticides.

“The PMRA’s flip-flop on neonics will go down in history as a failed attempt to reduce the overuse of pesticides accumulating in our environment and causing ecological harm,” said Lisa Gue, manager of national policy for the David Suzuki Foundation.

Morrissey’s story has left other scientists working on public health and environmental issues spooked that they could be the next targets. From chemicals like PFAS to the climate impacts of greenhouse gases, the world’s largest polluters have a long history of muffling research into their harms and convincing regulators to turn a blind eye.

“This could happen to any of us,” said Chelsea Rochman, a freshwater ecologist and microplastics expert at the University of Toronto. Her work has been key to Canadian and global efforts to better regulate plastic. “I’m lucky they haven’t targeted me yet.”

A ‘Morrissey Report’

Morrissey knew something was amiss as soon as she heard that the federal government had done an about-face on its neonics ban.

In February 2016, the professor and freshwater ecologist shared unpublished water sampling data she had collected from wetlands in Saskatchewan farmland with the federal pesticide regulator. The data complemented her published studies on neonic contamination, which the PMRA also reviewed. Few had ever collected such a detailed trove of information about the water flowing from Canada’s millions of acres of prairie farmland into the region’s marshes, creeks and seasonal ponds — and her findings were damning.

Much of the water she tested was filled with enough neonic pesticides to blow through the government’s safety guidelines, and the government cited her findings and other research to justify its proposed ban on imidacloprid and initiate a special review of two other neonics. Yet, five years after she submitted her data to the pesticide regulator, it reversed course and approved the pesticides’ ongoing use.

Photo by Liam Richards/National Observer

Mystified, Morrissey raced to figure out what had happened and filed a formal rebuttal to the regulator’s decision, called a “notice of objection.” Notices of objection must be submitted within 60 days of the regulator’s decision and present an argument refuting the agency’s decision based on scientific research, similar to a formal research paper.

Time and convenience were not on her side. Most of the data used by the PMRA to reverse the ban was considered proprietary to the pesticide companies that produce imidacloprid and was locked away in the agency’s files. The only way Morrissey — or anyone else — could view the data was on an encrypted thumb drive mailed to her by the agency. She signed an affidavit promising not to copy the data, which was locked in a view-only and unsearchable format, and use it only to write her objection.

When the thumb drive finally arrived in the mail, it revealed what Morrissey had feared.

“There’s what amounts to a whole ‘Morrissey Report,’” she told Canada’s National Observer. Industry did a “big job behind the scenes” to convince the PMRA it should exclude her data from its final assessment, she said. “They wanted to try and prove that we were wrong.”

How, she wondered, had Bayer even known about her inconvenient data?

‘Bad news every time’

Morrissey didn’t know it when she uncovered the hidden file on her work, but efforts by industry and government officials to undermine her findings started almost immediately after the proposed ban became public in November 2016. Within weeks, federal and provincial officials met with Canada’s largest agribusiness lobbyists to find ways to prevent the proposed ban from going through.

A trove of internal meeting minutes obtained this year through access-to-information legislation (hosted on a database maintained by the Investigative Journalism Foundation) depicts meetings between officials from the PMRA, Agriculture and Agri-Food Canada, and Environment and Climate Change Canada, as well as provincial government and industry group representatives. The representatives met for hours under the auspices of a so-called “multi-stakeholder forum” convened by Agriculture and Agri-Food Canada about imidacloprid and two other neonics the government proposed to ban, clothianidin and thiamethoxam.

With hundreds of members, the forum was ostensibly tasked with informing farmers and industry groups about the risk assessment process and helping them inform the government’s decisions and find pesticide alternatives, according to the documents. Bayer was invited to participate in the forum, the company told Canada’s National Observer in an emailed statement.

But in practice, meeting minutes from December 2016 show that federal officials and industry representatives collaborated to find ways to skirt Canada’s pesticide laws and keep neonics in use. Although the people aren’t identified in the minutes due to privacy laws, the tone is collegial, deferential to industry and aimed at preserving neonic use.

Under Canadian pesticide laws, the government must implement pesticide bans or restrictions if they find that a pesticide poses an excessive threat to human health or the environment. Morrissey’s data was of particular interest to the forum because her findings were among those cited by the government to justify the proposed ban.

Early in the discussion, a speaker cites Morrissey’s data, asking if any future research would have to go through the same research process Morrissey used to collect her data, adding, “hope it doesn’t have the same outcome.”

The government’s goal is not to “take away products from agriculture,” they said — but the agency couldn’t approve a pesticide if they considered data that showed doing so would break the law.

The group kicked around ideas about how to circumvent Morrisey’s problematic findings. One speaker said “based on observations from Bayer, [we need] a broader discussion on how monitoring is done, and where.”

“If we look hard enough we will find things. If we look at the most sensitive species and sampling that is done in protected areas, then bad news every time. [There is] value in discussing where and what type of body [sic]” that sampling occurs, they said.

Another person responded that the regulator wants “to know if there is a path forward out of this, and…to get to a place where environmental risks are in an acceptable place. No matter how that happens.” They continue by saying that, for the regulator to back off the proposed ban, it needs “information that shows the product is acceptable.”

Bayer heeded the call.

Industry-selected data

Morrissey was on the phone with a colleague from Ducks Unlimited when she learned the backstory to what she calls Bayer’s “Morrissey report.”

Bayer was funding a Ducks Unlimited research project, and in a meeting earlier that year, the company’s representatives had pulled up her unpublished wetland data from 2014. Data she had shared with the PMRA — not with Bayer.

That dataset — showing high levels of neonics in prairie wetlands — had somehow made its way from the pesticide regulator into the hand of the pesticide manufacturer. Morrissey had shared it with the regulator thinking it was confidential; the PMRA had told her in an email that it would only be shared with industry if they signed an affidavit to use it as part of the registration process and return it afterwards.

If she had known it would be shared with industry without her consent — which is technically allowed according to an obscure provision of Canada’s pesticide laws — she would never have included locations or farm identifiers.

“I was pretty shocked,” she said. “I’ve never shared unpublished data again with the PMRA since then.”

In an emailed statement, a PMRA spokesperson said that pesticide companies “have an opportunity to review and provide comments on data submitted by third parties with respect to [their] product(s),” and admitted the agency had shared the data under the applicable laws.

Armed with Morrissey’s data, Bayer hired a team of researchers to verify the “relevancy” of the sites Morrissey’s team had examined three years earlier. Both Morrissey and Canada’s National Observer saw the final 27-page report, which is not peer-reviewed, in the encrypted files she requested to write her formal objection.

“I was like ‘wow,'” Morrissey recalled. Bayer had pared down her data to remove problematic sites and used the document to convince the PMRA to reject over half of the wetland samples it had used in its 2016 proposal to ban the chemical.

Morrissey’s sampling tested 115 wetlands in early summer alongside bird breeding surveys conducted annually along prairie roads. The wetlands were all within 100 metres of the road, but only some were identified with exact GPS coordinates to protect the landowners’ confidentiality. She found most of the wetlands contained dangerous levels of neonics, especially clothianidin and thiamethoxam which are more commonly used on the Prairies than imidacloprid.

If these wetlands become contaminated with neonics, they can kill off the insects with impacts throughout the ecosystem. Other research backs Morrissey’s statement, emphasising that seasonal wetlands are critical to sustain biodiversity.

In contrast, Bayer replicated her tests during the end of summer when fields were dry and neonics weren’t running into the water. Instead of visiting and taking water samples from the sites, they relied primarily on Google Earth and Street View to find the wetlands Morrissey sampled and evaluate if they were relevant to the PMRA’s pesticide risk assessment. Bayer’s team only visited “a few sites” in person, the report says.

Many of the wetlands Morrissey studied had dried up during the drought or didn’t appear on Google Earth, while the snow she had tested was long melted, making it impossible to test for neonic contamination. Bayer’s researchers also claimed that Morrissey’s GPS location data was inaccurate, but did not reach out for the specific GPS coordinates, Morrissey told Canada’s National Observer.

In an emailed statement to Canada’s National Observer, Bayer did not deny compiling the report and said that as a member of the “multi-stakeholder forum,” it helped generate water monitoring data between 2017 and 2019.

The PMRA appears to have adopted Bayer’s method to decide which sites Morrissey had sampled were “relevant” to its aquatic risk assessment: in the regulator’s final decision to allow the pesticide’s continued use, it echoes nearly word-for-word Bayer’s conclusion that most of Morrissey’s data was “not relevant” to the risk assessment.

In a statement, a PMRA spokesperson said that “the report provided by Bayer contains a critical analysis of the ecological relevance of the water bodies selected for the 2014 data collected by Dr. Morrissey. The rationales provided by Bayer were critically considered by the PMRA.”

The agency used similar justifications to exclude from its final decision Morrissey’s published research, which also showed dangerous levels of neonic contamination in prairie wetlands.

In an emailed statement, a PMRA spokesperson said “The lack of GPS coordinates is one consideration among other factors” in the decision to exclude data.

However, researchers note the PMRA’s own risk assessment guidance doesn’t require researchers to submit GPS coordinates for sampling sites.

The PMRA relied more heavily on data from 27 industry-run studies of simulated outdoor environments, or mesocosms. Those studies found that farmers could continue to use imidacloprid and other neonics without breaching the agency’s safety thresholds, she wrote in her notice of objection. It let the industry provide water quality samples collected several times a season from sites with minimal neonic contamination, which “flooded” the assessment with enough “clean” data to drown out studies that found high levels of neonic contamination, she told Canada’s National Observer.

Environment and Climate Change Canada, the Canadian Council of Ministers of the Environment, and European Union and Dutch pesticide regulators consider mesocosm studies too scientifically weak to set water quality guidelines for pesticides.

Regardless, the industry’s effort worked. In its 2021 decision to approve the continued use of imidacloprid, the PMRA rejected over half of the wetland samples it had used in its 2016 proposal to ban the chemical. All had been collected by Morrissey’s lab, published in her peer-reviewed, public scientific articles and submitted to the PMRA, she notes in her notice of objection.

Summary of Prairie wetlands excluded in the 2021 decision to reverse the proposed imidacloprid ban that had been included in the original 2016 decision included in Christy Morrissey’s notice of objection. Chart by Christy Morrisey

Instead, the agency relied on 303 samples — 66 per cent of them collected by pesticide companies or agricultural industry groups.

Eliminating Morrissey’s data enabled federal regulators to justify their controversial decision by pointing to water quality datasets where dangerous levels of neonics occurred two-thirds less frequently than if Morrissey’s data was included in the evaluation.

Industry ‘allowed to hide’

Nearly three years have passed since Morrissey submitted her objection to the federal pesticide regulator’s decision to keep neonics on the market. In theory, the agency should review it and, if it determines the complaint has “scientific merit,” send it to an external committee for additional review.

She has yet to receive a response from the PMRA on whether it believes her formal objection has merit, nor has it proceeded to an external review, she told Canada’s National Observer.

In an emailed statement, the PMRA said “the timeline for completing a review of an objection depends on a variety of factors. They include the number and complexity of objections received, additional clarification needed from objectors, as well as the number of objections raised…and volume of supporting evidence received. As a result, the timeline to complete the review of an NoO is determined on a case-by-case basis.”

Neonics remain in use — but it’s nearly impossible to know how much is being used. Usage data is considered proprietary information, while sales data is only publicly available for imidacloprid, and only from 2012 to present. That data shows a steady increase in sales, until Quebec restricted the use of neonics in 2019.

Canada’s National Observer asked the PMRA if it was aware that Bayer was compiling a report about Morrissey’s work, but the agency did not respond to the question.

“Clearly, it got bad — to the point where decisions were being made that are not scientific at all and industry was being allowed to hide under the guise of proprietary information,” said Morrissey. “At the end of the day, if you’re using these chemicals in the environment on a huge scale, you have to be open and transparent.”

Regardless of whether the PMRA’s efforts to be more transparent and accountable succeed, they will do nothing to keep neonics out of the environment for years. Without a change to Canada’s pesticide laws, the health and environmental impacts of neonics are next scheduled to be reviewed in 2036.

Morrissey’s frustration was still palpable when she talked with Canada’s National Observer last month. Neonics are still being sprayed on fields, leaching into wetlands and “killing things,” she said. And without her efforts — which came on top of her teaching and research responsibility — few would know that their continued use has been enabled by a close collaboration between Canadian regulators and the pesticide industry.

“Industry had about four and a half years to produce new data and get data thrown out, to allow the decision to be manipulated,” she said. “That’s how they did it.”

When it comes to healthy eating, fruits and vegetables reign supreme. But along with all their vitamins, minerals and other nutrients can come something else: an unhealthy dose of dangerous pesticides.

Though using chemicals to control bugs, fungi and weeds helps farmers grow the food we need, it’s been clear since at least the 1960s that some chemicals also carry unacceptable health risks. And although certain notorious pesticides, such as DDT, have been banned in the US, government regulators have been slow to act on others. Even when a dangerous chemical is removed from the market, chemical companies and growers sometimes just start using other options that may be as dangerous.

Consumer Reports, which has tracked the use of pesticides on produce for decades, has seen this pattern repeat itself over and over. “It’s two steps forward and one step back – and sometimes even two steps back,” says James E Rogers, who oversees food safety at Consumer Reports.

To get a sense of the current situation, Consumer Reports recently conducted our most comprehensive review ever of pesticides in food. To do it, we analyzed seven years of data from the US Department of Agriculture, which each year tests a selection of conventional and organic produce grown in or imported to the US for pesticide residues. We looked at 59 common fruits and vegetables, including, in some cases, not just fresh versions but also canned, dried or frozen ones.

Our new results continue to raise red flags.

Pesticides posed significant risks in 20% of the foods we examined, including popular choices such as bell peppers, blueberries, green beans, potatoes and strawberries. One food, green beans, had residues of a pesticide that hasn’t been allowed to be used on the vegetable in the US for over a decade. And imported produce, especially some from Mexico, was particularly likely to carry risky levels of pesticide residues.

But there was good news, too. Pesticides presented little to worry about in nearly two-thirds of the foods, including nearly all of the organic ones. Also encouraging: the largest risks are caused by just a few pesticides, concentrated in a handful of foods, grown on a small fraction of US farmland. “That makes it easier to identify the problems and develop targeted solutions,” Rogers says – though he acknowledges that it will take time and effort to get the Environmental Protection Agency, which regulates the use of pesticides on crops, to make the necessary changes.

The way the EPA assesses pesticide risk doesn’t reflect cutting-edge science Consumer Reports senior scientist Michael Hansen

In the meantime, our analysis offers insights into simple steps you can take to limit exposure to harmful pesticides, such as using our ratings to identify which fruits and vegetables to focus on in your diet, and when buying organic produce can make the most sense.

What’s safer, what’s risky, and why

Sixteen of the 25 fruits and 21 of the 34 vegetables in our analysis had low levels of pesticide risk. Even children and pregnant people can safely eat more than three servings a day of those foods, Consumer Reports’ food safety experts say. Ten foods were of moderate risk; up to three servings a day of them are OK.

The flip side: 12 foods presented bigger concerns. Children and pregnant people should consume less than a serving a day of high-risk fruits and vegetables, and less than half a serving a day of very high-risk ones. Everyone else should limit consumption of those foods, too.

View image in fullscreen Photograph: Sarah Anne Ward/Consumer Reports

To come up with that advice, we analyzed the USDA’s test results for 29,643 individual food samples. We rated the risk of each fruit or vegetable by factoring in how many pesticides showed up in the food, how often they were found, the amount of each pesticide detected and each chemical’s toxicity.

The Alliance for Food and Farming, a farming industry organization, pointed out to Consumer Reports that more than 99% of foods tested by the USDA contained pesticide residues below the Environmental Protection Agency’s legal limits (referred to as tolerances).

But Consumer Reports’ scientists think many EPA tolerances are set too high. That’s why we use lower limits for pesticides that can harm the body’s neurological system or are suspected endocrine disruptors (meaning they may mimic or interfere with the body’s hormones). Consumer Reports’ approach also accounts for the possibility that other health risks may emerge as we learn more about these chemicals.

“The way the EPA assesses pesticide risk doesn’t reflect cutting-edge science and can’t account for all the ways the chemicals might affect people’s health, especially given that people are often exposed to multiple pesticides at a time,” says Consumer Reports senior scientist Michael Hansen. “So we take a precautionary approach, to make sure we don’t underestimate risks.”

In our analysis, a fruit or vegetable can contain several pesticides but still be considered low-risk if the combination of the number, concentration and toxicity of them is low. For example, broccoli fared well not because it had no pesticide residues but because higher-risk chemicals were at low levels and on just a few samples.

Some of the most problematic foods, on the other hand, had relatively few residues but worrisome levels of some high-risk pesticides.

Case in point: watermelon. It’s very high-risk mainly because of a pesticide called oxamyl. Only 11 of 331 conventional, domestic watermelon samples tested positive for oxamyl. But it’s among those that Consumer Reports’ experts believe require extra caution because of their potential for serious health risks.

Green beans are another example. They qualify as high-risk primarily because of a pesticide called acephate or one of its breakdown products, methamidophos. Only 4% of conventional, domestic green bean samples were positive for one or both – but their pesticide levels were often alarmingly high. In one sample from 2022 (the most recent year for which data was available), methamidophos levels were more than 100 times the level Consumer Reports’ scientists consider safe; in another, acephate levels were seven times higher. And in some 2021 samples, levels were higher still.

You can eat a variety of healthy fruits and vegetables without stressing too much about pesticide risk Registered dietitian Amy Keating

This is especially troubling because neither chemical should be on green beans at all: growers in the US have been prohibited from applying acephate to green beans since 2011, and methamidophos to all food since 2009.

“When you grab a handful of green beans at the supermarket or pick out a watermelon, your chance of getting one with risky pesticide levels may be relatively low,” Rogers says. “But if you do, you could get a much higher dose than you should, and if you eat the food often, the chances increase.”

In some cases a food qualifies as high-risk because of several factors, such as high levels of a moderately dangerous pesticide on many samples. Example: chlorpropham on potatoes. It’s not the most toxic pesticide – but it was on more than 90% of tested potatoes.

How pesticides can harm you

Pesticides are one of the only categories of chemicals we manufacture “specifically to kill organisms”, says Chensheng (Alex) Lu, an affiliate professor at the University of Washington in Seattle who researches the health effects of pesticide exposure. So it’s no surprise, he says, that pesticides used to manage insects, fungi and weeds may harm people, too.

While there are still open questions about exactly how and to what extent chronic exposure to pesticides can harm our health, scientists are piecing together a compelling case that some can, drawing on a mix of laboratory, animal and human research.

One type of evidence comes from population studies looking at health outcomes in people who eat foods with relatively high pesticide levels. A recent review in the journal Environmental Health, which looked at six such studies, found evidence linking pesticides to increased risks of cancer, diabetes and cardiovascular disease.

Stronger evidence of pesticides’ dangers comes from research looking at people who may be particularly vulnerable to pesticides, including farm workers and their families. In addition to the thousands of workers who become ill from pesticide poisonings every year, studies have linked on-the-job use of a variety of pesticides with a higher risk of Parkinson’s disease, breast cancer, diabetes and many more health problems.

Other research found that exposure during pregnancy to a common class of pesticides called organophosphates was associated with poorer intellectual development and reduced lung function in the children of farm workers.

Pregnancy and childhood are times of particular vulnerability to pesticides, in part because certain pesticides can be endocrine disruptors. Those are chemicals that interfere with hormones responsible for the development of a variety of the body’s systems, especially reproductive systems, says Tracey Woodruff, a professor of environmental health sciences at the University of California, San Francisco.

Another concern is that long-term exposure to even small amounts of pesticides may be especially harmful to people with chronic health problems, those who live in areas where they are exposed to many other toxins and people who face other social or economic health stresses, says Jennifer Sass, a senior scientist at the Natural Resources Defense Council.

View image in fullscreen Photograph: Sarah Anne Ward/Consumer Reports

That’s one of the reasons, she says, regulators should employ extra safety margins when setting pesticide limits – to account for all the uncertainty in how pesticides might harm us.

How to stop eating pesticides

While our analysis of USDA pesticide data found that some foods still have worrisome levels of certain dangerous pesticides, it also offers insights into how you can limit your pesticide exposure now, and what government regulators should do to fix the problem in the long term.

Eat lots of low-risk produce. A quick scan of this chart makes one thing clear: there are lots of good options to choose from.

“That’s great,” says Amy Keating, a registered dietitian at Consumer Reports. “You can eat a variety of healthy fruits and vegetables without stressing too much about pesticide risk, provided you take some simple steps at home.” (See Can you wash pesticides off your food? A guide to eating fewer toxic chemicals.)

Your best bet is to choose produce rated low-risk or very low-risk in our analysis and, when possible, opt for organic instead of riskier foods you enjoy. Or swap in lower-risk alternatives for riskier ones. For example, try snap peas instead of green beans, cantaloupe in place of watermelon, cabbage or dark green lettuces for kale, and the occasional sweet potato instead of a white one.

But you don’t need to eliminate higher-risk foods from your diet. Eating them occasionally is fine.

“The harm, even from the most problematic produce, comes from exposure during vulnerable times such as pregnancy or early childhood, or from repeated exposure over years,” Rogers says.

Switch to organic when possible. A proven way to reduce pesticide exposure is to eat organic fruits and vegetables, especially for the highest-risk foods. We had information about organically grown versions for 45 of the 59 foods in our analysis. Nearly all had low or very low pesticide risk, and only two domestically grown varieties – fresh spinach and potatoes – posed even a moderate risk.

Organic foods’ low-risk ratings indicate that the USDA’s organic certification program, for the most part, is working.

It’s always worth considering organic produce, [though] it’s most important for the fruits and vegetables that pose the greatest risk James E Rogers, head of food safety at Consumer Reports

Pesticides aren’t totally prohibited on organic farms, but they are sharply restricted. Organic growers may use pesticides only if other practices – such as crop rotation – can’t fully address a pest problem. Even then, farmers can apply only low-risk pesticides derived from natural mineral or biological sources that have been approved by the USDA’s National Organic Program.

Less pesticide on food means less in our bodies: multiple studies have shown that switching to an organic diet quickly reduces dietary exposure. Organic farming protects health in other ways, too, especially of farm workers and rural residents, because pesticides are less likely to drift into the areas where they live or to contaminate drinking water.

And organic farming protects other living organisms, many of which are even more vulnerable to pesticides than we are. For example, organic growers can’t use a class of insecticides called neonicotinoids, a group of chemicals that may cause developmental problems in young children – and is clearly hazardous to aquatic life, birds and important pollinators including honeybees, wild bees and butterflies.

The rub, of course, is price: organic food tends to cost more – sometimes much more.

“That’s why, while we think it’s always worth considering organic produce, it’s most important for the handful of fruits and vegetables that pose the greatest pesticide risk,” Rogers says. He also says that opting for organic is most crucial for young children and during pregnancy, when people are extra vulnerable to the potential harms of the chemicals.

Watch out for some imports. Overall, imported fruits and vegetables and those grown domestically are pretty comparable, with roughly an equal number of them posing a moderate or worse pesticide risk. But imports, particularly from Mexico, can be especially risky.

Seven imported foods in our analysis pose a very high risk, compared with just four domestic ones. And of the 100 individual fruit or vegetable samples in our analysis with the highest pesticide risk levels, 65 were imported. Most of those – 52 – came from Mexico, and the majority involved strawberries (usually frozen) or green beans (nearly all contaminated with acephate, the pesticide that’s prohibited for use on green beans headed to the US).

A spokesperson for the Food and Drug Administration told Consumer Reports that the agency is aware of the problem of acephate contamination on green beans from Mexico. Between 2017 and 2024, the agency has issued import alerts on 14 Mexican companies because of acephate found on green beans. These alerts allow the FDA to detain the firms’ food shipments until they can prove the foods are not contaminated with the illegal pesticide residues in question.

The Fresh Produce Association of the Americas, which represents many major importers of fruits and vegetables from Mexico, did not respond to a request for comment.

Rogers, at Consumer Reports, says: “Clearly, the safeguards aren’t working as they are supposed to.” As a result, “consumers are being exposed to much higher levels of very dangerous pesticides than they should.” Because of those risks, he suggests checking packaging on green beans and strawberries for the country of origin, and consider other sources, including organic.

How to solve the pesticide problem

Perhaps the most reassuring, and powerful, part of Consumer Reports’ analysis is that it demonstrates that the risks of pesticides are concentrated in just a handful of foods and pesticides.

Of the nearly 30,000 total fruit and vegetable samples Consumer Reports looked at, just 2,400, or about 8%, qualified as high-risk or very high-risk. And among those samples, just two broad classes of chemicals, organophosphates and a similar type of pesticide called carbamates, were responsible for most of the risk.

“That not only means that most of the produce Americans consume has low levels of pesticide risk, but it makes trying to solve the problem much more manageable, by letting regulators and growers know exactly what they need to concentrate on,” says Brian Ronholm, head of food policy at Consumer Reports.

View image in fullscreen Photograph: Sarah Anne Ward/Consumer Reports

Organophosphates and carbamates became popular after DDT and related pesticides were phased out in the 1970s and 1980s. But concerns about these pesticides soon followed. While the EPA has removed a handful of them from the market and lowered limits on some foods for a few others, many organophosphates and carbamates are still used on fruits and vegetables.

Take, for instance, phosmet, an organophosphate that is the main culprit behind blueberries’ poor score. Until recently, phosmet rarely appeared among the most concerning samples of pesticide-contaminated food. But in recent years, it’s become a main contributor of pesticide risk in some fruits and vegetables, according to our analysis.

“That’s happened in part because when a high-risk pesticide is banned or pushed off the market, some farmers switch to a similar one still on the market that too often ends up posing comparable or even greater harm,” says Charles Benbrook, an independent expert on pesticide use and regulation, who consulted with Consumer Reports on our pesticide analysis.

We just don’t need [pesticides]. And the foods American consumers eat every day would be much, much safer without them Brian Ronholm, head of food policy at Consumer Reports

Consumer Reports’ food safety experts say our current analysis has identified several ways the EPA, FDA and USDA could better protect consumers.

That includes doing a more effective job of working with agricultural agencies in other countries and inspecting imported food, especially from Mexico, and conducting and supporting research to more fully elucidate the risks of pesticides. In addition, the government should provide more support to organic farmers and invest more federal dollars to expand the supply of organic food – which would, in turn, lower prices for consumers.

But one of the most effective, and simple, steps the EPA could take to reduce overall pesticide risk would be to ban the use of any organophosphate or carbamate on food crops.

The EPA told Consumer Reports that “each chemical is individually evaluated based on its toxicity and exposure profile”, and that the agency had required extra safety measures for several organophosphates.

But Consumer Reports’ Ronholm says that approach is insufficient. “We’ve seen time and again that doesn’t work. Industry and farmers simply hop over to another related chemical that may pose similar risks.”

Canceling two whole classes of pesticides may sound extreme. “But the vast majority of fruits and vegetables eaten in the US are already grown without hazardous pesticides,” Ronholm says. “We just don’t need them. And the foods American consumers eat every day would be much, much safer without them.”

Read more from this pesticide investigation:

Find out more about pesticides at Consumer Reports