22
Apr
Dramatic Array of Pesticides Used Outdoors Make Their Way Inside, Contaminating the Indoor Environment
(Beyond Pesticides, April 22, 2025) While it has been widely found that farmworkers bear the brunt of agricultural pesticide exposures in fields and outbuildings, the outdoor use of chemicals contaminating living spaces is documented in an increasing number of studies. Two recent studies add to earlier findings that raise exposure and health concerns.
A large European study of house dust contaminants, published in Science of the Total Environment, finds more than 1,200 anthropogenic compounds, including numerous organophosphates, the phthalate DEHP, PCBs, pharmaceuticals and personal care products. And, a recent Argentine study, “Pesticide contamination in indoor home dust: A pilot study of non-occupational exposure in Argentina,” examines contaminant levels in household dust in villages and towns distributed throughout the Pampas region, where soybeans, corn, sunflowers, and livestock, especially cattle, are raised. The study participants were not agricultural workers, but teachers, government workers, librarians, retirees, college students, doctors, lawyers, artists and business people.
The Argentine study reinforces what has been previously reported, which emphasizes findings that there is no doubt that pesticide residues accumulate in homes adjacent to agricultural fields and pastures. For example, in 2023, Beyond Pesticides reported on a study of 598 California homes near agricultural areas sampled for carpet dust at intervals over a year. Pesticides applied to fields and livestock—including the usual suspects, chlorpyrifos, diazinon, permethrin, carbaryl—were abundant in the dust, along with fumigants, insect and rodent repellents, and other non-agricultural toxic chemicals. The European study emphasizes previously reported determinations that the health effects of combined exposures has not been a priority for chemical companies or regulators. The European researchers attempted to determine acceptable daily intakes (ADI) for 202 of the compounds, but only 46 “had consensus-based ADI values.” In other words, of the 1,200 anthropogenic compounds detected, a measure of potential toxicity was available for only about 4 percent.
Homes in agricultural areas are not necessarily safer spaces than fields or outbuildings. And children bear the brunt of interior exposures because they are smaller than adults, breathe faster, and spend more time on or near the ground. Children exposed to pesticides in their first year experience more than twice the risk of developing asthma compared to children not exposed to pesticides. And especially for younger children, the exposures from indoor dust may be higher than through food.
More recently, researchers have focused on non-agricultural exposures in residences located in towns and cities. At first glance, it might seem that urban dwellers would be less exposed than agricultural workers to pesticides; but this is most definitely not the case: urban dwellers just tend to be exposed to different pesticides. While farmworkers take the brunt of the chemicals applied to food, fiber and biofuels, urban dwellers are hit primarily by insecticides used in the indoor environment for fleas, mites, ants, and roaches, for example, but also pesticides used outdoors, such as fungicides, insecticides, and herbicides used in gardens, golf courses, and parks, which make their way indoors. But many pesticides are used in all these environments. Moreover, indoor environments may pose even more of a threat because they tend to concentrate residues of pesticides both brought in from outside and applied indoors, whether those homes are those of agricultural workers or urban residents.
Participants in the Argentine study completed questionnaires on household demographics, pet ownership, pesticide use, gardening, and habits such as whether shoes are left outside. For each household, dust was collected with broom and dustpan several times over 10 days and the samples consolidated. The researchers checked for 49 pesticides, finding 41 compounds (including metabolites). All the samples contained mixtures, averaging 19 pesticides per sample and with a maximum of 32 per sample. Twelve pesticides were detected in more than 75 percent of the samples. Imidacloprid, carbaryl, glyphosate, atrazine and piperonyl butoxide were detected in all samples. (Piperonyl butoxide is not directly pesticidal but increases the potency of pyrethrin insecticides.) Seven of the 49 are used as both agricultural and veterinary or household pest compounds. The authors note that many of the pesticides not associated with residential use likely came from greenspaces and golf courses. There is a strong sampling of pesticides banned in either the U.S. or E.U. or both, including carbofuran (U.S. and E.U.), aldicarb (E.U.), diazinon (U.S. and E.U.), and hexachlorobenzene (banned globally under the Stockholm Convention). Of the compounds detected, Argentina bans diazinon, 2,4DB, fipronil and chlorpyrifos-ethyl.
For seven of the compounds identified, including glyphosate, atrazine, and imidacloprid, the highest concentrations were over one part per million (1.0 ppm). In the U.S., for many consumer products, glyphosate residue tolerances are below this number. For example, EPA’s tolerances for glyphosate residues in stevia leaves and berries are each 0.1 ppm. This tolerance is ten times lower than the detected concentrations of just one of the pesticides found in the study.
Indoor exposures present an added twist compared to outdoor ones. The Argentine authors noted that the number and concentrations of pesticides in indoor dust can be significantly higher than in outdoor dust and air. Indoors, chemical compounds break down more slowly because they are far less exposed to sunlight, humidity and microbial action. Even long-banned chemicals such as DDT, other organochlorine pesticides, and PCBs remain in many indoor environments because they are so persistent, and they continue to pose hazards to residents and pets.
This has been known for decades; a 2009 Beyond Pesticides analysis of an EPA study noted that most floors in occupied U.S. homes had measurable levels of pesticides. Fipronil and permethrin were found in abundance, along with diazinon, chlorpyrifos and chlordane. DDT was found in higher percentages than its breakdown product DDE, suggesting that indoor environments preserve the original active components of pesticides much longer than outdoor environments. DDT was globally banned for agricultural use under the Stockholm Convention in 2004. It is still used indoors where malaria is endemic.
The Argentine results are consistent with a very large European study published in 2023. The study took 625 samples of the environment of agricultural sites in ten countries: air, surface water, sediment, soils, crops, and dust inside agricultural workers’ homes. The researchers found 197 pesticide residues indoors. Organic farmers had slightly fewer residues than conventional farmers, but the predominant pesticides were very similar in each type and very consistent with the Argentine samples. One major contrast was that in organic farmhouses 2,4-D had the highest median concentrations, whereas in conventional farmhouses the highest was glyphosate. Two-thirds of the residues in indoor dust overall are “highly hazardous to mammals.” Disturbingly, of all the environmental compartments tested, “indoor dust contained the highest number of pesticide residues and the highest pesticide concentrations,” the authors wrote. They also stressed that pre-market risk evaluations fail to capture two crucial aspects of pesticides’ effects, because they are not required to assess all routes of exposure, including indoor environments, and they do not consider mixtures.
For the Argentine study participants, as for nearly everyone, pets pose a vexing problem, being significant contributors to household dust: 93 percent of participants had pets and 51 percent had used flea repellents (mostly imidacloprid & fipronil). The authors cited a Netherlands study that found imidacloprid and fipronil in 100 percent of dog hair samples. The role of pets was also observed in the 2023 European study, highlighting the urgent need to develop non-toxic parasite control for pets. Other pests targeted were flies, mosquitoes, slugs and ants. Two thirds of participants in the Argentine study brought shoes inside.
Residential studies like this demonstrate unequivocally that we live in a miasma of many different pesticides. The list of documented health effects of pesticides is too long to repeat here, but it includes harms to every physiological system that supports life in humans, wildlife, livestock, pets, fish, aquatic and invertebrates, and beneficial and non-target fungi and microbes. Neurological, respiratory, metabolic, hematological, reproductive, endocrine systems—all are altered in ways that hamper health at every level of the biosphere.
Beyond Pesticides’ archive documents the increasing scientific literature about the extent, composition and hazards of exposure to pesticide mixtures. For example, in March we analyzed a study showing that the combination of abamectin and spirodiclofen degrades the intestinal barriers in mice, implying similar damage to the human colon that can lead to colorectal cancer and other diseases
It cannot be overemphasized that the mixtures of pesticides, together with the myriad other chemical products people use in their homes, contribute significantly to the burden of chemical exposures and have received far too little attention from regulators. The days of testing one pesticide active ingredient at a time and determining levels of gross damage in rodents rather than homing in on the cellular-level consequences to full-body processes should be over.
It is possible to reduce the use of toxic pesticides in homes, gardens, and public spaces. As a holistic solution, organic land management practices offer both health and environmental benefits, with proven commercial viability and effectiveness in both agricultural and nonagricultural uses. Become a Parks Advocate through the Parks for a Sustainable Future program. You can also help protect yourself and your family by Eating with a Conscience and making The Safer Choice to avoid hazardous home, garden, community, and food use pesticides. Beyond Pesticides urges the elimination of petrochemical pesticides and synthetic fertilizers by 2032.
Sources:
Pesticide contamination in indoor home dust: A pilot study of non-occupational exposure in Argentina
Environmental Pollution
Aparicio et al.
Environmental Pollution, May 2025
https://www.sciencedirect.com/science/article/pii/S0269749125005810
Pesticide residues with hazard classifications relevant to non-target species including humans are omnipresent in the environment and farmer residences
Silva et al.
Environment International 2023
https://www.sciencedirect.com/science/article/pii/S0160412023005536#ab015
Study Finds that Pesticides Linger in Homes
Beyond Pesticides, June 17, 2009
https://beyondpesticides.org/dailynewsblog/2009/06/study-finds-that-pesticides-linger-in-homes/
Comprehensive characterization of European house dust contaminants: Concentrations and profiles, geographical variability, and implications for chemical regulation and health risk
Haglund et al.
Science of The Total Environment, December 2024
https://www.sciencedirect.com/science/article/abs/pii/S0048969724077969
Indoor Air Pollution: Pesticides Continue to Make their Way Into Homes
Beyond Pesticides, February 1, 2023
https://beyondpesticides.org/dailynewsblog/2023/02/indoor-air-pollution-pesticides-continue-to-make-their-way-into-homes/
