Costa Rica farmers apply nearly twice the official pesticide rate to crops, study finds

Q COSTA RICA — A scientific study estimates that Costa Rica’s cultivated land uses an average of 21.9 kilograms of pesticide active ingredients per hectare each year—nearly twice the official national figure.

The difference, researchers say, is largely explained by how the country calculates the area included in its agricultural indicator.

The study, published in August 2026 in Environment International, calculated pesticide use at 21.91 kilograms per hectare when it examined cropland alone. The official figure reported by Costa Rica’s Ministry of Agriculture and Livestock is 11.04 kilograms per hectare.

That comparison does not necessarily mean the ministry failed to count pesticide use. Rather, the two figures use different denominators. The official indicator includes both cultivated land and managed pasture, where pesticide use is substantially lower. When the researchers included pastures in their own model, they calculated an average of 11.07 kilograms per hectare—almost identical to the ministry’s figure, according to Delfino.cr.

Pastures accounted for roughly half of the area analyzed but used an estimated 1.04 kilograms per hectare. Removing that land from the calculation nearly doubled the average for cropland.

Export crops account for the highest intensities

The study found considerable differences among crops. Bananas had the highest estimated average intensity, at 78.88 kilograms per hectare, followed by pineapples, rice, tomatoes and potatoes.

Banana production also showed a marked increase over the period examined. The model estimated use of 60.68 kilograms per hectare in 2012, rising to 103.95 kilograms in 2024.

The province of Limón recorded the highest estimated pesticide intensity. Its average was 35.77 kilograms per hectare when pastures were included and approximately 57.5 kilograms when the analysis was limited to cultivated land. The researchers linked the elevated figures to the concentration of export-oriented banana and pineapple production in the Caribbean region.

Four active ingredients accounted for about 51% of the estimated annual pesticide volume: the fungicide mancozeb, the herbicide glyphosate, the insecticide diazinon and the nematicide ethoprophos. Mancozeb alone represented approximately 36% of the total estimated load.

A reconstructed estimate, not a direct farm survey

The figures are not based on direct measurements of every pesticide application made on Costa Rican farms. Instead, the researchers reconstructed national use from official trade and agricultural records.

Their analysis began with import and export data to estimate how much active ingredient remained in the country. The team then allocated those quantities across crops using information on registered products, authorized doses, application frequency and cultivated area.

To carry out the work, the researchers created the Base de Datos Integrada de Plaguicidas de Costa Rica (CRIPD)—Costa Rica Integrated Pesticide Database. The database drew on more than 71,000 commercial records from the State Phytosanitary Service and other official sources. By cross-checking those records with Ministry of Finance databases, the researchers corrected more than 30,000 errors, including duplicate entries and incorrectly entered quantities.

The methodology carries important limitations. It assumes that applications correspond to the maximum doses and frequencies listed in official records and that pesticide intensity is consistent across regions for the same crop. Actual farm practices may differ: some producers may apply less than the modeled amount, while others may exceed recommended frequencies.

The geographic analysis also relied on data from the 2014 agricultural census, meaning it does not capture every subsequent change in where crops are grown. The results are therefore best understood as estimates of national and regional patterns rather than direct measurements from individual farms.

Hazard levels did not improve consistently

The study examined not only the quantity of pesticides used but also the hazard characteristics of the active ingredients. The researchers found that the 32 ingredients responsible for 90% of estimated use were highly hazardous in at least one category evaluated.

The trends varied. Some indicators improved, while others showed no statistically significant change. Several indicators worsened, particularly those linked to potential toxicity for aquatic organisms.

Indicators associated with carcinogenic potential, endocrine disruption and acute toxicity through skin contact began at elevated levels and did not show statistically significant improvement. Some environmental properties, including chemical mobility and behavior in water or soil, improved modestly.

The distinction between hazard and risk is important. Hazard refers to a substance’s inherent ability to cause harm. Risk also depends on exposure, dose, environmental conditions and how a substance is used. The study did not determine how many people became ill or measure damage to specific ecosystems.

The authors argue that the findings challenge the assumption that agricultural modernization automatically reduces pesticide dangers by replacing older chemicals with safer alternatives. Widely used substances such as mancozeb, glyphosate and diazinon have remained on the market for decades, in part because generic pesticide markets can extend the commercial life of older active ingredients.

Tropical ecosystems remain poorly studied

The researchers also identified gaps in the scientific data available for tropical environments. For some aquatic ecotoxicology indicators, information was unavailable for substances representing up to 31% of the estimated pesticide volume.

Tropical aquatic invertebrates are among the groups that remain insufficiently represented in existing studies. The researchers noted that many international toxicity parameters were developed under temperate conditions, which may not fully reflect Costa Rica’s climate and ecosystems.

The analysis also assessed active ingredients individually. That leaves open questions about the effects of pesticide mixtures applied together. The article cited previous research indicating that combinations of mancozeb and glyphosate produced stronger neurotoxic effects than glyphosate alone.

These limitations do not invalidate the study’s estimates, but they do place boundaries around what the numbers can show. They can identify patterns in pesticide use and hazard; they cannot, by themselves, establish actual human exposure or prove damage to a particular river, community or ecosystem.

What the findings mean for policy

The central policy issue is not simply whether Costa Rica uses 11 or 22 kilograms of pesticides per hectare. Both numbers can be accurate within their respective definitions. The larger problem is that a single national average can conceal major differences between pasture and intensive cropland, as well as between regions and crops.

A national figure that combines low-use pasture with banana or pineapple plantations may be useful for broad comparisons, but it is less informative for evaluating local exposure or environmental pressure. In Limón, for instance, the cropland estimate is far higher than the national average, yet that concentration disappears when all agricultural land is combined.

The researchers recommend publishing separate pesticide-use estimates for crops and pastures. They also call for a public system recording applications by crop and region, similar to the system used in California. More detailed records would make it easier to identify hotspots, assess trends and compare policies using consistent areas and time periods.

They further recommend stronger environmental monitoring and more research into human exposure, particularly around banana and pineapple plantations in the Caribbean region.

The study also arrives as countries work toward the Kunming-Montreal Global Biodiversity Framework’s goal of halving the risks associated with pesticides and highly hazardous chemicals by 2030. Meeting that target will require more than a national average. Costa Rica will need to know which substances are being used, where they are applied, in what quantities and what happens to them after they enter tropical soils and waterways.

The study’s most significant contribution may therefore be methodological. It shows that the answer to “How much pesticide does Costa Rica use?” depends heavily on what land is counted. It also shows why quantity alone is not enough: the identity, toxicity, location and combination of the chemicals matter just as much.