Ecotoxicology of agrochemicals used in valle de Santiago Guanajuato, Mexico Ecotoxicologia de agroquímicos utilizados em valle de Santiago Guanajuato,

The application of pesticides in the agricultural sector represents multiple benefits such as pest and disease control, however, their application entails risks to the environment and the health of people, which can be accidental or due to improper handling. Therefore, this work focuses on the qualitative determination of the ecotoxicology of pesticides used by seasonal farmers in the Municipality of Valle de Santiago. Information on the most commonly used pesticides in the study area was collected through surveys of seasonal agricultural producers and the main points of sale for agrochemicals. The registry of commercial products with the Federal Commission for Protection against Sanitary Risks in Mexico was consulted to verify the active ingredient and its registered use. The environmental impact of the active ingredient was estimated based on a qualitative matrix to


INTRODUCTION
The use of phytosanitary products in agriculture represents an undeniable benefit, guaranteeing higher agricultural production and making it much more profitable. However, their application entails toxic risks to health, either through accidental exposure or inappropriate handling of products (Fernandez, Viciana, & Drovandi, 2003).
The assessment of potential effects of pesticides on the environment is an important part of the regulatory process, where risk assessment defines a relationship between expected exposure levels and effects on agroecosystems and ecosystems. This exposure involves a quantitative estimation of the concentration that the pesticide can reach in different compartments due to human activity, always starting from an intentional release into the environment (Schaaf, 2013).
It is worth mentioning that their use is of fundamental aid in the agricultural environment, but it has a great impact on the ecological system since their particles go into the atmosphere and, through rainfall, fall into the environment affecting many species that are not their target.
In general, the environmental behavior of all these substances can be included in what is known as "diffuse pollution", characterized by not originating at a defined point, but rather at multiple, poorly identifiable points. This type of pollution can cause especially concerning situations over time since the environment can become increasingly polluted, resulting in extensive affected Brazilian Journal of Animal and Environmental Research, Curitiba, v.6, n.2, p. 1563-1572, abr./jun., 2023 areas (Fernandez, Viciana, & Drovandi, 2003). Therefore, this work focuses on the qualitative determination of the total ecotoxicology of the pesticides used by seasonal farmers in the Municipality of Valle de Santiago.

LITERATURE REVIEW
In Mexico, the cultivated agricultural area in the last 20 years is 20 million hectares, of which the greatest use is under seasonal conditions, then reduced to 15.5 million hectares, while irrigation agriculture has remained during this period at 5 million, corresponding to 75% of the country's cultivated area. The problem for grain and vegetable crops has been the different types of diseases, pests, and weeds that harm from the seed to the plant and the fruits, which have been countered with the application of pesticides (Garcia-Gutierrez & Rodriguez-Meza, 2012).
Pesticides are substances or mixtures of substances used to control pests in agricultural crops, insects that act as disease vectors, control of insects and mites that affect the production, processing, storage, transportation, or marketing of food, agricultural products, and animal feed (FAO, 2003).
Once applied in the environment, pesticides are chemically prone to a series of transformations at the physical, chemical, and biological levels, such as phenomena of adsorption on soils and plants, volatilization, photolysis, and chemical or microbial degradation that affect ecosystems, agroecosystems, and human populations as reported by Uribe et al. (2012) and Valderrama et al. (2012).
These substances can also be carried away by air and/or water currents, which facilitate their dissemination over long distances; it should be added that volatile residues go into the atmosphere and return with precipitation to other places (Lopez-Geta et al., 1992).
According to Guadino (1981), pesticides can be chronologically classified into: The available information regarding the volume and types of pesticides applied annually in agricultural fields and the degree of organic contamination with toxic products in bodies of water is practically non-existent. As of the end of production in 2018, the states with the highest agricultural production at the national level were Guanajuato, Sinaloa, Tamaulipas, Zacatecas, and others (SADER, 2018), where intensive use of agrochemicals is noteworthy. In contrast, the areas with the highest use of pesticides in agriculture or for sanitary purposes over the last ten years were: Sinaloa, Chiapas, Veracruz, Jalisco, Nayarit, Colima, Sonora-Baja California, and Tamaulipas. These states accounted for around 70% of pesticide consumption (García-Gutiérrez & Rodríguez-Meza, 2012).
It has been emphasized globally since 2003 that it is necessary to regulate the use and application of these pesticides, especially to have a registry and carry out surveillance programs on environmental contamination, poisoning, and monitoring of the residues generated by these compounds (FAO, 2003).
In our country, the intersecretarial commission for the control of the process and use of pesticides, fertilizers, and toxic substances (CICOPLAFEST), now COFEPRIS (Federal Commission for the Protection Against Sanitary Risks), was created. However, the indiscriminate use of these compounds is recognized as a threat to health and the environment (Cortinas de Nava,

2007). Data from INEGI (2009) indicate that the technology applied in agricultural surfaces is based
on fertilization, use of chemical herbicides and insecticides, while natural fertilizers are applied in lesser amounts.
To estimate the qualitative impact of pesticides, data can be obtained from the following sources: For Ecotoxicology, data is obtained from pesticide labels. This information is printed on the products, making it easily accessible. It can be found under the name of technical data sheet.
Human toxicity: this information can be extracted from different sources: the United States Environmental Protection Agency (EPA) and the International Agency for Research on Cancer (IARC), through their official websites. Although it can also be extracted from laboratory and university data through toxicological reports of different products.
Environmental behavior: this data is extracted from work done by laboratories, universities, entities, as well as from product labels, in some cases, this information can be obtained (especially for persistence in the soil).

MATERIAL AND METHODS
The study area where the project was carried out was in the municipality of Valle de Santiago, located in the southern part of the state of Guanajuato. It has an area of 820.1 km2. The area dedicated to agriculture is 70.95% of the total municipal territory, and the crops that are mostly established are sorghum, wheat, barley, corn, beans, and alfalfa. Agriculture in Valle de Santiago is mostly rain-fed, and there are 11,406 agricultural production units that cover a total of 60,793.53 hectares (INEGI, 2017).
Information about the most commonly used pesticides applied with sprayers in the area was collected in two stages: the first through surveys directed at producers and workers involved in rainfed agriculture production, and the second through a survey of the main agrochemical sales points in the municipality. The survey included sections corresponding to the crop planted, type of pesticide applied (commercial name), whether the active ingredient was known, and the management provided when applying it.
With the list of commercial names, the product registry with the Federal Commission for Protection against Sanitary Risks (COFEPRIS) was consulted, which verified the active ingredient and the registered use. The environmental impact of the active ingredient was estimated based on a qualitative matrix to determine total ecotoxicology proposed by (Fernández, Viciana, and Drovandi 2003), which considers subfactors such as toxicological category, toxicity to bees, birds, and fish.
With the above values, the formula proposed by Schaaf (2015) was used to determine the total ecotoxicology (ET) rating.

RESULTS AND DISCUSSION
A total of 19 products (pesticides) used in the study area were recorded, of which 6 were insecticides, 12 were herbicides, and one was a fungicide. Among the insecticides used for pest control (Table 2) in maize and sorghum crops, the active ingredient sulfoxaflor stands out, which is a systemic insecticide with xylem and translaminar movement that acts as a neurotoxin. It acts on the central nervous system of insects, interfering with the transmission of nerve stimuli, and has been shown to be highly toxic to bees (Babcock et al., 2011).

Two systemic organophosphate insecticides (Ethyl Chlorpyrifos and Dimethoate) with
insecticidal and acaricidal activity through ingestion and contact were recorded. And two from the group of synthetic pyrethroids (Lambda cyhalothrin, Cypermethrin) which are highly toxic to bees and aquatic species (He et al., 2008). Regarding the herbicides used (Table 3), the application of Pinoxaden stands out, which is a herbicide for selective post-emergence weed control in wheat and barley, which exerts a dual control effect by inhibiting the synthesis of new fatty acids and the elongation of their long chains (Campagna & Rueegg, 2006) it is slightly toxic to fish and algae and highly toxic to microcrustaceans.
On the other hand, Nicosulfuron, which is a systemic product from the sulfonylurea group that is selective to corn crops, formulated as an aqueous concentrated suspension, is applied postemergence for weed control. However, it is mentioned that this herbicide can cause damage to rice crops (Esqueda, 2000) and can also be harmful if absorbed through the skin. Prolonged or frequently repeated skin contact can cause allergic reactions in some people. For Flucarbazone sodium, there are reports from more than 15 years ago that weeds began to develop resistance to this herbicide (Espinoza & Diaz 2005).
Weed control in wheat: Improper use of this product can contaminate groundwater. Avoid handling it near water wells and do not apply it where the level of the aquifer is shallow Es ligeramente tóxico para peces y algas y muy tóxico para microcrustáceos. Evitar que el producto entre en contacto con ambientes acuáticos.

Control de malezas en trigo
El uso inadecuado de este producto puede contaminar el agua subterránea. Evite manejarlo cerca de pozos de agua y no lo aplique en donde el nivel de los mantos acuíferos sea poco profundo

Everest
Flucarbazone de sodio Post-emergence application in wheat cultivation can cause nausea, vomiting, trembling of limbs and body, excessive salivation, spasms, and difficulty breathing, and can trigger allergic reactions in sensitive individuals. When handling the product, do not contaminate the air, soil, rivers, lakes, reservoirs, or water tanks.
Non-toxic to fish and other aquatic organisms. Not toxic to birds and bees. No es toxico para aves y abejas, Accent L Nicosulfuron Weed control in corn crops.
It is a product that can be harmful if absorbed through the skin. Prolonged contact can cause allergic reactions in some people. Improper use of this product can contaminate groundwater.

Atrazina Atrazina
Weed control in crops such as corn.
It is moderately toxic to fish. Avoid product contact with aquatic environments. It is moderately toxic to birds.
Effects have been reported in animals on the following organs: adrenal gland, bone marrow, eye, kidney, liver, spleen, testes, and thyroid. The product is highly toxic to aquatic organisms in an aqueous base.
Highly toxic to aquatic organisms. Highly toxic to aquatic organisms, with long-lasting harmful effects. Regarding the only fungicide that reports its use in the study area (Fenbuconazole), it is a systemic fungicide (Table 4), where the active ingredient is absorbed by the leaves and transported in the plant to growth areas and parts via xylem, which is mentioned to have low toxicity to birds, bees, and soil microorganisms. It presents low toxicity towards birds, bees, earthworms, and soil microorganisms. It has low or negligible mobility in the soil, therefore its risk of contaminating groundwater is low.
The qualitative estimation of the total ecotoxicology of the active ingredients contained in products used in seasonal agriculture in Valle de Santiago, Gto, shows that insecticides have the highest value, and to a lesser degree, herbicides (Table 5).

CONCLUSION
The use of pesticides in the study area recorded a total of 19 products, of which 6 are insecticides, 12 herbicides, and one fungicide. The qualitative estimation of the total ecotoxicology of the active ingredients contained in the pesticides used in seasonal agriculture shows that insecticides have the highest value and herbicides to a lesser degree.