**Insecticide Residuality of Mexican Populations Occupationally Exposed**

María-Lourdes Aldana-Madrid, María-Isabel Silveira-Gramont, Fabiola-Gabriela Zuno-Floriano and Guillermo Rodríguez-Olibarría

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/53980

**1. Introduction**

In this chapter the information generated by two research projects conducted in Sonora, Mexico (2003-2010) with the objective to assess the presence of insecticide residues (organo‐ chlorine and organophosphates) in corporal fluids of two population groups that live and work in agricultural areas (agricultural workers) are described. The presence of residues in body fluids (blood, urine, semen and breast milk) will be related to social, labor, environ‐ mental factors, health status (obtained from surveys, and clinical histories), and biochemical and biological indicators, with the purpose of elucidating the degree and persistence of the exposure to these insecticides.

In the countries in development as Mexico, the handling of toxic compounds as pesticides is inadequate; it is possible that people can be exposed to higher concentrations than that al‐ lowed by the maximum limits (LMP), as they demonstrate it studies carried out with chil‐ dren in San Luis Potosí state [1], in some endemic areas of malaria in Mexico like Quintana Roo [2], Chiapas and Oaxaca [3-5], and in labor exposed people of Sonora state [6,7]. This evidence suggests that the populations that work in agricultural fields, as well as those that inhabit the surrounding area could have higher exposure risk, as well as chronic contamina‐ tion that the populations with a basal exposure.

The state of Sonora is amongst the regions of Mexico with more pesticide use; it is calculated that 80% of the total applied in the country is for the production of grains and export vegeta‐ bles [8]. There are not reliable statistics of pesticide intoxications in rural areas, and there are

© 2013 Aldana-Madrid et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Aldana-Madrid et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

not epidemiologic studies to detect chronic effects of the pesticides; those should exist at least for the agricultural journeymen and for vulnerable groups, since they lack elementary protection, and don't have the correct information about pesticide toxicity.

cal fluids, and for the detection of morphological, histological, and molecular changes in

Insecticide Residuality in Mexican Populations Occupationally Exposed

http://dx.doi.org/10.5772/53980

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The degree of pesticide contamination depends on several factors, such as the formula‐ tion of the pesticide, the active ingredient, the time of exposure, the direct or indirect contact, the quantity used, the pesticides mixtures, the climate and season of the year when it's applied, and the person's age, amongst others [18, 19]. There are environmen‐ tal indicators, health indicators, and other elements that help determine the exposure risk, such as the person residence and occupational history, the clinical history, as well as the presence of the pesticides studied in drinking water, in the ground, in the atmos‐ phere, and in the fresh or processed foods in the region where the studied populations inhabit. The exposure can be increased with the daily time dedicated to the activity, as well as the years of work, the exposure form, the use of protective gear, and/or the

Due to the previously mentioned situations it was considered important to study the de‐ gree of exposure to pesticides on workers in those agricultural areas that also reside in

Sonora State territory has 179,355 km2 and it is located in Sierra Madre Occidental; geo‐ graphically it is north 32° 29', to south 26° 18' of north latitude, to east 108° 25', to west 115° 03'. The weather in coastal of Sonora is dry. The average annual temperature is around 22°C, being the average maximum 38°C (June and July) and the average mini‐ mum temperature is 5°C (January). Only 7% of the land is appropriate for agricultural use and ninety five percent of this area is irrigated. In July and August the rain reaches 450 mm. The weather in Sonora State restricts the agricultural activities. However, in vil‐ lages Yaqui and Mayo, valleys of Hermosillo, Caborca and Guaymas the major crops with irrigation are wheat, cotton, safflower, watermelon, sesame, garbanzo, sorghum, corn and vine [23]. The agriculture in the south of Sonora is based on 90% of crops such

*Group 1, field workers*. The municipal headboards included in this group are localized in the following coordinates: Obregon city 27º 29' north latitude and 109º39' west latitude with a height of 10 m above sea level and Navojoa 27º 05' north latitude and 109º39' west latitude

The town council Cajeme has a population of 175,177 men, from this population, 6,983 live in Yaqui town. In Huatabampo there are 38,563 men, specifically in "Jupare" (1,026 men). Navojoa has a population of 69,341 from this population, 445 men live in 5 de Ju‐

physical proximity of the housing to agricultural fields [20-22].

target organs [2-4,6,7].

their proximity.

**2.1. Site description**

**2.2. Population study**

with 40 m above sea level [23].

**2. Materials and methods**

as corn, wheat, oleaginous and cotton [24].

The exposure doses can be small but persistent, causing chronic health problems [8]. DDT (bis[4-chlorophenyl]-1,1,1-trichloroethane, also called dichlorodiphenyl trichloro‐ ethane); was first used to protect military areas and personnel against malaria, typhus, and other vector-terminal diseases [9]. In Mesoamerica (Mexico, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama) DDT was used until the year 2000; Mexi‐ co and Nicaragua being the last nations that applied the insecticide in agriculture and for the control of malaria (the amount used for Mexico is approximately 69,545 tons be‐ tween 1957 and 2000) [10].

Technical-grade DDT contains 65-80% p,p'-DDT, 15-21% o,p'-DDT, and up to 4% p,p'-DDD (bis[4-chlorophenyl]-1,1,-dichloroethane)[11]. When sprayed, DDT can drift, sometimes for long distances. In the soil, the compound can evaporate or attach to wind-blown dust. In the environment, DDT breaks down to p,p'-DDE (bis[4-chlorophenyl]-1,1-dichloroethene) [12], an extremely stable compound that resists further environmental breakdown or metabolism by organism; DDE is the form usually found in human tissue in the highest concentration, especially in areas where there has been no recent use of the parent compound [9]. DDT and DDE can also be transferred from the placenta and breast milk to fetuses and infants. Al‐ though some ingested DDT is converted to DDA (bis[4-chlorophenyl]-acetic acid) and ex‐ creted, any non-metabolized DDT and any DDE produced is stored in fat, as is all absorbed DDE, which cannot be metabolized. DDT and DDE are highly soluble in lipid; their concen‐ trations are much higher in human adipose tissues (about 65% fat) than in breast milk (2.5-4% fat), and higher in breast milk than in blood or serum (1% fat) [13]. DDT and DDE concentrations increase with age [14].

The use of DDT in Central and South America, Mexico, Africa, and some Asian coun‐ tries where this has been used for vector control in the past 5-10 years, DDT concentra‐ tions in human tissues remain high. For example, in Mexico, the total DDT concentration in breast milk fat was 5.7 µg/g in 1994-95 and 4.7 µg/g in 1997-98 [15]. Others Mexican data where workers used DDT to control mosquitoes, have very high DDT concentra‐ tions. Mexican data revealed that the geometric mean of total DDT was 104.48 µg/g in adipose tissue of 40 DDT sprayers in 1996 [16]; however in Finland, USA, and Canada, the value was less than 1 µg/g in adipose tissue in the general population [17]. In anoth‐ er Mexican study, the serum concentration of p,p'-DDE was much higher in DDT spray‐ ers (188 µg/L) than in children (87 µg/L); also in adults (61 µg/L) who lived in sprayed houses, but were not otherwise exposed to DDT [3].

The organophosphate insecticides have the advantage of low environmental persistence over the chlorinated pesticide compounds. However, studies carried out in individuals with exposure to insecticides in Mexico, and other countries, associate the pesticide exposure with adverse health effects, as much in the humans as in experimental animals. These dam‐ ages can be evident by the presence of certain biochemical indicators in the different biologi‐ cal fluids, and for the detection of morphological, histological, and molecular changes in target organs [2-4,6,7].

The degree of pesticide contamination depends on several factors, such as the formula‐ tion of the pesticide, the active ingredient, the time of exposure, the direct or indirect contact, the quantity used, the pesticides mixtures, the climate and season of the year when it's applied, and the person's age, amongst others [18, 19]. There are environmen‐ tal indicators, health indicators, and other elements that help determine the exposure risk, such as the person residence and occupational history, the clinical history, as well as the presence of the pesticides studied in drinking water, in the ground, in the atmos‐ phere, and in the fresh or processed foods in the region where the studied populations inhabit. The exposure can be increased with the daily time dedicated to the activity, as well as the years of work, the exposure form, the use of protective gear, and/or the physical proximity of the housing to agricultural fields [20-22].

Due to the previously mentioned situations it was considered important to study the de‐ gree of exposure to pesticides on workers in those agricultural areas that also reside in their proximity.
