Risk of genotoxic damage in schoolchildren exposed to organochloride pesticides

Abstract

This study identified and determined organochloride pesticide (OCs) concentrations in hair samples from children at two elementary schools: one exposed to fumigations in agricultural fields, the other unexposed. Three concentrations of OCs levels in the hair were compared (high, medium, low), and total nuclear abnormalities in buccal cells were determined: micronuclei (MNi), condensed chromatin, karyorrhexis, pyknosis, binucleate cells, karyolysis, lobed nuclei, and apoptosis. No significant differences were found for the presence of MNi between the schoolchildren from the exposed and unexposed schools, but the prevalence of OCs in both schools was over 50%, as well as the frequencies of MNi in the children were over 58%. Findings show a significant difference between the frequency of MNi in the total sample of schoolchildren (exposed school + unexposed school) in relation to the concentration of OCs detected in their hair. The children from exposed school that showed the higher concentrations of OCs in hair had higher levels of genotoxic damage in the buccal cells; compared against children with lower concentrations of OCs. The most frequent nuclear abnormalities in the exposed children were lobed nuclei (79.4%), binucleate cells (66.66%), apoptosis (65.07), and MNi (58.7%). We determined the prevalence ratio (PR) and prevalence odds ratio (POR) for the presence of MNi in buccal cells in relation to the OCs concentrations in the hair samples. Both ratios were high for MNi [PR 3.93, 95% confidence interval (CI) 1.97-7.84, p = 0.0003; and POR 7.97, 95% CI 2.62-24.28, p = 0.0003], indicating a 7.97 times greater risk that the exposed children will present > 0.2% of MNi when OCs concentrations exceed 0.447 μg/g. These indicators may be useful biomarkers of genotoxic damage in children exposed to persistent, highly-toxic compounds. Results suggest the potential risk to which those schoolchildren are exposed on a daily basis due to fumigations in nearby agricultural fields.

Figure 1

Frequency (%) of OCs in the hair of the study population from the exposed and unexposed schools. αHCH, hexachlorocyclohexane alpha; βHCH, beta; δHCH, delta; γHCH, gamma; AL, aldrin; DIE, dieldrin; END, endrin; ENA, endrin aldehyde; ENK, endrin ketone; CC, cis-chlordane; TG, trans-gamma chlordane; HE, heptachlor; EH, epoxyheptane; ES IA, endosulfan IA; ES IIB, endosulfan IIB; ES, endosulfan sulfate; DDD, dichloro diphenyl dichloroethane; DDE, dichloro diphenyl dichloroethylene; DDT, dichloro diphenyl trichloroethane.

Figure 2

Concentration (μg/g) of total sum OCs in the hair of the study population from the exposed and unexposed schools. αHCH, hexachlorocyclohexane alpha; βHCH, beta; δHCH, delta; γHCH, gamma; AL, aldrin; DIE, dieldrin; END, endrin; ENA); ENA, endrin aldehyde; ENK, endrin ketone; CC, cis-chlordane; TG, trans-gamma chlordane; HE, heptachlor; EH, epoxyheptane; ES IA, endosulfan IA; ES IIB, endosulfan IIB; ES, endosulfan sulfate; DDD, dichloro diphenyl dichloroethane; DDE, dichloro diphenyl dichloroethylene; DDT, dichloro diphenyl trichloroethane.

Figure 3

Concentration of total OCs (μg/g) in the two study groups. Values are expressed as medians (inter-quartile range); a Mann–Whitney U test exposed school versus unexposed school.

Figure 4

Microscope images of the mayor nuclear abnormalities observed in the micronuclei assay. (A) Normal cell, (B) Micronuclei, (C) Lobed nuclei, (D) Condensed chromatin, (E) Binucleated Cell, (F) Pyknosis, (G) Karyorrhexis, (H) Karyolysis, (I) Apoptosis.

Figure 5

Frequency (%) of nuclear abnormalities in unexposed and exposed schoolchildren: Micronuclei (MNi), Condensed chromatin (CC), Karyorrhexis (KR), Pyknosis (PK), Binucleated cells (BN), Karyolysis (KL), Lobed nuclei (LN), and Apoptosis (AT). *Significant differences (p < 0.05) by chi square test.

Figure 6

Number of total abnormal cells (TAC) in the two study groups. Values are expressed as means ± standard deviation; student’s T test between exposed school versus unexposed school.

Figure 7

Correlation between abnormal cells versus total concentration of OCs in both study groups. (A) Micronuclei versus OCs, (B) other abnormal cells versus OCs; (C) total abnormal cells versus OCs.

Figure 8

Number of total abnormal cells (TAC) in the study population stratified by OC concentration tertiles. Values are expressed as medians (inter-quartile range); Mann–Whitney U test; ^alow versus high concentration group (p = 0.045).