Pesticide use patterns and their association with cytokine levels in Mexican flower workers.

OBJECTIVE: Occupational exposure to pesticides is a known risk for disrupting cellular immune response in flower workers due to their use of multiple chemical products, poor work conditions, and inadequate protection. Recently, the analysis of pesticide use patterns has emerged as an alternative to studying exposure to mixtures of these products. This study aimed to evaluate the association between exposure to different patterns of pesticide use and the cytokine profile of flower workers in the State of Mexico and Morelos, Mexico. METHODS: A cross-sectional study was carried out on a population of 108 flower workers. Serum levels of IL-4, IL-5, IL-6, IL-8, IL-10 cytokines were analyzed by means of multiplex analysis, and TNF-α and IFN-γ using an ELISA test. Pesticide use patterns were generated by principal components analysis. RESULTS: The analysis revealed that certain patterns of pesticide use, combining insecticides and fungicides, were associated with higher levels of pro-inflammatory cytokines, particularly IL-6 and IFN-γ. CONCLUSION: These findings indicate that pesticides may possess immunotoxic properties, contributing to increased inflammatory response. However, further comprehensive epidemiological studies are needed to establish a causal relationship.

Levels and determinants of urinary cadmium in general population in Spain: Metal-MCC-Spain study.

BACKGROUND: Cadmium is a ubiquitous and persistent metal, associated with different harmful health effects and with increased morbidity and mortality. Understanding the main sources of exposure is essential to identify at risk populations and to design public health interventions. OBJECTIVE: To evaluate cadmium exposure in a random-sample of general adult population from three regions of Spain, assessed by the urinary cadmium (U-Cd) concentration, and to identify its potential determinants and sex-specific differences, including sociodemographic, lifestyle and dietary factors. MATERIALS AND METHODS: We measured U-Cd (µg/g creatinine) in single urine spot samples from 1282 controls enrolled in the multicase-control study in common tumors in Spain (MCC-Spain) with inductively coupling plasma-mass spectrometry equipped with an octopole reaction systems (ICP-ORS-MS). The association between sociodemographic, lifestyle, and dietary characteristics and U-Cd concentrations was evaluated using geometric mean ratios (GMR) estimated by multiple log-linear regression models. RESULTS: Overall, geometric mean U-Cd concentration was 0.40 (95%CI: 0.38, 0.41) µg/g creatinine. Levels were higher in women than in men (GMR]: 1.19; 95%CI: 1.07, 1.32), and increased with age in males (ptrend< 0.001). Cigarette smoking was clearly associated to U-Cd levels (GMRformer vs non-smokers: 1.16; 95%CI: 1.05, 1.29; GMRcurrent vs non-smokers: 1.42; 95%CI: 1.26, 1.60); the relationship with secondhand tobacco exposure in non-smokers, was restricted to women (pinteraction = 0.02). Sampling season and region also seemed to influence U-Cd concentrations, with lower levels in summer (GMRsummer vs average: 0.79; 95%CI: 0.71, 0.88), and higher levels in North-Spain Asturias (GMRAsturias vs average: 1.13; 95%CI: 1.04, 1.23). Regarding diet, higher U-Cd concentration was associated with eggs consumption only in men (pinteraction = 0.04), just as rice intake was associated in women (pinteraction = 0.03). CONCLUSION: These results confirmed that tobacco exposure is the main modifiable predictor of U-Cd concentrations, and remark that the role of dietary/sociodemographic factors on U-Cd levels may differ by sex.

Dietary flavonoid patterns and prostate cancer: evidence from a Mexican population-based case-control study.

Flavonoids are a broad group of bioactive compounds with anticarcinogenic effects on the prostate that have been scarcely evaluated in Latin American populations. Our objective was to evaluate the association between dietary patterns of flavonoid intake and prostate cancer (PC) in a population-based case-control study carried out in Mexico City. Based on a semi-quantitative FFQ with a frame reference of 3 years before diagnosis or interview, we used an updated database for estimating the daily intake (mg/d) of flavones, flavonols and flavanols for 395 confirmed incident PC cases and 797 population controls matched by age (± 5 years). Histological PC differentiation was evaluated using the Gleason score at diagnosis. Flavonoid dietary intake patterns (FDIP) were determined through principal component analysis, and their association with PC was estimated using logistic regression models. Three FDIP were identified: gallate pattern (GP) characterised by (-)-epicatechin-3-O-gallate, (-)-epigallocatechin-3-O-gallate and (+)-gallocatechin; luteolin pattern (LP) characterised by luteolin and (-)-epigallocatechin-3-O-gallate; and a mixed pattern (MP) that included (+)-catechin, (-)-epicatechin and quercetin. A higher GP (ORT3 v.T1 = 0·47; 95 % CI 0·33, 0·66) and LP intake (ORT3 v. T1 = 0·39; 95 % CI 0·27, 0·59) were associated with a decreased PC likelihood. In contrast, a higher MP intake (ORT3 v. T1 = 2·32; 95 % CI 1·67, 3·23) increased PC likelihood. The possible differential and synergistic anticarcinogenic role of flavonoid compounds in PC deserves further study.

Revisión rápida de los efectos de la variación de la temperatura y la humedad en la morbilidad y mortalidad por Covid-19.

Objetivo. Resumir y analizar la evidencia de la asociación entre Covid-19 y factores climáticos. Material y métodos. Se utilizó la metodología de revisiones rápidas de Cochrane. Se buscaron artículos publicados del 1 de enero al 27 de abril de 2020 en una base de datos académica y preprints. Los títulos y resúmenes fueron revisados por dos investigadores y los textos completos por cinco investigadores. Resultados. De 354 artículos identificados, 26 cumplieron los criterios de elegibilidad establecidos. De éstos, 20 observaron una asociación inversa. Al evaluar su calidad, nueve calificaron con validez moderada, porque si bien ajustaron por covariables en el análisis, son estudios ecológicos. Conclusiones. A pesar de la homogeneidad de resultados, los factores climáticos explican un porcentaje pequeño de la variación de Covid-19. Son necesarios estudios con periodo de análisis más largo que capten tendencia y estacionalidad e incluyan factores de riesgo individuales.

Para-occupational exposure to pesticides, PON1 polymorphisms and hypothyroxinemia during the first half of pregnancy in women living in a Mexican floricultural area.

BACKGROUND: Adequate maternal thyroxine (T4) concentrations during the first half of pregnancy are fundamental to the embryo's or fetus' neural development. Organophosphate pesticides (OP) can act as thyroid disruptors and genetic polymorphisms for paraoxonase 1 (PON1), an enzyme that detoxifies OP, could be involved in individual's susceptibility to them. We assessed the association between para-occupational exposure to pesticides, including OP, during pregnancy and maternal hypothyroxinemia, as well as the potential genetic susceptibility conferred by PON1 polymorphisms. METHODS: We analyzed information from 381 healthy pregnant women (< 17 gestational weeks), who lived in a floricultural region of Mexico where pesticides, including OP, are routinely used. Women who were para-occupationally exposed to pesticides were those whose partner had an occupation involving contact with these products. Thyroid-Stimulating Hormone (TSH) and free T4 concentrations were determined using ELISA, and hypothyroxinemia was defined as free T4 concentrations <0.76 ng/dL. PON1192QR, PON155LM and PON1-108CT polymorphisms were determined through Polymerase Chain Reaction (PCR). The association between para-occupational exposure and genetic polymorphisms and hypothyroxinemia was estimated using logistic regression models. RESULTS: One hundred and sixty two women (42.52%) were classified as para-occupationally exposed to pesticides. Hypothyroxinemia prevalence was 54%, and it was not significantly associated with pesticide para-occupational exposure (OR: 1.21 95% CI 0.75-1.94). Independently of para-occupational exposure, the likelihood of hypothyroxinemia was higher among women who were carriers of PON155MM than in those with PON155LL genotype (OR MM vs LL: 3.03; 95%CI 1.62, 5.70). PON1192 RR (OR RR vs QQ: 1.72; 95%CI 0.93, 3.17) and PON1-108TT (OR TT vs CC: 1.60; 95%CI 0.90, 2.70) genotypes were marginally associated with hypothyroxinemia. No significant interaction was observed between pesticides para-occupational exposure and PON1 polymorphisms. CONCLUSIONS: These results suggest that PON1 polymorphisms could affect thyroid function during pregnancy in women living in areas where pesticides, including OP, are routinely used. Low exposure variability in this population, could be a possible explanation for the lack of association between para-occupational exposure and thyroid function.

Effect of exposure to p,p´-DDE during the first half of pregnancy in the maternal thyroid profile of female residents in a Mexican floriculture area.

BACKGROUND: Dichlorodiphenyldichloroethene (p,p´-DDE), the main metabolite of dichlorodiphenyltrichloroethane (DDT), has been associated with changes in human thyroid hormone levels. Maternal thyroid hormones are essential for adequate fetal neurodevelopment during the first half of pregnancy. OBJECTIVE: To evaluate the association between maternal p,p´-DDE concentration and the maternal thyroid profile during the first half of pregnancy. MATERIALS AND METHODS: We analyzed the information of 430 pregnant women from a Mexican floriculture area, with a gestational age ≤16 weeks. By questionnaire, we obtained sociodemographic, reproductive, and life-style, information. Serum concentrations of thyroid stimulating hormone (TSH), and total and free T3 and T4 were determined by means of Enzyme-Linked ImmunoSorbent Assay (ELISA). p,p´-DDE was analyzed by Gas Chromatography. The association between p,p´-DDE and thyroid profile was assessed through linear and logistic regression models. RESULTS: Thirty eight percent of women had p,p´-DDE levels below the Limit of Detection and 12.3% below the Limit of Quantification. Within the quantifiable range, median was 53.03ng/g. TSH >2.5 mIU/L was present in 9.3% of women; 47.7% had isolated hypothyroxinemia; 3.5% had subclinical hypothyroidism, and 5.8% had overt hypothyroidism. We observed a significant positive association between quantifiable p,p´-DDE and total T3 serum levels in comparison with those with concentrations below the Limit of Detection (ß=0.19; 95% CI=0.06, 0.34). There were no significant associations with other hormones of the thyroid profile or with clinical diagnosis. CONCLUSIONS: Our findings suggest that p,p´-DDE exposure, even at low concentrations, could disrupt thyroid homeostasis during pregnancy.

Association between organochlorine pesticide exposure and thyroid hormones in floriculture workers.

Several studies have suggested that exposure to DDT may be related to changes in thyroid hormone levels in animals and humans, even though results across studies are inconsistent. The aim of this study was to assess the association between exposure to p,p'-DDE (a stable metabolite of DDT) and serum levels of thyroid hormones in floriculture workers. A longitudinal study was conducted on 136 male subjects from the States of Mexico and Morelos, Mexico, who were occupationally exposed to pesticides, during agricultural periods of high (rainy season) and low (dry season) levels of pesticide application. Using a structured questionnaire, a survey was carried out on socio-demographic characteristics, anthropometry, clinical history, alcohol and tobacco consumption, residential chemical exposure, and occupational history. Blood and urine samples were collected to determine serum levels of TSH, total T3, total T4, and p,p'-DDE, and metabolites of organophosphate pesticides (OP), respectively. The analysis of the associations between p,p'-DDE levels and thyroid hormone profile adjusting by potential confounding variables including urinary OP metabolites was carried out using multivariate generalized estimating equation (GEE) models. Our results showed that the geometric means of p,p'-DDE levels were 6.17 ng/ml and 4.71 ng/ml in the rainy and dry seasons, respectively. We observed positive associations between the serum levels of p,p'-DDE and those of total T3 (ß=0.01, 95% CI: -0.009, 0.03), and total T4 (ß=0.08, 95% CI:0.03, 0.14) and negative but no significant changes in TSH in male floricultural workers, supporting the hypothesis that acts as thyroid disruptor in humans.

[Correct utilization of breast cancer detection techniques in Mexican women]. / Utilización correcta de las técnicas de detección de cáncer de mama en mujeres mexicanas.

OBJECTIVE: Identify the characteristics associated with correct utilization of self examination (SE), clinical exam (CE) and mammography (MA) for breast cancer (BC) early detection. MATERIALS AND METHODS: Interviews were undertaken with 1 030 Mexican women (n=1 030), 20 to 88 years of age, regarding their reproductive and sociodemographic characteristics. An index of correct utilization was constructed based on the form and frequency practice of those techniques. RESULTS: The prevalence of correct utilization of SE was 11% and 5.4% for CE. Further, 7.6% of women 40-49 years of age with 2 or more BC risk factors had MA during the two years prior to the interview, and for 31.6% among women ≥50 years of age the MA was annually. The main determinant of MA utilization was having financial protection from either IMSS, ISSSTE or Seguro Popular. CONCLUSIONS: It is necessary to improve the correct utilization of BC detection techniques in Mexico.

Association between exposure to organophosphate pesticides and cytokine levels in a population of flower workers in Mexico.

The ability of organophosphate pesticides to disturb immune function has been demonstrated by in vivo and in vitro studies, but evidence of such effects on humans remains scarce. To assess the association between organophosphate pesticides exposure and cytokine levels in Mexican flower workers, a cross-sectional study was carried out. A questionnaire was provided to 121 male flower workers, and urine and blood samples were collected. Using gas chromatography, urinary concentrations of dialkylphosphate metabolites were determined. The serum cytokine levels, IL-4, IL-5, IL-6, IL-8, and IL-10, were measured using multiplex analysis, and levels of INF-γ and TNF-α by ELISA. We found that a higher dialkylphosphate concentration decreased the pro-inflammatory cytokines INF-γ (ß = -0.63; 95 % CI: -1.22, -0.05), TNF-α (ß= -1.18; 95 % CI: -2.38, 0.02), and IL-6 (ß= -0.59; 95 % CI: -1.29, 0.12), and increased IL-10 (ß=0.56; 95 % CI: 0.02, 1.09), the main anti-inflammatory cytokine, suggesting an imbalance of the immune response in flower workers.

Exposure to p,p´-DDE during early pregnancy, anthropometry, and gestational age at birth, in a flower-growing region of Mexico.

Prenatal exposure to dichlorodiphenyldichloroethylene (p,p´-DDE) may interfere with fetal development; however, studies evaluating anthropometry and gestational age at birth show inconsistent results. Typically, p,p´-DDE exposure has been measured during the third trimester and missed the key early pregnancy period. We evaluated the association between p,p´-DDE exposure before week 18 of pregnancy and anthropometry at birth, as well as gestational length, in 170 mother-child pairs from a cohort study in a flower-growing mexican region. Maternal serum p,p´-DDE concentrations were determined by gas chromatography. The associations between p,p´-DDE and z-scores of birth weight, birth length, and gestational age were evaluated by linear multiple regression models. Logistic regression models were used for low birth weight and small size for gestational age. Effect modification by child's sex was explored. The average gestational age at the blood sample extraction was 10.6 weeks. p,p'-DDE was detected in 64.7% of mothers, at a geometric mean of 0.24 ng/mL. Prenatal p,p´-DDE exposure was not associated with the birth outcomes in the whole sample. However, a high p,p´-DDE exposure was marginally associated with greater small for gestational age risk in male newborns (OR≥0.076ng/mL vs <0.076 ng/mL = 3.09, 95% CI: 0.61; 15.58), but not in female (p for interaction = 0.08).Even though, we found no reductions in anthropometric measurements or gestational length associated with early prenatal p,p´-DDE exposure, the potential effect modification by infant's sex in terms of small for the gestational age risk deserves future studies.

[Basic health indicators in the NutrIMSS program: a retrospective study]. / Indicadores básicos de salud en el programa NutrIMSS: estudio retrospectivo.

Background: The NutrIMSS program is granted to populations with chronic conditions to improve basic health indicators and its effectiveness in this population is unknown. Objective: To analyze the change in the basic health indicators of patients who attended the NutrIMSS Program, at the UMF No. 2 of the IMSS in Mexico City, during the period 2018 to 2019. Material and methods: From 105 files of IMSS beneficiaries, a retrospective cohort study was carried out considering two measurements, before and after the NutrIMSS program. To evaluate the average change over time of health indicators, GEE models (Generalized Estimation Equations) and multiple linear regression models were used. Statistical analysis was used using the statistical program StataCorp 2015. Results: Patients who attended the Program showed changes between the beginning and end of the period with an average of three months of follow-up. They presented a decrease in the following health indicators: body weight of 1 kg, body mass index: 0.8 kg/m2, glucose of 13 mg/dL, triglycerides of 57 mg/dL and cholesterol of 17 mg/dL (p < 0.005 in all cases). There was no difference in the level of blood pressure. Conclusions: The NutrIMSS program influenced the improvement of the health indicators of the population of the program and is an ally to improve the health of the IMSS beneficiary population.

Introducción: el programa NutrIMSS se otorga a población con padecimientos crónicos para mejorar los indicadores básicos de salud; sin embargo, se desconoce su efectividad en esta población. Objetivo: analizar el cambio en los indicadores básicos de salud de pacientes que acudieron al programa NutrIMSS, en la UMF No. 2 del Instituto Mexicano del Seguro Social (IMSS) en la Ciudad de México, durante el periodo 2018 a 2019. Material y métodos: a partir de 105 expedientes de derechohabientes del IMSS se realizó un estudio de cohorte retrospectiva, considerando dos mediciones, antes y después del programa NutrIMSS. Para evaluar el cambio promedio en el tiempo de los indicadores de salud se utilizaron modelos GEE (Ecuaciones de Estimación Generalizadas) y modelos de regresión lineal múltiple. Para el análisis estadístico se utilizó el programa estadístico StataCorp 2015. Resultados: los pacientes que acudieron a NutrIMSS mostraron cambios entre el inicio y el fin del periodo, con un promedio de seguimiento de tres meses. Presentaron una disminución en los siguientes indicadores de salud: peso corporal de 1 kg, índice de masa corporal: 0.8 kg/m2, glucosa de 13 mg/dL, triglicéridos de 57 mg/dL y colesterol de 17 mg/dL (p < 0.005, en todos los casos). No se presentó diferencia en el nivel de la tensión arterial. Conclusiones: el programa NutrIMSS influyó para mejorar los indicadores de salud de la población del programa y es un aliado en la mejora de la salud de la población derechohabiente del IMSS.

Effect of exposure to p,p'-DDE on male hormone profile in Mexican flower growers.

OBJECTIVES: p,p'-Dichlorodiphenyldichloroethene (p,p'-DDE) acts as an androgen receptor antagonist, however data regarding its hormonal effects in men are limited. The objective of this study was to evaluate the association between serum levels of p,p'-DDE and reproductive hormone profile in Mexican male flower growers. METHODS: A longitudinal study was carried out in a population of men working in the production of flowers and ornamental plants in two Mexican states during July-October 2004 (rainy season) and December 2004-May 2005 (dry season). A questionnaire including information on socioeconomic characteristics, tobacco and alcohol use, presence of chronic and acute diseases, occupational history and anthropometry was used and blood and urine samples were obtained. Serum levels of p,p'-DDE were analysed by gas chromatography; FSH, LH, testosterone, oestradiol, inhibin B and prolactin levels were measured by enzymatic immunoassay. Urinary levels of dialkylphosphates (DAPs) were analysed by gas chromatography. Associations between serum levels of p,p'-DDE and male reproductive hormones (both transformed to their natural logarithm) were evaluated using multivariate generalised estimating equation (GEE) models. RESULTS: Median p,p'-DDE levels were 677.2 ng/g lipid (range 9.4-12 696.5) during the rainy season and 626.7 ng/g lipid (range 9.4-13 668.1) during the dry season. After adjusting for potential confounders (age, body mass index, state of residence and DAPs), p,p'-DDE levels were negatively associated with prolactin (ß=-0.04; 95% CI -0.07 to -0.008) and testosterone (ß=0.04; 95% CI -0.08 to 0.005) and positively with inhibin B (ß=0.11; 95% CI 0.02 to 0.21). CONCLUSION: These results indicate that p,p'-DDE can affect hypothalamic-pituitary-gonadal axis function in humans.

Effect on risk of anencephaly of gene-nutrient interactions between methylenetetrahydrofolate reductase C677T polymorphism and maternal folate, vitamin B12 and homocysteine profile.

OBJECTIVE: To evaluate the effects on anencephaly risk of the interaction between the maternal profile of folate, vitamin B12 and homocysteine and the 677C→T polymorphism in the gene encoding methylenetetrahydrofolate reductase (MTHFR). DESIGN: Case-control study paired (1:1) on maternity clinic, date of birth and state of residence. Cases of anencephaly were identified using the Registry of the Mexican Neural Tube Defect Epidemiological Surveillance System. Case and control mothers were selected from the same maternity departments. All mothers completed a structured questionnaire and blood samples were obtained to determine the MTHFR 677C→T polymorphism and biochemical profile. SETTING: Mexico, Puebla and Guerrero states, Mexico. SUBJECTS: A total of 151 mothers of cases and controls were enrolled from March 2000 to February 2001. We had complete information on biochemical profile and MTHFR C677T polymorphism for ninety-eight mothers of cases and ninety-one mothers of controls. RESULTS: The adjusted models show that the risk of anencephaly in mothers with 677TT genotype was reduced by 18 % (OR = 0·82; 95 % CI 0·72, 0·94) for each 1 ng/ml increment in serum folate. In terms of tertiles, mothers with 677TT genotype with serum folate levels in the upper tertile (>14·1 ng/ml) had a 95 % lower risk to have a child with anencephaly than mothers with serum folate levels in the first and second tertiles (P trend = 0·012). CONCLUSIONS: Our data agree with the hypothesis of a gene-nutrient interaction between MTHFR 677C→T polymorphism and folate status. We observed a protective effect on anencephaly risk only in mothers with 677TT genotype as serum folate levels increased.

Exposure to organophosphate pesticides and male hormone profile in floriculturist of the state of Morelos, Mexico.

BACKGROUND: Studies on experimental animals have found that organophosphate (OP) pesticides may act as endocrine disruptors; however, their effects on the human hormonal profile have not yet been adequately characterized. We evaluate the association between exposure to OP pesticides, measured through dialkyl phosphate (DAP) metabolites urinary levels, and the male hormone profile. METHODS: A cross-sectional study was performed in 104 floriculturists of Morelos, Mexico. A structured questionnaire was applied to get information on sociodemographic characteristics, anthropometry, clinical history, alcohol and tobacco consumption, and work history. DAP metabolites [dimethylphosphate (DMP), dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate (DEP), diethylthiophosphate (DETP) and diethyldithiophosphate] were determined using gas-liquid chromatography. Serum levels of FSH, LH, prolactin, testosterone, inhibin B and estradiol were determined using enzyme-linked immunosorbent assay. Multiple linear regression was used to study the association between DAP metabolite levels and male hormonal profile. Data were adjusted by p,p'-dichlorodiphenyldichloroethene serum levels and other potential confounders. RESULTS: There was a negative association between inhibin B and urinary levels of DMP, DEP, DETP and total DAP metabolites. DEP levels were negatively associated with serum FSH concentrations, but marginally and positively associated with those of testosterone. DETP was marginally associated with lower LH serum levels. There were no other significant associations among OP metabolites and serum hormone levels. CONCLUSIONS: Inhibin B and FSH vary according to levels of DAP metabolites in men occupationally exposed to OP pesticides. These results suggest that OP pesticides could act as endocrine disruptors in humans; however, most hormonal values fell within the wide normal range and associations were small. There is, therefore, a need for further investigation to elucidate their biological and clinical relevance.

Interaction between organophosphate pesticide exposure and PON1 activity on thyroid function.

Organophosphate pesticides are widely used in agricultural purposes. Recently, a few studies have demonstrated the ability of these chemicals to alter the function of the thyroid gland in human. Moreover, the paraoxonase-1 enzyme (PON1) plays an important role in the toxicity of some organophosphate pesticides, with low PON1 activity being associated with higher pesticide sensitivity. This study evaluates the interaction between exposure to organophosphate compounds and PON1 enzyme activity on serum levels of TSH and thyroid hormones in a population of workers occupationally exposed to pesticides. A longitudinal study was conducted on a population of floriculture workers from Mexico, during two periods of high and low-intensity levels of pesticide application. A structured questionnaire was completed by workers containing questions on sociodemographic characteristics and other variables of interest. Urine and blood samples were taken, and biomarkers of exposure (dialkylphosphates), susceptibility (PON1 polymorphisms and activity) and effect (thyroid hormone levels) were determined. Interaction between dialkylphosphates and PON1 polymorphisms or PON1 activity on hormone levels was evaluated by generalized estimating equation (GEE) models. A significant interaction was found between serum diazoxonase activity and total dialkylphosphates (ΣDAP) on TSH levels. Thus, when PON1 activity was increased we observed a decrease in the percentage of variation of TSH level for each increment in one logarithmic unit of the ΣDAP levels. This interaction was also observed with the PON1(192)RR genotype. These results suggest a stronger association between organophosphate pesticides and thyroid function in individuals with lower PON1 activity.

Association between organophosphate pesticides exposure and thyroid hormones in floriculture workers.

The ability of organophosphate pesticides to disturb thyroid gland function has been demonstrated by experimental studies on animal, but evidence of such effects on human remains scarce. The aim of this study was to assess the association between exposure to organophosphate compounds and serum levels of thyroid hormones in floriculture workers. A longitudinal study was conducted on 136 male subjects from the State of Mexico and Morelos, Mexico, occupationally exposed to organophosphate pesticides, during agricultural periods of high (rainy season) and low (dry season) levels of pesticide application. Using a structured questionnaire, a survey was carried out on sociodemographic characteristics, anthropometry, clinical history, alcohol and tobacco consumption, residential chemical exposure, and occupational history. Urine and blood samples were taken the day after pesticide application to determine urine dialkylphosphate (DAP) levels, serum levels of TSH, total T(3), total T(4), serum PON1 activity, and serum p,p'-DEE levels. The analysis of the association between DAP levels and thyroid hormonal profile was carried out using multivariate generalized estimating equation (GEE) models. Our results showed an increase in both TSH and T(4) hormones in serum associated with a increase in total dimethylphosphate levels (SigmaDMP) in urine (p-trend<0.001) and a decrease in total T(3) serum levels with an increase of SigmaDMP levels in the urine (p-trend=0.053). These results suggest that exposure to organophosphate pesticides may be responsible of increasing TSH and T(4) serum hormone levels and decreasing T(3) serum hormone levels, therefore supporting the hypothesis that organophosphate pesticides act as endocrine disruptors in humans.

Identifying pesticide use patterns among flower growers to assess occupational exposure to mixtures.

OBJECTIVES: Exposure assessment to a single pesticide does not capture the complexity of the occupational exposure. Recently, pesticide use patterns analysis has emerged as an alternative to study these exposures. The aim of this study is to identify the pesticide use pattern among flower growers in Mexico participating in the study on the endocrine and reproductive effects associated with pesticide exposure. METHODS: A cross-sectional study was carried out to gather retrospective information on pesticide use applying a questionnaire to the person in charge of the participating flower growing farms. Information about seasonal frequency of pesticide use (rainy and dry) for the years 2004 and 2005 was obtained. Principal components analysis was performed. RESULTS: Complete information was obtained for 88 farms and 23 pesticides were included in the analysis. Six principal components were selected, which explained more than 70% of the data variability. The identified pesticide use patterns during both years were: 1. fungicides benomyl, carbendazim, thiophanate and metalaxyl (both seasons), including triadimephon during the rainy season, chlorotalonyl and insecticide permethrin during the dry season; 2. insecticides oxamyl, biphenthrin and fungicide iprodione (both seasons), including insecticide methomyl during the dry season; 3. fungicide mancozeb and herbicide glyphosate (only during the rainy season); 4. insecticides metamidophos and parathion (both seasons); 5. insecticides omethoate and methomyl (only rainy season); and 6. insecticides abamectin and carbofuran (only dry season). Some pesticides do not show a clear pattern of seasonal use during the studied years. CONCLUSIONS: The principal component analysis is useful to summarise a large set of exposure variables into smaller groups of exposure patterns, identifying the mixtures of pesticides in the occupational environment that may have an interactive effect on a particular health effect.

Maternal MTHFR polymorphisms and risk of spontaneous abortion.

OBJECTIVE: To asses the association between intake of folate and B vitamins and the incidence of spontaneous abortion (SA) according to the maternal methylenetetrahydrofolate reductase (MTHFR) polymorphisms (677 C>T and 1298 A>C). MATERIAL AND METHODS: We conducted a nested case-control study within a perinatal cohort of women recruited in the state of Morelos, Mexico. Twenty-three women with SA were compared to 74 women whose pregnancy survived beyond week 20th. Intake of folate and B vitamins respectively, was estimated using a validated food frequency questionnaire. Maternal MTHFR polymorphisms were determined by PCR-RFLP and serum homocysteine levels by HPLC. RESULTS: Carriers of MTHFR 677TT and 1298AC genotypes respectively showed an increased risk of SA (OR 677TT vs. CC/CT=5.0; 95% CI: 1.2, 20.9 and OR 1298 AC vs. AA=5.5; 95% CI: 1.1, 26.6). CONCLUSIONS: Our results support the role of MTHFR polymorphisms as a risk factor for SA, regardless of dietary intake of B vitamins.

Interaction between MTHFR 677C>T, PON1 192Q>R and PON1 55L>M polymorphisms and its effect on non-recurrent spontaneous abortion in Mexican women.

MTHFR is a key enzyme in folate metabolism. Some genetic polymorphisms code for a less efficient enzyme, increasing serum concentrations of homocysteine. This has been associated with inadequate feto-maternal circulation and increased risk of spontaneous abortion. Paroxonase 1 (PON1) is a multifunctional enzyme that can detoxify homocysteine through its homocysteine thiolactonase activity. We evaluate the association between MTHFR 677 C>T polymorphisms and non-recurrent spontaneous abortion and its interaction with PON1 polymorphisms involved in homocysteine metabolism in women living in floricultural areas in Mexico. Sociodemographic, reproductive history, folic acid consumption during pregnancy and environmental exposure data of 264 women who had been pregnant sometime during the 10 years prior to study enrolment were collected. MTHFR 677 C>T, PON1 192Q>R and PON1 55L>M genotypes were determined by PCR amplification. Information on pregnancy outcome and maternal genotypes was obtained for 484 pregnancies: 34 non-recurrent spontaneous abortions (gestational age < 20 weeks) and 450 controls. GEE models were used to evaluate the association between MTHFR polymorphism and non-recurrent spontaneous abortion, and its interaction with PON1 polymorphisms. After adjusting for potential confounders, no significant association was found between the MTHFR 677 C>T maternal polymorphism and non-recurrent spontaneous abortion (OR CT vs CC= 0.39, 95% CI: 0.14-1.05; OR TT vs CC = 0.63, 95% CI: 1.22-1.80). No interactions with PON1 192Q>R or PON1 55L>M polymorphisms were identified (p for interaction = 0.88 and 0.41, respectively). PON1 55L>M maternal polymorphism was associated with higher risk of spontaneous abortion (OR LM/MM vs LL = 4.14, 95% CI: 1.49-11.54). Our results do not demonstrate an interaction between the MTHFR 677 C>T and PON1 192Q>R or PON1 55L>M maternal polymorphisms neither an independent association of MTHFR 677 C>T polymorphism with non-recurrent spontaneous abortion, whereas PON1 55LM/MM maternal genotype increase the odds of this event.

State of Children Environmental Health Research in Latin America.

BACKGROUND: Promotion of biomedical research along with the development of evidence-based prevention policies have been suggested as an effective way to reduce environmental risks for children's health in Latin America. However, there is little information on the current state of childhood environmental health research, which might help identify its strengths and limitations, as well as to design a strategy to improve the future of child environmental health research in the region. OBJECTIVE: To describe the current state of environmental health research on children exposed to environmental pollutants in Latin America. METHODOLOGY: We performed a comprehensive search of published peer-reviewed environmental health articles (1994-2014), dealing with the exposure of Latin American children to chemical compounds. We described the type of studies and their research topics, and identified networks of co-authors. We also analyzed the relationship between research funding sources and the impact factor (IF) of the journal where research was published. RESULTS: The average number of publications was about 20 per year. Mexico and Brazil produced almost 70% of the 409 identified papers. The most studied contaminant was lead, but research on this element has declined since 2005. Retrospective studies were the most frequent, and also showed a decreasing trend. Most studies did not assess health effects. Four groups of leading investigators and two collaboration models for scientific production were identified. Except for Mexico, there was very little collaboration with North American and European countries. Compared to articles that did not report financial support, those that received international funding had on average an IF around 7, and those with national funding reached a mean IF near 3. CONCLUSION: There is a limited number of publications and insufficient collaboration between Latin-American scientists. It is necessary to identify strategies to stimulate South-South-North alliances and strengthen the scarce research on the environmental health of children in the region.