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.

Effect of prenatal exposure to organophosphates and pyrethroid pesticides on neonatal anthropometric measures and gestational age.

Several studies have examined the association between prenatal exposure to organophosphate and pyrethroid pesticides and their impact on foetal growth and newborn anthropometry; however, the available evidence is limited and inconclusive. This study examined whether prenatal organophosphate and pyrethroid pesticide exposure was associated with anthropometric measures at birth (weight, length, head circumference), ponderal index, gestational age, and prematurity in 537 mother-child pairs. These were randomly selected from the 800 pairs participating in the prospective birth cohort GENEIDA (Genetics, early life environmental exposures and infant development in Andalusia). Six non-specific organophosphate metabolites (dialkylphosphates, DAPs), one metabolite relatively specific to chlorpyrifos (3,5,6-trichloro-2-pyridinol, TCPy) and a common metabolite to several pyrethroids (3-phenoxybenzoic acid, 3-PBA) were measured in maternal urine from the 1st and 3rd pregnancy trimesters. Information on anthropometric measures at birth, gestational age and prematurity was retrieved from medical records. The sum on a molar basis of DAPs with methyl (Æ©DMs) and ethyl (Æ©DEs) moieties and the sum of the 6 DAPs metabolites (Æ©DAPs) was calculated for both trimesters of pregnancy. High urinary levels of dimethyl phosphate (DMP) during the 3rd trimester were associated with a decrease in birth weight (ß = -0.24; 95% CI: 0.41; -0.06) and birth length (ß = -0.20; 95% CI: 0.41; 0.02). Likewise, ΣDMs during 3rd trimester were near-significantly associated with decreased birth weight (ß = -0.18; 95% CI: 0.37; 0.01). In turn, increased urinary TCPy during 1st trimester was associated with a decreased head circumference (ß = -0.31; 95% CI: 0.57; -0.06). Finally, an increase in 3-PBA in the 1st trimester was associated with a decreased gestational age (ß = -0.36 95% CI: 0.65-0.08), whereas increased 3-PBA at 1st and 3rd trimester was associated with prematurity. These results indicate that prenatal exposure to organophosphate and pyrethroid insecticides could affect normal foetal growth, shorten gestational age and alter anthropometric measures at birth.

Childhood chromium exposure and neuropsychological development in children living in two polluted areas in southern Spain.

This study aimed to assess the association between exposure to chromium and neuropsychological development among children. A cross-sectional study was conducted with 393 children aged 6-11 years old randomly selected from State-funded schools in two provinces in Southern Spain (Almeria and Huelva), in 2010 and 2012. Chromium levels in urine and hair samples were analyzed by inductively coupled plasma mass spectrometry with an octopole reaction system. Neuropsychological development was evaluated using the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and three computerized tests from the Behavioural Assessment and Research System (BARS): Reaction Time Test (RTT), Continuous Performance Test (CPT) and Selective Attention Test (SAT). Multivariable linear regression models adjusted for potential confounders, including heavy metals, were applied to examine the association between chromium levels and neuropsychological outcomes. A 10-fold increase in urine chromium levels was associated with a decrease of 5.99 points on the WISC-IV Full-Scale IQ (95% CI: 11.98 to -0.02). Likewise, a 10-fold increase in urine chromium levels in boys was associated with a decrease of 0.03 points in the percentage of omissions (95% CI: 0.0 to 0.05) in the SAT, with an increase of 68.35 points in latency (95% CI: 6.60 to 130.12) in the RTT, and with an increase in the number of trials with latencies > 1000 ms (ß = 37.92; 95% CI: 2.73 to 73.12) in the RTT. An inverse significant association was detected between chromium levels in hair and latency in the SAT in boys (ß = -50.53; 95% CI: 86.86 to -14.22) and girls (ß = -55.95; 95% CI: 78.93 to -32.97). Excluding trials with latencies >1000 ms in the RTT increased latency scores by 29.36 points in boys (95% CI: 0.17 to 58.57), and 39.91 points in girls (95% CI: 21.25 to 58.59). This study is the first to show the detrimental effects of postnatal chromium exposure on neuropsychological development in school-aged children.

Biomonitoring of common organophosphate metabolites in hair and urine of children from an agricultural community.

Levels of dialkylphosphate (DAP) metabolites were measured in hair and urine of children that lived close to intensively farmed areas of Almeria (Southeast Spain). The levels were used as proxies for exposure of these children to organophosphate pesticides (OPs). Determinants of exposure to DAPs were also examined. Urine and hair samples were collected from 222 children aged 3-11 years and information on lifestyle and dietary habits was collected from questionnaires administered to mothers. Urinary DAPs were analyzed by ultra-high performance liquid-chromatography coupled to triple-quadrupole tandem mass-spectrometry (UHPLC-QqQ-MS/MS) and hair DAPs by gas-chromatography coupled to mass spectrometry (GC-MS). Detection rates ranged from 21.8% for diethylphosphate (DEP) and diethylthiophosphate (DETP) to 35.9% for dimethylphosphate (DMP) in urine; and from 42.3% for DETP to 92.8% for DMP in hair. Diethyldithiophosphate (DEDTP) was detected in 0.5% of urine samples (one child), and in 26.6% of children's hair samples. A lack of correlation was observed for individual DAP metabolites and ΣDAPs between urine and hair samples, except for DEDTP. Urinary DAP levels of our child population were lower than those reported for children from other countries, including NHANES 1999-2000 data. The main determinants of hair DAP levels were age, sex, vegetable intake, parental exposure to pesticides at work, time spent playing indoors, monthly income and father's education level. Conversely, none of the predictors studied was significantly associated with urinary DAPs except age. Overall, hair has advantages over urine as it is easier to collect, handle and store, and allows for assessment of cumulative exposure to OPs, thus providing a greater insight for human biomonitoring.

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.

Occupational predictors of urinary dialkyl phosphate concentrations in Mexican flower growers.

Background Flower growers have high potential for exposures to pesticides. Occupational factors, such as tasks performed, the production method (organic or conventional), the use of personal protective equipment (PPE), and workplace characteristics influence the intensity of pesticide exposure. Objective To evaluate occupational characteristics affecting urinary concentration of dialkylphosphate (DAP) metabolites of organophosphate pesticides among a group of Mexican floricultural workers. Methods A questionnaire was administered to 117 workers who also provided a first morning urine sample. According to tasks performed and the production methods, pesticide contact was defined as low, medium, or high. PPE use was categorized as acceptable, fairly acceptable, and unacceptable. Urinary concentration of DAP metabolites were determined using gas-liquid chromatography. Association between occupational characteristics and DAP urinary concentrations was assessed by means of linear regression models. Results After adjusting for potential confounders, the workers in the medium and high contact categories had significantly higher DAP concentrations than those in the low contact category (ß: 0.3, CI 95%: 0.1-0.5). Greenhouse workers had greater DAP concentrations than outdoors workers (ß: 0.3, CI 95%: 0.1-0.5). Compared with non-acceptable use of PPE, acceptable use of PPE was associated with lower DAP concentrations (ß: -0.4, CI 95% -0.6 to -0.1). Conclusion Improved safety training is needed for correct PPE usage, especially among flower growers who use conventional pest control methods and who work in a greenhouse environment.

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.

Postnatal arsenic exposure and attention impairment in school children.

Over the last few decades there has been an increased concern about the health risks from exposure to metallic trace elements, including arsenic, because of their potential neurotoxic effects on the developing brain. This study assessed whether urinary arsenic (UA) levels are associated with attention performance and Attention-Deficit/Hyperactivity Disorder (ADHD) in children living in an area with high industrial and mining activities in Southwestern Spain. A cross-sectional study was conducted on 261 children aged 6-9 years. Arsenic levels were determined in urine samples. Attention was measured by using 4 independent tools: a) tests from the Behavioral Assessment and Research System (BARS) designed to measure attention function: Simple Reaction Time Test (RTT), Continuous Performance Test (CPT) and Selective Attention Test (SAT); b) AULA Test, a virtual reality (VR)-based test that evaluates children's response to several stimuli in an environment simulating a classroom; c) Child Behavior Checklist (CBCL), administered to parents; and d) Teacher's Report Form (TRF), administered to teachers. Multivariate linear and logistic regression models, adjusted for potential confounders, were used to estimate the magnitude of the association between UA levels and attention performance scores. Higher UA levels were associated with an increased latency of response in RTT (ß = 12.3; 95% confidence interval (CI): 3.5-21.1) and SAT (ß = 3.6; 95% CI: .4-6.8) as well as with worse performance on selective and focalized attention in the AULA test (ß for impulsivity = .6; 95% CI: .1-1.1; ß for inattention = .5; 95% CI: .03-1.0). A dose-response relationship was observed between UA levels and inattention and impulsivity scores. In contrast, results from the CBCL and TRF tests failed to show a significant association with UA levels. In conclusion, UA levels were associated with impaired attention/cognitive function, even at levels considered safe. These results provide additional evidence that postnatal arsenic exposure impairs neurological function in children.

Pre- and postnatal exposures to pesticides and neurodevelopmental effects in children living in agricultural communities from South-Eastern Spain.

BACKGROUND: Childrens exposure to neurotoxic compounds poses a major problem to public health because oftheir actively developing brain that makes them highly vulnerable. However, limited information is available on neuropsychological effects in children associated with pre- and postnatal exposures to pesticides. OBJECTIVE: To evaluate the association between current and pre- and postnatal exposures to pesticides and their effects on neurodevelopment in children aged 6­11 years living in agricultural communities from South-Eastern Spain. METHODS: An ambispective study was conducted on 305 children aged 6­11 years randomly selected from public schools of the study area. Current exposure to organophosphate pesticides was assessed measuring children's urinary levels of dialkylphosphates (DAPs). Both prenatal and postnatal residential exposure to pesticides was estimated by developing a geographical information system (GIS) technology-based index that integrated distance-weighted measure of agricultural surface, time-series of crop areas per municipality and year, and land-use maps. Neuropsychological performance was evaluated with the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV). The association of pre- and postnatal and current pesticide exposure with WISC-IV scale scores was assessed using multivariate linear regression models and generalized estimating equation (GEE) models, respectively. RESULTS: Greater urinary DAP levels were associated with a poorer performance on intelligence quotient and verbal comprehension domain, with effects being more prominent in boys than in girls. The influence of an increase in 10 ha per year in crop surface around the child's residence during the postnatal period was associated with decreased intelligence quotient, processing speed and verbal comprehension scores. As regards prenatal exposure to pesticides, a poor processing speed performance was observed. These effects were also more prominent in boys than in girls. CONCLUSIONS: Our results suggest that postnatal exposure to pesticides can negatively affect children's neuropsychological performance. Prenatal exposure was weakly associated to neurodevelopment impairment.

Polymorphisms of pesticide-metabolizing genes in children living in intensive farming communities.

Polymorphisms in genes encoding xenobiotic-metabolizing enzymes (XME) are important parameters accounting for the wide inter-individual variability to environmental exposures. Paraoxonase-1 (PON1), butyrylcholinesterase (BChE) and Cytochrome-P450 constitute major classes of XME involved in the detoxification of pesticide chemicals, in particular organophosphates. This study explored the allelic frequency, linkage disequilibrium and haplotype analysis of ten common polymorphic variants of seven key genes involved in organophosphate metabolism (BCHE-K, BCHE-A, PON1 Q192R, PON1 L55M, PON1 -108C/T, CYP2C19 G681A, CYP2D6 G1846A, CYP3AP1 -44G/A, GSTM1∗0 and GSTT1∗0) in a children population living near an intensive agriculture area in Spain. It was hypothesized that individuals with unfavorable combinations of gene variants will be more susceptible to adverse effects from organophosphate exposure. Genomic DNA from 496 healthy children was isolated and amplified by PCR. Hydrolysis probes were used for the detection of eight specific SNPs and two copy number variants (CNVs) by using TaqMan® Assay-based real-time PCR. Frequencies of SNPs and CNVs in the target genes were in Hardy-Weinberg equilibrium and broadly consistent with European populations. Linkage disequilibrium was found between the three PON1 genetic polymorphisms studied and between BCHE-K and BCHE-A. The adverse genotype combination (unusual BCHE variants, PON1 55MM/-108TT and null genotype for both GSTM1 and GSTT1) potentially conferring a greater genetic risk from exposure to organophosphates was observed in 0.2% of our study population. This information allows broadening our knowledge about differential susceptibility toward environmental toxicants and may be helpful for further research to understand the inter-individual toxicokinetic variability in response to organophosphate pesticides exposure.

Biomonitoring of arsenic, cadmium, lead, manganese and mercury in urine and hair of children living near mining and industrial areas.

Huelva (South West Spain) and its surrounding municipalities represent one of the most polluted estuaries in the world owing to the discharge of mining and industrial related pollutants in their proximity. A biomonitoring study was conducted to assess exposure to arsenic and some trace metals (cadmium, mercury, manganese and lead) in urine and scalp hair from a representative sample of children aged 6-9 years (n=261). This is the only study simultaneously analyzing those five metal elements in children urine and hair. The potential contribution of gender, water consumption, residence area and body mass index on urinary and hair metal concentrations was also studied. Urine levels of cadmium and total mercury in a proportion (25-50%) of our children population living near industrial/mining areas might have an impact on health, likely due to environmental exposure to metal pollution. The only significant correlation between urine and hair levels was found for mercury. Children living near agriculture areas showed increased levels of cadmium and manganese (in urine) and arsenic (in hair). In contrast, decreased urine Hg concentrations were observed in children living near mining areas. Girls exhibited significantly higher trace metal concentrations in hair than boys. The greatest urine arsenic concentrations were found in children drinking well/spring water. Although human hair can be a useful tool for biomonitoring temporal changes in metal concentrations, levels are not correlated with those found in urine except for total mercury, thus providing additional information.

Cadmium exposure and neuropsychological development in school children in southwestern Spain.

This study assessed the association between cadmium exposure and neuropsychological development in children from a region with high industrial and mining activities in southwestern Spain. We conducted a cross-sectional study with 261 children aged 6-9 years between January and March 2012. Cadmium exposure was measured in urine and hair of children, and neuropsychological development was assessed with the Wechsler Intelligence Scale for Children-Fourth Edition (WISC-IV) and with three computerized tests from the Behavioral Assessment and Research System (BARS): Reaction Time Test (RTT), Continuous Performance Test (CPT) and Selective Attention Test (SAT). Multivariate linear regression models, adjusted for potential confounders, were used to estimate the association between neuropsychological development and cadmium exposure measured in urine and hair samples. Geometric means of urine and hair cadmium levels were 0.75 µg/g creatinine and 0.01 µg/g, respectively. We observed that doubling of levels of cadmium in urine was associated with a reduction of two points (95% CI: -3.8 to -0.4) in the Full-Scale intelligence quotient (IQ) in boys. By domains, association was statistically significant for Verbal Comprehension (ß=-2.0; p=0.04) and close to the significance level for Perceptual Reasoning (ß=-1.8; p=0.06). Among girls, only Verbal Comprehension showed suggestive associations with cadmium exposure (ß=-1.7; p=0.06). Cadmium exposure is associated with cognitive delays in boys in our region. Our results provide additional evidence of the neurotoxic effect of low-level postnatal cadmium exposure among children, and support the hypothesis of differences between sexes in the neurotoxic effect of metals on children.

Association of arsenic, cadmium and manganese exposure with neurodevelopment and behavioural disorders in children: a systematic review and meta-analysis.

The aim of this study was to analyse the scientific evidence published to date on the potential effects on neurodevelopment and behavioural disorders in children exposed to arsenic, cadmium and manganese and to quantify the magnitude of the effect on neurodevelopment by pooling the results of the different studies. We conducted a systematic review of original articles from January 2000 until March 2012, that evaluate the effects on neurodevelopment and behavioural disorders due to pre or post natal exposure to arsenic, cadmium and manganese in children up to 16 years of age. We also conducted a meta-analysis assessing the effects of exposure to arsenic and manganese on neurodevelopment. Forty-one articles that evaluated the effects of metallic elements on neurodevelopment and behavioural disorders met the inclusion criteria: 18 examined arsenic, 6 cadmium and 17 manganese. Most studies evaluating exposure to arsenic (13 of 18) and manganese (14 of 17) reported a significant negative effect on neurodevelopment and behavioural disorders. Only two studies that evaluated exposure to cadmium found an association with neurodevelopmental or behavioural disorders. The results of our meta-analysis suggest that a 50% increase of arsenic levels in urine would be associated with a 0.4 decrease in the intelligence quotient (IQ) of children aged 5-15 years. Moreover a 50% increase of manganese levels in hair would be associated with a decrease of 0.7 points in the IQ of children aged 6-13 years. There is evidence that relates arsenic and manganese exposure with neurodevelopmental problems in children, but there is little information on cadmium exposure. Few studies have evaluated behavioural disorders due to exposure to these compounds, and manganese is the only one for which there is more evidence of the existence of association with attention deficit disorder with hyperactivity.

Association between PON1 genetic polymorphisms and miscarriage in Mexican women exposed to pesticides.

BACKGROUND: Placental oxidative stress has been involved in the pathogenesis of certain reproductive adverse effects, including miscarriage. Paraxonase 1 (PON1) is a high-density lipoprotein(HDL)-linked enzyme that prevents oxidation of low-density lipoproteins (LDL) and is involved in detoxification from organophosphate pesticides. OBJECTIVE: To assess the association between maternal PON1 polymorphisms (PON1192Q/R, PON155 L/M y PON1-108C/T) and the risk of miscarriage in women chronically exposed to organophosphate pesticides in Mexico. METHODS: In a cross-sectional study, socio-demographic data, reproductive history data, environmental exposures, and other variables of concern were collected by means of a questionnaire from 264 women (floriculturists and wives of floriculturists) who had been pregnant sometime during the 10 years preceding the study. Blood samples were also collected from them. PON1192 and PON155 genotypes were determined by PCR amplification, and PON1-108 genotypes, by a TaqMan real-time polymerase chain reaction assay. Complete information regarding the results of pregnancy and maternal genotype tests was obtained for 514 pregnancies (35 miscarriages and 479 controls). The association between PON1 genotypes and miscarriage was evaluate through GEE models. RESULTS: The risk of miscarriage by mothers with PON1192RR genotype was 2.2 higher than by mothers with PON1192QR/PON1192QQ genotype (95% CI 0.93-5.17). The risk was close to 4 times higher in mothers with PON155MM/PON155LM genotype than in mothers with PON155LL genotype (OR=3.9; 95% CI 1.38-11.0). No significant differences were found in risk of miscarriage based on the maternal PON1-108C/T genotype. No evidence was found of an interaction between the various PON1 genotypes and the mothers' floricultural activity during pregnancy. CONCLUSIONS: This study suggests that there is an effect of genetic maternal PON1 polymorphisms on miscarriage and provides additional evidence that combines with the growing information about the ways in which certain PON1 genotypes can affect the development of the fetus in utero.

Effect of current tobacco consumption on the male reproductive hormone profile.

The knowledge about the effect of cigarette smoking on the male reproductive function is still limited. The objective of this study was to evaluate the association between active exposure to tobacco smoke and the male reproductive hormone profile in a group of 136 Mexican flower growers. Serum levels of FSH, LH, prolactin, total testosterone, Inhibin B and estradiol were measured using enzyme-linked immunoabsorbent assay. Weight and height were also measured and a structured questionnaire was applied to get information on sociodemographic characteristics, clinical and work history and alcohol and tobacco consumption (current smoking habit and number of cigarettes smoked per day). Based on this information tobacco consumption was divided into four categories: never-smokers, ex-smokers, current smokers under five cigarettes/day and current smokers over or equal to five cigarettes/day. Using the group of never-smokers as reference and after adjusting for potential confounders, current smokers of five or more cigarettes/day showed significantly higher levels of LH (ß=0.33, p=0.01), prolactin (ß=0.18, p=0.03) and testosterone (ß=0.21, p=0.02). Current smokers of less than five cigarettes/day also showed higher levels of prolactin (ß=0.12, p=0.03) and testosterone (ß=0.18, p<0.01). Hormone levels of ex-smokers were similar to those of never-smokers. Our results are compatible with the hypothesis that tobacco consumption may act as an endocrine disruptor on the male hormone profile.

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.

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.

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.

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.

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.