Research Methods and Procedures:We used cross-sectional data from 7503 adults of Mexican descent residing in Harris County, TX, to evaluate the relationships among BMI, birthplace, and years of residency in the U.S., controlling for demographic characteristics, physical activity level, and acculturation level. Results: U.S.-born adults had an increased risk (between 34% and 65%) of obesity compared with their Mexicanborn counterparts. After controlling for recognized confounders and risk factors, this association was maintained in the highly acculturated only. Among highly acculturated obese U.S.-born men, 6% of the cases were attributable to the joint effect of birthplace and acculturation; in women, this proportion was 25%. Among Mexican-born women, there was an increasing trend in mean BMI with increasing duration of residency in the U.S.. Compared with immigrants who had lived in the U.S. for Ͻ5 years, Mexicanborn women who had resided in the U.S. for Ն15 years had an adjusted BMI mean difference of 2.12 kg/m 2 (95% confidence interval, 1.53-2.72). Discussion: Mexican-born men and women have a lower risk of obesity than their U.S.-born counterparts, but length of U.S. residency among immigrants, especially in women, is directly associated with risk of obesity. Development of culturally specific interventions to prevent obesity in recent immigrants may have an important public health effect in this population.

In this article we identify factors potentially associated with pesticide exposure among farmworkers, grade the evidence in the peer-reviewed literature for such associations, and propose a minimum set of measures necessary to understand farmworker risk for pesticide exposure. Data sources we reviewed included Medline, Science Citation Index, Social Science Citation Index, PsycINFO, and AGRI-COLA databases. Data extraction was restricted to those articles that reported primary data collection and analysis published in 1990 or later. We read and summarized evidence for pesticide exposure associations. For data synthesis, articles were graded by type of evidence for association of risk factor with pesticide exposure as follows: 1 = association demonstrated in farmworkers; 2 = association demonstrated in nonfarmworker sample; 3 = plausible association proposed for farmworkers; or 4 = association plausible but not published for farmworkers. Of more than 80 studies we identified, only a third used environmental or biomarker evidence to document farmworker exposure to pesticides. Summaries of articles were compiled by level of evidence and presented in tabular form. A minimum list of data to be collected in farmworker pesticide studies was derived from these evidence tables. Despite ongoing concern about pesticide exposure of farmworkers and their families, relatively few studies have tried to test directly the association of behavioral and environmental factors with pesticide exposure in this population. Future studies should attempt to use similar behavioral, environmental, and psychosocial measures to build a body of evidence with which to better understand the risk factors for pesticide exposure among farmworkers.

Reproductive effects from phthalate exposure have been documented mostly in animal studies. This study explored the association between prenatal exposure to phthalate metabolites, anogenital distance and penile measurements in male newborns in Toluca, State of Mexico. A total of 174 pregnant women provided urine samples for phthalate analysis during their last prenatal visit, and the 73 who gave birth to male infants were included in the study. The 73 male newborns were weighed and measured using standardized methods after delivery. After adjusting for creatinine and supine length at birth, significant inverse associations were observed between an index of prenatal exposure to total phthalate exposure and the distance from the anus to anterior base of the penis (β = −0.191 mm per 1 µg/l, P = 0.037), penile width (β = −0.0414, P = 0.050) and stretched length (β = −0.2137, P = 0.034); prenatal exposure to mono-2-ethylhexyl phthalate exposure was associated with a reduction in the stretched length of the penis (β = −0.2604, P = 0.050). Human exposure to phthalates is a public health concern, and the system most vulnerable to its potential effects seems to be the immature male reproductive tract.

Objective: The goal of this study was to evaluate the relationship between maternal and childhood BMI at baseline in a group of 5-to 18-year-old children and their mothers, all of whom were of Mexican origin, low socioeconomic status, and enrolled in a cohort study in Houston, TX. Research Methods and Procedures: Using data from 438 mother-child dyads residing in the same household, we completed logistic regression analyses to determine maternal factors associated with the child being overweight or at-risk-for-overweight, after adjusting for the child's gender, age, and level of physical activity and other maternal confounders. Results: Almost one-half of the boys and girls (47% and 44%, respectively) were either overweight or at-risk-foroverweight. Obese mothers were twice as likely to have an overweight and/or at-risk-for-overweight child compared with normal-weight mothers. Women born in the U.S. were twice as likely to have an overweight and/or at-risk-foroverweight child compared with women born in Mexico. In addition, women with less than a high school education were twice as likely to have an overweight child compared with their more educated peers. Discussion: The high prevalence of overweight or at-riskfor-overweight among Mexican-origin children of low socioeconomic status suggests a continued need to develop and implement culturally sensitive preventive interventions for this minority population. Our data also suggest a need to tailor such interventions particularly for children of obese mothers and those born in the U.S.

Imprinted genes often affect body size-related traits such as weight. However, the association of imprinting with obesity, especially childhood obesity, has not been well studied. Mexican-American children have a high prevalence, approaching 50%, of obesity and/or overweight. In a pilot study of 75 Mexican-American children, we analyzed the relationships among obese/overweight status, methylation status and single-nucleotide polymorphism (SNP) status at a CpG site in a differentially methylated region (DMR) of the imprinted H19/IGF2 locus. We observed a significant difference in SNP rs10732516 frequency between boys and girls among the overweight and obese children but not among the lean children. We also found that children with lower methylation of the polymorphic CpG site (CpG4) in the H19 DMR had higher birth weights than did children with higher methylation (P = 0.04). Our results suggest that CpG4 methylation status may be associated with childhood obesity in Mexican-American children in a sex-specific manner.