Dietary intake of choline and neural tube defects in Mexican Americans.

BACKGROUND: Low maternal intake of dietary choline and betaine (a choline derivative) has recently been investigated as a possible risk factor for neural tube defects (NTDs). METHODS: This case-control study examined the NTD risk associated with choline and betaine in 409 Mexican-American women who gave birth during 1995 to 2000 in the 14-county border region of Texas. RESULTS: Using data from the food frequency questionnaire and the lowest quartiles of intake as the reference categories, a protective association was suggested between higher intakes of choline and betaine and NTD risk although the 95% confidence intervals for all risk estimates included 1.0. For choline intake in the second, third, and fourth quartiles, adjusted odds ratios were 1.2, 0.80, and 0.89, respectively. Betaine appeared more protective with odds ratios of 0.62, 0.73, and 0.61, respectively, for the second, third, and fourth quartiles of intake. CONCLUSION: Study findings suggest that dietary betaine may help to prevent NTDs.

Periconceptional maternal alcohol consumption and neural tube defects.

BACKGROUND: Neural tube defects (NTD)s, which occur when the neural tube fails to close during early gestation, are some of the most common birth defects worldwide. Alcohol is a known teratogen and has been shown to induce NTDs in animal studies, although most human studies have failed to corroborate these results. Using data from the National Birth Defects Prevention Study, associations between maternal reports of periconceptional (1 month prior through 2 months postconception) alcohol consumption and NTDs were examined. METHODS: NTD cases and unaffected live born control infants, delivered from 1997 through 2005, were included. Interview reports of alcohol consumption (quantity, frequency, variability, and type) were obtained from 1223 case mothers and 6807 control mothers. Adjusted odds ratios (aOR)s and 95% confidence intervals were estimated using multivariable logistic regression analysis. RESULTS: For all NTDs combined, most aORs for any alcohol consumption, one or more binge episodes, and different type(s) of alcohol consumed were near unity or modestly reduced (≥ 0.7 < aOR ≤ 1.1) and were not statistically significant. Findings were similar for individual NTD subtypes. CONCLUSIONS: These findings suggest no elevated association between maternal periconceptional alcohol consumption and NTDs. Underreporting of alcohol consumption, due to negative social stigma associated with alcohol consumption during pregnancy, and limited reports for mothers with early pregnancy loss of a fetus with an NTD may have affected the estimated odds ratios. Future studies should aim to increase sample sizes for less prevalent subtypes, reduce exposure misclassification, and improve ascertainment of fetal deaths and elective terminations.

Prenatal exposure to nitrosatable drugs, vitamin C, and risk of selected birth defects.

UNLABELLED: Nitrosatable drugs, such as secondary or tertiary amines and amides react with nitrite in an acidic environment to form N-nitroso compounds, teratogens in animal models. Vitamin C is a known nitrosation inhibitor. METHODS: Using data from the National Birth Defects Prevention Study, we assessed nitrosatable drug exposure and vitamin C intake during the first trimester among 11,606 case-mothers of infants with oral clefts, limb deficiencies (LDs), or congenital heart defects and 6807 control-mothers of infants without major birth defects during 1997-2005. Daily intake of vitamin C was estimated from maternal interviews that elicited information about supplement use and dietary intake. RESULTS: With no reported use of nitrosatable drugs as the referent group, a lower odds ratio (OR) was observed for transverse LDs among births to mothers exposed to secondary amine drugs and daily vitamin C supplementation (adjusted odds ratio [aOR] 1.2, 95% confidence interval [CI] 0.83-1.8) compared with women taking these drugs and no supplementation (aOR 2.7, 95% CI 1.5-4.6). The OR for longitudinal LDs associated with secondary amine exposure was lower with daily dietary vitamin C intake ≥85 mg (aOR 1.2, 95% CI 0.68-2.0) compared with <85 mg (aOR 1.9, 95% CI 1.2-3.1). Daily vitamin C supplementation in combination with higher dietary vitamin C intake reduced associations between nitrosatable drug exposures and limb deficiencies and atrial septal defects not otherwise specified. CONCLUSION: Prenatal dietary and vitamin C supplement intake may diminish the association between nitrosatable drug exposure during pregnancy and selected birth defects.

Maternal dietary intake of nitrates, nitrites and nitrosamines and selected birth defects in offspring: a case-control study.

BACKGROUND: Dietary intake of nitrates, nitrites, and nitrosamines can increase the endogenous formation of N-nitroso compounds in the stomach. Results from animal studies suggest that these compounds might be teratogenic. We examined the relationship between maternal dietary intake of nitrates, nitrites (including plant and animal sources as separate groups), and nitrosamines and several types of birth defects in offspring. METHODS: For this population-based case-control study, data from a 58-question food frequency questionnaire, adapted from the short Willett Food Frequency Questionnaire and administered as part of the National Birth Defects Prevention Study (NBDPS), were used to estimate daily intake of dietary nitrates, nitrites, and nitrosamines in a sample of 6544 mothers of infants with neural tube defects (NTD)s, oral clefts (OC)s, or limb deficiencies (LD)s and 6807 mothers of unaffected control infants. Total daily intake of these compounds was divided into quartiles based on the control mother distributions. Odds ratios (OR)s and 95% confidence intervals (CI)s were estimated using logistic regression; estimates were adjusted for maternal daily caloric intake, maternal race-ethnicity, education, dietary folate intake, high fat diet (>30% of calories from fat), and state of residence. RESULTS: While some unadjusted ORs for NTDS had 95% (CI)s that excluded the null value, none remained significant after adjustment for covariates, and the effect sizes were small (adjusted odds ratios [aOR]<1.12). Similar results were found for OCs and LDs with the exception of animal nitrites and cleft lip with/without cleft palate (aORs and CIs for quartile 4 compared to quartile 1 =1.24; CI=1.05-1.48), animal nitrites and cleft lip (4th quartile aOR=1.32; CI=1.01-1.72), and total nitrite and intercalary LD (4th quartile aOR=4.70; CI=1.23-17.93). CONCLUSIONS: Overall, odds of NTDs, OCs or LDs did not appear to be significantly associated with estimated dietary intake of nitrate, nitrite, and nitrosamines.

Neural tube defects on the Texas-Mexico border: what we've learned in the 20 years since the Brownsville cluster.

We reviewed the published findings from the Texas Neural Tube Defect Project, a 6-year case-control study (1995-2000) of neural tube defects (NTDs) on the Texas-Mexico border. In this review, we highlight what was learned about environmental, genetic, and nutritional factors (i.e., those related to the folate and other metabolic pathways) and the novel putative risk factors that emerged from this study of Mexican American women living on the Texas-Mexico border. Our investigations of the micronutrients and metabolic pathways involved confirmed the findings of other researchers that increased folate intake has a protective effect and that low serum B(12) , high serum homocysteine levels, and obesity independently contribute to risk. Studies of this population also have implicated hyperinsulinemia and low ferritin, metabolic risk factors, which require additional study to elucidate their physiologic mechanism. Environmental contaminants such as heavy metals, pesticides, and polychlorinated biphenyls (PCBs), which were of community concern, did little to explain NTD risk. Studies in this folic acid deficit-population also revealed several novel risk factors, namely, diarrhea, stress, fumonisins, and the combination of nitrosatable drug exposure with high nitrate/nitrite intake. In conclusion, the 23 studies among the Mexican American women living along the Texas-Mexico border have demonstrated the multifactorial nature of NTDs and that a population deficient in folic acid will be vulnerable to a variety of insults whether brought on by individual behaviors (e.g., obesity) or through the surrounding environment (e.g., fumonisins). Birth Defects Research (Part A), 2012. © 2012 Wiley Periodicals, Inc.

Nitrosatable drug exposure during the first trimester of pregnancy and selected congenital malformations.

BACKGROUND: Nitrosatable drugs can react with nitrite in the stomach to form N-nitroso compounds, and results from animal studies suggest that N-nitroso compounds are teratogens. With data from the National Birth Defects Prevention Study, the relation between prenatal exposure to nitrosatable drugs and limb deficiencies, oral cleft, and heart malformations in offspring was examined. METHODS: Maternal reports of drugs taken during the first trimester of pregnancy were classified with respect to nitrosatability for mothers of 741 babies with limb deficiencies, 2774 with oral cleft malformations, 8091 with congenital heart malformations, and 6807 without major congenital malformations. Nitrite intake was estimated from maternal responses to a food frequency questionnaire. RESULTS: Isolated transverse limb deficiencies and atrioventricular septal defects were associated with secondary amine drug exposures (adjusted odds ratios [aORs], 1.51; 95% confidence limit [CI], 1.11-2.06 and aOR, 1.97; 95% CI, 1.19-3.26, respectively). Tertiary amines were associated with hypoplastic left heart syndrome (aOR, 1.50; 95% CI, 1.10-2.04) and single ventricle (aOR, 1.61; 95% CI, 1.06-2.45). These two malformations were also significantly associated with amide drugs. For several malformations, the strongest associations with nitrosatable drug use occurred among mothers with the highest estimated dietary nitrite intake, especially for secondary amines and atrioventricular septal defects (highest tertile of nitrite, aOR, 3.30; 95% CI, 1.44-7.58). CONCLUSION: Prenatal exposure to nitrosatable drugs may be associated with several congenital malformations, especially with higher nitrite intake. The possible interaction between nitrosatable drugs and dietary nitrite on risk of congenital malformations warrants further attention.

Dieting to lose weight and occurrence of neural tube defects in offspring of Mexican-American women.

Lowered maternal weight gain and reduction in early pregnancy have been associated with risk of neural tube defects (NTDs) in offspring. We examined the association of self-reported maternal dieting behaviors on the occurrence of NTDs. We conducted a population based case-control study among Mexican-American women who were residents of the 14 Texas counties bordering Mexico. Case women had an NTD-affected pregnancy identified at birth or prenatally and had deliveries during the years 1995-2000. Control women were those who delivered live born infants without an apparent congenital malformation, randomly selected and frequency-matched to cases by year and facility. One hundred eighty-four case women and 225 control women were asked in person about the use of nutritional supplements, dieting to lose weight, and type of weight reduction supplements used during the 3 months before conception. Women who reported being on a diet to lose weight during the 3 months before conception had an NTD odds ratio (OR) of 1.9 (95% confidence interval (CI) = 1.1, 3.3) compared with those not reporting being on a diet. Neither consuming vitamin drinks (OR = 1.2) nor using diet pills (OR = 1.6) during the 3 months before conception had ORs that were different from the null, when compared to women not reporting those behaviors. The risk effect for dieting did not differ markedly among normal or underweight (OR = 2.0, 95% CI = 0.7, 5.6), overweight (OR = 1.9, 95% CI = 0.7, 5.0), or obese women (OR = 1.5, 95% CI = 0.6, 4.0). No effect was seen among dieting women who were consuming at least 1.0 mg/day of folate (OR = 1.1, CI = 0.3, 4.5). Maternal dieting prior to conception may increase the risk of NTDs in offspring.

Nitrosatable drug exposure during early pregnancy and neural tube defects in offspring: National Birth Defects Prevention Study.

Nitrosatable drugs, such as secondary or tertiary amines and amides, form N-nitroso compounds in the presence of nitrite. Various N-nitroso compounds have been associated with neural tube defects in animal models. Using data from the National Birth Defects Prevention Study, the authors examined nitrosatable drug exposure 1 month before and 1 month after conception in 1,223 case mothers with neural tube defect-affected pregnancies and 6,807 control mothers who delivered babies without major congenital anomalies from 1997 to 2005. Nitrite intakes were estimated from mothers' responses to a food frequency questionnaire. After adjustment for maternal race/ethnicity, educational level, and folic acid supplementation, case women were more likely than were control women to have taken tertiary amines (odds ratio = 1.60, 95% confidence interval (CI): 1.31, 1.95). This association was strongest with anencephalic births (odds ratio = 1.96, 95% CI: 1.40, 2.73); odds ratios associated with tertiary amines from the lowest tertile of nitrite intake to the highest tertile were 1.16 (95% CI: 0.59, 2.29), 2.19 (95% CI: 1.25, 3.86), and 2.51 (95% CI: 1.45, 4.37), respectively. Odds ratios for anencephaly with nitrosatable drug exposure were reduced among women who also took daily vitamin supplements that contained vitamin C. Prenatal exposure to nitrosatable drugs may increase the risk of neural tube defects, especially in conjunction with a mother's higher dietary intake of nitrites, but vitamin C might modulate this association.

Maternal smoking, passive tobacco smoke, and neural tube defects.

BACKGROUND: Although cigarette smoke is a well-established toxin and harmful to the developing embryo, the evidence for an independent effect on the occurrence of neural tube defects (NTDs) is mixed. In this study, we examined the relation between NTDs and maternal exposures to cigarette smoke, including passive smoke exposure. METHODS: We used cases and controls from the large, multistate, population-based National Birth Defects Prevention Study. A total of 1041 NTD cases and 5862 live birth controls, delivered during 1997 to 2004, were available for analyses. Mothers were interviewed by telephone between 6 weeks and 24 months after delivery. Participation rates were 71% for NTD case mothers and 69% for control mothers. RESULTS: Compared with nonsmokers (and also not exposed to passive cigarette smoke), mothers exposed only to passive smoke had an increased NTD odds ratio (OR, 1.7; 95% confidence interval [CI], 1.4-2.0), adjusted for race-ethnicity, and study center. There was no increased OR for mothers who actively smoked 24 or fewer cigarettes per day. Mothers who smoked 25 or more cigarettes per day had an elevated OR (OR, 1.6; 95% CI, 0.9-3.0), but the OR adjusted for race-ethnicity, and center was compatible with the null. CONCLUSION: Results suggest that maternal exposure to passive smoke is associated with NTDs. Women who plan on becoming pregnant should minimize their exposure to passive smoke and refrain from smoking.

Prevalence and patterns of nitrosatable drug use among U.S. women during early pregnancy.

BACKGROUND: Experimental evidence indicates that certain drugs, that are secondary or tertiary amines or amides, form N-nitroso compounds in the presence of nitrite in an acidic environment. Nitrosatable drugs have been associated with birth defects in a few epidemiologic studies. This study describes the prevalence and patterns of nitrosatable drug use among U.S. women during early pregnancy and examines maternal factors associated with such use. METHODS: Data were analyzed from the National Birth Defects Prevention Study and included 6807 mothers who gave birth to babies without major congenital malformations during 1997 to 2005. Information was collected by telephone interview about medication use, demographic factors, and maternal health. Drugs taken during the first trimester were classified according to nitrosatability, amine and amide functional groups, and primary indication of use. RESULTS: Approximately 24% of the women took one or more nitrosatable drugs during the first trimester, including 12.4%, 12.2%, and 7.6% who respectively took secondary amines, tertiary amines, or amides. Five of the ten most commonly taken drugs were available over the counter. Women who were non-Hispanic white (29.5%), with 1 year or more college education (27.3%) or 40 years or older (28.8%) had the highest prevalence of use. Supplemental vitamin C, an inhibitor of nitrosation, was not taken by 41.6% and 19.3% of nitrosatable drug users during the first and second months of pregnancy, respectively. CONCLUSIONS: In this U.S. population, ingestion of drugs classified as nitrosatable was common during the first trimester of pregnancy, especially among non-Hispanic white, more educated, and older mothers.

Dietary methionine intake and neural tube defects in Mexican-American women.

BACKGROUND: Nutrients other than maternal folic acid are also thought to play a role in preventing neural tube defects (NTDs). Evidence suggests that methionine interacts with folic acid and vitamin B(12) in the methylation of contractile proteins involved in closing the neural folds. The role of dietary intake of methionine in NTD risk has not been specifically studied among Mexican Americans, a population with one of the highest prevalences of NTDs in the United States. METHODS: We conducted a case-control study of 184 Mexican American women with NTD-affected pregnancies (case women) and 225 women with normal offspring (control women) who resided along the Texas-Mexico border. The average daily intakes of methionine were calculated from periconceptional food frequency questionnaire data. Women were categorized according to quartiles of daily methionine intake, based on the control mothers' distribution, and the risk for an NTD-affected pregnancy was calculated using the lowest quartile of intake as the referent. RESULTS: With adjustment for income, body mass index, hyperinsulinemia, and diarrhea, the odds ratios for increasing quartile of methionine intake were: 0.95 (95% confidence interval [CI], 0.48,1.90), 0.92 (95% CI, 0.46,1.84), and 0.66 (95% CI, 0.30,1.45). Some evidence of interaction between dietary methionine and serum vitamin B(12) was noted particularly at higher levels of both components. CONCLUSIONS: This study was limited by a small sample size but examined this association in an exclusively Hispanic population. Results were suggestive of a potential protective effect for NTDs with increasing maternal dietary methionine intake.

Maternal characteristics associated with the dietary intake of nitrates, nitrites, and nitrosamines in women of child-bearing age: a cross-sectional study.

BACKGROUND: Multiple N-nitroso compounds have been observed in animal studies to be both mutagenic and teratogenic. Human exposure to N-nitroso compounds and their precursors, nitrates and nitrites, can occur through exogenous sources, such as diet, drinking water, occupation, or environmental exposures, and through endogenous exposures resulting from the formation of N-nitroso compounds in the body. Very little information is available on intake of nitrates, nitrites, and nitrosamines and factors related to increased consumption of these compounds. METHODS: Using survey and dietary intake information from control women (with deliveries of live births without major congenital malformations during 1997-2004) who participated in the National Birth Defects Prevention Study (NBDPS), we examined the relation between various maternal characteristics and intake of nitrates, nitrites, and nitrosamines from dietary sources. Estimated intake of these compounds was obtained from the Willet Food Frequency Questionnaire as adapted for the NBDPS. Multinomial logistic regression models were used to estimate odds ratios and 95% confidence intervals for the consumption of these compounds by self-reported race/ethnicity and other maternal characteristics. RESULTS: Median intake per day for nitrates, nitrites, total nitrites (nitrites + 5% nitrates), and nitrosamines was estimated at 40.48 mg, 1.53 mg, 3.69 mg, and 0.472 microg respectively. With the lowest quartile of intake as the referent category and controlling for daily caloric intake, factors predicting intake of these compounds included maternal race/ethnicity, education, body mass index, household income, area of residence, folate intake, and percent of daily calories from dietary fat. Non-Hispanic White participants were less likely to consume nitrates, nitrites, and total nitrites per day, but more likely to consume dietary nitrosamines than other participants that participated in the NBDPS. Primary food sources of these compounds also varied by maternal race/ethnicity. CONCLUSIONS: Results of this study indicate that intake of nitrates, nitrites, and nitrosamines vary considerably by race/ethnicity, education, body mass index, and other characteristics. Further research is needed regarding how consumption of foods high in nitrosamines and N-nitroso precursors might relate to risk of adverse pregnancy outcomes and chronic diseases.

Maternal serum homocysteine and risk for neural tube defects in a Texas-Mexico border population.

BACKGROUND: To better understand the neural tube defect (NTD) causal pathway, the authors measured homocysteine, an indicator of tissue micronutrient deficiencies. The authors examined independent and joint associations of serum homocysteine, B12, and folate and red blood cell (RBC) folate with NTD-affected pregnancies. METHODS: Case women in this population-based study had NTD-affected pregnancies and resided and delivered in one of the 14 Texas-Mexico border counties from 1995 through 2000. Control women were study area residents delivering normal live births during the same period. The authors measured homocysteine levels using tandem mass spectroscopy; competitive binding was used for other biomarkers. RESULTS: Homocysteine testing was done on 103 cases and 139 controls. Odds ratios (ORs) were increased in all upper homocysteine quintiles compared to the lowest quintile (1.7, 1.3, 2.8, 2.4). Women with high homocysteine values had increased ORs regardless of high versus low levels for B12 (OR = 3.5, 4.8, respectively) or RBC folate (OR = 2.9, 3.5, respectively). CONCLUSIONS: High serum homocysteine levels are associated with NTD-affected pregnancies. Moreover, high homocysteine levels have a detrimental effect on NTD-risk even when serum B12 or RBC folate levels are high. Excess homocysteine might play an independent role in the development of NTDs.

The prevalence and predictors of anencephaly and spina bifida in Texas.

Texas shares a 1255-mile border with Mexico and encompasses a variety of ecosystems, industries and other potential environmental exposures. The Texas Birth Defects Registry is an active surveillance system which covers all pregnancy outcomes (livebirths, fetal deaths and elective pregnancy terminations). This study describes the occurrence and the predictors of neural tube defects (anencephaly and spina bifida) in Texas between 1999 and 2003. Birth prevalence, crude and adjusted prevalence ratios and 95% confidence intervals were calculated using Poisson regression, for each defect, by fetal/infant sex, delivery year and maternal sociodemographic characteristics. Among approximately 1.8 million livebirths, a total of 1157 neural tube defects cases were ascertained by the Registry, resulting in an overall prevalence of 6.33 cases per 10 000 livebirths. The prevalences of anencephaly and spina bifida were 2.81 and 3.52 per 10 000 livebirths respectively. Prevalences of both defects were highest in Hispanics, among mothers living along the border with Mexico, among women of higher parity and among mothers who were 40+ years of age. In addition, the prevalence of each defect was higher among women with no record of prenatal care and among women with less than 7 years of education. Hispanic ethnicity was an important predictor for anencephaly, along with sex, maternal age, parity and border residence. However, only border residence and delivery year were significant predictors for spina bifida.

Maternal residential proximity to waste sites and industrial facilities and conotruncal heart defects in offspring.

Most studies of the relationship between maternal residential proximity to sources of environmental pollution and congenital cardiovascular malformations have combined heart defects into one group or broad subgroups. The current case-control study examined whether risk of conotruncal heart defects, including subsets of specific defects, was associated with maternal residential proximity to hazardous waste sites and industrial facilities with recorded air emissions. Texas Birth Defects Registry cases were linked to their birth or fetal death certificate. Controls without birth defects were randomly selected from birth certificates. Distances from maternal addresses at delivery to National Priority List (NPL) waste sites, state superfund waste sites, and Toxic Release Inventory (TRI) facilities were determined for 1244 cases (89.5% of those eligible) and 4368 controls (88.0%). Living within 1 mile of a hazardous waste site was not associated with risk of conotruncal heart defects [adjusted odds ratio (aOR) = 0.83, 95% confidence interval (CI) = 0.54, 1.27]. This was true whether looking at most types of defects or waste sites. Only truncus arteriosus showed statistically elevated ORs with any waste site (crude OR: 2.80, 95% CI 1.19, 6.54) and with NPL sites (crude OR: 4.63, 95% CI 1.18, 13.15; aOR 4.99, 95% CI 1.26, 14.51), but the latter was based on only four exposed cases. There was minimal association between conotruncal heart defects and proximity to TRI facilities (aOR = 1.10, 95% CI = 0.91, 1.33). Stratification by maternal age or race/ethnic group made little difference in effect estimates for waste sites or industrial facilities. In this study population, maternal residential proximity to waste sites or industries with reported air emissions was not associated with conotruncal heart defects or its subtypes in offspring, with the exception of truncus arteriosus.

Validity of parental work information on the birth certificate.

BACKGROUND: In the most recent revision (2003) of the U.S. standard certificate of live births, the National Center for Health Statistics recommended that all states collect maternal and paternal usual occupation. Because such information might be useful in the surveillance of job-related risk areas, we assessed the quality of parental work information on the U.S. birth certificate. METHODS: Occupational histories obtained from maternal interviews with Texas (USA) participants in the National Birth Defects Prevention Study were linked to and compared with parental work information on birth certificates. With occupational information from interviews serving as the gold standard, we assessed the quality of occupational information on the birth certificate with measures of sensitivity, specificity, and the kappa statistic. RESULTS: Of the 649 births available for study, parental occupation agreed between the birth certificate and interview for 77% of mothers and 63% of fathers with similar agreement by case-control status. Among occupations and industries with 10 or more workers by interview, sensitivity of the birth certificate information ranged from 35% to 100% for occupational groups and 55% to 100% for industrial sectors. Specificities of occupations/industries studied ranged from 93 to 100%. Kappa statistics for maternal occupations (0.76 to 0.90) and industries (0.59 to 0.94) were higher than those for paternal occupations (0.48 to 0.92) and industries (0.47 to 0.89). Mothers were frequently misclassified as homemakers or otherwise unemployed while the paternal information was often missing altogether on the birth certificate. Women who worked as health diagnosing and treating practitioners were the least likely (0%) and women in food preparation or serving occupations were the most likely (65%) to be misclassified as not employed on the birth certificate. Among fathers, the proportion of missing occupations was the lowest for occupations in business or financial operations (0%) and highest for occupations in food preparation and serving (30%). CONCLUSION: Sensitivity of occupation/industry information on birth certificates varies although the specificity of such information may exceed 95%. Quality of this information also varies by maternal and paternal occupation with misclassification as homemaker a limiting factor among maternal and missing information a limiting factor among paternal work information.

Residential proximity to waste sites and industrial facilities and chromosomal anomalies in offspring.

A few studies have found chromosomal anomalies in offspring associated with a maternal residence near waste sites, but did not examine the effect of living near industrial facilities, and most combined specific anomalies into heterogeneous groups. With a case-control study design, we investigated whether maternal residential proximity to hazardous waste sites or industrial facilities with chemical air emissions was associated with chromosomal anomalies in births. Maternal residences of 2099 Texas births with chromosomal anomalies and 4368 control births without documented malformations were related to boundaries of hazardous waste sites and street addresses of industrial facilities through geographic information systems. With adjustment for maternal age, race/ethnicity, and education, maternal residence within 1mile of a hazardous waste site (relative to farther away) was not associated with chromosomal anomalies in offspring except for Klinefelter variants among Hispanic births (odds ratios (OR) 7.9, 95% confidence interval (CI) 1.1-42.4). Women 35 years or older who lived within 1mile of industries with emissions of heavy metals were two times more likely (95% CI 1.1-4.1) than women living farther away to have offspring with chromosomal anomalies including trisomies 13, 18, or 21 or sex chromosome abnormalities. Among women 40 years or older, maternal residence within a mile of industries with solvent emissions was associated with chromosomal anomalies in births (OR 4.8, 95% CI 1.2-42.8). Study findings suggest some relation between residential proximity to industries with emissions of solvents or heavy metals and chromosomal anomalies in births to older mothers.

Parental occupation, Hispanic ethnicity, and risk of selected congenital malformations in offspring.

OBJECTIVES: Evidence suggests that parental occupation and Hispanic ethnicity may be risk factors for some birth defects. Because few studies have examined the effect of Hispanic ethnicity on occupational associations, we examined whether risk associated with certain occupations was heightened in Hispanics compared with non-Hispanic Whites. DESIGN: In this case-control study among Texas births occurring from 1996 through 2000, cases of neural tube defects, isolated oral clefts, and chromosomal anomalies were linked to their respective live birth certificates. A random sample of 4965 live births without documented congenital malformations served as the comparison group. Parental occupations were categorized into groups according to previously published associations. Logistic regression was used to obtain odds ratios (OR) and 95% confidence intervals (CI) for the selected congenital malformations in relation to parental occupations. RESULTS: Maternal occupations as cook or nurse were associated with oral clefts (OR 3.3, 95% CI .6-16.0) and neural tube defects (OR 3.1, 95% CI .5-13.1), respectively, among births to Hispanic mothers, but not with births to non-Hispanic White mothers. Hispanic fathers who were electricians were more likely to have offspring with chromosomal anomalies, especially trisomy 18 (OR 7.4, 95% CI 1.6-25.5), associations not seen among offspring of non-Hispanic White fathers. Risk estimates also differed by Hispanic ethnicity between oral clefts and paternal occupations of electronic equipment operator, farmworker, janitor, police officer, and printer. CONCLUSIONS: In this study, we found differences for risk of several congenital malformations by Hispanic ethnicity in relation to parental occupation. We recommend further study of these risks in other Hispanic populations.

Maternal exposures to hazardous waste sites and industrial facilities and risk of neural tube defects in offspring.

PURPOSE: We examined the relationship between maternal proximity to hazardous waste sites and industrial facilities and neural tube defect (NTD) risk. METHODS: Texas Birth Defects Registry cases were linked with their birth or fetal death certificates; controls (without defects) were randomly selected from birth certificates. Distances from maternal addresses at delivery to National Priority List (NPL) and state superfund sites and Toxic Release Inventory (TRI) facilities were determined for 655 cases and 4368 controls. RESULTS: Living within 1 mile of an NPL or state superfund site was not related to NTD risk (adjusted odds ratio [OR] = 1.0; 95% confidence intervals [CI] = 0.6, 1.7). Living within 1 mile of a TRI facility carried a slight risk (adjusted OR = 1.2; 95% CI = 1.0, 1.5). The effect was highest among mothers 35 years and older (OR = 2.7; 95% CI = 1.4, 5.0) and among non-Hispanic white mothers (OR = 1.8; 95% CI = 1.1, 2.8). CONCLUSIONS: Hazardous waste sites posed little risk for NTDs in offspring. Close proximity to industrial facilities with chemical air emissions was associated with NTD risk in some subgroups. Further investigation is needed to determine if the effects are real or due to unresolved confounding or bias.

Match rate and positional accuracy of two geocoding methods for epidemiologic research.

PURPOSE: This study compares the match rate and positional accuracy of two geocoding methods: the popular geocoding tool in ArcGIS 9.1 and the Centrus GeoCoder for ArcGIS. METHODS: We first geocoded 11,016 Texas addresses in a case-control study using both methods and obtained the match rate of each method. We then randomly selected 200 addresses from those geocoded by using both methods and obtained geographic coordinates of the 200 addresses by using a global positioning system (GPS) device. Of the 200 addresses, 110 were case maternal residence addresses and 90 were control maternal residence addresses. These GPS-surveyed coordinates were used as the "true" coordinates to calculate positional errors of geocoded locations. We used Wilcoxon signed rank test to evaluate whether differences in positional errors from the two methods were statistically significantly different from zero. In addition, we calculated the sensitivity and specificity of the two methods for classifying maternal addresses within 1500 m of toxic release inventory facilities when distance is used as a proxy of exposure. RESULTS: The match rate of the Centrus GeoCoder was more than 10% greater than that of the geocoding tool in ArcGIS 9.1. Positional errors with the Centrus GeoCoder were less than those of the geocoding tool in ArcGIS 9.1, and this difference was statistically significant. Sensitivity and specificity of the two methods are similar. CONCLUSIONS: Centrus GeoCoder for ArcGIS for geocoding gives greater match rates than the geocoding tool in ArcGIS 9.1. Although the Centrus GeoCoder has better positional accuracy, both methods give similar results in classifying maternal addresses within 1500 m of toxic release inventory facilities when distance is used as a proxy of exposure.