Hyesook Park

Prenatal Exposure to Phthalates and Infant Development at 6 Months: Prospective Mothers and Children’s Environmental Health (MOCEH) Study

Background: There are increasing concerns over adverse effects of prenatal phthalate exposure on the neurodevelopment of infants. Objectives: Our goal was to explore the association between prenatal di(2-ethylhexyl) phthalate and dibutyl phthalate exposure and the Mental and Psychomotor Developmental Indices (MDI and PDI, respectively) of the Bayley Scales of Infant Development at 6 months, as part of the Mothers and Children’s Environmental Health Study. Methods: Between 2006 and 2009, 460 mother–infant pairs from Seoul, Cheonan, and Ulsan, Korea, participated. Prenatal mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono(2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono-n-butyl phthalate (MBP) were measured in one urine sample acquired from each mother during the third trimester of pregnancy. Associations with log-transformed creatinine-corrected phthalate concentrations were estimated using linear regression models adjusted for potential confounders. Results: MDI was inversely associated with the natural log concentrations (micrograms per gram creatinine) of MEHHP [β = –0.97; confidence interval (CI), –1.85 to –0.08] and MEOHP (β = –0.95; CI, –1.87 to –0.03), and PDI was inversely associated with MEHHP (β = –1.20; CI, –2.33 to –0.08). In males, MDI was inversely associated with MEHHP (β = –1.46; CI, –2.70 to –0.22), MEOHP (β = –1.57; CI, –2.87 to –0.28), and MBP (β = –0.93; CI, –1.82 to –0.05); PDI was inversely associated with MEHHP (β = –2.36; CI, –3.94 to –0.79), MEOHP (β = –2.05; CI, –3.71 to –0.39), and MBP (β = –1.25; CI, –2.40 to –0.11). No significant linear associations were observed for females. Conclusions: The results suggest that prenatal exposure to phthalates may be inversely associated with the MDI and PDI of infants, particularly males, at 6 months.

Interaction between GSTM1/GSTT1 Polymorphism and Blood Mercury on Birth Weight

Background Mercury (Hg) is toxic to both the reproductive and nervous systems. In addition, glutathione S-transferases (GSTs), which conjugate glutathione to a variety of electrophilic compounds, are involved in the detoxification of Hg. Objective In this study we examined the association between prenatal exposure to Hg and birth weight as well as the influence of GST polymorphisms. Methods The total Hg concentration in maternal and cord blood was measured from 417 Korean women and newborns in the Mothers and Children’s Environmental Health study from 2006 to 2008. Information on birth weight was collected from the patients’ medical records. The genotyping of glutathione S-transferase M1 (GSTM1) and glutathione S-transferase T1 (GSTT1) polymorphisms was carried out using polymerase chain reaction. Regression analysis was performed to determine the association between the blood Hg concentration and birth weight in mothers with GSTM1 and GSTT1 polymorphisms. Results The geometric mean levels of Hg in the maternal blood during late pregnancy and in cord blood were 3.30 μg/L and 5.53 μg/L, respectively. For mothers with the GSTT1 null genotype, elevated Hg levels in maternal blood during late pregnancy were associated with an increased risk of lower birth weight. For mothers with both GSTM1 and GSTT1 null genotype, both maternal and cord blood Hg levels were associated with lower birth weight. Conclusions This study suggests that the interactions of Hg with GSTM1 and GSTT1 polymorphisms play a role in reducing birth weight.

Prenatal bisphenol A and birth outcomes: MOCEH (Mothers and Children's Environmental Health) study.

Bisphenol A (BPA) is used primarily in the production of polycarbonate plastics and epoxy resins. Widespread exposure to BPA has created a great deal of concern regarding its potential adverse effects on human health. This study examined the relationship between prenatal BPA exposure and birth outcomes, including birth weight, birth length, and ponderal index considering gender difference. A multi-center birth cohort study, Mothers and Childrens Environmental Health (MOCEH) has been established in Korea since 2006. Study subjects are 757 pregnant women from the original cohort, who had their urinary BPA level measured during the third trimester, as well as information on birth outcome, prior medical history, psychosocial status, health behavior, environmental exposure as well as socio-demographic characteristics. Regression analysis was performed to assess the effect of BPA on birth outcome. The geometric mean concentration of BPA in pregnant women was 1.29 μg/L (1.87 μg/g creatinine) during late pregnancy. Urinary BPA concentrations were shown to be higher in women with a higher income level. Univariate regression analysis revealed a significant association between BPA levels and birth weight. In adjusted analysis, the second tertile of maternal BPA exposure exhibited an increase in birth weight, relative to the first tertile (p=0.04). These relationships were more pronounced in male neonates. Also, prenatal exposure to BPA was associated with an increase of ponderal index in total, and especially female neonates. This study shows that the association of prenatal exposure to BPA with anthropometric measures, such as birth weight and birth length, differed by gender. Further study is required to more fully elaborate this relationship between prenatal BPA exposure and birth outcome.

PM10 and Pregnancy Outcomes : A Hospital-Based Cohort Study of Pregnant Women in Seoul

Objective: The aim of this study was to evaluate the effects of PM10 on birth outcomes using a prospective cohort of pregnant women. Methods: The multicenter prospective study was conducted in Korea from 2001 to 2004. To estimate the effects of PM10 exposure on birth outcomes, the logistic and linear regression model and the generalized additive model for nonlinear relationships were used. Results: Stillbirths were affected by PM10 level during the third trimesters (OR = 1.10, 95% CI = 1.02–1.14), and birth defects were influenced by the PM10 exposure during the second trimesters (OR = 1.16, 95% CI = 1.00–1.34). Intrauterine growth retardation was affected by the first trimesters PM10 exposure. On the other hand, premature birth was affected by the PM10 exposure during the third trimester, and low-birth-weight births were affected by the PM10 level during entire trimesters of pregnancy. Conclusions: PM10 exposure during pregnancy may result in adverse birth outcomes with different critical periods.

Influence of maternal serum levels of vitamins C and E during the second trimester on birth weight and length

Objective: It has been known that maternal oxidative stress during pregnancy plays an important role in fetal growth. However, the association between antioxidant vitamin levels and birth outcomes is not conclusive. We investigated the relationship between maternal serum levels of vitamins C and E during the second trimester and birth weight and length.Design: Prospective cohort study.Setting: Outpatient-clinic of obstetrics, Ewha Womans University Hospital, South Korea.Subjects and methods: The study subjects were 239 healthy, pregnant women who visited an obstetric clinic for antenatal care, and their singleton live births, in Seoul, Korea, between August 2001 and March 2003. We measured the levels of vitamins C and E in maternal serum during the period 24–28 gestational weeks. Each woman was interviewed for dietary intake by trained interviewers during the second trimester.Results: The serum concentration of maternal vitamin C during the second trimester was significantly associated with birth weight and length in the group of full-term deliveries. An increase of 1 μg/ml in the serum vitamin C level increased the birth weight by 27.2 g and the birth length by 0.17 cm. When we considered the levels of vitamins C and E together in the relationship with birth weight and length, we found that the heaviest birth weight and the longest birth length belonged to the group of upper vitamin C/upper vitamin E. However, dietary intake estimated by 24-h recall method was not a predictor of the levels of serum vitamins C and E.Conclusion: We found that maternal serum vitamin C levels during the second trimester were positively correlated with birth weight and length in full-term babies. We also found that birth weight and length were highest when the levels of both vitamins C and E were high. Our results indicate the importance of antioxidant nutrient balance for pregnant women who are exposed to various oxidants through food, drinking water, or inhaled air.

Relationships between pregnancy outcomes, biochemical markers and pre-pregnancy body mass index.

Objective:We examined the relationships between pre-pregnancy maternal body mass index (BMI), pregnancy outcomes and biochemical markers.Design:This study was conducted as a cross-sectional analysis.Subjects:Korean women in their second and third trimesters of pregnancy were recruited at two hospitals in the metropolitan Seoul area. Pre-pregnancy BMI was categorized in four groups according to the Asia-Pacific standard.Measurements:Fasting blood samples were obtained and analyzed for serum levels of homocysteine, folate and high-sensitivity C-reactive protein (hs-CRP). Concentrations of fetal fibronectin were assessed in the cervix and vagina, and cervical length was measured.Results:Obese subjects had a lower education level and a lower income level than subjects of normal weight. The level of maternal stress was positively associated with pre-pregnancy BMI. Normal weight subjects were more likely to eat breakfast and consume meals of appropriate size than the rest of our sample. In overweight and obese subjects, weight gain during pregnancy was significantly lower than in the underweight and normal subjects. High pre-pregnancy maternal BMI increased the risks of preterm delivery (odds ratio (OR)=2.85, confidence interval (CI)=1.20–6.74), low-birth-weight (LBW) infants (overweight subjects: OR=5.07, CI=1.76–14.63; obese subjects: OR=4.49, CI=1.54–13.13) and macrosomia. In obese subjects, the average serum folate level was significantly lower than in the underweight subjects. In obese subjects, the average serum hs-CRP level was significantly higher than in the rest of our sample.Conclusion:Pregnancy outcomes are influenced by pre-pregnancy BMI. These findings suggest that women can minimize their risks of preterm delivery, LBW and macrosomia by maintaining normal pre-pregnancy BMI.

Risk Factors for Machinery-related Injury among Iowa Farmers: A Case-Control Study Nested in the Agricultural Health Study

Abstract Farm machinery is a major cause of injury morbidity and mortality among farmers. This case-control study assessed risk factors for machinery-related injuries among Iowa farmers. A screener questionnaire sent to 6,999 farmers in 1998 identified 205 farmers who had machinery-related injuries requiring medical advice/treatment in the previous year. Possible risk factors for injury were assessed among these farmers compared with 473 farmers with no injury in the previous year. A multiple logistic regression analysis showed significant associations between machinery-related injury and hours per week spent on farmwork (OR = 2.02; 95% CI 1.38–2.94), fewer years of farming experience (OR = 1.79; 95% CI 1.14–2.79), wearing a hearing aid (OR = 4.37; 95% CI 1.55–12.25), and a high CAGE score suggesting problem drinking (OR = 2.49; 95% CI 1.00–6.19). This is the first study to show associations between machinery-related injury and hearing impairment, problem drinking, and fewer years of farming experience. These findings may be useful for future interventions to decrease injuries related to farm machinery.

Brightness temperatures of the lunar surface: Calibration and global analysis of the Clementine long‐wave infrared camera data

The scientific payload on the Clementine spacecraft included a long-wave infrared (LWIR) camera with a single passband centered at a wavelength of 8.75 μm. The Clementine orbit deviated by ±30° from Sun synchronous, and for two lunar months, dayside nadir-looking images were obtained near local noon. During the systematic mapping phase of the Clementine mission, approximately 220,000 thermal-infrared images of the lunar surface were obtained. We have completed the calibration of the LWIR camera. Here we present the various steps involved in the calibration routine and the associated uncertainty analysis. The LWIR calibration routine can be outlined as follows: convert measured data number values to radiance via a calibration equation; subtract a zero-flux background image from each lunar image; divide by a flatfield frame; identify bad pixels; smooth over only bad pixels; adjust radiances to reflect the absolute calibration; and convert radiances to brightness temperatures via the Planck function. Observed LWIR radiances can be converted to brightness temperatures, which provide information on various physical properties of the lunar surface. We also present here the LWIR global data set. The LWIR data from noontime orbits demonstrate that the Lambertian temperature model of cos1/4(i) is a fair approximation for nadir-looking temperatures, rather than the cos1/6(i) behavior observed for ground-based measurements of the full Moon. Deviations from the Lambertian model are likely due to surface roughness effects and variations in infrared emissivity. In addition, the LWIR global data set reveals the dayside lunar thermal emission to be largely governed by albedo and by the solar incidence angle.

Prenatal lead and cadmium co-exposure and infant neurodevelopment at 6 months of age: The Mothers and Children's Environmental Health (MOCEH) study

BACKGROUND This study aimed to explore the developmental effects of prenatal exposure to Pb and Cd on infant cognitive development at 6 months of age. METHODS Between 2006 and 2010, the blood levels of Pb and Cd were measured in 884 mothers during their early and late pregnancy. The mental (MDI) and psychomotor (PDI) development index scores of the infants were assessed using the Bayley Scales of Infant Development. The development index scores were adjusted for birth weight, maternal age, maternal education level, family income, breastfeeding status, and residential area. RESULTS The geometric mean of the maternal blood concentration was 1.36μg/dL (10th percentile=0.83; 90th percentile=2.13; range=0.26-9.10) for Pb and 1.42μg/L (10th percentile=1.01; 90th percentile=2.16; range=0.03-9.87) for Cd during the early pregnancy period and 1.27μg/dL (10th percentile=0.77; 90th percentile=2.10; range=0.12-4.28) for Pb and 1.52μg/L for Cd (10 percentile=1.07; 90th percentile=2.10; range=0.43-3.73) during the late pregnancy period. The prenatal Pb and Cd concentrations during the early pregnancy period showed no association with the adjusted MDI or PDI scores. The antagonistic interaction between the prenatal Pb and Cd levels during the early pregnancy period had a significant effect on the MDI score (B=-4.64, 95% CI=-8.17 to -1.12, p=0.01), but the effect of this interaction did not reach statistical significance for the PDI score (B=-3.69, 95% CI=-7.94 to 0.56, p=0.09). The Pb levels during the late pregnancy period were inversely associated with the MDI score (B=-1.94, 95% CI=-3.60 to -0.29, p=0.02) but not with the PDI score (B=-1.69, 95% CI=-3.65 to 0.27, p=0.09). The prenatal Cd levels during the late pregnancy period showed no association with the MDI or PDI score. However, the MDI score (B=-3.20, 95% CI=-5.35 to -1.06, p<0.01) and the PDI score (B=-2.86, 95% CI=-5.55 to -0.16, p=0.04) of infants with Cd levels >1.51μg/L were significantly associated with the Pb level, whereas there were no such associations for infants with Cd levels <1.51μg/L. These results suggest that there is a synergistic effect modification between Pb and Cd during the late pregnancy period. CONCLUSIONS These findings suggest that there is dose-dependent interaction between prenatal exposure to Pb and prenatal exposure to Cd. The results further demonstrate the biological complexities of examining the neurodevelopmental effects of co-exposure to multiple toxicants.

Influence of genetic susceptibility on the urinary excretion of 8-hydroxydeoxyguanosine of firefighters

OBJECTIVES Oxidative DNA damage has been implicated in carcinogenesis. The DNA damage can be assessed from the urinary excretion of the DNA-repair product 8-hydroxydeoxyguanosine (8-OH-dG). The factors were investigated that influenced the excretion of urinary 8-OH-dG in 78 firefighters. METHODS 53 Out of 78 firefighters were exposed to fire within 5 days of the study and 25 were not. 8-OH-dG was measured by ELISA and the distribution of the genotypes of CYP1A1, CYP2E1, GSTM1, and GSTT1 was measured by polymerase chain reaction. RESULTS The homozygous wild type frequencies of CYP1A1 MspI, CYP1A1 ile-val, CYP2E1, GSTM1, and GSTT1 were 31.5%, 56.2%, 60.3%, 50.7%, and 53.4%, respectively. The geometric mean of urinary 8-OH-dG was 14.1 ng/mg creatinine in more active firefighters and 12.3 ng/mg creatinine in non-exposed and less active subjects. Significantly increased concentrations of urinary 8-OH-dG were found to be associated with cigarette smoking, and 14% of the variation of 8-OH-dG was explained by cigarettes smoked per day. The CYP1A1MspI, CYP1A1 ile-val, GSTM1, and GSTT1 genetic polymorphisms were not found to be significantly associated with the urinary excretion of 8-OH-dG. However, the subjects carrying the CYP2E1 mutant type excreted higher concentrations of 8-OH-dG and there was a marginally significant interaction of GSTT1 with firefighting activity. Multiple regression analysis confirmed that smoking was the strongest predictor of excretion of 8-OH-dG. Age, body mass index, and firefighting activity were not significant predictive factors for urinary 8-OH-dG. CONCLUSION Smoking and CYP2E1 gene polymorphism may be important factors in carcinogenesis and the GSTT1 positive genotype may be a genetic susceptibility factor in firefighters who are exposed regularly to various chemical carcinogens.