Current cigarette smoking and decreased serum levels of α-Klotho, an anti-aging hormone, among US adult participants.

BACKGROUND AND AIMS: Cigarette smoking is a well-established risk factor for cardiovascular disease and other aging-related disorders; yet the pathogenesis of these diseases induced by smoking remains relatively underexplored. This study was to assess the association between cigarette smoking and serum α-Klotho levels, an anti-aging protein, in US adults. METHODS AND RESULTS: Data on 4196 participants aged 40-79 years from the 2013-2016 National Health and Nutrition Examination Survey was analyzed for the association using multiple general linear models. Smoking was assessed using both questionnaire data and serum cotinine measurements. Both past and current smokers exhibited significantly lower levels of α-Klotho, with the light smokers exhibiting the lowest levels [geometric mean: 720.85 pg/mL; 95% CI: 662.53, 784.31], compared with non-smokers [806.75 (790.69, 823.13)]. A significantly inverse association between current smoking and α-Klotho levels was revealed. This relationship extended across smoking intensities, with even light smokers displaying the strongest association. After adjusting for potential confounders, light (smoked <5 pack-years), moderate (5-19 pack-years), and heavy smoking (≥20 pack-years) were associated with reductions of 10.81% (-16.91, -4.28), 6.43% (-10.24, -2.47), and 3.38% (-6.83, 0.19) of Klotho levels, respectively, when compared to non-smoking. Active smoking, defined as serum cotinine levels ≥10 ng/mL, was associated with a 4.59% decrease (-6.91, -2.23) in α-Klotho levels. CONCLUSION: The study demonstrates an inverse relationship between current smoking and serum α-Klotho levels among middle-aged and older adults. Our findings suggest that Klotho may play an important role in smoking-induced diseases. Further investigations are warranted to explore these interactions.

Covariation between serum cotinine and blood lead levels among US pediatric populations: Trends from 1999 to 2018.

BACKGROUND: Tobacco smoke, including both active and passive smoke, can be an important source of lead exposure. However, the relationship between passive tobacco smoke exposure (PTSE) and blood lead levels (BLL), especially in vulnerable populations, needs to be further explored. The present study was to assess the covariation between serum cotinine, a measure of PTSE, and BLL in a pediatric population during 1999-2018. METHODS: Data on 21,817 children, aged 3-19 years, was extracted from the biennial nationally representative surveys. The trends of the prevalence of lead exposure (BLL ≥ 3.5 µg/dL) and PTSE (cotinine ≥ 1 ng/mL but < 10 ng/mL) were determined, and the covariation between BLL and cotinine was assessed. The population attributable fraction (PAF) of PTSE to the BLL was proxied using the partial R2 of the hierarchical linear regression. The association between PTSE and lead exposure was estimated using multivariate logistic regression. RESULTS: A parallel decreasing trend in the prevalence of lead exposure and PTSE was observed. Similarly, the means of both BLL and cotinine declined simultaneously. Overall, the PAF from PTSE towards blood lead was 7 %, doubling the PAF from race/ethnicity and family income combined. Stratified by race/ethnicity, PAF from PTSE was 8 % in Blacks and Whites and 4 % for Hispanics. The odds ratio of PTSE with lead exposure was 2.45 (95 % CI, 1.75, 3.44), 2.00 (1.21, 3.33), and 1.16 (0.64, 2.13) for Black, White, and Hispanic children, respectively. Cotinine mean remained two times higher in Blacks than non-Black children at the end of the study period. CONCLUSION: Serum cotinine and BLL may have a significant association in children that persists even as both have been steadily declining in recent years. The contribution from PTSE to blood lead variations could be greater than that from socioeconomic factors. Further reducing lead exposure might be achieved by eliminating PTSE, particularly for the Black pediatric population.

Exposure to p-dichlorobenzene and prevalent endocrine-related reproductive cancers among US women.

P-dichlorobenzene (p-DCB) is a pest repellent and air deodorant that is commonly found in the household and public buildings. Exposure to p-DCB has been suggested to have potential metabolic and endocrine effects. Little is known about its association with endocrine-related female cancers. In this cross-sectional study, a nationally representative subsample of 4459 women, aged 20 years or older, in the 2003-2016 National Health and Nutrition Examination Survey was analyzed for the association between p-DCB exposure, measured as urinary concentrations of 2,5-dichlorophenol (2,5-DCP), the primary metabolite of p-DCB, and prevalent endocrine-related female cancers (defined as breast, ovarian, and uterine cancers) using multivariate logistic regression models, adjusting for potential confounders. Of the study participants, 202 women (weighted prevalence, 4.20%) reported being diagnosed with any of these endocrine-related reproductive cancers. Women with reproductive cancers showed a statistically significant increase in urinary 2,5-DCP concentrations (weighted geometric mean, 7.97 vs. 5.84 µg/g creatinine; p < 0.0001), compared to women without these cancers. After adjusting for potential confounders, we found that women in the moderate (1.94- < 28.10 µg/g creatinine) and high level (≥ 28.10 µg/g creatinine) of 2,5-DCP had significantly increased odds of endocrine-related reproductive cancers (odds ratio of 1.66 (95% CI: 1.02, 2.71) and 1.89 (1.08, 3.29), respectively), as compared with those in the low exposure group (< 1.94 µg/g creatinine). This study demonstrates a potential relation between p-DCB exposure and prevalent endocrine-related reproductive cancers in US women. Prospective and mechanistic studies would further explore these interactions and elucidate the pathogenesis of endocrine-related female cancers potentially associated with p-DCB exposure.

The Diverging Trend in Exposure to Environmental Tobacco Smoke Among US Children.

OBJECTIVE: Environmental tobacco smoke exposure (ETSE) was race/ethnicity-specific, but how the race/ethnicity-specific ETSE has changed over time, diverging or converging, remains unclear. We examined ETSE trends by race/ethnicity in US children aged 3-11 years. METHODS: We analyzed the data of 9678 children who participated in the biennial National Health and Nutrition Examination Surveys, 1999-2018. ETSE was defined as serum cotinine ≥ 0.05 ng/ml, with ≥ 1 ng/ml as heavy exposure. For trend description, adjusted biennial prevalence ratios (abiPR: the ratio associated with a 2-year increase in time) were estimated by race/ethnicity. The prevalence ratios between races/ethnicities were used to quantify ethnoracial differences in different survey periods. Analyses were performed in 2021. RESULTS: The overall ETSE prevalence was cut by almost half, from 61.59% (95% confidence interval = 56.55%, 66.62%) in the 1999-2004 survey to 37.61% (33.90%, 41.31%) in 2013-2018, exceeding the national 2020 health target (47.0%). However, the decrease occurred unequally between races/ethnicities. Heavy ETSE declined significantly in white [abiPR = 0.80 (0.74, 0.86)] and Hispanic children [0.83 (0.74, 0.93)], but insignificantly in black children [0.97 (0.92, 1.03)]. Consequently, the adjusted prevalence ratio between black children and white children increased from 0.82 (0.47, 1.44) in 1999-2004 to 2.73 (1.51, 4.92) in 2013-2018 for heavy ETSE. Hispanic children remained at the lowest risk throughout the study period. CONCLUSION: Overall ETSE prevalence was cut by half between 1999 and 2018. However, due to uneven declines, the gaps between black children and others have expanded in heavy ETSE. Special vigilance is needed in preventive medicine practice with black children.

Exposure to endocrine-disrupting metals and serum estrogen levels among US women.

Multiple factors could affect estrogen levels in the body; however, the impact of exposure to endocrine-disrupting chemicals on estrogen levels in humans remains inconclusive. This cross-sectional study was to assess the association between blood levels of endocrine-disrupting metals (including cadmium, lead, and mercury) and serum estradiol levels in 1618 women (aged ≥ 20 years) who participated in the 2013-2016 National Health and Nutrition Examination Survey. Using multiple general linear models, we estimated percent changes of estradiol levels in association with blood metal concentrations. Age-specific analysis was further conducted. The median level of blood cadmium, lead, and mercury was 0.31 µg/L (range: 0.07-7.23), 0.76 µg/dL (0.11-12.80), and 0.73 µg/L (0.20-36.90), respectively, and the median estradiol level was 31.10 pg/mL (range: 2.12-523.00) among women aged 20-80 years. After adjusting for potential confounders, a 10 % increase in blood cadmium and lead levels was associated with 1.43 % (95 % CI: 0.50, 2.37) increased levels and 1.45 % (- 2.17, - 0.11) decreased levels of estrogen, respectively, in the total study population. When stratified by age, the positive association with cadmium was only seen in women aged 20-49 years [1.47 % (0.39, 2.56) increased estradiol] and the inverse association with lead was seen among women aged 50-80 years [3.40 % (- 4.78, - 2.00) decreased estradiol]. Mercury was not significantly associated with estrogen levels. Our study demonstrates a potential relationship between exposure to endocrine-disrupting cadmium and lead and serum estrogen levels in US women. Age-specific associations were observed. Prospective and mechanistic studies are warranted to further explore these interactions and the associated reproductive toxicities.

Urinary Concentrations of Endocrine-Disrupting Metals and Prevalent Breast Cancer in US Women.

The toxic metals cadmium, lead, and mercury are endocrine-disrupting agents that could produce estrogenic effects involving breast carcinogenesis. In this study, we further explored the relationship between exposure to these metals and prevalent breast cancer among female participants, aged 20 years or older, in the 2007-2016 National Health and Nutrition Examination Survey (NHANES). Exposure was determined by measuring urinary concentrations of metals using inductively coupled plasma mass spectrometry. Urine creatinine-corrected concentrations of metals were calculated for each study participant. Multivariate logistic regression models were constructed to examine the association between urinary metals and prevalent breast cancer, adjusting for potential confounders. Of the 3352 study participants, 106 had been diagnosed with breast cancer (weighted prevalence, 3.13%). The results show that women with breast cancer had significantly higher urinary concentrations of lead and cadmium (both p < 0.0001) than those without breast cancer. After adjusting for all the covariates included in the study, however, only urinary lead was shown to be significantly associated with increased prevalence of breast cancer, with an odds ratio of 2.95 (95% CI: 1.13, 7.70) in the highest quartile of urinary lead concentrations (≥ 0.71 µg/g creatinine) as compared with the lowest quartile. No statistically significant associations were observed between urine cadmium or mercury levels and breast cancer. This study demonstrates a potential association between lead exposure and prevalent breast cancer among US women. Prospective and mechanistic studies are warranted to further investigate this interaction and explore the role of lead in breast carcinogenesis.

Crossover Trends in Current Cigarette Smoking Between Racial and Ethnic Groups of US Adolescents Aged 12-19 Years Old, 1999-2018.

OBJECTIVE: To examine the racial difference and trends in cigarette smoking among adolescents from 1999 to 2018. METHODS: We analyzed the data of 10,760 adolescents aged 12-19 who participated in the National Health and Nutrition Examination Surveys (NHANES), 1999-2018. Current tobacco smoking (CTS) was defined as participants with serum cotinine ≥10 ng/mL. Adjusted biennial prevalence ratios (abiPR: the ratio associated with a two-year increase in time) were estimated. RESULTS: Diverging trends in CTS prevalence were revealed in adolescents. The steepest decrease occurred in Hispanics aged 12-17, with 15% declining every two calendar years [abiPR = 0.85(0.77, 0.94)]. The sharpest increase occurred with Blacks aged 18-19 years [abiPR = 1.06(0.99, 1.14)]. A crossover of prevalence trend between Blacks and Whites occurred in adolescents aged 18-19 years old due to the diverging trends. The average CTS prevalence was significantly higher in Whites than in Blacks in the early [(1999-2008, 13.65% (11.85%, 15.46%) vs. 8.80% (7.55%, 10.04%)], but Blacks had a higher average in recent years [(2009-2018, 8.32% (6.53%, 10.12%) vs. 7.77% (5.86%, 9.68%)]. For adolescents aged 18-19 years, the survey cycles or calendar years linearly explained 71% of the variations in the prevalence for Hispanics, 60% for Whites, but only 1% for Blacks. CONCLUSIONS: A crossover in the trend of current tobacco smoking occurred between 1999 and 2018 due to an increase in prevalence among Black adolescents and a significant decrease in prevalence among other racial groups.

Exposure to p-dichlorobenzene and serum α-Klotho levels among US participants in their middle and late adulthood.

P-dichlorobenzene (p-DCB) is a volatile compound commonly used as pest repellent and air deodorant in the home and public buildings, leading to a widespread exposure in indoor environments. There has been an increasing concern about its metabolic and endocrine effects. In this study, we explored the relation between p-DCB exposure and serum levels of soluble α-Klotho, an anti-aging hormone, in US adults. A nationally representative subsample of 1485 adults 40-79 ages in the 2013-2016 National Health and Nutrition Examination Survey was analyzed for the association between p-DCB exposure, measured as urinary concentrations of 2,5-dichlorophenol (2,5-DCP), the major metabolite of p-DCB, and serum α-Klotho levels using multiple general linear models, adjusting for potential confounders. Age- and sex-specific analyses were further conducted. The weighted geometric mean of urinary 2,5-DCP was 2.43 µg/L and the weighted mean of serum α-Klotho was 831.97 pg/mL in the study participants during 2013-2016. After adjusting for potential confounders and urinary creatinine, urinary 2,5-DCP was significantly associated with decreased serum levels of α-Klotho (regression coefficient ß = -9.88; p = 0.0133) in the total study population. When age- and sex-specific analyses being conducted, a significantly inverse association was found in older adults aged 60-79 years (ß = -20.40; p = 0.0001) and in males (ß = -13.81; p = 0.0097), but not in the middle ages (40-59 years) and in females. The strongest association was observed in older (60-79 years) male participants, with a 25.43 pg/mL reduction of α-Klotho levels per 1-unit increase of 2,5-DCP concentrations (p = 0.0008). This is the first study demonstrating a relation between p-DCB exposure, measured as 2,5-DCP, and decreased α-Klotho levels in older males. Additional studies would further explore these interactions and elucidate the pathogenesis of the potential effects of p-DCB exposure on aging.

Ambient air emissions of endocrine-disrupting metals and the incidence of hormone receptor- and HER2-dependent female breast cancer in USA.

Limited evidence exists on the relationship between exposure to endocrine-disrupting metals in ambient air and hormone receptor- and HER2-dependent breast cancer. This study investigates the association between ambient air emissions of endocrine-disrupting metals and the incidence of female breast cancer of different receptor status. County-level data from the US national datasets were analyzed for the association between emissions of various metals including arsenic, cadmium, chromium VI, lead, and mercury, and the annual age-adjusted incidence of hormone receptor-dependent breast cancer for 1990-2016 and HER2-dependent breast cancer for 2010-2016 using adjusted linear regression models. Lead emissions showed the strongest association among the metals examined with the incidence of different receptor status breast cancers, including ER-positive, ER-negative, PR-negative, HER2-negative, and Triple-negative breast cancers, with the adjusted ß ranging from 917.26 for ER-negative to 3182.37 for HER2-negative breast cancer. Arsenic and mercury showed significant associations with the incidence of ER-positive, ER-negative, PR-positive, and PR-negative breast cancers. However, cadmium emissions were only significantly associated with ER-negative breast cancer. Moreover, chromium was not associated with any subtypes of breast cancer. Among all of the metals, only lead and mercury emissions showed significant associations with HER2-negative and Triple-negative breast cancer incidence. The results from this study suggest that increased exposure to endocrine-disrupting metals, especially lead, in ambient air could be associated with an increased incidence of female breast cancers with various receptor status in the US. Prospective studies are warranted to further explore this relationship.

Blood Lead Levels and Risk of Deaths from Cardiovascular Disease.

Environmental exposure could be an important modifiable risk factor for cardiovascular disease (CVD). In this study, we investigated the relation between lead exposure, measured as blood lead levels (BLLs) and CVD mortality in a national cohort. A total of 15,036 adults aged ≥19 who participated in the National Health and Nutrition Examination Survey (1988 to 1994) as the baseline examination were followed up through December 31, 2010. Adjusted hazard ratios (HRs) derived from Cox proportional hazard regressions were used to estimate the risk of dying from CVD in association with BLLs. Cardiovascular mortality was 3.76, 8.11, and 14.77 per 1,000 person-years for patients in low, moderate, and high BLLs, respectively. After adjusting for potential confounders, patients in the high lead level had a significantly increased risk of death from all CVD (HR 1.35, 95% confidence interval 1.03 to 1.77), compared with those with low level. Participants in both moderate and high lead levels showed a significantly increased risk of death from heart disease, with an HR of 1.37 (1.04 to 1.81) and 1.60 (1.21 to 2.13), respectively. A significant linear association with all CVD and heart disease deaths was also seen with an HR of 1.08 (1.00 to 1.16) and 1.09 (1.02 to 1.16), respectively, per 1-unit increase in BLLs. In conclusion, the study demonstrates that increasing BLLs were associated with an increased risk of cardiovascular deaths, especially from heart disease. This further supports the possible cardiovascular effects that lead poses on patients at low levels of exposure and the importance of further reducing lead exposure in the general population.

Plasma and water fluoride levels and hyperuricemia among adolescents: A cross-sectional study of a nationally representative sample of the United States for 2013-2016.

Exposure to excessive fluoride has been associated with a number of adverse health outcomes; however, there is a lack of evidence on the relation between fluoride exposure and serum uric acid levels, especially in human populations. The present study examined a potential relationship between fluoride exposure, measured as both plasma and water fluoride concentrations, and uric acid levels in an adolescent population. A nationally representative subsample of 1933 adolescents, aged 12-19 years, in the 2013-2016 National Health and Nutrition Examination Survey was analyzed for the association of fluoride concentrations with serum uric acid levels using multivariate general linear and logistic regression models, adjusting for potential confounders. Since uric acid levels change during development, hyperuricemia was defined in this study as over the mean plus one standard deviation for each sex and age group of adolescents. Of the study participants, 276 adolescents (weighted prevalence, 16.56%) had hyperuricemia. A significant and dose-dependent increase in prevalence of hyperuricemia was seen among the participants cross increasing quartiles of plasma fluoride (p-trend = 0.0017). After adjusting for potential confounders, we found that adolescents in the higher quartiles of plasma fluoride (≥0.32 µmol/L) and in the highest quartile of water fluoride (≥0.73 mg/L) had significantly increased odds of hyperuricemia compared with those in the lowest quartile. A 1.95-fold increased odds (95% CI: 1.37, 2.77) of hyperuricemia was also observed when analyzing plasma fluoride concentrations as continuous variable. A general linear model revealed that a 1 µmol/L increase in ln-plasma fluoride was associated with a 0.212 mg/dL (p < 0.0001) increased serum uric acid level. Furthermore, a positive relationship was observed between water and plasma fluoride concentrations (ß = 0.1907; p < 0.0001). Our study demonstrates a potential relation between fluoride exposure and hyperuricemia in adolescents. Further studies are warranted to overcome the limitations of this study to examine the impact of long-term exposure to low levels of fluoride during development on hyperuricemia and its related health outcomes.

sKlotho is associated with the severity of brick tea-type skeletal fluorosis in China.

The change of serum soluble Klotho (sKlotho) content is related to a variety of osteoarthropathy. However, its association with the severity of skeletal fluorosis (SF) is not clear. Here, the association of tea fluoride exposure with serum sKlotho levels and the severity of SF were investigated and further verified in a rat model of fluorosis. A cross sectional case control study was conducted in residents over 50 years old from brick-tea drinking areas in Qinghai and Xinjiang Provinces, China. Concentrations of fluoride in brick tea water and urine were determined by ion selective electrode method, and the levels of serum sKlotho were determined by ELISA method. Linear regression and ordered logistic regression models were constructed to examine the relationship among fluoride exposure, serum sKlotho levels and the severity of SF. The kidney and small intestine of Wistar rats were isolated for detection of Klotho by immunohistochemistry (IHC), and femoral artery blood was sampled to measure the serum levels of sKlotho. An increase of 1 mg/day in tea fluoride intake (TFI) was associated with a 12.070 pg/mL (95% CI: 0.452-23.689) increase in serum sKlotho levels and a 1.163-fold (95% CI: 1.007-1.342) increase in the severity of SF after adjusting for age, gender, and ethnicity. Serum sKlotho levels were also positively associated with the severity of SF (P < 0.05). The mediation analysis showed that serum sKlotho levels mediated 17.76% of the increase in the severity of SF caused by an increase of 1 mg/day of TFI. Moreover, a significant increase of serum sKlotho levels in fluoride-exposed groups was also seen in the rat model. The present study suggests that serum sKlotho may be a potential mediator of SF in brick tea-type fluorosis endemic areas.

Red blood cell folate and cardiovascular deaths among hypertensive adults, an 18-year follow-up of a national cohort.

A shift towards high folate concentration has emerged following folate fortification. However, the association between folate and health outcomes beyond neural tube defects remains inconclusive. To assess the relationship between red blood cell (RBC) folate and the risk of cardiovascular death among hypertensive patients, we analyzed the data of 2,986 adults aged 19 or older with hypertension who participated in the National Health and Nutrition Examination Survey (1991-1994) as the baseline examination and were followed up through December 31, 2010. After 32,743 person-years of follow-up with an average of 11.7 (standard error = 0.03) years, 1192 deaths were recorded with 579 cardiovascular deaths. The median survival time was significantly shorter in adults in the high folate quartile than in patients in the low folate quartile: 11.97 vs. 13.85 years for heart diseases and 13.37 vs. 14.82 years for myocardial infarction deaths. The cardiovascular mortality was 13.04, 16.95, and 26.61/1,000 person-years for the groups with low, intermediate and high folate quartiles, respectively. After adjustment for age, sex and other factors, a J-shaped association emerged. The hazard ratios (HRs) of all cardiovascular deaths in patients with low, intermediate, and high folate quartiles were 1.09 (0.94, 1.27), 1.00 (reference), and 1.44 (1.31, 1.58), respectively. The corresponding HRs of acute myocardial infarction were 1.13 (0.86, 1.50), 1.00, and 2.13 (1.77, 2.57), respectively. The estimates remained significant after adjustment for BMI and medication use. Compared to moderate RBC folate levels, high folate levels were significantly associated with an increased risk of cardiovascular deaths, especially acute myocardial infarction.

Pet ownership and risk of dying from cancer: observation from a nationally representative cohort.

We longitudinally examined the relationship between pet ownership and risk of dying from cancer in a nationally representative cohort of 13,725 adults in the Third National Health and Nutrition Examination Survey, 1988-1994. The vital status was followed through 31 December 2010. Women who owned pets (any type) presented one-year shorter survival time (15.88 years) than non-pet owner (16.83 years). A larger difference of survival time was particularly seen in bird owners (13.01 years) compared to non-bird owners (16.82 years). After adjusting for potential confounders, hazard ratio (HR) of dying from cancer associated with any type of pets was 1.08 (95% CI = 0.77-1.50) for men and 1.40 (1.01-1.93) for women. The association in women was presumably driven by owning birds [HR 2.41 (1.34-4.31)] or cats [HR 1.48 (0.97-2.24)]. Keeping birds and cats in the household was associated with an increased risk of dying from cancer, especially in women.

Blood levels of endocrine-disrupting metals and prevalent breast cancer among US women.

A growing body of evidence has pointed to a role of environmental chemical exposures in breast cancer etiology. This study was to examine the association between exposure to the endocrine-disrupting metals, including cadmium (Cd), lead (Pb), and mercury (Hg), and breast cancer in US women. A nationally representative subsample of 9260 women aged ≥ 20 years in the 2003-2012 National Health and Nutrition Examination Survey was analyzed for the association of blood levels of these metals with prevalent breast cancer using multivariate logistic regression models. Of the study participants, 284 women (weighted prevalence, 2.8%) were self-reported being diagnosed with breast cancer during 2003-2012. Breast cancer women showed significantly elevated blood levels of Cd and Pb, but not Hg. After adjusting for potential confounders, we found that women in all of the higher quartiles of blood lead levels (BLLs) had significantly increased odds ratio of prevalent breast cancer compared with those in the lowest quartile. However, a significant association with prevalent breast cancer was not seen with blood levels of either Cd or Hg. Our study demonstrates a potential relationship between lead exposure, measured as BLLs, and female breast cancer. Additional epidemiologic and mechanistic studies would further explore these interactions and elucidate the potential role of lead exposure in breast cancer etiology.

Endocrine-disrupting metals in ambient air and female breast cancer incidence in US.

Metals could act as endocrine disruptors that mimic the actions of hormones, such as estrogens, and contribute to the development and progression of breast cancer. In this study, we examined the association between ambient air emissions of several endocrine-disrupting metals and the incidence of female breast cancer in the United States by analyzing county-level data from national datasets. Linear regression analysis was conducted to evaluate the association in unadjusted and adjusted models. Of the metals analyzed, air emissions of arsenic, cadmium, lead, and mercury, but not chromium VI, were significantly associated with the incidence of all breast cancers, after adjusting for potential confounders. Emissions of arsenic, lead, and mercury were found to be significantly associated with the incidence of estrogen receptor (ER)-positive breast cancer. Among these metals, air emissions of lead showed the strongest association with breast cancer incidence with the ß of 3756.66 (95% CI: 1660.29, 5853.03) for all breast cancers and 2433.85 (440.59, 4427.10) for ER-positive breast cancer. Our results demonstrate that exposure to endocrine-disrupting metals in ambient air may be associated with an increased incidence of breast cancer in the United States. Further studies are needed to explore these interactions and to elucidate mechanisms of action.

Pet ownership and the risk of dying from lung cancer, findings from an 18 year follow-up of a US national cohort.

PURPOSE: In contrast to the popularity of pets, research on the health effects of living with pets, particularly, on the risk of cancer, is minimal and inconclusive. We longitudinally examined relationships between pet ownership and the risk of dying from lung cancer. METHODS: We analyzed nationally representative data of 13,725 adults aged ≥ 19 who answered the question about pet ownership in the Third National Health and Nutrition Examination Survey, 1988-1994, as the baseline survey. Vital status was followed through December 31st, 2010. RESULTS: About 43% of the study population owned pets, with 20.4% having cats and 4.6% having birds. A total of 213 lung cancer deaths were recorded by the end of 183,094 unweighted person-years of follow-up with a lung-cancer specific death rate of 1.00 per 1000 person-years. After adjustment for cigarette smoking, alcohol drinking, physical activity, body mass index, history of atopic conditions, and serum cotinine, owning a pet (any) was associated with a doubled mortality rate among women for lung cancer [hazard ratio (HR)= 2.31 (1.41-3.79)] over non-owners. This association was largely attributed to having a cat or a bird. The HR was 2.85 (1.62-5.01) for cats, and 2.67 (0.68-10.5) for birds. The HR for dogs was 1.01 (0.57-1.77). No significant patterns of association were observed among men either for any pets or for a subtype of pet. CONCLUSIONS: Living with a pet, especially, a cat or a bird, was significantly associated with elevated hazard of dying from lung cancer among women. The detrimental effect that pets conferred was not explained by confounding from cigarette smoking or atopic conditions.

Exposure to ambient PM2.5 during pregnancy and preterm birth in metropolitan areas of the state of Georgia.

A number of studies has pointed to air pollution as an additional factor that could be associated with preterm birth. We assessed in this study the association between exposure to PM2.5 in ambient air during pregnancy and preterm birth in metropolitan areas of the state of Georgia, where the rate of preterm birth has been among the highest in the nation over the years. Birth data were obtained from the National Center for Health Statistics natality dataset. The study population consisted of 53,094 singleton live births between January 1 and December 31, 2004 in nine metropolitan counties of Georgia. Preterm birth was defined as birth, which occurs before 37 weeks of gestation. County-level daily air quality index (AQI) data obtained from the US Environmental Protection Agency (EPA) was used to estimate individual exposure levels of PM2.5 for each study participant based on the county of residence for the duration of the pregnancy. A multivariate logistic regression analysis was conducted to assess the association, adjusting for potential confounders. Of the infants whose mothers resided in the nine metropolitan counties of Georgia, 4543 (8.6%) were born preterm. A higher rate of preterm birth (9.8%) was observed in infants whose mothers were exposed to ambient PM2.5 with AQI values > 50 than the ones with AQI ≤ 50 (EPA standard for good air quality conditions). Mothers with exposure to PM2.5 at average AQI values greater than 50 during the entire pregnancy were at increased risk of preterm birth (odds ratio 1.15; 95% CI 1.07, 1.25), after adjusting for sex of infant, mother's age, race/ethnicity, education, marital status, prenatal care, cigarette smoking, alcohol consumption, and season of conception. The study provides more evidence on the role of PM2.5 in preterm birth. Reducing exposure to ambient particulate matter, especially in urban areas, for pregnant women would be necessary to improve the health of infants.

Ambient air emissions of polycyclic aromatic hydrocarbons and female breast cancer incidence in US.

To examine ambient air pollutants, specifically polycyclic aromatic hydrocarbons (PAHs), as a factor in the geographic variation of breast cancer incidence seen in the US, we conducted an ecological study involving counties throughout the US to examine breast cancer incidence in relation to PAH emissions in ambient air. Age-adjusted incidence rates of female breast cancer from the surveillance, epidemiology, and end results (SEER) program of the US National Cancer Institute were collected and analyzed using SEER*Stat 8.3.2. PAH emissions data were obtained from the Environmental Protection Agency. Linear regression analysis was performed using SPSS 23 software for Windows to analyze the association between PAH emissions and breast cancer incidence, adjusting for potential confounders. Age-adjusted incidence rates of female breast cancer were found being significantly higher in more industrialized metropolitan SEER regions over the years of 1973-2013 as compared to less industrialized regions. After adjusting for sex, race, education, socioeconomic status, obesity, and smoking prevalence, PAH emission density was found to be significantly associated with female breast cancer incidence, with the adjusted ß of 0.424 (95% CI 0.278, 0.570; p < 0.0001) for emissions from all sources and of 0.552 (95% CI 0.278, 0.826; p < 0.0001) for emissions from traffic source. This study suggests that PAH exposure from ambient air could play a role in the increased breast cancer risk among women living in urban areas of the US. Further research could provide insight into breast cancer etiology and prevention.

Serum folate and cobalamin levels and urinary dimethylarsinic acid in US children and adults.

Nutritional status could affect arsenic metabolism and toxicity in the general population chronically exposed to low levels of inorganic arsenic. In this study, we examined the association of serum folate and cobalamin with urinary concentrations of dimethylarsinic acid (DMA), the most abundant metabolite of inorganic arsenic measured in urine, in children and adults who participated in the 2003-2006 US National Health and Nutrition Examination Surveys. A total of 1161 children (aged 6-19 years) and 1938 adults (aged 20-85 years) were analyzed for the association using multivariate general linear models, adjusting for potential confounders. We observed a positive association between serum levels of folate and cobalamin and creatinine-corrected urinary concentrations of DMA in both children and adults. Furthermore, serum levels of folate and cobalamin were inversely associated with homocysteine (Hcy). These results suggest that dietary intake of folate and cobalamin may exhibit protective functions against arsenic toxicity by increasing arsenic metabolism to the less toxic metabolite DMA and decreasing serum levels of Hcy.