Browsing by Author "Clark, Maggie, committee member"
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Item Open Access Association between exposure to cadmium and lead during gestation and adverse birth outcomes in the household air pollution intervention network (HAPIN) trial(Colorado State University. Libraries, 2024) Alhassan, Mohamed Adnan, author; Peel, Jennifer, advisor; Clark, Maggie, committee member; Keller, Kayleigh, committee member; Neophytou, Andreas, committee memberLow- and middle-income countries (LMICs) are particularly vulnerable to the adverse effects of metal exposure. These countries' rapid industrialization coupled with population growth, result in substantial environmental exposures, which many governments have limited capacity to formally regulate. Even when regulations exist, many governments have a limited capacity to enforce those regulations. Additionally, LMICs bear a disproportionate burden of adverse birth outcomes, including low birth weight and preterm birth, which carry long-term health implications such as increased risk of chronic diseases, developmental delays, and mortality. Several studies have examined the association between metals and adverse birth outcomes such as low birth weight and preterm births. Specifically, despite the low number of studies, cadmium has been consistently linked to lower birth weights, smaller sizes for gestational age, and reduced head circumference. However, the association between lead exposure and birth outcomes shows inconsistent results. This inconsistency in findings, along with the low number of studies overall, especially in LMICs, regarding lead has prompted further investigation in our current study. Here we utilized data from the Household Air Pollution Intervention Network (HAPIN) trial, a randomized controlled trial conducted in rural areas of Guatemala, Peru, Rwanda, and India. The HAPIN trial evaluated the impact of replacing biomass stoves with liquefied petroleum gas stoves on various health outcomes, including infant birth weight among 3200 participants. The participants in the current analysis included pregnant women with a live singleton birth with exposure and birth data (n=2396). Maternal exposure to cadmium and lead were evaluated by analyzing dried blood spots using inductively coupled mass spectrometry. Blood spots were collected at baseline (9 - <20 weeks gestational age) and 32-36 weeks gestational age; we also evaluated the average of these two measurements. Birth weight was measured using a digital infant scale, with low birth weight defined as <2500 grams, and gestational age at birth was determined using screening data and ultrasonography, with preterm birth defined as <37 weeks. We utilized linear regression for birth weight and gestational age, logistic regression for dichotomous low birth weight, and Cox proportional hazards model for preterm birth. The models accounted for infant sex, maternal age, nulliparity, body mass index, maternal hemoglobin, mother's dietary diversity, food insecurity, tobacco smoking in the household, and study arm. We assessed effect modification by study location, sex, and study arm by including an interaction term. In sensitivity analyses, we included study location, household assets, maternal education in the models; replaced values below the limits of detection (LOD) with LOD/√2, and evaluated metal concentrations standardized by potassium levels. We also excluded maternal hemoglobin from the main model. The mean birth weight was 3,020 (standard deviation [SD]=445.5) grams, and 10.3% of all births were classified as low birth weight. The mean gestational age was 39.5 weeks (SD=1.7 weeks), and 5.2% of the births were preterm. The median lead concentration across the time points was 1.4 μg/dL (IQR: 0.9 – 2.2 μg/dL), and the median cadmium concentration was 1.0 ng/mL (IQR: 0.7 – 1.4 ng/mL), values comparable to those found in other studies. Overall, the results did not indicate a consistent or strong association between lead or cadmium and adverse birth outcomes. Baseline cadmium levels showed a modest increase in the odds ratio for low birth weight (OR per IQR increase: 1.2, 95% CI: 0.97 to 1.47). Sensitivity analyses closely aligned with the main findings. All the results for effect modification did not indicate differences in the strata. The study found a suggestive, but inconsistent evidence between exposure to cadmium and low birth weight. This study has some limitations. There is potential for non-differential measurement error due to the hematocrit effect, which alters the estimated spot volume based on participants' hematocrit levels. A sensitivity analysis using potassium standardized metal concentrations partially addressed this, but individual hematocrit variability can still bias the observed association towards the null, with a moderate magnitude. The probability of the bias is moderate. The chromatographic effect, which can cause variations in concentration due to the interaction between blood and the analyte with the filter paper, was also partially addressed using internal standards, blanks, calibration samples, quality controls, and reference materials. This potential bias is of low probability and magnitude, biasing the observed association toward the null. Confounding bias was considered a concern due to incomplete adjustment for covariates like seasonal variation, which can affect metal exposure and birth outcomes. Sensitivity analyses supported the main model findings, suggesting a low probability and magnitude of confounding bias, which could bias the observed association towards or away from the null. Despite residual confounding concerns linked to socio-economic indicators like assets and diet diversity, the sensitivity analyses did not deviate from the main model findings, indicating a small probability and magnitude of the bias, which would bias the observed association in either direction. The study had several strengths including a large sample size compared to previous studies, especially those in LMICs and it was conducted in three distinct rural LMIC settings, which, to the best of our knowledge, had not been done before. This study's strength lies in its large sample size of 2,152 participants with complete data, enhancing its statistical robustness and addressing the common issue of small sample sizes and missing data in prior LMIC research. Additionally, its unique examination across three distinct rural LMIC settings provides valuable insights into the regional variations affecting the outcomes studied. Future steps include using whole blood samples instead of dried blood spots (DBS) and measuring exposure at multiple time points, particularly at birth via the umbilical cord, could yield more accurate concentrations. It is also recommended that subsequent studies employ better socio-economic indicators to reduce residual confounding effects. Expanding the geographical scope of the study to include a broader range of urban areas within the HAPIN countries would improve the generalizability of the findings. Additionally, future research should consider analyzing the effects of metal mixtures to better replicate real-world environmental conditions and interactions. The results are generally consistent with existing limited data indicating no evidence of an association between lead and adverse birth outcomes and a potential association between higher cadmium exposure during pregnancy with increased risk of low birth weight.Item Open Access Cookstove startup material characterization and quantification and acute cardiopulmonary effects from controlled exposure to cookstove air pollution(Colorado State University. Libraries, 2018) Fedak, Kristen M., author; Peel, Jennifer L., advisor; Volckens, John, advisor; Clark, Maggie, committee member; Nelson, Tracy, committee member; Wilson, Ander, committee memberTo view the abstract, please see the full text of the document.Item Open Access Efficiency of AC vs. DC distribution systems in commercial buildings(Colorado State University. Libraries, 2022) Santos, Arthur FelÃcio Barbaro dos, author; Young, Peter, advisor; Zimmerle, Daniel, advisor; Cale, James, committee member; Clark, Maggie, committee memberDecarbonization and modernization of the grid, electrification of transportation, and energy storage are some of the trends pushing towards the significant growth of power electronics in the past few decades. The massive application of such devices has increased the interest in direct current (DC) power distribution as an alternative to the conventional alternating current (AC) distribution systems in residential and commercial buildings. This increase in non-linear loads, however, substantially increases current harmonics, which compromises the lifespan, efficiency, and/or operability of distribution components, such as transformers and protection equipment. Additionally, when comparing the efficiency of AC vs. DC distribution systems, the literature is often based on simulation studies rather than real measured data. In this regard, this study focuses on three major topics: a) Harmonic cancellation within building circuits; b) Endpoint use efficiency comparison for AC and DC in-building distribution systems; and c) A cautionary note on using smart plugs for research data acquisition. The analyses are based on recorded power consumption data from office-based appliances, made by smart plugs, combined with detailed characterization of sampled Miscellaneous Electric Loads (MELs') power converters. While harmonic cancellation studies often assume that AC converters operate across their rated power range, measured realistic power profiles reported in this work show that MELs operate below 40% of rated power the majority of the time when not in standby mode. This makes the harmonic cancellation significantly lower than that predicted when using full-range power assumptions, which could provide incorrect guidance to building design engineers. In contrast, increased diversity of MELs increases harmonic cancellation. Blending typical office loads with lighting, for instance, improves the harmonic cancellation to near the levels predicted by traditional methods. Regarding the endpoint efficiency of AC and DC distribution systems, no systematic efficiency advantage was found, when endpoint AC/DC converters were compared to a similar, commercially available, DC/DC converter powering the same load profile. That goes in the opposite direction of prior studies, which estimate converters' efficiency based on datasheet information or the efficiency at rated load.Item Open Access Examination of the complex relationships among dietary components, type II diabetes, weight change, and breast cancer risk among Singaporean Chinese women(Colorado State University. Libraries, 2015) Canales, Lorena Lea, author; Peel, Jennifer, advisor; Clark, Maggie, committee member; Bachand, Annette, committee member; Nelson, Tracy, committee member; Ryan, Elizabeth, committee memberType II diabetes and breast cancer are on the rise in Asian populations that have typically had lower burdens of disease. Intake of dietary components high in nutrients with anti-oxidative and anti-inflammatory properties, such as green tea, soy, fruits and vegetables, may protect against the development of type II diabetes and may improve HbA1c (glycated hemoglobin) levels, a clinically relevant biomarker of diabetes and prediabetes. Furthermore, modifiable lifestyle factors such as diabetes, weight change and diet that influence endogenous hormone levels and the insulin pathway may play a role in the development of breast cancer. This dissertation includes three aims that examined different aspects of the complex relationships between diet, diabetes, weight change, and breast cancer risk in the Singapore Chinese Health Study, a prospective cohort study that enrolled 63,257 Chinese men and women aged 45-74 years between 1993 and 1998. First, we examined the association between intake of green tea, soy, and a vegetable-fruit-soy dietary pattern on HbA1c levels among self-reported, nondiabetic men and women, examined separately (Aim 1). We also evaluated type II diabetes and weight change (separately) in relation to risk of breast cancer, as well as the potential interaction of diet (soy and green tea intake) with the exposures of interest among women only (Aims 2 and 3). Dietary intake was assessed at baseline (1993-1998) by in-person interviews using a validated 165-item food frequency questionnaire. HbA1c levels were measured from blood samples collected in the follow-up period after baseline enrollment (1999-2004), and self-reported diabetes diagnosis was determined at the follow-up interview. Self-reported weights at the baseline and follow-up interviews were used to determine weight change. Multivariable linear regression (Aim 1) and proportional hazards regression models (Aims 2 and 3) were used to evaluate these associations. In Aim 1, adjusted mean HbA1c levels were inversely related to soy protein intake (p-value = 0.02; p for trend across the four quartiles of soy protein intake = 0.05) among women; the mean HbA1c difference between the highest and lowest quartile of soy protein intake of 0.07%. We also observed higher HbA1c levels for women with higher green tea intake (p for trend of 0.11), which was in the direction opposite to that hypothesized. In Aim 2, we observed a non-statistically significant increase in breast cancer risk among women with type II diabetes (adjusted hazard ratio [HR]=1.24, 95% confidence interval [CI]: 0.82, 1.86). The assessment of the joint effects of diabetes and lower soy isoflavone intake suggested a weak non-significant interaction between these variables on breast cancer risk; the HR for breast cancer was slightly elevated among those with lower soy isoflavone intake, while among those with higher isoflavone intake the HR was consistent with a null association. There was no evidence of interaction when evaluating soy food, soy protein and green tea intake on the diabetes and breast cancer association. In Aim 3, we did not observe evidence of an increase in breast cancer risk among women reporting weight gain between baseline and follow-up interviews; however, we observed an increase in risk among women who lost between 3 and 5 kilograms between baseline and follow-up interviews (HR=1.31, 95% CI: 0.94, 1.83), which was in the direction opposite of what was hypothesized. This result was similar when we removed breast cancer cases diagnosed within the first two years of follow-up. There was no evidence of interaction between weight change and soy and green tea intake. In conclusion, we provide suggestive evidence that soy protein intake is associated with decreased HbA1c levels among self-reported nondiabetic women. Furthermore, our results suggest that soy isoflavone intake may weakly modify the association between type II diabetes and breast cancer risk. Collectively, the results of these three studies indicate that soy intake may be protective for the development and progression of type II diabetes and could also attenuate the adverse impact of type II diabetes on breast cancer risk. However, given that these results are suggestive for different soy components and the short follow-up time of the prospective evaluation of breast cancer risk, further research is needed to investigate this question. Furthermore, research among populations with varying levels of soy intake is also needed to assess these associations.Item Open Access Impact of a cookstove intervention on exposure and blood pressure in rural Honduran women(Colorado State University. Libraries, 2018) Heiderscheidt, Judy Marie, author; Peel, Jennifer, advisor; Keefe, Thomas, advisor; Clark, Maggie, committee member; Magennis, Ann, committee member; Stallones, Lorann, committee memberTo view the abstract, please see the full text of the document.Item Open Access Occupational exposure to bioaerosols at Colorado dairies(Colorado State University. Libraries, 2023) Craig, Amanda, author; Brazile, William, advisor; Reynolds, Stephen, committee member; Clark, Maggie, committee member; Ellis, Bob, committee member; Autenrieth, Dan, committee memberThe dairy industry is vital to the American economy and impacts both the general population and the workers immediately involved in dairy production. The United States is a significant contributor to the global industry producing approximately 14.6% of the global milk supply. To accomplish this, large herd dairy operations (>1000 head of cattle) operate 24 hours a day, 365 days a year. The long production hours and large herd size result in an increase in the number of injuries and illness in dairy workers. One type of illness diagnosed in dairy farmers is respiratory disease. Multiple researchers have shown that some workers in modern dairy operations have pulmonary function cross-shift declines and lower pulmonary function as well as increased rates of obstructive respiratory conditions such as chronic bronchitis, organic dust toxicity syndrome, occupational asthma, chronic obstructive pulmonary disease, and hypersensitivity pneumonitis (Reynolds, Lundqvist et al. 2013, Reynolds, Nonnenmann et al. 2013).Respiratory disease is caused by exposure to bioaerosols that consist of bacteria, fungi (and the corresponding constituents), pollen, animal dander, feed, and manure. Although bioaerosol exposure can cause infection, the immunological response the body has to bioaerosols that result in decreased lung function is more prevalent in dairy workers. Although some researchers have examined culturable bacteria and fungi, the viable organisms only represent a small fraction of what is detected in the air at the dairies (Katja Radon and Jörg Hartung 2002). One method used to identify Gram-negative bacteria is the recombinant factor C (rFC) assay, a rapid diagnostic assay to identify concentrations of endotoxins present in dairy environments. While endotoxins have explained a portion of the respiratory problems in dairy workers, they do not explain all of the respiratory diseases (May, Romberger et al. 2012). Little research has been performed to determine concentrations of fungi at dairies. Some work has been done using GC/MS to identify fungal markers, but the current research is the first study to use the rapid diagnostic (Glucatell) assay to quantify worker exposure to fungi at dairies. The primary goal of this study was to better characterize dairy worker exposure to bioaerosols through two sample analysis techniques: next generation sequencing (NGS) and rapid diagnostic assays (rFC and Gluactell). The specific aims of this dissertation were to 1) identify similarities and differences in bacterial communities between button samplers and biosamplers co-located inside a cattle pen, 2) characterize worker exposure to the microbial community on dairy farms in comparison to environmental sources, and 3) characterize worker exposure to two bioaerosols constituents based on dairy worker task. For Specific Aim 1, area air samples were taken for five consecutive days to compare the button and biosamplers co-located inside a fresh cow pen and then analyzed using NGS to determine the identity and quantity of bacteria. The current study was the first to compare the biosamplers and button samplers for NGS analysis at a dairy. The results from this study will help researchers make better decisions on the type of sampler that should be employed for collecting airborne bacteria. The researchers found that the biosampler was more effective at collecting samples for NGS. The two samplers had significantly different microbial communities that were identified based on the Principle Coordinate Analysis (PCoA) plot. However, upon further analysis the alpha diversity plot showed relatively similar Shannon and Inverse Simpson indices suggesting both samplers were sampling from the same core microbiome. Therefore, the difference between the samplers is likely due to the high variance in the samples and not actual differences in the microbial community. The alpha diversity plot also had a high operational taxonomic units (OTU) count indicating that the dairy microbiome has a high count of rare bacteria and a low count of dominant bacteria. The biosampler had a higher relative abundance of bacteria across all five sampling days. The majority of the top identified bacteria were Gram-positive. Currently, little research has been done to assess the impact of Gram-positive bacteria on worker respiratory health. Based on these results, future research should focus on Gram-positive bacteria as they may substantially contribute to respiratory disease. Some of the identified bacterial genera have potentially pathogenic species, but data on the species level is needed to determine the potential for infection. Both viable and non-viable bacteria and their corresponding constituents can act as inflammagens, potentially causing cross-shift lung function decline and respiratory disease (May, Romberger et al. 2012). Both samplers collected bacterial communities that could be analyzed and used for NGS, but the biosampler was identified as the better sampler because of the higher OTU counts and greater bacterial diversity. However, depending on the type of sample information required, the button sampler may be advantageous because it can be used for personal samples and throughout the entire day. For Specific Aim 2, personal and area air, hand swabs, and soil samples were collected at one dairy for five consecutive days and analyzed using NGS. The sample sets were then compared to identify differences and similarities between the sample type, identity of the bacteria, and potential for worker exposure. The difference between sampler (button vs biosamplers) was significantly different. The sample type explained more than 50% of the differences seen in the microbial community. The biosampler compared to the button sampler had a lot of variation within their respective types which could explain some of the differences between the communities due to the differences in sampling length and time of day. The variation in the biosampler was mainly due to the second sample taken on each day. The area air samples had the highest relative abundance between the sample types. Soil was thought to have the highest relative abundance but because the number of samples were biased toward air samples (n=60 vs n=15) when the most prevalent top bacteria were chosen they were driven by the air samples. The majority of the bacteria were also found to be Gram-positive across all the samples. The most common source of the bacteria based on the genera information was soil which was expected based on the dusty nature of the dairy environment. Some genera identified have potential pathogenic species, but this dataset did not provide information on the species level. No conclusions can be made on the possibility of infection from the bacteria in these samples. For Specific Aim 3, four dairies were recruited to assess airborne concentrations of Gram-negative bacteria, fungi and dust. Workers were binned into eight different tasks, and the task samples were compared to identify differences in exposure between the tasks. Differences in site and season were not statistically significant and were not included in subsequent analyses. The concentration of dust over a full work shift ranged from 0.95-5.6 mg/m3 and were lower than expected. The highest dust concentration was below the Occupational Safety Health Administration Permissible Exposure Limit (OSHA PEL) of 10 mg/m3 but was not below the suggested Occupational Exposure Limit (OEL) from the American Conference of Governmental Industrial Hygienists (ACGIH) of 2.4 mg/m3 indicating that dust exposure may be a concern for some of the tasks. Machine operators and milkers had the highest geometric mean dust concentrations with concentrations of 0.356 and 0.305 mg/m3 respectively. The endotoxin concentrations ranged from 0.078-40 EU/m3 which was lower than other research observing endotoxins concentrations at dairies and below the suggested OEL of 90 EU/m3. Multi-task workers and milkers had the highest endotoxin concentrations (Donham 2000). The β-glucan concentrations ranged from 0.2-212 pg/m3 with the highest task concentrations found in multi-task workers and machine operators. There is not a suggested OEL for β-glucans but concentrations measured in this study were higher than other studies in waste processing facilities (Douwes 2005). Ultimately, there was not one task that was consistently higher between the different exposure variables and there were no significant differences between any of the tasks. No conclusions or recommendations could be made on the task-based exposures at the dairies. However, even at low concentrations, exposure to agricultural dusts have been shown to induce responses from cytokines (Poole, Dooley et al. 2010). The genetic polymorphism TLR4 has also been demonstrated to cause workers to be more predisposed to sensitization to endotoxins at extremely low concentrations (Reynolds 2012).Item Open Access Plasma metabolome of children with aberrant cholesterol and modulation by navy bean and rice bran consumption(Colorado State University. Libraries, 2018) Li, Katherine Jia, author; Ryan, Elizabeth, advisor; Prenni, Jessica, committee member; Clark, Maggie, committee memberAbnormal cholesterol in childhood predicts cardiovascular disease (CVD) risk in adulthood. Navy beans and rice bran have demonstrated efficacy in regulating blood lipids in adults and children; however, their effects on modulating the child plasma metabolome has not been investigated and warrants investigation. A pilot, randomized-controlled, clinical trial was conducted in 38 children (10 ± 0.8 years old) with abnormal cholesterol. Participants consumed a snack for 4 weeks containing either: no navy bean or rice bran (control); 17.5 g/day cooked navy bean powder; 15 g/day heat-stabilized rice bran, or; 9 g/day navy beans and 8 g/day rice bran. Plasma metabolites were extracted using 80% methanol for global, non-targeted metabolic profiling via ultra-high performance liquid-chromatography tandem mass spectrometry. To examine correlations between baseline serum lipid levels and plasma metabolites, non-parametric Spearman's correlation coefficients (rs) were computed between serum total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides (TG) with 805 plasma metabolites. Differences in plasma metabolite levels after 4 weeks of dietary intervention compared to control and baseline were analyzed using analysis of variance and Welch's t-tests (p≤0.05). Approximately 29% of the plasma metabolome (235 metabolites) were significantly correlated with serum lipids. Plasma cholesterol was positively correlated with serum total cholesterol, and 27 plasma metabolites were found to be strongly correlated with serum TG (rs ≥0.60; p≤0.0001). Navy bean and/or rice bran consumption influenced 71 plasma compounds compared to control (p≤0.05), with lipids representing 46% of the total plasma metabolome. Significant changes were determined for 18 plasma lipids in the navy bean group and 10 plasma lipids for the rice bran group compared to control, and 48 lipids in the navy bean group and 40 in the rice bran group compared to baseline. This supports the hypothesis that consumption of these foods impact blood lipid metabolism with implications for reducing CVD risk in children. Complementary and distinct lipid pathways were affected by the diet groups, including acylcarnitines and lysolipids (navy bean), sphingolipids (rice bran), and phospholipids (navy bean + rice bran). Navy bean consumption decreased free fatty acids associated with metabolic diseases (palmitate and arachidonate) and increased the relative abundance of endogenous anti-inflammatory lipids (endocannabinoids, N-linoleoylglycine, 12,13-diHOME). Several diet-derived amino acids, phytochemicals, and cofactors/vitamins with cardioprotective properties were increased compared to control and/or baseline, including 6-oxopiperidine-2-carboxylate (1.87-fold), N-methylpipecolate (1.89-fold), trigonelline (4.44- to 7.75-fold), S-methylcysteine (2.12-fold) (navy bean), salicylate (2.74-fold), and pyridoxal (3.35- to 3.96-fold) (rice bran). Findings from this pilot study support the need for investigating the effects of these foods for longer durations to reduce CVD risk.Item Open Access Telomere length as a biomarker of exposure to indoor woodstove smoke in rural Honduras: a feasibility field study(Colorado State University. Libraries, 2017) Altina, Noelia, author; DeLuca, Jennifer, advisor; Bailey, Susan, advisor; Ross, Eric, committee member; Clark, Maggie, committee memberTelomeres, the natural ends of linear chromosomes, are important for maintaining genome stability. Telomere length is an inherited trait influenced by a host of lifestyle and environmental factors, which have been shown to accelerate the rate of telomere shortening, and thus of aging. Indoor air pollution is one of the environmental factors known to influence the length of telomeres. It has been reported that people exposed to this kind of contamination, have an increased risk for pulmonary diseases, cardiovascular diseases and cancer. The accumulation of evidence correlating telomere length with different diseases and chronological age supports the use of short telomere frequency as an informative biomarker of general health status and aging. Epidemiological studies suggest that increased frequencies of nuclear aberrations (micronuclei, buds) are also correlated with exposure to air pollution.Item Open Access Translating biomass gasifier research to a market ready stove(Colorado State University. Libraries, 2019) Tillotson, James William, author; Marchese, Anthony, advisor; Clark, Maggie, committee member; Jathar, Shantanu, committee memberTo view the abstract, please see the full text of the document.