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BACKGROUND: Hypoglycemia in neonates is common and contributes to 4.0–5.8% of neonatal intensive care unit (NICU) admissions. In utero nicotine exposure is underexplored as a potential contributor to neonatal hypoglycemia. Rat models have shown that in utero nicotine exposure can be associated with a reduction in pancreatic beta cell mass, leading to glucose dysregulation. The primary aim of this work is to study the risk of developing hypoglycemia after birth in a population of in utero nicotine-exposed neonates. METHODS: We conducted a retrospective matched cohort study that augmented an existing dataset of neonates admitted to a level IV NICU with household-based in utero nicotine exposure (N = 335). Neonates in the control group parents denied household smoking (N = 325), were born within a 6-month timeframe, and were within a birthweight of 50 grams of a nicotine-exposed neonate. Data reviewed included gestational age, growth parameters, maternal history of diabetes, and glucose levels within the first three hours of life per unit protocol. RESULTS: 660 neonates were included in the analysis. In utero nicotine exposure demonstrated a 94.3% posterior probability (PP) for greater hypoglycemia risk (RR = 1.185, 95% CrI = [0.953, 1.445]). A 94.6% PP was demonstrated when neonates who were small for gestational age, intrauterine growth-restricted, and born to diabetic mothers were excluded (n = 482; RR = 1.271, 95% CrI = [0.946, 1.669]). CONCLUSION: Nicotine exposure in utero was found to be a potential risk factor for developing hypoglycemia after birth. Mechanisms of action should be explored, and additional research on in utero nicotine exposure risks should follow. [ABSTRACT FROM AUTHOR]

The gateway drug model is a popular conceptualization of a progression most substance users are hypothesized to follow as they try different legal and illegal drugs. Most forms of the gateway hypothesis are that "softer" drugs lead to "harder," illicit drugs. However, the gateway hypothesis has been notably difficult to directly test--that is, to test as competing hypotheses in a single model that licit drug use might lead to illicit drug use "or" the reverse. This article presents a novel statistical technique, dual-process discrete-time survival analysis, which enables this comparison. This method uses mixture-modeling software to estimate 2 concurrent time-to-event processes and their effects on each other. Using this method, support for the gateway hypothesis in the National Longitudinal Survey of Youth, 1997, was weak. However, this article was not designed as a strong test of causal direction but more as a technical demonstration and suffered from certain technological limitations. Both these limitations and future directions are discussed. (Contains 1 footnote, 3 tables, and 1 figure.)

Objective  Tobacco residue, also known as third-hand smoke (THS), contains toxicants and lingers in dust and on surfaces and clothes. THS also remains on hands of individuals who smoke, with potential transfer to infants during visitation while infants are hospitalized in neonatal intensive care units (NICUs), raising concerns (e.g., hindered respiratory development) for vulnerable infants. Previously unexplored, this study tested handwashing (HW) and sanitization efficacy for finger-nicotine removal in a sample of adults who smoked and were visiting infants in an NICU. Study Design  A cross-sectional sample was recruited to complete an interview, carbon monoxide breath samples, and three nicotine wipes of separate fingers (thumb, index, and middle). Eligible participants (n  = 14) reported current smoking (verified with breath samples) and were randomly assigned to 30 seconds of HW (n  = 7) or alcohol-based sanitization (n  = 7), with the order of finger wipes both counterbalanced and randomly assigned. After randomization, the first finger was wiped for nicotine. Participants then washed or sanitized their hands and finger two was wiped 5 minutes later. An interview assessing tobacco/nicotine use and exposure was then administered, followed by a second breath sample and the final finger wipe (40–60 minutes after washing/sanitizing). Results  Generalized linear mixed models found that HW was more effective than sanitizer for nicotine removal but failed to completely remove nicotine. Conclusions  Without proper protections (e.g., wearing gloves and gowns), NICU visitors who smoke may inadvertently expose infants to THS. Research on cleaning protocols are needed to protect vulnerable medical populations from THS and associated risks. Key Points NICU infants may be exposed to THS via visitors. THS is not eliminated by HW or sanitizing. THS removal protections for NICU infants are needed. [ABSTRACT FROM AUTHOR]

Introduction: Thirdhand smoke (THS) is ultrafine particulate matter and residue resulting from tobacco combustion, with implications for health-related harm (eg, impaired wound healing), particularly among hospitalized infants. Project aims were to characterize nicotine (THS proxy) transported on neonatal intensive care unit (NICU) visitors and deposited on bedside furniture, as well as infant exposure.Methods: Cross-sectional data were collected from participants in a metropolitan NICU. Participants completed a survey and carbon monoxide breath sample, and 41.9% (n = 88) of participants (n = 210) were randomly selected for finger-nicotine wipes during a study phase when all bedside visitors were screened for nicotine use and finger-nicotine levels. During an overlapping study phase, 80 mother-infant dyads consented to bedside furniture-nicotine wipes and an infant urine sample (for cotinine analyses).Results: Most nonstaff visitors' fingers had nicotine above the limit of quantification (>LOQ; 61.9%). Almost all bedside furniture surfaces (93.8%) and infant cotinine measures (93.6%) had values >LOQ, regardless of household nicotine use. Participants who reported using (or lived with others who used) nicotine had greater furniture-nicotine contamination (Mdn = 0.6 [interquartile range, IQR = 0.2-1.6] µg/m2) and higher infant cotinine (Mdn = 0.09 [IQR = 0.04-0.25] ng/mL) compared to participants who reported no household-member nicotine use (Mdn = 0.5 [IQR = 0.2-0.7] µg/m2; Mdn = 0.04 [IQR = 0.03-0.07] ng/mL, respectively). Bayesian univariate regressions supported hypotheses that increased nicotine use/exposure correlated with greater nicotine contamination (on fingers/furniture) and infant THS exposure.Conclusions: Potential furniture-contamination pathways and infant-exposure routes (eg, dermal) during NICU hospitalization were identified, despite hospital prohibitions on tobacco/nicotine use. This work highlights the surreptitious spread of nicotine and potential THS-related health risks to vulnerable infants during critical stages of development.Implications: THS contamination is underexplored in medical settings. Infants who were cared for in the NICU are vulnerable to health risks from THS exposure. This study demonstrated that 62% of nonstaff NICU visitors transport nicotine on their fingers to the NICU. Over 90% of NICU (bedside) furniture was contaminated with nicotine, regardless of visitors' reported household-member nicotine use or nonuse. Over 90% of infants had detectable levels of urinary cotinine during NICU hospitalizations. Results justify further research to better protect infants from unintended THS exposure while hospitalized. [ABSTRACT FROM AUTHOR]

Background: Substance use during pregnancy has been linked to adverse birth and other outcomes. Screening and intervention in the prenatal clinic are recommended, and reliance on patient reports or selective urine drug screening is inadequate. The aim of this prospective project was to determine substance use identification rates associated with common screening practices, compared to universal screening, among pregnant women seeking care at an urban, academic obstetric clinic. Methods: Women attending their first prenatal visit (N = 275) completed a self‐report questionnaire on lifetime and current substance use. A urine drug screening was also conducted, the results of which were not reported to providers. Participants' charts were reviewed to obtain the results of provider‐ordered screens. Results: The sample was primarily African‐American and Latino, with Medicaid insurance. Ten women (4.6%) reported current marijuana use, while more than double that number (n = 27; 11.6%) screened positive for marijuana via universal screening. The majority of women who screened positive via universal screening did not have a provider‐ordered urine drug screening, and less than one‐third (29.3%) of clinician‐ordered screens were positive for at least one substance. Finally, 90% of women who reported they were using marijuana were not selected by providers for a screen. Discussion: Data demonstrate the high proportion of women using marijuana and the limitations of patient self‐report and selective, nonroutine screening to identify substance use during pregnancy. Effective, standardized, clinic‐wide strategies are needed to support providers in identifying pregnant women who use substances in order to increase the frequency of education and intervention. [ABSTRACT FROM AUTHOR]

Hepatitis C virus (HCV) in the U.S. has tripled in the prior five years, and injecting drug use is the primary risk for HCV, with up to 90% of older and former people who inject drugs (PWIDs) testing positive. Laboratory testing of HCV for any PWIDs is the gold standard, however many PWIDs lack access to health treatment or services. Identifying risks of HCV via a data science approach would aid community health workers (CHW) to rapidly link those most at risk of infection with treatment. This study employed a data-science approach to determine the strongest risk factors of HCV in a sample of Mexican-Americans WIDs n = 221 (96 negative/125 positive). Data included 238 demographic and psychosocial predictors. A Random Forest machine learning algorithm demonstrated significant prediction improvement over baseline no information rate comparison. Strongest risks for positive HCV included sharing drug-use equipment and younger age at first heroin use; receiving drug-education during incarceration was protective. A ROC curve fit to the prediction yielded an area under the curve of 0.77. Predictive variables of HCV in the present analysis can be obtained via screening by CHW. Identification of patients most at risk of HCV within community settings can maximize treatment utilization. [ABSTRACT FROM AUTHOR]

INTRODUCTION Non-smoking policies are strictly enforced in neonatal intensive care units (NICUs), which may still become contaminated by thirdhand smoke (THS), posing potential health risks to medically fragile infants. Study aims were to explore contamination routes by characterizing nicotine levels (THS proxy) found on the fingers of NICU medical staff and to assess finger-nicotine correlates. METHODS NICU medical staff were surveyed regarding smoking and electronic nicotine devices (ENDS) use/exposure, and household characteristics. Approximately 35% of staff were randomly selected for a finger-nicotine wipe. Three separate quantile regressions modeled percentiles associated with: presence of any finger nicotine, fingernicotine levels above the median field blank level (i.e. 0.377 ng/wipe), and finger-nicotine levels two times the median blank. RESULTS The final sample size was 246 (n=260 approached; n=14 refusals). Over three-quarters (78.5%) reported some exposure to tobacco smoke or ENDS vapor/aerosols. After field-blank adjustments, the median nicotine level (ng/finger wipe) was 0.232 (IQR: 0.021--0.681) and 78.3% of medical staff had measurable finger-nicotine levels. Both being near smoking in friends'/family members' homes and finger-surface area were related to elevated finger-nicotine levels (p<0.05) in the median blank model. CONCLUSIONS Almost four in five NICU staff had measurable finger nicotine, with finger surface area and frequency of reported exposure to tobacco smoke in friends'/family members' homes emerging as important correlates. Future research will determine the impact of THS on NICU infants. Medical personnel working in a NICU should be cognizant of secondhand smoke and THS, particularly inside friends'/family members' homes, to reduce potential NICU contamination and infant exposures. [ABSTRACT FROM AUTHOR]

Background: Cocaine and methamphetamine have similar withdrawal symptoms and many individuals concurrently use both substances; however, no measures concurrently assess withdrawal from multiple stimulants. Objectives: This study's aim was to explore the Stimulant Selective Severity Assessment (SSSA), a modified version of the Cocaine Selective Severity Assessment (CSSA), in a sample of stimulant users to determine if it can assess withdrawal symptoms in users of one or more stimulants. Methods: Baseline data were analyzed from the STimulant Reduction Intervention using Dosed Exercise trial, a multisite randomized clinical trial that evaluated exercise versus health education on drug use outcomes in individuals with stimulant use disorders. Data were analyzed for internal consistency, construct validity, and scale dimensionality. Results: Internal consistency for the full sample was good (α = 0.81; N = 302), with similar alphas in Cocaine (0.81; n = 177) and Cocaine/Other Stimulant (0.82; n = 92) groups, but with much lower alpha for the group without cocaine use (Other Stimulant, i.e., primarily methamphetamine, α = 0.66; n = 32). Support for construct validity was evidenced by significant positive correlations (r = 0.17 to 0.67) with measures of stimulant craving, depressive symptoms, and pain. Four factors were revealed. Conclusions/Importance: The Stimulant Selective Severity Assessment is a new measure that can be used to assess withdrawal symptoms in users of cocaine or cocaine plus methamphetamine, but it should not be administered to users of methamphetamine only. [ABSTRACT FROM AUTHOR]

Background: Missing data in substance use disorder (SUD) research pose a significant threat to internal validity. Participants terminate involvement or become less likely to attend intervention and research visits for many reasons, which should be addressed prior to becoming problematic. During a 9-month study targeting stimulant abuse, early dropouts and participant reported attendance barriers led to implementing a structured, pre-randomization protocol with participants about retention and solution-focused strategies (the "Fireside Chat"). Our aim is to outline this approach and present data on intervention participation and research visit attendance after implementation.Methods/design: STimulant Reduction using Dosed Exercise (STRIDE) was a two-arm, multisite randomized clinical trial testing treatment-as-usual for stimulant abuse/dependence augmented by Exercise or Health Education. For both groups, study intervention visits at the site were scheduled 3/week for 12weeks followed by 1/week for 24weeks. During The Chat, research staff thoroughly reviewed participants' expectations, and barriers and solutions to retention. Fifteen participants were randomized (to Exercise or Health Education) prior to and fourteen were randomized after Chat implementation. Intervention and monthly follow-up attendance (before and after implementation) were compared at the site (N=29) that developed and rigorously implemented The Chat.Results: Individuals who participated in The Chat (n=14) attended significantly more intervention visits during weeks 1-12 (p<0.001) and weeks 13-36 (p<0.05) and attended more research visits (p<0.001).Discussion: Proactive discussion of expectations and barriers prior to randomization was associated with greater study attendance. SUD researchers should consider tailoring this approach to suit their needs. Further investigation is warranted. [ABSTRACT FROM AUTHOR]

This is a case report regarding a patient who presented with 6 months of dysphagia and subsequent 40-pound weight loss. The patient underwent imaging, suggestive of pulmonary TB. Further workup of his dysphagia with esophagogastroduodenoscopy and bronchoscopy revealed two bronchoesophageal fistulas. Tuberculosis is an important differential diagnosis of prolonged dysphagia in immunocompetent patients. [ABSTRACT FROM AUTHOR]

Background: Studies reveal that electronic cigarette (e-cigarette) and hookah use are increasing among adolescents and young adults. However, the long-term health effects are unknown, especially with regards to pregnancy. Because of the increased use in women of reproductive age, and the unknown long-term health risks, our primary objectives were to determine the perceived risks of e-cigarette and hookah use in pregnancy, and learn common colloquial terms associated with e-cigarettes. Furthermore, we sought to determine if there is a stigma associated with e-cigarette use in pregnancy.Methods: Eleven focus groups including 87 participants were conducted immediately following regularly scheduled CenteringPregnancy® prenatal care with women at three different clinics in the greater Houston area. A minimum of two facilitators led the groups, using ten lead-in prompts, with Spanish translation as necessary. Facilitators took notes which were compared immediately following each group discussion and each group was audio recorded and transcribed. Three facilitators utilized NVivo 9.0 software to organize the transcribed data into nodes to identify major themes. To increase rigor, transcripts were further analyzed by two obstetricians who were instructed to find the major themes.Results: Analyses revealed contradicting themes concerning e-cigarette use. In general, e-cigarettes were perceived as safer alternatives to regular tobacco cigarettes, especially if used as smoking cessation devices. A major theme is that use in pregnancy is harmful to the fetus. However, it was perceived that use for smoking cessation in pregnancy may have fewer side effects. We found that a common term for e-cigarettes is "Blu." In our discussion of hookah use, participants perceived use as popular among teenagers and that use in pregnancy is dangerous for the fetus.Conclusions: Although a strong theme emerged against hookah use, we found contradicting themes in our discussions on e-cigarette use in pregnancy. It is possible that e-cigarette use will not carry the same stigma as regular cigarette smoking in pregnancy. In addition, the impression of e-cigarettes as a healthier alternative to smoking may influence use in pregnancy. Clinicians need to be prepared for questions of e-cigarette safety and efficacy as smoking cessation devices from their pregnant patients who smoke, and women who smoke and are planning to become pregnant. [ABSTRACT FROM AUTHOR]

Objective: The neonatal intensive care unit (NICU) is an ideal setting to intervene with an under served population on secondhand smoke exposure (SHSe). Unfortunately, attrition may compromise outcomes. Baseline characteristics associated with intervention and follow-up attendance were investigated in mothers who participated in a novel SHSe prevention study designed for households with a smoker and a NICU-admitted infant. Methods: Intervention participants received two motivational, NICU-based counseling sessions; usual care participants received pamphlets. Home-based follow-up assessments occurred at 1, 3 and 6 months. Sociodemographic, smoking history, and psychosocial factors were analyzed. Results: Mothers from households with greater numbers of cigarettes smoked and fewer children had higher odds of both intervention and follow-up attendance. Maternal smoking abstinence (lifetime), more adults in the home and higher perceived interpersonal support were also associated with higher odds of follow-up visit completion. Conclusions: Innovative strategies are needed to engage mothers in secondhand smoke interventions, especially mothers who smoke, have lower levels of social support and have greater childcare responsibilities. [ABSTRACT FROM AUTHOR]

Background The rapid rise in the number of methamphetamine users, relative to cocaine users, has brought the number of each to nearly equal levels, making research on similarities and differences across these groups a needed area of exploration. Craving is postulated to play a significant role in relapse for both user types, yet group differences on observed scale scores have been reported without first assessing the prerequisite measurement equivalence (invariance) of the items, which is essential for meaningful group comparisons. Methods/design Baseline data from stimulant users in residential treatment (N = 301; n = 177 cocaine; n = 124 methamphetamine) were used to assess the measurement invariance of the 10-item Stimulant Craving Questionnaire (STCQ), which was adapted from a cocaine-specific measure. Results The unifactorial STCQ demonstrated measurement invariance across cocaine and methamphetamine users for factor loadings (metric), common residual covariances between item pairs, and item intercepts (scalar), as determined by fit indices (RMSEA < 0.05; CFI & TLI > 0.95; SRMR < 0.10). The latent mean, as well as 5 (out of 10) item means and the overall composite scale score, was significantly greater for methamphetamine users compared to cocaine users. Discussion Results indicate the STCQ is an invariant tool for the assessment of stimulant craving across the two most prevalent user types. Methamphetamine users had significantly higher levels of observed and latent craving than cocaine users, demonstrating a potentially meaningful difference in craving between users of these two stimulants. Future research will determine if treatments and statistical models need to account for craving variations across methamphetamine and cocaine users. [ABSTRACT FROM AUTHOR]

Over the course of a month, this 34-year-old woman had sought care at our facility--and another--on 3 separate occasions for painful bruises (visits #1 and #3) and deep vein thrombosis (visit #2). The bruises first appeared acutely on her arms, prompting her first visit to our ED and leading to a hospital stay. Several weeks later, the patient developed new bruise-like lesions on her earlobes, face, trunk, and lower extremities. In between these 2 visits, the patient was seen in another ED (and admitted) for right upper extremity DVT and was started on enoxaparin, followed by warfarin. The patient had no history of trauma, but did have a 7-year history of cocaine abuse. The initial bruises appeared one week after using cocaine from a different dealer. On her most recent visit, her vitals and physical examination were unremarkable, apart from the skin findings. Her complete blood count, complete metabolic panel, and urinalysis were unremarkable. On her previous admissions, the patient's urine drug test had been positive for cocaine. She'd also tested positive for cytoplasmic antineutrophil cytoplasmic antibodies, antinuclear antibodies, anti-double stranded DNA, and anticardiolipin IgM. WHAT IS YOUR DIAGNOSIS? HOW WOULD YOU TREAT THIS PATIENT? [ABSTRACT FROM AUTHOR]

Aim: Mothers of infants in the neonatal intensive care unit (NICU) have very low breastfeeding rates and these high-respiratory-risk (HRR) NICU infants may benefit from breastfeeding through decreased risk for respiratory illnesses. This population's increased risk for maternal depression and high rates (22%) of maternal smoking may negatively affect breastfeeding. Objective: This exploratory study investigated associations of breastfeeding with depressive symptoms and maternal smoking in mothers of HRR NICU infants (i.e. presence of one household smoker and birth weight <1500 g or mechanical ventilation ≥12 h). Methods: Breastfeeding, depression and smoking data were collected from 104 mothers in the NICU following delivery. Results: Fifty-five (52.9%) mothers reported breastfeeding, 39 (37.5%) had a Center for Epidemiological Studies Depression Scale (CES-D) score (≥16) suggestive of depression, and 36 (34.6%) reported smoking. Mothers with CES-D scores ≥16 were less likely to breastfeed compared to those with scores <16 (38.5% versus 61.5%; p = 0.02). Breastfeeding and smoking were not significantly associated ( p < 0.10). Mothers of HRR infants with significant depressive symptoms who smoke have significantly lower breastfeeding rates (21%) than mothers who are not depressed and do not smoke (65%). Conclusions: Interventions to improve breastfeeding initiation and continuation that target depression and smoking are necessary. [ABSTRACT FROM AUTHOR]

Abstract: Background: Over one-third of all children live with at least one parent who smokes cigarettes, which is associated with compromised child health. The impact of secondhand smoke exposure (SHSe) in medically fragile infants born prematurely is likely to be much higher. The Baby's Breath II study tests whether a hospital-initiated, motivational-enhancement program will result in less SHSe relative to conventional care in high-risk, low birthweight (LBW) infants discharged from a neonatal intensive care unit (NICU). The design and protocol for the ongoing BBII trial is described. Methods/design: Eligible participants are: (1) primary caregivers (typically mothers) of NICU infants who were born at LBW (<2500g) or ventilated for more than 12h; and (2) who smoke or live with at least one smoker. This randomized controlled trial has two conditions: Motivational interviewing plus incentives (MI+) and conventional care (CC). MI+ participants receive two hospital-based and two home-based counseling sessions, as well as incentives (i.e., prize-based draws) for (a) intervention attendance and (b) biochemical validation (i.e., urine cotinine dipstick) indicative of low or no infant SHSe. Participants in the control group receive conventional education-based care. Assessments are completed at baseline, mid-point, and 1- and 4-months post-intervention. Discussion: This study is the first to determine the efficacy of a brief intervention for reducing SHSe among high-risk, LBW infants discharged from a NICU, with the potential for saving lives and healthcare costs. Strengths, limitations and challenges to the conduct of this trial are discussed. [Copyright &y& Elsevier]

The gateway drug model is a popular conceptualization of a progression most substance users are hypothesized to follow as they try different legal and illegal drugs. Most forms of the gateway hypothesis are that 'softer' drugs lead to 'harder,' illicit drugs. However, the gateway hypothesis has been notably difficult to directly test-that is, to test as competing hypotheses in a single model that licit drug use might lead to illicit drug use or the reverse. This article presents a novel statistical technique, dual-process discrete-time survival analysis, which enables this comparison. This method uses mixture-modeling software to estimate 2 concurrent time-to-event processes and their effects on each other. Using this method, support for the gateway hypothesis in the National Longitudinal Survey of Youth, 1997, was weak. However, this article was not designed as a strong test of causal direction but more as a technical demonstration and suffered from certain technological limitations. Both these limitations and future directions are discussed. [ABSTRACT FROM AUTHOR]

Microbiome differences have been found in adults who smoke cigarettes compared to non-smoking adults, but the impact of thirdhand smoke (THS ; post-combustion tobacco residue) on hospitalized infants' rapidly developing gut microbiomes is unexplored. Our aim was to explore gut microbiome differences in infants admitted to a neonatal ICU (NICU) with varying THS-related exposure. Forty-three mother-infant dyads (household member[s] smoke cigarettes, n = 32; no household smoking, n = 11) consented to a carbon monoxide-breath sample, bedside furniture nicotine wipes, infant-urine samples (for cotinine [nicotine's primary metabolite] assays), and stool collection (for 16S rRNA V4 gene sequencing). Negative binomial regression modeled relative abundances of 8 bacterial genera with THS exposure-related variables (i.e., household cigarette use, surface nicotine, and infant urine cotinine), controlling for gestational age, postnatal age, antibiotic use, and breastmilk feeding. Microbiome-diversity outcomes were modeled similarly. Bayesian posterior probabilities (PP) ≥75.0% were considered meaningful. A majority of infants (78%) were born pre-term. Infants from non-smoking homes and/or with lower NICU-furniture surface nicotine had greater microbiome alpha-diversity compared to infants from smoking households (PP ≥ 75.0%). Associations (with PP ≥ 75.0%) of selected bacterial genera with urine cotinine, surface nicotine, and/or household cigarette use were evidenced for 7 (of 8) modeled genera. For example, lower Bifidobacterium relative abundance associated with greater furniture nicotine (IRR<0.01 [<0.01, 64.02]; PP = 87.1%), urine cotinine (IRR = 0.08 [<0.01,2.84]; PP = 86.9%), and household smoking (IRR<0.01 [<0.01, 7.38]; PP = 96.0%; FDR p < 0.05). THS-related exposure was associated with microbiome differences in NICU-admitted infants. Additional research on effects of tobacco-related exposures on healthy infant gut-microbiome development is warranted. • Urine cotinine, surface nicotine, and home smoking measured THS-related exposure. • NICU infants' gut microbiome differences were associated with THS-related exposure. • Higher THS-related exposure was associated with less alpha diversity. • Higher THS-related exposure was associated with 7 of 8 bacterial genera variations. • A tobacco-specific carcinogen was detected in human breastmilk. [ABSTRACT FROM AUTHOR]