Trichloroethylene (TCE) in groundwater has the potential to volatilize through soil into indoor air where it can be inhaled. The purpose of this study was to determine whether individuals living above TCE-contaminated groundwater are exposed to TCE through vapor intrusion. We examined associations between TCE concentrations in various environmental media and TCE concentrations in residents. For this assessment, indoor air, outdoor air, soil gas, and tap water samples were collected in and around 36 randomly selected homes; blood samples were collected from 63 residents of these homes. Additionally, a completed exposure survey was collected from each participant. Environmental and blood samples were analyzed for TCE. Mixed model multiple linear regression analyses were performed to determine associations between TCE in residents' blood and TCE in indoor air, outdoor air, and soil gas. Blood TCE concentrations were above the limit of quantitation (LOQ; ≥ 0.012 µg L(-1)) in 17.5% of the blood samples. Of the 36 homes, 54.3%, 47.2%, and >84% had detectable concentrations of TCE in indoor air, outdoor air, and soil gas, respectively. Both indoor air and soil gas concentrations were statistically significantly positively associated with participants' blood concentrations (P = 0.0002 and P = 0.04, respectively). Geometric mean blood concentrations of residents from homes with indoor air concentrations of >1.6 µg m(-3) were approximately 50 times higher than geometric mean blood TCE concentrations in participants from homes with no detectable TCE in indoor air (P < .0001; 95% CI 10.4-236.4). This study confirms the occurrence of vapor intrusion and demonstrates the magnitude of exposure from vapor intrusion of TCE in a residential setting.

Background

At high medicinal doses perchlorate is known to decrease the production of thyroid hormone, a critical factor for fetal development. In a large and uniquely exposed cohort of pregnant women, we recently identified associations between environmental perchlorate exposures and decreased maternal thyroid hormone during pregnancy. Here, we investigate whether perchlorate might be associated with birthweight or preterm birth in the offspring of these women.

Methods

Maternal urinary perchlorate, serum thyroid hormone concentrations, birthweight, gestational age, and urinary nitrate, thiocyanate, and iodide were collected in 1957 mother-infant pairs from San Diego County during 2000-2003, a period when the county's water supply was contaminated with perchlorate. Associations between perchlorate exposure and birth outcomes were examined using linear and logistic regression analyses adjusted for maternal age, weight, race/ethnicity, and other factors.

Results

Perchlorate was not associated with birth outcomes in the overall population. However, in analyses confined to male infants, log₁₀ maternal perchlorate concentrations were associated with increasing birthweight (β=143.1gm, p=0.01), especially among preterm births (β=829.1g, p<0.001). Perchlorate was associated with male preterm births ≥2500g (odds ratio=3.03, 95% confidence interval=1.09-8.40, p-trend=0.03). Similar associations were not seen in females.

Conclusions

This is the first study to identify associations between perchlorate and increasing birthweight. Further research is needed to explore the differences we identified related to infant sex, preterm birth, and other factors. Given that perchlorate exposure is ubiquitous, and that long-term impacts can follow altered birth outcomes, future research on perchlorate could have widespread public health importance.

Background

The FDA is considering a mandated reduction in the nicotine content of cigarettes. Clinical trials have been limited by non-study cigarette use (noncompliance), which could mask compensation. The goal of this study was to assess whether compensation occurs when smokers provided with very low nicotine cigarettes cannot access normal nicotine cigarettes.

Methods

In a within-subjects, crossover design, current smokers (n = 16) were confined to a hotel for two 4-night hotel stays during which they were only able to access the research cigarettes provided. The hotel stays offered normal nicotine cigarettes or very low nicotine content (VLNC) cigarettes, in an unblinded design, available for "purchase" via a study bank.

Results

In the context of complete compliance with the study cigarettes (n = 16), there was not a significant increase during the VLNC condition for cigarettes smoked per day, expired carbon monoxide, or N-acetyl-S-(cyanoethyl)-l-cysteine (cyanoethyl-MA, metabolite of acrylonitrile). There was a significant nicotine × time interaction on urine N-acetyl-S-(3-hydroxypropyl)-l-cysteine (hydroxypropyl-MA, metabolite of acrolein), driven by an increase in the VLNC condition during the first 24 hours. By the end of the VLNC condition, there was no evidence of compensation across any measure of smoking or smoke exposure.

Conclusions

Among current smokers who exclusively used VLNC cigarettes for 4 days, there was no significant compensatory smoking behavior.

Impact

These data, combined with the larger body of work, suggest that a mandated reduction in nicotine content is unlikely to result in an increase in smoking behavior to obtain more nicotine.

Background

A mandated reduction in the nicotine content of cigarettes could reduce smoking rate and prevalence. However, one concern is that smokers may compensate by increasing the intensity with which they smoke each cigarette to obtain more nicotine. This study assessed whether smokers engage in compensatory smoking by estimating the mouth-level nicotine intake of low nicotine cigarettes smoked during a clinical trial.

Methods

Smokers were randomly assigned to receive cigarettes with one of five nicotine contents for 6 weeks. An additional group received a cigarette with the lowest nicotine content, but an increased tar yield. The obtained mouth-level nicotine intake from discarded cigarette butts for a subset of participants (51-70/group) was estimated using solanesol as described previously. A compensation index was calculated for each group to estimate the proportion of nicotine per cigarette recovered through changes in smoking intensity.

Results

There was no significant increase in smoking intensity for any of the reduced nicotine cigarettes as measured by the compensation index (an estimated 0.4% of the nicotine lost was recovered in the lowest nicotine group; 95% confidence interval, -0.1 to 1.2). There was a significant decrease in smoking intensity for very low nicotine content cigarettes with increased tar yield.

Conclusions

Reductions in nicotine content did not result in compensatory changes in how intensively participants smoked research cigarettes.

Impact

Combined with data from clinical trials showing a reduction in cigarettes smoked per day, these data suggest that a reduction in nicotine content is unlikely to result in increased smoke exposure.

Accurate and reliable measurements of exposure to tobacco products are essential for identifying and confirming patterns of tobacco product use and for assessing their potential biological effects in both human populations and experimental systems. Due to the introduction of new tobacco-derived products and the development of novel ways to modify and use conventional tobacco products, precise and specific assessments of exposure to tobacco are now more important than ever. Biomarkers that were developed and validated to measure exposure to cigarettes are being evaluated to assess their use for measuring exposure to these new products. Here, we review current methods for measuring exposure to new and emerging tobacco products, such as electronic cigarettes, little cigars, water pipes, and cigarillos. Rigorously validated biomarkers specific to these new products have not yet been identified. Here, we discuss the strengths and limitations of current approaches, including whether they provide reliable exposure estimates for new and emerging products. We provide specific guidance for choosing practical and economical biomarkers for different study designs and experimental conditions. Our goal is to help both new and experienced investigators measure exposure to tobacco products accurately and avoid common experimental errors. With the identification of the capacity gaps in biomarker research on new and emerging tobacco products, we hope to provide researchers, policymakers, and funding agencies with a clear action plan for conducting and promoting research on the patterns of use and health effects of these products.

Introduction

In response to reducing cigarette nicotine content, people who smoke could attempt to compensate by using more cigarettes or by puffing on individual cigarettes with greater intensity. Such behaviors may be especially likely under conditions where normal nicotine content (NNC) cigarettes are not readily accessible. The current within-subject, residential study investigated whether puffing intensity increased with very low nicotine content (VLNC) cigarette use, relative to NNC cigarette use, when no other nicotine products were available.

Aims and methods

Sixteen adults who smoke daily completed two four-night hotel stays in Charleston, South Carolina (United States) in 2018 during which only NNC or only VLNC cigarettes were accessible. We collected the filters from all smoked cigarettes and measured the deposited solanesol to estimate mouth-level nicotine delivery per cigarette. These estimates were averaged within and across participants, per each 24-h period. We then compared the ratio of participant-smoked VLNC and NNC cigarette mouth-level nicotine with the ratio yielded by cigarette smoking machines (when puffing intensity is constant).

Results

Average mouth-level nicotine estimates from cigarettes smoked during the hotel stays indicate participants puffed VLNC cigarettes with greater intensity than NNC cigarettes in each respective 24-h period. However, this effect diminished over time (p < .001). Specifically, VLNC puffing intensity was 40.0% (95% CI: 29.9, 53.0) greater than NNC puffing intensity in the first period, and 16.1% (95% CI: 6.9, 26.0) greater in the fourth period.

Conclusion

Average puffing intensity per cigarette was elevated with exclusive VLNC cigarette use, but the extent of this effect declined across four days.

Implications

In an environment where no other sources of nicotine are available, people who smoke daily may initially attempt to compensate for cigarette nicotine reduction by puffing on individual cigarettes with greater intensity. Ultimately, the compensatory behavior changes required to achieve usual nicotine intake from VLNC cigarettes are drastic and unrealistic. Accordingly, people are unlikely to sustain attempts to compensate for very low cigarette nicotine content.

Background: Biomarkers of tobacco exposure have a central role in studies of tobacco use and nicotine intake. The most significant exposure markers are nicotine itself and its metabolites in urine. Therefore, it is important to evaluate the performance of laboratories conducting these biomarker measurements.Methods: This report presents the results from a method performance study involving 11 laboratories from 6 countries that are currently active in this area. Each laboratory assayed blind replicates of seven human urine pools at various concentrations on three separate days. The samples included five pools blended from smoker and nonsmoker urine sources, and two additional blank urine samples fortified with pure nicotine, cotinine, and hydroxycotinine standards. All laboratories used their own methods, and all were based on some form of liquid chromatography/tandem mass spectrometry.Results: Overall, good agreement was found among the laboratories in this study. Intralaboratory precision was good, and in the fortified pools, the mean bias observed was < + 3.5% for nicotine, approximately 1.2% for hydroxycotinine, and less than 1% for cotinine (1 outlier excluded in each case). Both indirect and direct methods for analyzing the glucuronides gave comparable results.Conclusions: This evaluation indicates that the experienced laboratories participating in this study can produce reliable and comparable human urinary nicotine metabolic profiles in samples from people with significant recent exposure to nicotine.Impact: This work supports the reliability and agreement of an international group of established laboratories measuring nicotine and its metabolites in urine in support of nicotine exposure studies. Cancer Epidemiol Biomarkers Prev; 27(9); 1083-90. ©2018 AACR.