Community violence, including homicides involving firearms, is a significant public health concern. From 2019 to 2020, firearm-related homicides increased by 39% for youths and young adults aged 10-24 years, and rates of suicide by firearm increased by approximately 15% among the same age group. Findings from the nationally representative 2021 Youth Risk Behavior Survey were used to analyze disparities and correlates of witnessing community violence and gun carrying among a nationally representative sample of high school students. Chi-square tests and logistic regression accounting for the complex sampling of the survey were used to assess demographic differences by student sex, race and ethnicity, age, and sexual identity in ever witnessing community violence, gun carrying in the past 12 months, and their associations with substance use and suicide risk. Measures of substance use included current binge drinking and marijuana use and lifetime prescription opioid misuse and illicit drug use. Suicide risk included seriously considered attempting suicide and attempted suicide in the past 12 months. Overall, approximately 20% of students witnessed community violence and 3.5% of students carried a gun. American Indian or Alaska Native, Black, and Hispanic students were more likely to witness community violence and to report carrying a gun than their White peers. Males were more likely to witness community violence and carry a gun than females. Lesbian, gay, or bisexual students were more likely to witness community violence than their heterosexual peers. Also, witnessing community violence consistently was associated with increased odds of gun carrying, substance use, and suicide risk for both males and females and when comparing Black, White, and Hispanic students. These findings highlight the importance of comprehensive violence prevention strategies that incorporate health equity to mitigate the effects of violence exposure on substance use and suicide risk among youths.

BACKGROUND: Research shows associations between bullying victimization and substance use for teens. However, more research about this relationship for younger adolescents and across race/ethnicity is needed. METHODS: Prevalence and pooled logistic regression analyses of 2019 Middle School Youth Risk Behavior Survey data from 13 states (N = 74,059 students) examined associations between self-reported bulling victimization (at school, electronically, and both) and having ever tried cigarette smoking, alcohol, or marijuana; used an electronic vapor product; or misused prescription pain medicine. Regression analyses were adjusted by age and sex/race/ethnicity. RESULTS: All 3 measures of bullying victimization were significantly associated (p < .05) with the 5 substance use behaviors examined (adjusted prevalence ratios ranged from 1.29 to 2.32). These associations held across sexes. Significant associations were found within all 7 race/ethnicity categories, with the most associations reported for the non-Hispanic (NH) white, NH black or African American, Hispanic/Latino, and NH Asian groups. CONCLUSION: The association between bullying and substance use by middle school is a highly relevant issue to consider as students return to classrooms.

Suicide and homicide are the second and third leading causes of death, respectively, among youths aged 14-17 years (1); nearly one half (46%) of youth suicides and most (93%) youth homicides result from firearm injuries (1). Understanding youth gun carrying and associated outcomes can guide prevention initiatives (2). This study used the updated measure of gun carrying in the 2017 and 2019 administrations of CDC's Youth Risk Behavior Survey* (YRBS) to describe the national prevalence of gun carrying for reasons other than hunting or sport among high school students aged <18 years and to examine the associations between gun carrying and experiencing violence, suicidal ideation or attempts, or substance use. Gun carrying during the previous 12 months was reported by one in 15 males and one in 50 females. Gun carrying was significantly more likely among youths with violence-related experiences (adjusted prevalence ratio [aPR] range = 1.5-10.1), suicidal ideation or attempts (aPR range = 1.8-3.5), or substance use (aPR range = 4.2-5.6). These results underscore the importance of comprehensive approaches to preventing youth violence and suicide, including strategies that focus on preventing youth substance use and gun carrying (3).

In multiple and related forms, violence is a serious public health issue with lasting impacts on health and wellness in the United States. Community health workers (CHWs) are frontline public health workers and trusted members of communities. We aimed to analyze recent examples of CHW activities in violence prevention public health programs with a goal of informing future programs and research. We collected more than 300 documents published between 2010 and 2020 to identify public health programs to prevent violence including CHW activities. We used an iterative process to develop and apply a coding scheme to the CHW activities. We identified 20 public health programs to prevent violence which included CHW activities. CHWs most often addressed community violence, youth violence, and family violence and played an average of 8 of 10 core roles per program. Fewer than a third (i.e., 6 programs) reported community-focused CHW activities to address upstream and structural determinants of health inequities. This first examination, to our knowledge, of the intersection of the CHW and violence prevention literature shows that CHWs have played many of their core roles in public health programs to address multiple forms of violence. (Am J Public Health. Published online ahead of print June 23, 2022:e1-e11. https://doi.org/10.2105/AJPH.2022.306865).

Introduction: The objective of this observational, cross-sectional study was to identify, document, and assess the progress made to date in implementing various processes involved in statewide community health worker (CHW) workforce development initiatives. Methods: From September 2017 to December 2020, we developed and applied a conceptual model of processes involved in implementing statewide CHW initiatives. One or more outputs were identified for each model process and assessed across the 50 states, D.C., and Puerto Rico using peer-reviewed and gray literature available as of September 2020. Results: Twelve statewide CHW workforce development processes were identified, and 21 outputs were assessed. We found an average of eight processes implemented per state, with seven states implementing all 12 processes. As of September 2020, 45 states had a multi-stakeholder CHW coalition and 31 states had a statewide CHW organization. In 20 states CHWs were included in Medicaid Managed Care Organizations or Health Plans. We found routine monitoring of statewide CHW employment in six states. Discussion: Stakeholders have advanced statewide CHW workforce development initiatives using the processes reflected in our conceptual model. Our results could help to inform future CHW initiative design, measurement, monitoring, and evaluation efforts, especially at the state level.

CONTEXT: The Centers for Disease Control and Prevention supports the engagement of community health workers (CHWs) to help vulnerable populations achieve optimum health through a variety of initiatives implemented in several organizational units. PROGRAM: This article provides a unified and comprehensive logic model for these initiatives that also serves as a common framework for monitoring and evaluation. IMPLEMENTATION: We developed a logic model to fully describe the levels of effort needed to effectively and sustainably engage CHWs. We mapped monitoring and evaluation metrics currently used by federally funded organizations to the logic model to assess the extent to which measurement and evaluation are aligned to programmatic efforts. EVALUATION: We found that the largest proportion of monitoring and evaluation metrics (61%) currently used maps to the "CHW intervention level" of the logic model, a smaller proportion (37%) maps to the "health system and community organizational level," and a minimal proportion (3%) to the "statewide infrastructure level." DISCUSSION: Organizations engaging CHWs can use the logic model to guide the design as well as performance measurement and evaluation of their CHW initiatives.

CONTEXT: There is a need for knowledge translation to advance health equity in the prevention and control of cardiovascular disease and type 2 diabetes. One recommended strategy is engaging community health workers (CHWs) to have a central role in related interventions. Despite strong evidence of effectiveness for CHWs, there is limited information examining the impact of state CHW policy interventions. This article describes the application of a policy research continuum to enhance knowledge translation of CHW workforce development policy in the United States. METHODS: During 2016-2019, a team of public health researchers and practitioners applied the policy research continuum, a multiphased systematic assessment approach that incorporates legal epidemiology to enhance knowledge translation of CHW workforce development policy interventions in the United States. The continuum consists of 5 discrete, yet interconnected, phases including early evidence assessments, policy surveillance, implementation studies, policy ratings, and impact studies. RESULTS: Application of the first 3 phases of the continuum demonstrated (1) how CHW workforce development policy interventions are linked to strong evidence bases, (2) whether existing state CHW laws are evidence-informed, and (3) how different state approaches were implemented. DISCUSSION: As a knowledge translation tool, the continuum enhances dissemination of timely, useful information to inform decision making and supports the effective implementation and scale-up of science-based policy interventions. When fully implemented, it assists public health practitioners in examining the utility of different policy intervention approaches, the effects of adaptation, and the linkages between policy interventions and more distal public health outcomes.

OBJECTIVE: Approximately 800 000 strokes occur annually in the United States. Stroke systems of care policies addressing prehospital and in-hospital care have been proposed to improve access to time-sensitive, lifesaving treatments for stroke. Policy surveillance of stroke systems of care laws supported by best available evidence could reveal potential strengths and weaknesses in how stroke care delivery is regulated across the nation. DESIGN: This study linked the results of an early evidence assessment of 15 stroke systems of care policy interventions supported by best available evidence to a legal data set of the body of law in effect on January 1, 2018, for the 50 states and Washington, District of Columbia. RESULTS: As of January 1, 2018, 39 states addressed 1 or more aspects of prehospital or in-hospital stroke care in law; 36 recognized at least 1 type of stroke center. Thirty states recognizing stroke centers also had evidence-supported prehospital policy interventions authorized in law. Four states authorized 10 or more of 15 evidence-supported policy interventions. Some combinations of prehospital and in-hospital policy interventions were more prevalent than other combinations. CONCLUSION: The analysis revealed that many states had a stroke regulatory infrastructure for in-hospital care that is supported by best available evidence. However, there are gaps in how state law integrates evidence-supported prehospital and in-hospital care that warrant further study. This study provides a baseline for ongoing policy surveillance and serves as a basis for subsequent stroke systems of care policy implementation and policy impact studies.

Community health workers (CHWs) are becoming a well-recognized workforce to help reduce health disparities and improve health equity. Although evidence demonstrates the value of engaging CHWs in health care teams, there is a need to describe best practices for integrating CHWs into US health care settings. The use of existing health promotion and implementation theories could guide the research and implementation of health interventions conducted by CHWs. We conducted a standard 5-step scoping review plus stakeholder engagement to provide insight into this topic. Using PubMed, EMBASE, and Web of Science, we identified CHW intervention studies in health care settings published between 2000 and 2017. Studies were abstracted by 2 researchers for characteristics and reported use of theory. Our final review included 50 articles published between January 2000 and April 2017. Few studies used implementation theories to understand the facilitators and barriers to CHW integration. Those studies that incorporated implementation theories used RE-AIM, intervention mapping, cultural tailoring, PRECEDE-PROCEED, and the diffusion of innovation. Although most studies did not report using implementation theories, some constructs of implementation such as fidelity or perceived benefits were assessed. In addition, studies that reported intervention development often cited specific theories, such as the transtheoretical or health belief model, that helped facilitate the development of their program. Our results are consistent with other literature describing poor uptake and use of implementation theory. Further translation of implementation theories for CHW integration is recommended.

The current study has two aims. First the method of spectral reflectance was used to measure evaporation rates of thin ( approximately 25-300 mum) films of neat liquid volatile organic chemicals exposed to a well-regulated wind speed u. Gas phase evaporation mass transfer coefficient (kevap) measurements of 10 chemicals, 9 of which were measured at similar u, are predicted (slope of log-log data = 1.01; intercept = 0.08; R(2) = 0.996) by a previously proposed mass transfer correlation. For one chemical, isoamyl alcohol, the dependence of kevap on u(0.52) was measured, in support of the predicted exponent value of (1/2). Second, measured kevap of nicotine was used as an input in analytical models based on diffusion theory to estimate the absorbed fraction (Fabs) of a small dose (5 muL/cm(2)) applied to human epidermis in vitro. The measured Fabs was 0.062 +/- 0.023. Model-estimated values are 0.066 and 0.115. Spectral reflectance is a precise method of measuring kevap of liquid chemicals and the data are well-described by a simple gas phase mass transfer coefficient. For nicotine under the single exposure condition measured herein, Fabs is well-predicted from a theoretical model that requires knowledge of kevap, maximal dermal flux and membrane lag time.

More efficacious treatment regimens are needed for tuberculosis, however, drug development is impeded by a lack of reliable biomarkers of disease severity and of treatment effect. We conducted a directed screen of host biomarkers in participants enrolled in a tuberculosis clinical trial to address this need. Serum samples from 319 protocol-correct, culture-confirmed pulmonary tuberculosis patients treated under direct observation as part of an international, phase 2 trial were screened for 70 markers of infection, inflammation, and metabolism. Biomarker assays were specifically developed for this study and quantified using a novel, multiplexed electrochemiluminescence assay. We evaluated the association of biomarkers with baseline characteristics, as well as with detailed microbiologic data, using Bonferroni-adjusted, linear regression models. Across numerous analyses, seven proteins, SAA1, PCT, IL-1beta, IL-6, CRP, PTX-3 and MMP-8, showed recurring strong associations with markers of baseline disease severity, smear grade and cavitation; were strongly modulated by tuberculosis treatment; and had responses that were greater for patients who culture-converted at 8weeks. With treatment, all proteins decreased, except for osteocalcin, MCP-1 and MCP-4, which significantly increased. Several previously reported putative tuberculosis-associated biomarkers (HOMX1, neopterin, and cathelicidin) were not significantly associated with treatment response. In conclusion, across a geographically diverse and large population of tuberculosis patients enrolled in a clinical trial, several previously reported putative biomarkers were not significantly associated with treatment response, however, seven proteins had recurring strong associations with baseline radiographic and microbiologic measures of disease severity, as well as with early treatment response, deserving additional study.

Calls for government-funded activities to be “evidence based” are ubiquitous. “Gold standard” studies, including randomized controlled trials and systematic reviews (Isett, Head, and VanLandingham 2016), have expanded the availability of evidence-based programs and practices (VanLandingham and Silloway 2016). However, because of their complexity, large-scale policies (comprising services, laws, rules, and regulations implemented at the population level) are more difficult to study experimentally, resulting in evidence gaps. | Public policies should be informed by the best information available. This article focuses on the utility of early evidence assessment and provides an example of one approach called the Quality and Impact of Component (QuIC) Evidence Assessment. This approach provides a systematic and timely method for policy analysis that can be applied to many types of emerging and complex public policies.

In vitro human skin benzene permeation was measured from gasoline formulations with benzene concentrations ranging from 0.8 to 10 vol% and from neat benzene. Steady-state fluxes (JSS), permeability coefficients (kp) and lag times (tlag) were calculated from infinite dose exposures. Permeation of benzene from small gasoline doses administered over a two-day period was also studied. The thermodynamic activity of benzene in gasoline at 30 degrees C was determined and the solution is near-ideal over the range from 0.8 to 100 vol%. JSS through human epidermal membranes were linear (R2=0.92) with concentration over the range from 0.8 to 10 vol%. JSS (mug/cm2/h) from gasoline (0.8 vol% benzene=6.99 mg/ml) through epidermis and full-thickness skin were 9.37+/-1.41 and 1.82+/-0.44, respectively. Neat benzene JSS was 566+/-138. Less than 0.25% of the total applied benzene mass from finite doses (10 mul/cm2) of gasoline was detected in receptor cells, and a small reduction of barrier function was observed from six total doses administered over 2 days. Application of these results to dermal exposure assessment examples demonstrates a range of systemic benzene uptakes that can be expected from occupational and consumer dermal exposures to gasoline, depending on the type and extent of exposure.

The impact of the complex structure of the stratum corneum on transdermal penetration is not yet fully described by existing models. A quantitative and thorough study of skin permeation is essential for chemical exposure assessment and transdermal delivery of drugs. The objective of this study is to analyze the effects of heterogeneity, anisotropy, asymmetry, follicular diffusion, and location of the main barrier of diffusion on percutaneous permeation. In the current study, the solution of the transient diffusion through a two-dimensional-anisotropic brick-and-mortar geometry of the stratum corneum is obtained using the commercial finite element program COMSOL Multiphysics. First, analytical solutions of an equivalent multilayer geometry are used to determine whether the lipids or corneocytes constitute the main permeation barrier. Also these analytical solutions are applied for validations of the finite element solutions. Three illustrative compounds are analyzed in these sections: diethyl phthalate, caffeine and nicotine. Then, asymmetry with depth and follicular diffusion are studied using caffeine as an illustrative compound. The following findings are drawn from this study: the main permeation barrier is located in the lipid layers; the flux and lag time of diffusion through a brick-and-mortar geometry are almost identical to the values corresponding to a multilayer geometry; the flux and lag time are affected when the lipid transbilayer diffusivity or the partition coefficients vary with depth, but are not affected by depth-dependent corneocyte diffusivity; and the follicular contribution has significance for low transbilayer lipid diffusivity, especially when flux between the follicle and the surrounding stratum corneum is involved. This study demonstrates that the diffusion is primarily transcellular and the main barrier is located in the lipid layers.

Nicotine plus flavorings in a propylene glycol (PG) vehicle are the components of electronic cigarette liquids (e-liquids), which are vaporized and inhaled by the user. Dermal exposure to nicotine and e-liquids may occur among workers in mixing and filling of e-cigarettes in the manufacturing process. Inadvertent skin contact among consumers is also a concern. In vitro nicotine permeation studies using heat-separated human epidermis were performed with surrogate and two commercial e-liquids, neat and aqueous nicotine donor formulations. Steady-state fluxes (Jss), and lag times (tlag) were measured for each formulation. In addition, transient (4 h) exposure and finite dose (1-10 mul/cm2) experiments were undertaken using one commercial e-liquid. Average Jss (mug/cm2/h) from formulations were: nicotine in PG (24 mg/ml): 3.97; commercial e-liquid containing menthol (25 mg/ml nicotine): 10.2; commercial e-liquid containing limonene (25 mg/ml nicotine): 23.7; neat nicotine: 175. E-liquid lag times ranged from 5 to 10 h. Absorbed fraction of nicotine from finite doses was approximately 0.3 at 48 h. The data were applied to transient exposure and finite dose dermal exposure assessment models and to a simple pharmacokinetic model. Three illustrative exposure scenarios demonstrate use of the data to predict systemic uptake and plasma concentrations from dermal exposure. The data demonstrate the potential for significant nicotine absorption through skin contact with e-cigarette refill solutions and the neat nicotine used to mix them.Journal of Exposure Science and Environmental Epidemiology advance online publication, 7 December 2016; doi:10.1038/jes.2016.68.

Skin is commonly stored frozen and then thawed prior to use for in vitro permeation experiments. Does frozen storage of skin alter its barrier property? Numerous studies have found contradictory answers to this question. In this study, the steady-state flux and lag time of diethyl phthalate (DEP) were measured for fresh human skin and skin frozen at -85 degrees C for 1, 2, 3, 6, 9, 12, and 18 months with 10% glycerol as a cryoprotective agent. No significant differences in steady-state flux were found between fresh and previously frozen samples (p = 0.6). For lag time, a significant (p = 0.002) difference was found among all groups, but comparisons with fresh skin were not significant. Does glycerol have a cryoprotective effect? The steady-state flux and lag time of DEP and caffeine were measured through human skin stored at -85 degrees C for up to 12 months with and without 10% glycerol. No significant differences in steady-state flux or lag time were found between samples stored with or without glycerol for either DEP or caffeine (p ≥ 0.17). These findings support the use of frozen skin to measure the passive permeation of chemicals in studies unconcerned with viability and metabolism. Published by S. Karger AG, Basel.

Community health workers (CHWs) are expected to improve patient care and population health while reducing health care costs. Law is a tool states are using to build a supportive infrastructure for the CHW workforce. This study assessed the extent existing state law pertaining to the CHW workforce aligned with best available evidence. We used the previously developed Quality and Impact of Component (QuIC) Evidence Assessment method to identify and prioritize those components that could comprise an evidence-informed CHW policy at the state level. We next assessed the extent codified statutes and regulations in effect as of December 31, 2014 for the 50 states and D.C. included the components identified in the evidence assessment. Fourteen components of an evidence-informed CHW policy were identified; eight had best, three had promising, and three had emerging evidence bases. Codified law in 18 states (35.3 % of 51) pertained to the CHW workforce. Fifteen of these 18 states authorized at least one of the 14 components from the evidence assessment (maximum: nine components, median: 2.5). The most frequently authorized component was a defined scope of practice for CHWs (authorized by eight states) followed by a standard core competency curriculum and inclusion of CHWs in multidisciplinary health care teams (each authorized by six states). States could consider the components presented in this article when developing new or strengthening existing law.

An essential strategy expected to reduce the global burden of chronic and cardiovascular disease is evidence-based policy. However, it is often unknown what specific components should constitute an evidence-based policy intervention. We have developed an expedient method to appraise and compare the strengths of the evidence bases suggesting that individual components of a policy intervention will contribute to the positive public health impact of that intervention. Using a new definition of "best available evidence," the Quality and Impact of Component (QuIC) Evidence Assessment analyzes dimensions of evidence quality and evidence of public health impact to categorize multiple policy component evidence bases along a continuum of "emerging," "promising impact," "promising quality," and "best." QuIC was recently applied to components from 2 policy interventions to prevent and improve the outcomes of cardiovascular disease: public-access defibrillation and community health workers. Results illustrate QuIC's utility in international policy practice and research.

The goal of these studies was to measure and interpret the skin permeability characteristics of 2-hydroxypropyl acrylate (HPA) as a model compound that is completely miscible with water. METHODS: In vitro permeation from HPA-H2O binary mixtures through human epidermis and silicone membranes was measured. Thermodynamic activities of HPA and H2O in these mixtures were determined. Permeation was also measured through epidermis and silicone from donor solutions with constant HPA activity but different H2O activities. Water uptake into desiccated human stratum corneum (SC) equilibrated with HPA-H2O mixtures was determined. RESULTS: Steady-state flux of HPA through silicone was a linear function of HPA activity but not HPA concentration. For epidermis on the other hand, flux increased with HPA activity only for HPA activities ≤ 0.35. At constant HPA activity, flux decreased 4.5-fold as water activity decreased from 1 to 0.8. Incubation of SC with HPA-H2O mixtures resulted in substantial changes in SC water content, dependent on the water activity of the mixture and consistent with measured SC water sorption data. CONCLUSIONS: These experiments provide unequivocal evidence of a substantial increase in epidermal barrier function resulting from SC dehydration. Dehydration-related alterations in the SC appear responsible for the observed flux characteristics.

A novel high-performance liquid chromatographic/ultraviolet method was developed to detect lapachol (LP) and deoxylapachol (DLP) in wood dust as chemical markers of teak wood (a suspected human carcinogen). The specificity of this analysis was determined by noting the absence of LP and DLP in 12 other specimens of different woods belonging to the angiosperm family. The consistency was examined by analyzing teak from three different sources, where the percentages (wt/wt) of the chemicals ranged from 0.006 to 0.261 for LP and from 0.038 to 0.497 for DLP, respectively. Although the LP and DLP components of teak varied according to source, a very high correlation coefficient (r 2 > 0.98 always) was found between the content of the two markers in the bulk specimens and in bulk dust derived from them. The method was then applied to teak dust collected on polyvinylchloride filters from aerosol in an exposure chamber in the range of mass loadings between 0.03 and 3.65mg, which corresponds to a dust exposure between 0.124 and 8.703mg m-3 for a sampling time of 2h. A field test was also carried out in a small factory where teak was used. A good correlation was confirmed between LP and DLP versus the dust collected on the filter in both cases. LP and DLP can be markers to estimate the true quantities of teak dust inhaled in a workplace with mixed wood dust, provided the results are matched to the content of LP and DLP in the bulk wood. LP and DLP have also been proposed as the agents responsible for allergic reaction to teak dust. Therefore, it would be useful to evaluate the exposure to these two substances even without a relationship to teak dust exposure.

The application of numerical methods for mechanistic, diffusion-based modeling of skin permeation is reviewed. Methods considered here are finite difference, method of lines, finite element, finite volume, random walk, cellular automata, and smoothed particle hydrodynamics. First the methods are briefly explained with rudimentary mathematical underpinnings. Current state of the art numerical models are described, and then a chronological overview of published models is provided. Key findings and insights of reviewed models are highlighted. Model results support a primarily transcellular pathway with anisotropic lipid transport. Future endeavors would benefit from a fundamental analysis of drug/vehicle/skin interactions.

Recent data, using a murine model, have indicated that dermal exposure to perfluorooctanoic acid (PFOA) induces immune modulation, suggesting that this may be an important route of PFOA exposure. To investigate the dermal penetration potential of PFOA, serum concentrations were analyzed in mice following topical application. Statistically significant and dose-responsive increases in serum PFOA concentrations were identified. In vitro dermal penetration studies also demonstrated that PFOA permeates both mouse and human skin. Investigation into the mechanisms mediating PFOA penetration demonstrated that dermal absorption was strongly dependent upon the ionization status of PFOA. In addition, PFOA solid, but not 1% PFOA/acetone solution, was identified as corrosive using a cultured epidermis in vitro model. Despite its corrosive potential, expression of inflammatory cytokines in the skin of topically exposed mice was not altered. These data suggest that PFOA is dermally absorbed and that under certain conditions the skin may be a significant route of exposure.

New data sets on both (i) equilibrium theophylline (TH) partitioning/binding in stratum corneum and (ii) transient TH diffusion through human epidermis are explained by an extended partition-diffusion model with reversible binding. Data conform to a linear binding isotherm within the tested concentration range (0-2000 mcg/mL) with an equilibrium ratio of bound-to-free solute of approximately 1.4. The permeability coefficient for TH is 4.86 x 10(-5) cm/h, and the lag time is 20.1 h. Binding occurs as a slow process, significantly affecting the kinetics of dermal penetration.

1-Bromopropane (1-BP; CAS number 106-94-5), also known as n-propyl bromide, is a halogenated short-chain alkane used as an organic solvent with numerous commercial and industrial applications, including garment dry cleaning and vapor degreasing of metals. The purpose of this study was to determine the dermal absorption characteristics and corrosivity of 1-BP. Heat-separated human epidermal membranes were mounted on static diffusion cells. Different exposure scenarios were studied (infinite dose, finite dose, and transient exposure) using neat 1-BP and saturated aqueous solution as donor. Steady-state fluxes for infinite-dose neat 1-BP exposure averaged 625 to 960 mcg cm(-2) h(-1). The finite-dose (10 mcl/cm(2) = 13.5 mg/cm(2)) unoccluded donor resulted in penetration of <0.2% of the applied dose (22 mcg/cm(2)). A 10-min transient exposure to infinite dose resulted in total penetration of 179 mcg/cm(2). Steady-state 1-BP fluxes from neat application of a commercial dry cleaning solvent were similar (441 to 722 mcg cm(-2) h(-1)). The permeability coefficient of 1-BP in water vehicle was 0.257 +/- 0.141 cm/h. The absorption potential of 1-BP following dermal exposure is dependent upon the type and duration of exposure. Donor losses due to evaporation were approximately 500-fold greater than dermal absorption flux; evaporation flux was 420 mg cm(-2) h(-1). 1-BP is cytotoxic but not corrosive, based on results from a cultured reconstructed human epidermal model (EpiDerm Skin Corrosivity Test).

The purpose of the present study was to measure and compare permeability coefficients (k(p)) and lag times (tau) in human skin and hairless guinea pig (HGP) skin. Paired experiments employed heat-separated epidermal membranes from human and HGP sources mounted on static in vitro diffusion cells. Infinite-dose, saturated aqueous solutions of 6 industrial chemicals were used as donors: aniline, benzene, 1,2- dichloroethane, diethyl phthalate, naphthalene, and tetrachloroethylene. No significant differences were found between human and HGP skin for either k(p) or tau for any of these chemicals (p ≥ .24). HGP vs. human k(p) measurements, and HGP vs. human tau measurements, were highly correlated. For k(p), the slope of the linear correlation was close to unity (1.080 +/- 0.182) and the intercept close to 0 (0.015 +/- 0. 029 cm/h), with a correlation coefficient (r(2)) = 0.898. For tau, the slope was also close to unity (0.818 +/- 0.030) and the intercept close to 0 (-0.014 +/- 0.023 h), with r(2) = 0.994. These results suggest that HGP skin may serve as an excellent surrogate for human skin in in vitro dermal penetration studies.