Psychosocial influences on pregnancy and childbirth behaviours in north-western Nigeria: a cross-sectional analysis.

Antenatal care (ANC) and facility delivery are essential maternal health services, but uptake remains low in north-western Nigeria. This study aimed to assess the psychosocial influences on pregnancy and childbirth behaviours in Nigeria. Data were from a cross-sectional population-based survey of randomly sampled women with a child under 2 years conducted in Kebbi, Sokoto and Zamfara states of north-western Nigeria in September 2019. Women were asked about their maternal health behaviours during their last pregnancy. Psychosocial metrics were developed using the Ideation Model of Strategic Communication and Behaviour Change. Predicted probabilities for visiting ANC four or more times (ANC4+) and giving birth in a facility were derived using mixed-effects logistic regression models adjusted for ideational and socio-demographic variables. Among the 3039 sample women, 23.6% (95% CI: 18.0-30.3%) attended ANC4+ times and 15.5% (95% CI: 11.8-20.1%) gave birth in a facility. Among women who did not attend ANC4+ times or have a facility-based delivery during their last pregnancy, the most commonly cited reasons for non-use were lack of perceived need (42% and 67%, respectively) and spousal opposition (25% and 27%, respectively). Women who knew any ANC benefit or the recommended number of ANC visits were 3.2 and 2.1 times more likely to attend ANC4+ times, respectively. Women who held positive views about health facilities for childbirth had 1.2 and 2.6 times higher likelihood of attending ANC4+ times and having a facility delivery, respectively, while women who believed ANC was only for sickness or pregnancy complications had a 17% lower likelihood of attending ANC4+ times. Self-efficacy and supportive spousal influence were also significantly associated with both outcomes. To improve pregnancy and childbirth practices in north-western Nigeria, Social and Behavioural Change programmes could address a range of psychosocial factors across cognitive, emotional and social domains which have been found in this study to be significantly associated with pregnancy and childbirth behaviours: raising knowledge and dispelling myths, building women's confidence to access services, engaging spousal support in decision-making and improving perceived (and actual) maternal health services quality.

Understanding family planning outcomes in northwestern Nigeria: analysis and modeling of social and behavior change factors.

BACKGROUND: Northwestern Nigeria faces a situation of high fertility and low contraceptive use, driven in large part by high-fertility norms, pro-natal cultural and religious beliefs, misconceptions about contraceptive methods, and gender inequalities. Social and behavior change (SBC) programs often try to shift drivers of high fertility through multiple channels including mass and social media, as well as community-level group, and interpersonal activities. This study seeks to assist SBC programs to better tailor their efforts by assessing the effects of intermediate determinants of contraceptive use/uptake and by demonstrating their potential impacts on contraceptive use, interpersonal communication with partners, and contraceptive approval. METHODS: Data for this study come from a cross-sectional household survey, conducted in the states of Kebbi, Sokoto and Zamfara in northwestern Nigeria in September 2019, involving 3000 women aged 15 to 49 years with a child under 2 years. Using an ideational framework of behavior that highlights psychosocial influences, mixed effects logistic regression analyses assess associations between ideational factors and family planning outcomes, and post-estimation simulations with regression coefficients model the magnitude of effects for these intermediate determinants. RESULTS: Knowledge, approval of family planning, and social influences, particularly from husbands, were all associated with improved family planning outcomes. Approval of family planning was critical - women who personally approve of family planning were nearly three times more likely to be currently using modern contraception and nearly six times more likely to intend to start use in the next 6 m. Husband's influence was also critical. Women who had ever talked about family planning with their husbands were three times more likely both to be currently using modern contraception and to intend to start in the next 6 m. CONCLUSION: SBC programs interested in improving family planning outcomes could potentially achieve large gains in contraceptive use-even without large-scale changes in socio-economic and health services factors-by designing and implementing effective SBC interventions that improve knowledge, encourage spousal/partner communication, and work towards increasing personal approval of family planning. Uncertainty about the time-order of influencers and outcomes however precludes inferences about the existence of causal relationships and the potential for impact from interventions.

Assessment of an adolescent-girl-focused nutritional educational intervention within a girls' empowerment programme: a cluster randomised evaluation in Zambia.

OBJECTIVE: Adolescent girls are at risk for both macro- and micronutrient deficiencies affecting growth, maternal and child health. This study assessed the impact of an adolescent-girl-tailored nutritional education curriculum on nutritional outcomes, including knowledge, dietary behaviour, anthropometry and anaemia. DESIGN: A cluster-randomised evaluation was conducted with two study arms: girls in mentor-led weekly girls' groups receiving sexual and reproductive health and life-skills training assigned to an age-appropriate nutritional curriculum and control girls in the weekly girls' groups without the nutritional education. The primary analysis was intent-to-treat (ITT) generalised least squares regression. Secondary analysis using two-stage, instrumental-variables estimation was also conducted. SETTING: The intervention and evaluation were conducted in urban and rural areas across four of ten provinces in Zambia. PARTICIPANTS: In total, 2660 girl adolescents aged 10-19 years were interviewed in 2013 (baseline) and annually through 2017. RESULTS: ITT results indicate that exposure to the nutritional educational programme did not meaningfully change outcomes for adolescents or their children. Intervention adolescents were no more likely to correctly identify healthy foods (P = 0·51) or proper infant-feeding practices (P = 0·92); were no less likely to be stunted (P = 0·30) or underweight (P = 0·87) and no less likely to be anaemic (P = 0·38). Outcomes for children of intervention participants were not improved, including being breastfed (P = 0·42), stunted (P = 0·21), wasted (P = 0·77) or anaemic (P = 0·51). CONCLUSIONS: Even a high-quality nutritional educational intervention tailored to adolescents within an empowerment programme does not assure improved nutritional outcomes; adolescent preferences, resource control and household dynamics require consideration in the context of nutritional educational programmes.

The impact of the Adolescent Girls Empowerment Program (AGEP) on short and long term social, economic, education and fertility outcomes: a cluster randomized controlled trial in Zambia.

BACKGROUND: Adolescent girls in Zambia face risks and vulnerabilities that challenge their healthy development into young women: early marriage and childbearing, sexual and gender-based violence, unintended pregnancy and HIV. The Adolescent Girls Empowerment Program (AGEP) was designed to address these challenges by building girls' social, health and economic assets in the short term and improving sexual behavior, early marriage, pregnancy and education in the longer term. The two-year intervention included weekly, mentor-led, girls group meetings on health, life skills and financial education. Additional intervention components included a health voucher redeemable for general wellness and reproductive health services and an adolescent-friendly savings account. METHODS: A cluster-randomized-controlled trial with longitudinal observations evaluated the impact of AGEP on key indicators immediately and two years after program end. Baseline data were collected from never-married adolescent girls in 120 intervention clusters (3515 girls) and 40 control clusters (1146 girls) and again two and four years later. An intent-to-treat analysis assessed the impact of AGEP on girls' social, health and economic assets, sexual behaviors, education and fertility outcomes. A treatment-on-the-treated analysis using two-stage, instrumental variables regression was also conducted to assess program impact for those who participated. RESULTS: The intervention had modest, positive impacts on sexual and reproductive health knowledge after two and four years, financial literacy after two years, savings behavior after two and four years, self-efficacy after four years and transactional sex after two and four years. There was no effect of AGEP on the primary education or fertility outcomes, nor on norms regarding gender equity, acceptability of intimate partner violence and HIV knowledge. CONCLUSIONS: Although the intervention led to sustained change in a small number of individual outcomes, overall, the intervention did not lead to girls acquiring a comprehensive set of social, health and economic assets, or change their educational and fertility outcomes. It is important to explore additional interventions that may be needed for the most vulnerable girls, particularly those that address household economic conditions. Additional attention should be given to the social and economic environment in which girls are living. TRIAL REGISTRATION: ISRCTN29322231. Trial Registration Date: March 04, 2016; retrospectively registered.

Does schooling protect sexual health? The association between three measures of education and STIs among adolescents in Malawi.

While multiple studies have documented shifting educational gradients in HIV prevalence, less attention has been given to the effect of school participation and academic skills on infection during adolescence. Using the Malawi Schooling and Adolescent Study, a longitudinal survey that followed 2,649 young people aged 14-17 at baseline from 2007 to 2013, we estimate the effect of three education variables: school enrolment, grade attainment, and academic skills-numeracy and Chichewa literacy-on herpes simplex virus type 2 (HSV-2) and HIV incidence using interval-censored survival analysis. We find that grade attainment is significantly associated with lower rates of both HSV-2 and HIV among girls, and is negatively associated with HSV-2 but not HIV among boys. School enrolment and academic skills are not significantly associated with sexually transmitted infections (STIs) for boys or girls in our final models. Efforts to encourage school progression in high-prevalence settings in sub-Saharan Africa could well reduce, or at least postpone, acquisition of STIs.

"When He Asks for Sex, You Will Never Refuse": Transactional Sex and Adolescent Pregnancy in Zambia.

Pregnancy among adolescent girls in Zambia is a significant concern on its own and as a factor in school dropout and early marriage, with one-third of girls aged 15-19 having experienced pregnancy. Using qualitative and quantitative data from the Adolescent Girls Empowerment Program, we explore transactional sex as a driver of adolescent pregnancy. In qualitative interviews, transactional sex was repeatedly discussed as the main driver of pregnancy, as respondents indicated that when a girl feels that she "owes" a man sex, it prevents her from declining sex or using condoms. In addition, multivariate Cox proportional hazards models using four rounds of longitudinal data from a sample of unmarried and never pregnant adolescent girls (n=1,853) show that girls who have engaged in transactional sex face a hazard of first premarital pregnancy almost 30 percent greater than their peers who have not, independent of the effect of other risk-related sexual behaviors such as condom use and number of sexual partners. Identifying and understanding the role of transactional sex in adolescent pregnancy is important for designing effective curricula and programs that delay pregnancy, and highlights the importance of addressing access to economic resources in adolescent health outcomes.

A luminous quasar at a redshift of z = 7.085.

The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed by observations of quasars with redshifts of less than 6.5. It has been difficult to probe to higher redshifts, however, because quasars have historically been identified in optical surveys, which are insensitive to sources at redshifts exceeding 6.5. Here we report observations of a quasar (ULAS J112001.48+064124.3) at a redshift of 7.085, which is 0.77 billion years after the Big Bang. ULAS J1120+0641 has a luminosity of 6.3 × 10(13)L(⊙) and hosts a black hole with a mass of 2 × 10(9)M(⊙) (where L(⊙) and M(⊙) are the luminosity and mass of the Sun). The measured radius of the ionized near zone around ULAS J1120+0641 is 1.9 megaparsecs, a factor of three smaller than is typical for quasars at redshifts between 6.0 and 6.4. The near-zone transmission profile is consistent with a Lyα damping wing, suggesting that the neutral fraction of the intergalactic medium in front of ULAS J1120+0641 exceeded 0.1.

Cluster randomized evaluation of Adolescent Girls Empowerment Programme (AGEP): study protocol.

BACKGROUND: Adolescents in less developed countries such as Zambia often face multi-faceted challenges for achieving successful transitions through adolescence to early adulthood. The literature has noted the need to introduce interventions during this period, particularly for adolescent girls, with the perspective that such investments have significant economic, social and health returns to society. The Adolescent Girls Empowerment Programme (AGEP) was an intervention designed as a catalyst for change for adolescent girls through themselves, to their family and community. METHODS/DESIGN: AGEP was a multi-sectoral intervention targeting over 10,000 vulnerable adolescent girls ages 10-19 in rural and urban areas, in four of the ten provinces of Zambia. At the core of AGEP were mentor-led, weekly girls' group meetings of 20 to 30 adolescent girls participating over two years. Three curricula - sexual and reproductive health and lifeskills, financial literacy, and nutrition - guided the meetings. An engaging and participatory pedagogical approach was used. Two additional program components, a health voucher and a bank account, were offered to some girls to provide direct mechanisms to improve access to health and financial services. Embedded within AGEP was a rigorous multi-arm randomised cluster trial with randomization to different combinations of programme arms. The study was powered to assess the impact across a set of key longer-term outcomes, including early marriage and first birth, contraceptive use, educational attainment and acquisition of HIV and HSV-2. Baseline behavioural surveys and biological specimen collection were initiated in 2013. Impact was evaluated immediately after the program ended in 2015 and will be evaluated again after two additional years of follow-up in 2017. The primary analysis is intent-to-treat. Qualitative data are being collected in 2013, 2015 and 2017 to inform the programme implementation and the quantitative findings. An economic evaluation will evaluate the incremental cost-effectiveness of each component of the intervention. DISCUSSION: The AGEP program and embedded evaluation will provide detailed information regarding interventions for adolescent girls in developing country settings. It will provide a rich information and data source on adolescent girls and its related findings will inform policy-makers, health professionals, donors and other stakeholders. TRIAL REGISTRATION: ISRCTN29322231 . March 04 2016; retrospectively registered.

Models for nearly every occasion: Part III - One box decreasing emission models.

New one box "well-mixed room" decreasing emission (DE) models are introduced that allow for local exhaust or local exhaust with filtered return, as well the recirculation of a filtered (or cleaned) portion of the general room ventilation. For each control device scenario, a steady state and transient model is presented. The transient equations predict the concentration at any time t after the application of a known mass of a volatile substance to a surface, and can be used to predict the task exposure profile, the average task exposure, as well as peak and short-term exposures. The steady state equations can be used to predict the "average concentration per application" that is reached whenever the substance is repeatedly applied. Whenever the beginning and end concentrations are expected to be zero (or near zero) the steady state equations can also be used to predict the average concentration for a single task with multiple applications during the task, or even a series of such tasks. The transient equations should be used whenever these criteria cannot be met. A structured calibration procedure is proposed that utilizes a mass balance approach. Depending upon the DE model selected, one or more calibration measurements are collected. Using rearranged versions of the steady state equations, estimates of the model variables-e.g., the mass of the substance applied during each application, local exhaust capture efficiency, and the various cleaning or filtration efficiencies-can be calculated. A new procedure is proposed for estimating the emission rate constant.

Models for nearly every occasion: Part IV - Two-box decreasing emission models.

New two-box "well-mixed room" decreasing emission (DE) models are introduced for scenarios that involve local controls, such as some form of local exhaust or local exhaust with filtered return. In addition, these models allow for the recirculation of a filtered (or cleaned) portion of the general room ventilation. For each control device scenario, a steady state and transient near and far field model is presented. The transient equations predict the concentration at time t after the application of the substance. The steady state equations can be use to predict the steady, unvarying "average concentration per application" whenever there are continuous applications of a substance and sufficient time has elapsed. The steady state equations can also be used to calculate the TWA for a task (or a series of tasks) whenever the beginning and end concentrations for the task (or task series) are expected to be zero (or near zero). The transient equations should be used to predict TWA exposures whenever these criteria cannot be met, or it is necessary to predict short-term exposures or peak concentrations. A structured calibration procedure, based on a mass balance approach, is proposed for each model. Depending upon the model, one or more calibration measurements are collected. Rearranged versions of the steady state equations are used to calculate estimates of the mass applied during each application, the near field flowrate, and (depending upon the model) the various efficiencies (e.g., local exhaust capture efficiency and the recirculation filtration efficiency). The emission rate constant must be determined using either a published approximation algorithm or experimentally.

Models for nearly every occasion: Part I - One box models.

The standard "well mixed room," "one box" model cannot be used to predict occupational exposures whenever the scenario involves the use of local controls. New "constant emission" one box models are proposed that permit either local exhaust or local exhaust with filtered return, coupled with general room ventilation or the recirculation of a portion of the general room exhaust. New "two box" models are presented in Part II of this series. Both steady state and transient models were developed. The steady state equation for each model, including the standard one box steady state model, is augmented with an additional factor reflecting the fraction of time the substance was generated during each task. This addition allows the easy calculation of the average exposure for cyclic and irregular emission patterns, provided the starting and ending concentrations are zero or near zero, or the cumulative time across all tasks is long (e.g., several tasks to a full shift). The new models introduce additional variables, such as the efficiency of the local exhaust to immediately capture freshly generated contaminant and the filtration efficiency whenever filtered exhaust is returned to the workspace. Many of the model variables are knowable (e.g., room volume and ventilation rate). A structured procedure for calibrating a model to a work scenario is introduced that can be applied to both continuous and cyclic processes. The "calibration" procedure generates estimates of the generation rate and all of remaining unknown model variables.

Models for nearly every occasion: Part II - Two box models.

The "well-mixed room" two box models are often used to predict near and far field concentrations for a specific task, but are limited to scenarios where local exhaust controls are not used. In Part II of this series, new two box models are presented that permit local controls that either exhaust to the outside or return filtered air to the workspace. Additional models are presented that also allow for the recirculation of a filtered portion of the general ventilation flowrate. During the concentration increase phase the emission rate is assumed to be relatively constant. Both steady state and transient equations were developed for each scenario. An additional factor, representing the fraction of time that the substance is being emitted during a task or set of tasks, was added to the standard and new steady state models. This simple modification permits the easy calculation of the average near and far field concentrations for cyclic and irregular emission patterns, provided the starting and ending concentrations are identical (e.g., zero or near zero) or the cumulative task time is long (e.g., two or more task cycles to a full shift, depending upon the number of room air changes per task). Additional variables are introduced with the new models, such as the efficiency of a local control to immediately capture freshly generated contaminant and the filtration efficiency whenever filtered exhaust is returned to the workspace. Many of the model variables are knowable (e.g., room volume and ventilation rate). Others can be approximated using manufacturer specifications or published values (e.g., filtration efficiency). A structured procedure for calibrating a model to a work scenario is presented that can be applied to both continuous and cyclic processes. The "calibration" procedure generates estimates of all of the unknown model variables, including the generation rate and the effective near field flowrate (which takes into account potentially complex near field air currents as well as any thermal plumes created by a hot process).

Randomized evaluation and cost-effectiveness of HIV and sexual and reproductive health service referral and linkage models in Zambia.

BACKGROUND: Provision of HIV prevention and sexual and reproductive health services in Zambia is largely characterized by discrete service provision with weak client referral and linkage. The literature reveals gaps in the continuity of care for HIV and sexual and reproductive health. This study assessed whether improved service delivery models increased the uptake and cost-effectiveness of HIV and sexual and reproductive health services. METHODS: Adult clients 18+ years of age accessing family planning (females), HIV testing and counseling (females and males), and male circumcision services (males) were recruited, enrolled and individually randomized to one of three study arms: 1) the standard model of service provision at the entry point (N = 1319); 2) an enhanced counseling and referral to add-on service with follow-up (N = 1323); and 3) the components of study arm two, with the additional offer of an escort (N = 1321). Interviews were conducted with the same clients at baseline, six weeks and six months. Uptake of services for HIV, family planning, male circumcision, and cervical cancer screening at six weeks and six months were the primary endpoints. Pairwise chi-square and multivariable logistic regression statistical tests assessed differences across study arms, which were also assessed for incremental cost-efficiency and cost-effectiveness. RESULTS: A total of 3963 clients, 1920 males and 2043 females, were enrolled; 82 % of participants at six weeks were tracked and 81 % at six months; follow-up rates did not vary significantly by study arm. The odds of clients accessing HIV testing and counseling, cervical cancer screening services among females, and circumcision services among males varied significantly by study arm at six weeks and six months; less consistent findings were observed for HIV care and treatment. Client uptake of family planning services did not vary significantly by study arm. Integrated services were found to be more efficiently provided than vertical service provision; the cost-effectiveness for HIV/AIDS and cervical cancer was high in the enhanced service models. CONCLUSIONS: Study results provide evidence for increasing the linkages and integration of a selection of HIV and sexual and reproductive health services. The study provided cost-effective service delivery models that enhanced the likelihood of clients accessing some additional needed health services. TRIAL REGISTRATION: ISRCTN84228514 Retrospectively registered. The study was retrospectively registered in the ISRCTN clinical trials registry on 06 October 2015. The first recruitment of participants occurred on 17 December 2013.

Rating locomotive crew diesel emission exposure profiles using statistics and Bayesian Decision Analysis.

For more than 20 years CSX Transportation (CSXT) has collected exposure measurements from locomotive engineers and conductors who are potentially exposed to diesel emissions. The database included measurements for elemental and total carbon, polycyclic aromatic hydrocarbons, aromatics, aldehydes, carbon monoxide, and nitrogen dioxide. This database was statistically analyzed and summarized, and the resulting statistics and exposure profiles were compared to relevant occupational exposure limits (OELs) using both parametric and non-parametric descriptive and compliance statistics. Exposure ratings, using the American Industrial Health Association (AIHA) exposure categorization scheme, were determined using both the compliance statistics and Bayesian Decision Analysis (BDA). The statistical analysis of the elemental carbon data (a marker for diesel particulate) strongly suggests that the majority of levels in the cabs of the lead locomotives (n = 156) were less than the California guideline of 0.020 mg/m(3). The sample 95th percentile was roughly half the guideline; resulting in an AIHA exposure rating of category 2/3 (determined using BDA). The elemental carbon (EC) levels in the trailing locomotives tended to be greater than those in the lead locomotive; however, locomotive crews rarely ride in the trailing locomotive. Lead locomotive EC levels were similar to those reported by other investigators studying locomotive crew exposures and to levels measured in urban areas. Lastly, both the EC sample mean and 95%UCL were less than the Environmental Protection Agency (EPA) reference concentration of 0.005 mg/m(3). With the exception of nitrogen dioxide, the overwhelming majority of the measurements for total carbon, polycyclic aromatic hydrocarbons, aromatics, aldehydes, and combustion gases in the cabs of CSXT locomotives were either non-detects or considerably less than the working OELs for the years represented in the database. When compared to the previous American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) of 3 ppm the nitrogen dioxide exposure profile merits an exposure rating of AIHA exposure category 1. However, using the newly adopted TLV of 0.2 ppm the exposure profile receives an exposure rating of category 4. Further evaluation is recommended to determine the current status of nitrogen dioxide exposures. [Supplementary materials are available for this article. Go to the publisher's online edition of Journal of Occupational and Environmental Hygiene for the following free supplemental resource: additional text on OELs, methods, results, and additional figures and tables.].

Herpes simplex virus type 2 cross-sectional seroprevalence and the estimated rate of neonatal infections among a cohort of rural Malawian female adolescents.

OBJECTIVE: To assess herpes simplex virus type 2 (HSV-2) seroprevalence among rural Malawian adolescent women and estimate the number of neonatal herpes infections among infants of these adolescents. METHODS: A longitudinal cohort study of adolescents (14-16 years at entry) residing in rural Malawi was initiated in 2007 with annual observation. HSV-2 testing was introduced in 2010. In this study, we (1) determined, using cross-sectional analysis, risk factors for positive serostatus, (2) adjusted for non-response bias with imputation methods and (3) estimated the incidence of neonatal herpes infection using mathematical models. RESULTS: A total of 1195 female adolescents (age 17-20 years) were interviewed in 2010, with an observed HSV-2 seroprevalence of 15.2% among the 955 women tested. From a multivariate analysis, risk factors for HSV-2 seropositivity include older age (p=0.037), moving from the baseline village (p=0.020) and report of sexual activity with increasing number of partners (p<0.021). Adjusting for non-response bias, the estimated HSV-2 seroprevalence among the total female cohort (composed of all women interviewed in 2007) was 18.0% (95% CI 16.0% to 20.2%). HSV-2 seropositivity was estimated to be 25.6% (95% CI 19.6% to 32.5%) for women who refused to provide a blood sample. The estimated number of neonatal herpes infections among the total female cohort was 71.8 (95% CI 57.3 to 86.3) per 100 000 live births. CONCLUSIONS: The risk of HSV-2 seroconversion is high during adolescence, when childbearing is beginning, among rural Malawian women. Research on interventions to reduce horizontal and vertical HSV-2 transmission during adolescence in resource-limited settings is needed.

How informed are clients who consent? A mixed-method evaluation of comprehension among clients of male circumcision services in Zambia and Swaziland.

Comprehension is fundamental for informed consent--an individual's right to choose a medical procedure, such as male circumcision (MC). Because optimal benefits depend on post-surgical behaviors, comprehension is particularly critical for MC programs. We evaluated clients' comprehension of MC's risks and benefits, wound care instructions, and risk reduction post-MC using a true/false test (n = 1181) and 92 semi-structured interviews (SSIs) in Zambia and Swaziland. Most participants (89% Zambia, 93% Swaziland) passed the true/false test, although adolescents scored lower (significantly so in Swaziland) than adults and one-third (including nearly half of adolescents in Zambia) said MC has no risks. SSIs indicated confusion between "risk" of adverse surgical outcomes and reduced "risk" of HIV; most respondents acknowledged the 6 week abstinence period post-MC, yet few said resuming sex early increases HIV risk. Providers should distinguish between surgical "risks" and reduced HIV "risk," and emphasize that HIV risk increases with sex before complete healing.

Cohort mortality study of roofing granule mine and mill workers. Part I: Estimation of historical crystalline silica exposures.

A study was conducted to construct a job exposure matrix for the roofing granule mine and mill workers at four U.S. plants. Each plant mined different minerals and had unique departments and jobs. The goal of the study was to generate accurate estimates of the mean exposure to respirable crystalline silica for each cell of the job exposure matrix, that is, every combination of plant, department, job, and year represented in the job histories of the study participants. The objectives of this study were to locate, identify, and collect information on all exposure measurements ever collected at each plant, statistically analyze the data to identify deficiencies in the database, identify and resolve questionable measurements, identify all important process and control changes for each plant-department-job combination, construct a time line for each plant-department combination indicating periods where the equipment and conditions were unchanged, and finally, construct a job exposure matrix. After evaluation, 1871 respirable crystalline silica measurements and estimates remained. The primary statistic of interest was the mean exposure for each job exposure matrix cell. The average exposure for each of the four plants was 0.042 mg/m(3) (Belle Mead, N.J.), 0.106 mg/m(3) (Corona, Calif.), 0.051 mg/m(3) (Little Rock, Ark.), and 0.152 mg/m(3) (Wausau, Wis.), suggesting that there may be substantial differences in the employee cumulative exposures. Using the database and the available plant information, the study team assigned an exposure category and mean exposure for every plant-department-job and time interval combination. Despite a fairly large database, the mean exposure for > 95% of the job exposure matrix cells, or specific plant-department-job-year combinations, were estimated by analogy to similar jobs in the plant for which sufficient data were available. This approach preserved plant specificity, hopefully improving the usefulness of the job exposure matrix.

Cohort mortality study of roofing granule mine and mill workers. Part II. Epidemiologic analysis, 1945-2004.

The mortality of 2650 employees (93.4% males) in the mine and mill production of roofing granules at four plants was examined between 1945 and 2004. Hypotheses focused on diseases associated with exposure to silica: nonmalignant respiratory disease, lung cancer, and nonmalignant renal disease. Study eligibility required ≥ 1 year of employment by 2000. Work history and vital status were followed through 2004 with < 1% lost to follow-up. Industrial hygiene sampling data (1871 sampling measurements over a 32-year period) and professional judgment were used to construct 15 respirable crystalline silica exposure categories. A category was assigned to all plant-, department-, and time-dependent standard job titles. Cumulative respirable crystalline silica exposure (mg/m(3)-years) was calculated as the sum of the product of time spent and the average exposure for each plant-, department-, job-, and calendar-year combination. The cohort geometric mean was 0.17 mg/m(3)-years (geometric standard deviation 4.01) and differed by plant. Expected deaths were calculated using U.S. (entire cohort) and regional (each plant) mortality rates. Poisson regression was used for internal comparisons. For the entire cohort, 772 deaths (97.4% males) were identified (standardized mortality ratio 0.95, 95% CI 0.88-1.02). There were 50 deaths from nonmalignant respiratory diseases (1.14, 95% CI 0.85-1.51). Lagging exposure 15 years among the male cohort, the relative risks for nonmalignant respiratory disease were 1.00 (reference), 0.80, 1.94, and 2.03 (p value trend = 0.03) when cumulative exposure was categorized < 0.1, 0.1- < 0.5, 0.5- < 1.0, and ≥ 1.0 mg/m(3)-years, respectively. There was a total of 77 lung cancer deaths (1.11, 95% CI 0.88-1.39). Lagging exposure 15 years, the relative risks for males were 1.00 (reference), 1.83, 1.83, and 1.05 (p value trend = 0.9). There were 16 deaths from nonmalignant renal disease (1.76, 95% CI 1.01-2.86). This exposure-response trend was suggestive but imprecise. The study results are consistent with other cohorts with similar levels of exposure to respirable crystalline silica.