مجله دانشکده بهداشت و انستیتو تحقیقات بهداشتی
سال هشتم شماره 4 (پیاپی 32، زمستان 1389)

Presently not sufficient attention is paid to adolescent health promotion in many countries, because of the widespread belief that adolescents are generally healthy. The purpose of this study was to evaluate predictors of adolescent girl's quality of life using path analysis based on Pender's health promotion model.

The Pender's health promotion model served as the framework of this cross-sectional study, which included a total of 500 adolescent girls (grades 9-11) selected by stratified random sampling from 20 high schools for girls in 4 districts of Kashan province, Iran. Inclusion criteria were being in grades 9-11 and a written informed consent (from teachers, parents and the girls themselves). Data were collected through interviewing the girls, the interviewers being trained persons, using several standard questionnaires (for perceived self-efficacy, perceived affect, perceived barriers, perceived social support; health promoting lifestyle, and health-related quality of life). Data analysis was done using SPSS18 and LISREL 8.8, the statistical test being path analysis.

All constructs of the health promotion model and health promoting lifestyle were significantly related to adolescent girl's quality of life. Perceived self-efficacy (β=0.70, p<0/01) and perceived affect (β=0.21, p<0/01) had the highest correlation with the quality of life. The model and the health-promoting lifestyle as a mediator accounted for 73% and 39% of variance in adolescent girl's quality of life, respectively.

The findings of this study indicate that the health promotion model can be used to explain and predict the quality of life of adolescent girls. Thus, the Pender's health promotion model is recommended to health planners for promoting the quality of life in this population

Today in most of the work environments, such as nuclear, military and chemical industries, human error may result in catastrophic events. A common characteristic of large technological systems is that massive amounts of potentially dangerous materials are kept in one single unit controlled by control room operators. A control room is indeed the heart of a system of this type and any error in task performance by the operators may have undesirable consequences which could never be compensated. In this study we aimed to identify and assess human errors in the control room of the Aromatic Unit of Bouali-Sina Petrochemical Company, Iran using the CREAM method This was a cross-sectional and analytical-descriptive study carried out in the control room of the Aromatic Unit of Bouali-Sina Petrochemical Company, Iran with 39 operators. After a job analysis by the hierarchical task analysis (HTA), probable control modes and cognitive failure probability were determined for occupational tasks using the basic and the extended CREAM methodologies. Based on the results of the basic CREAM method, control modes for the tasks of action, Boardman and shift control supervisor were determined as Opportunistic Control mode, while for the task of control room head it was obtained as Tactical control mode. With regard to the error types, the following results were obtained on the basis of the extended method of CREAM: execution failure (51.70%), interpretation failure (19.55%), planning failure (14.94%), and observation failure (13.81%). The basic CREAM method showed the common performance factors (CPCs) leading to reduced performance reliability to be the number of simultaneous tasks, time of day (circadian rhythm), and adequacy and quality of training and experience. These factors caused the operators to choose an opportunistic control mode. In addition, based on the extended CREAM method results, the most noticeable cognitive failure was execution failure. In addition, the most important cognitive activities related to the control process in the control room were communication, execution, diagnosis, monitoring, and planning. Based on these findings, providing instructions and guidelines for work procedures, holding training courses, shift work scheduling, optimization of the communication systems and modifications in the control software are essential to minimize human errors in the Bouali Sina Petrochemical Company control room.

Cardiovascular diseases are the main cause of death in the world. Several factors such as lifestyle can alter incidence of these diseases. Cardiovascular diseases originate from childhood; therefore, early prevention must begin from childhood and adolescence in order to be able to modify risk factors. The aim of this study was to identify modifiable (tobacco smoke exposure, physical inactivity, hypertension, obesity, incorrect dietary habits and high blood pressure) and non-modifiable (family history) cardiovascular risk factors in Hamedani adolescents. This was a descriptive- analytic Cross- Sectional study, including 1000 students selected by stratified cluster sampling, from 8 high schools in Hamden, Iran. The subjects’ height, weight and blood pressure were measured and their body mass index (BMI) was calculated. A questionnaire was used to obtain information on life style. On the whole, 23% of the participants had a family history of hypertension and hyperlipidemia. The data also showed that 10.7% of the participants had a BMI more than 25kg/m², 59% had no physical activity, more than 50% had a high intake of salt, and 67% were exposed to passive tobacco smoke. The average length of time spent daily on watching T.V. or playing video games was 6 hours. Proportions of the subjects consuming saturated oils, high-fat dairy products, ready-to-eat foods, and junk foods (potato chips and puffed cereals) were 50.8%, 33.1%, 48.6%, and 75.4%, respectively. The most common method of cooking was frying (used by 35.9% of the families). Finally, 3.4% of the adolescents were smokers themselves and 25% of them said that their friends smoked, while 67.7% were exposed to cigarette smoke from their smoker-relatives. Most of the Hamedani adolescents are at risk of cardiovascular diseases risk factors. Primary intervention programs should be designed and implemented aiming at promoting the health and nutritional awareness and, ultimately, practice, of the general population with particular emphasis on adolescents.

Thalassemia, a heterogeneous disease, is one of the most common single-gene diseases worldwide. The aim of this study was to find associations between hematological indices and severity of beta-globin gene mutations in beta-thalassemia carriers. In this cross-sectional study, 30 beta-goblin gene mutations (b+ and b○) in 1206 unrelated beta-thalassemia carriers were investigated. In addition, their hematological indices, including CBC and electrophoresis results, were determined. The association between genetic findings and hematological parameters (mean corpuscular volume (MCV) and mean hematocrit corpuscular hematocrit (MCH)) were determined using the SPSS software, the statistical test being the t-test. The results indicated that b+-thalassemia carriers had higher MCV and MCH means than b○-thalassemia carriers. These findings would certainly have practical implications in public health. The results show a significant correlation between two hematological indices and certain types of mutations in beta-thalassemia carriers.

Many researchers have studied survival (time to death) of gastric cancer patients. Although gastric cancer diagnosed in early stages can be cured by surgery, chance of relapse still exists after operation. Hence, we should consider both events, that is, relapse of the disease and death, in order to be able to make a more precise estimation for survival of the patients. The purpose of this study was to use the competing risks method to estimate the cumulative incidence functions (CIF) of the relapse of disease and death and consequently to estimate the postoperative disease-free survival.

A total of 330 patients admitted to Iran Cancer Institute and operated between March 1995 and March 1999 were enrolled in the study. They were followed up for at least 5 years to estimate their 5-year disease-free survival. Information on their demographic, clinical, and therapeutic characteristics, as well as on the type and time of occurrence of the first event (relapse of disease or death) after surgery was collected from their medical records. The direct parametric method was applied to estimate CIFs of relapse of the disease and death, while to adjust the effects of some covariates the parametric regression model was used. Data analysis was done using the R software and a p-value <0.05 was considered statistically significant. The findings were compared with the results obtained on the basis of data analysis in which the competing events were not considered.

The median follow-up time was 37.9 months. Of all the patients 13% experienced relapse and 60.9% death as the first event after surgery. The CIFs of relapse of disease and death 5 years after operation, with due consideration of covariates, were estimated at 11.0% and 68.6%, respectively. Age, stage of disease, and complementary treatment were statistically associated with the CIF of death, while only complementary treatment was related to the CIF of relapse. Older patients and those in more advanced stages of disease were more likely to die after operation. Moreover, while complementary treatment after operation decreased the CIF of relapse of disease, it increased the CIF of death. The disease-free survival of patients 5 years after surgery was 20.4% (considering the effects of some covariates).

The competing risks method is recommended for analyzing survival data because of its capability in considering different events and, therefore, making it possible to make more precise estimations. By using this method, considering smaller variance estimates for model parameters and also narrow confidence intervals for the cumulative incidence functions of competing events, it is expected to obtain more precise results. Unfortunately, the results have revealed that the disease-free survival of gastric cancer patients is low in Iran.

Considering the acute and chronic effects of organic solvents to which vehicle painters are exposed for long periods of time, their evaluation and control is crucial for protection of health of the employees. This study aimed to find the most influential factors on exposure to, and spreading pollution with, benzene, toluene, xylem, and etylebenzene (BTEX) in order to be able to choose the best control measures. In a motor-vehicle company the vehicle painting process was studied in detail and the solvents used in paints and in spreading organic solvent stations were identified. Based on the types and concentrations of the variables being studied, using the NIOSH method a total of 240 air samples were collected (5 samples for each variable and the respective controls) and analyzed. The SPSS version 11.5 was used for data analysis, the statistical tests being multi-regression and analysis of variance. Exposure to benzene in all occupational tasks, as well as to toluene in top coating and undercoating stations exceeded, while exposure to etylebenzene and xylene did not reach, the respective permitted exposure limits (p<0.05). The most effective factors on exposure to all the four solvents were, in order of effectiveness, occupational task, gun type, and the type of paint sued (p<0.05). The effects of the variables studies – occupational task, gun and paint types – on exposure to BTEX relate to differences in occupational task work load, the type of gun used, and the paint organic solvent formulation. The reason for the potentially high exposure to benzene is its presence as an impurity in the paint solvents. Thus, it is highly recommended that in the process of control and evaluation special attention be paid to these factors.

Specific and unique characteristics of nanoparticles may entail specific and unique hazards. In addition, they may also exhibit toxicity under certain conditions. This study was conducted to investigate the toxicity of phenol-exposed and phenol-unexposed nano-TiO2 and nano-Fe/TiO2 particles. Stock solutions of the afore-mentioned nanoparticles were prepared at different concentrations and a sample of each was exposed to phenol. This was followed by exposing Daphnia Magna to the phenol- and non-phenol-exposed nanoparticles. LC50, NOEC and the concentrations at which mortality rates were 100% were determined 12 to 96 hours after exposure, while for the determination of the mortality rate of Daphnia the Probit model in SPSS version16 software was used. The results revealed that (1). The 48-hr LC50 values for phenol-unexposed nano-TiO2 and nano-Fe/TiO2 particles were 2705 and over 15000 mg/m3, respectively. The corresponding values for the phenol-exposed samples were 414 and 1253. (2). The 48-hr NOEC values for the phenol-exposed TiO2 and FeTiO2 were 41 and 789, respectively, the corresponding values for unexposed samples being 1253 and over 15000 mg/m3. (3). In addition, the 48-hr 100% mortality rates for phenol-unexposed nano-TiO2 and nano-Fe/TiO2 particles were, respectively, 1253 and over 15000 mg/m3, while for the phenol-exposed samples the corresponding rates were 1090 and over 2108. With regard to 48-hr LC50, the findings show that the toxicity of both nano-Fe: TiO2 and TiO2 increases as a result of exposure to phenol, the increase being 12-fold for the former and 6.5-fold for the latter. In general, however, based on LC50, it can be said that the toxicity of Fe:TiO2 nanoparticles, which has better catalytic characteristics, is lower in comparison to TiO2 nanoparticles. Thus, using Fe:TiO2 in preference to pure TiO2 should be investigated further, as it will be less hazardous to the environment.

Recently the use of heterotrophic plate count (HPC) has received much attention as a supplementary indicator of the MPN test in water quality control. The US Environmental Protection Agency (USEPA) has declared 500 cfu/mL as the maximum acceptable level for heterotrophic bacteria in distribution networks. Currently the HPC determination is not among the routine control items in Tabriz city and there is no published information on the presence of heterotrophic bacteria in that city's potable water. In this study the presence of HPC in potable water main was determined in Tabriz city, Iran. A total of 50 water samples, representing drinking water of the whole city of Tabriz, were taken randomly from different districts of Tabriz city and their HPC, coliform, residual chlorine, turbidity, temperature, and pH were measured. For the heterotrophic bacteria the R2A and Nutrients Agar culture media were used, while the spread plate count method was used for the HPC test. The statistical tests used for data analysis were the t-test and regression. In 50% of the samples heterotrophic bacteria were present. In 6 districts the HPC was higher than 500 cfu/mL. Based on Nutrient Agar and R2A, the HPC indicator in Tabriz drinking water was 184±340 and 154±315 cfu/mL, respectively, the growth rate being higher in the former medium. There was a significant correlation between the HPC and residual chlorine in both media (for Nutrients Agar, p<0.05; R= -0.347, and for R2A, p<0.05; R= -0.312). Also, there was a significant positive correlation between the HPC and pH (p<0.05). Further analysis of the data showed that the correlation between HPC values in both media was also significant (p<0.95, R= 0.95). The presence of heterotrophic bacteria in 50% of the water samples tested indicates that drinking water contamination with these bacteria is a public health problem in Tabriz city. As a result, monitoring of HPC at least once every 6 or, at least, 12 months, together with coliform bacteria, and the comparison of the results over time can help to better determine water quality in the distribution system, as well as boost the system operation and ensure drinking water with a high quality.