Journal of School of Public Health and

---

In a survey from 1999 to 2001, a total of 354 samples of soil and water were colleted from different areas and examined for the presence of AcanthamoebaandNaegleria spp. After sieving, filtration and centrifugation, samples were examined for the free living protozoa ( amphizoic amoeba ). Concurrently, a sediment of each sample was cultured in the non-nutrient agar medium enriched by E.coli. In the end, 10 Acanthomoeba spp. and 3 Naegleria sp. were isolated. Besides, we diagnosed one case of human Acanthomoeba infection in a person residing in the area.

---

The use of biological safety cabinets (BSCs) in laboratories has greatly increased over the last few decades. BSCs are used in laboratories to protect both the scientists and the experiments from contamination by biological hazards during tissue culture procedures. The function of BSCs depends upon the HEPA filtration, the fan performance and the airflow patterns in the cabinet. To ensure BSCs proper functioning, regular performance evaluation tests are necessary. Failure to observe this may lead to direct and indirect losses. The objective of this study which was conducted at a biological research center was to evaluate the performance of seven present BSCs used in different laboratories. Based on BS 5726 (1992), two sets of measurements were performed: a) Determination bioaerosol concentration in the cabinet and b) inflow and downflow velocity measurements at the cabinet. The results revealed that the lowest and the highest bioaerosol concentrations were 0.2 cfu/m3 and 1.33 cfu/m3, respectively. The lowest inflow mean velocity was found to be 0.33 m/s which was far less than the recommended value in BS 5726 (0.7 m/s). The highest inflow velocity was 1.1 m/s. The lowest downflow velocity equaled to 0.09 m/s which was below the recommended value (0.25- 0.5 m/s). The highest downflow measured was 0.55 m/s. As a conclusion, in general, none of the BSCs evaluated in this study provided sterile atmosphere at the cabinets. In no case, airflow patterns met the recommended values proposed in BS 5726.

---

Background and Aim: The purpose of this study was to assess the accuracy of the bootstrap method in logistic regression and to explore the method's use in logistic regression models in cases where the sample size is insufficient.
Materials and Methods: We use data from 150 patients who had undergone surgery at the Cancer Institute, Emam Khomeini hospital during from 1999 to 2001. Then we drew repeated samples of size 50 from these 150 patients.
Results: Applying ordinary logistic regression, an appropriate model we fitted to the initial data. Then confidence intervals and standard errors were computed for all regression coefficients. There are many situations where the sample size is insufficient and conditions for using ordinary logistic regression are not met. In these cases the use of the bootstrap method not only produces more accurate estimations of regression coefficients, but with repeated sampling, produces estimates very close to the true values. This holds for the estimation of regression coefficients, confidence intervals and standard errors of coefficients.
Conclusion: In this study we show the optimal number of replications and the optimal sample size when using the bootstrap method in studies involving relatively small sample sizes.

---

Background and Aim: Iran managed to eradicate the wild poliovirus in 2000. However, a large number of AFP cases are still detected each year because of close surveillance: there were 450 reported AFP cases in 1382. The expected number of cases for the year 1382 in the province of West Azarbayjan (with an under-15 population of 1100000) was 11, while the observed number was more than 6 times greater (70 cases). In this study we investigated the non-polio enteroviral agent which could cause the AFP cases especially in Azarbayjan Province. Hence, the main purpose of the study was to identify circulating non-polio enteroviruses, using cell lines RD, Hep2, L20 and RT-PCR.

Material and Methods: All stool specimens of AFP cases were treated with chloroform and then injected into the above-mentioned cell lines. The isolated viruses were identified by the NT method. In cases where polioviruses were isolated, intratypic differentiation (wild vs. vaccine strains) using hybridization and ELISA tests. Finally, we performed RT-PCR with pan-EV primers on all samples.

Results: Using cell cultures, we were able to isolate 10 viruses, 9 of which were isolated by the RD cell line and this is regarded as the most sensitive cell line. The RT-PCR also identified 16 different viruses, 7 of which were not isolated on the RD line. Thus, RT-PCR could increase viral detection by 10%, indicating a high degree of high sensitivity.

Conclusion: Although the combination of cell culture and RT-PCR for detection and identification of non-polio enteroviruses causing AFP is invaluable, more than 75% of AFP patients were enterovirus negative. Therefore, they must be checked for other agents such as flavivirus (viral) and Campylobacter jejuni (bacterial).

---

Background and Aim: Exposure to hexavalent chromium in plating operations is associated with skin ulceration, contact dermatitis, respiratory tract irritation, cancer, and kidney damage. We investigated the possibility of using biological monitoring to assess exposure to hexavalent chromium in chrome-plating workers. We compared mean Cr6 concentrations in the breathing zone plus urine chromium, β2 microglobulin (B2M), and N-acetyl-B-D- glucosaminidase (NAG) at the end of the working shift. Then we assessed the correlation between exposure to hexavalent chromium and biological indicators.

Materials and Methods: This study involved 45 chrome platers (Cases) and 40 zinc platers (Controls) in Isfahan. Air and urine samples were collected at the end of the work shift. Measurement of Cr6 concentrations in the workers' breathing zone was performed using the NIOSH Methods 7600. Urine Cr levels were determined by atomic absorption spectrophotometry, with a graphite furnace (Shimadsu, AA680). B2M and NAG were measured by Kits.

Results: Overall, geometric mean of hexavalent chromium concentrations in the breathing zone was significantly higher among chrome platers (14.577 μg/m3) compared to zinc platers (0.862 μg/m3, p<0.001). Moreover, the mean urine Cr concentrations were higher in chrome platers (9.198 vs. 1.811 μg / g creatinine, p<0.001). Similarly, there were significant differences between mean NAG in chrome platers (12.608IU/gr creatinine) and zinc platers (6.824 IU/g creatinine, p<0.001). Differences in B2M concentrations were not significant (p>0.05). A significant correlation was found between Cr6 concentrations in the chrome platers' breathing zone and their urinary chromium levels (r= 0.838, p<0.001). A similar association was found between concentrations of Cr6 and NAG in the breathing zone (r= 0.304, p<0.05).

Conclusion: As urinary B2M concentration did not change significantly, it may not be a sensitive indicator in evaluating exposure to hexavalent chromium. There were significant differences between mean urinary Cr and NAG concentrations in the two groups. The significant correlations between Cr and NAG concentrations indicate that these markers may be suitable indicators of exposure to hexavalent chromium. Our results indicate that NAG is an early indicator of renal dysfunction in chrome platers.

---

Background and Aim: Lead is a toxic metal used in different industries and occupational and environmental exposure to it is quite likely to occur. Because of its high potential toxicity, serious damages to those exposed to it are common. Since the ceramic industry, in which lead is used, is considered a domestic industry in Iran, in this study occupational exposure of glaze workers to lead was assessed in a ceramic industry.

Materials and Methods: A total of 55 glaze workers (39 tillers and 16 potters) were selected as the case group. Association of lead concentration with several variables, including work shift, work type, ventilation system, and the number of extra work hours during the previous month, was determined. A sampling pump (SKC Co.) and ester cellulose filters with a pore size of 0.8 µm, 37 mm in diameter, were used for sampling. The flow-rate was adjusted at 2 l/min based on the NIOSH 7300 method. After sampling, filters were transferred to the laboratory and digested in a mixture of nitric acid and per chlorate solution (4:1) and analyzed by ICP-AES. To minimize probable errors and pollution during sampling and sample handling, samples were also taken from employees in the administration department to serve as control. Spiro metric tests were performed on both the case and the control groups.

Results: The lead concentrations were higher than the threshold limit value (TLV) (0.17 mg/m). Independent t-test showed that there was a significant relation between concentration of the lead present in the breathing zone air and 2 independent variables, including shifts work (morning and afternoon) and the ventilation system among tillers. Also, based on the one-way ANOVA, there was a significant relation between concentration of the lead present in the breathing zone and the number of extra working hours over the shift.

Conclusion: The mean lead concentration in the breathing zone was higher than the respective TLV. Considering the hazardous nature of lead, protective measures─ personal, occupational and environmental─ should be taken. Moreover, clinical examination of job applicants at the time of employment, as well as periodic examinations and Spiro metric tests on the workers, are also strongly recommended.

---

Background and Aim: Wearing high-heeled shoes increases the height of the center of gravity and takes the line of gravity away from the center of the base of support. This may result in the loss of body balance. In this study the effect of 3 heel heights on the static and dynamic postural stability in healthy young women was investigated.

Materials and Methods: In this cross-over quasi-experimental study with repeated measures, three dynamic indices of anteroposterior, mediolateral, and overall stability were determined using Biodex stabilometer and static stability using a modified CTSIB test. The measurements were made at 4 conditions of the feet, i. e., barefoot, and wearing shoes with a heel height of 3, 5, or 7 centimeters.

Results: The mean static stability index in the barefoot condition was significantly different from that in any the 3 conditions of wearing heels. With the eyes closed, the most unstable condition was in the case of the 7-cm heel, which caused also the most unstable dynamic condition the differences were all statistically significant.

Conclusion: The findings indicate that postural instability increases with increases in the height of shoe heels. On the whole, considering both the static and dynamic stability, the 3-cm heel can be recommended as the optimum-height heel.

---

Background and Aim:  Shift work may induce adverse effects such as health problems on human life. The purpose of this study was to investigate shift work-related health problems and their associated risk factors among workers of petrochemical industries.

Materials and Methods: This cross-sectional study was carried out in 21 petrochemical companies affiliated to the National Petrochemical Industries Company, Iran. The study population consisted of 3580 workers (44.2% shift- and 55.8% day-workers). Data were collected on demographic characteristics, shift schedules, and health problems using anonymous questionnaires. Statistical analyses and modeling were performed using SPSS version 11.5.

Results: The mean age of the day-workers with a job tenure of 8.87±7.22 years and of the shift-workers with a job tenure of 8.22±7.02 years was 34.56±8.19 and 33.15±7.73 years, respectively. Analysis of the data showed that prevalence of health problems among shift-workers was higher than that of day-workers. Furthermore, based on multiple linear regression analysis, it was revealed that, in addition to shift-working itself, other variables such as long working-hours, type of employment, age, job tenure, education, and job title also had a role in creating problems.             

Conclusion: Although in the shift-working system the main risk factor associated with health problems among the workers is the work itself, there are also other risk factors, such as demographic and occupational variables.

---

Background and Aim: Iran National Polio Laboratory (NPL) is a member of the World Health Organization (WHO) Polio Laboratories Network. NPL receives stool specimens from acute flaccid paralysis (AFP) cases from all the provinces throughout Iran for poliovirus detection and identification. Furthermore, the NPL also detects non-polio enteroviruses (NPEVs) in these specimens.  Recently, NPEVs have come to be believed to be one of the most important causes of AFP following wild poliovirus.  This paper reports the prevalence of different types of NPEVs isolated from the specimens of AFP cases between 1995 and 2000.

Materials and Methods: Stool collection, virus detection and serotype identification were performed according to the WHO standard procedures.

Results: A total of 2180 stool specimens from AFP cases were received at the National Polio Laboratory. Coxsackie B viruse and echoviruses 6, 11, 7 and 13 had the highest frequency, identified in 23.7%, 14.4%, 12.7%, 11% and 10.2% of the NPEVs isolated from AFP cases, respectively. Four cases of echovirus 20 were identified, in 2 cases the patiets having died and in one the patient having been afflicted with residual paralysis. There have been no reports of death or residual paralysis (paralysis continuing after 60 days) due to echoviruse 20.

Conclusion:  Considering the upward trend of AFP cases in Iran, even after wild poliovirus eradication, studies are needed to determine the frequency and type identification of NPEVs and the relationship between NPEVs and residual paralysis in the post-eradication era (2000 onwards).

---

 Background and Aim: Sand flies are responsible for transmission of leishmaniasis, papatasi fever and carrion disease. Warning of sand fly population is the first step for the establishment of baseline data for the vector control operations of visceral leishmaniasis (VL). In order to attempt to the difference between species composition and bieocology of sand flies, the comparative research was carried out in west and east of Meshkinshahr district where having high and low prevalence of VL as well as mild semiarid and semiarid steppe climates respectively.

 Materials and Methods : Sand flies were biweekly collected using sticky paper traps from indoor and outdoor shelters from four villages at west and east of Meshkinshahr district. The specimens was removed from sticky paper traps and washed in acetone and preserved in 70% alcohol. The preserved sand flies were mounted using Puri’s media and identified using valid keys. The labeled specimens were deposited in Medical Entomology Museum, School of Public Health under code GC22ST6-93 .

 Results: During this study, totally 783 and 400 sand flies were respectively caught from indoor (19-27%) and outdoor (73-81%) of both at west and east. The sex ratios of collected sand flies were estimated 2.3 and 1.9. in latter areas. The genera percentage of sand flies were 66.3-64.5% for Phlebotomus and 33.7-35.5% for Sergentomyia compromising of 7 subgenera which included in 20 and 17 species respectively in west and east areas. For the first time, Se.sintoni and Se.mervynae was reported in Meshkinshahr district.

 Conclusion: The Ph.kandelakii and Ph.perfiliewi were introduced as prevalent species in the west area compared to the east. In the west area, activity duration and number of generation was higher than east. The prevalent species in the east area was Ph.papatasi. The high density of Ph.anderjevi was seen in both studied areas. The most proven vectors of visceral leishmaniasis were revealed in the west of Meshkinshahr district.

---

Background and Aim: Considering that a person’s identity in formed during adolescence and that such identity formation is of particular importance in this period and the many factors that play important roles in it, the present study was conducted to determine the factors related with identity formation among high school students in Mazandaran Province, Iran.
Materials and Methods: This was a descriptive-analytic cross-sectional study. The participants were 394 high school students in Mazandaran Province, Iran selected by random cluster sampling. Data were collected using 3 questionnaires, namely, the Benion and Adams Identity Scale Questionnaire (EOM-EIS-2), the Identification Factors Questionnaire and a Demographic Questionnaire. For data analysis, Wilcoxon, Spearman correlation and linear regression tests were used.
Results: Over half (51.8%) of the participants were girls and 48.2% boys. The results of regression analysis showed that the factors studied (family, personality, school, community and culture and media) could explain 22.7%, 11.2%, 10.5% and 21.2% of the variance in turbulent, early, delayed and advanced self-identification in adolescents, respectively.
Conclusion: Based on the results of this study, it is recommended to organize parenting and student training courses and make the school environment more favorable for the students, as well as include extracurricular activities in the school to help students identify themselves more easily.

---

Background and Aim: This was a 3-month cross-sectional study conducted from October to December 2021 on 170 people involved in food preparation and distribution in Haraz intercity road restaurants with the aim of measuring their knowledge, attitude and practice regarding food preparation and distribution.
Materials and Methods: The data collection tool was a questionnaire with two sections, that is, a researcher-made demographic questionnaire (age, gender, level of education, type of job in a restaurant, work experience, place of residence and history of attending training courses), and a section with questions about knowledge, attitude, and practice assessment based on the World Health Organization standards.
Results: Analysis of the data showed that 97.1%, 100% and 100% of the people had a good level of knowledge, a positive attitude and good practice, respectively. In addition, there were statistically significant relationships between knowledge and age, educational level and participation in educational courses.
Conclusion: The 25- to 40-year age group, people with university education and those with experience in participating in training courses were found to have the highest level of knowledge. The level of knowledge in key number four (keeping food at a safe temperature) and attitude and practice in key number 3 (full cooking) had the lowest averages. Also, considering that 82.4% of the people had not participated in any training courses, the need to hold appropriate training courses for them by the relevant agencies and motivate them to increase their knowledge and, subsequently, increase and improve their attitudes and practice can improve the situation.