Effects of long-term exposure to hydrogen sulfide on human red blood cells.

BACKGROUND: Hydrogen sulfide (H2S) exhibits both physiological and toxicological roles in the biological systems. Acute exposure to high levels of H2S is life threatening while long-term exposure to ambient levels of H2S elicits human health effects. OBJECTIVE: To study the harmful effects of long-term exposure to low levels of H2S on human blood cells. METHODS: 110 adult workers from Iran who were occupationally exposed to 0-90 ppb H2S for 1-30 years were studied. The participants aged between 18 and 60 years and were exposed directly or indirectly to sulfur compounds (exposed group). The origin of H2S was natural gas processing plants. A control group consisting of 110 males who were not in contact with H2S was also studied. For all participants, hematological profile including total hemoglobin and red blood cell count and sulfhemoglobin, methemoglobin levels were measured. RESULTS: Among all parameters evaluated in this study the mean methemoglobin and sulfhemoglobin levels were significantly higher among workers who were exposed to sulfur compounds than the control group. Major differences throughout the study period for sulfhemoglobinemia among exposed groups were observed. CONCLUSION: Long-term exposure to even low levels of H2S in workplaces may have potential harmful effects on human health.

Oxidative stress induced in the workers of natural gas refineries, no role for GSTM1 and GSTT1 polymorphisms.

Oxidative stress has an important role in the pathophysiology of many occupational diseases. In this controlled exposure study, the intensity of oxidative stress biomarkers was assessed in the workers of natural sweet and sour gas refineries (SwGR and SoGR, respectively) and compared with controls. In addition, the role of gluthatione S-transferase M1 (GSTM1)-null and GSTT1-null polymorphisms on the intensity of oxidative stress and liver function tests (LFTs) was investigated. Blood samples were taken and measured for lipid peroxidation (LPO) level, total antioxidant capacity (TAC) and total thiol molecules (TTMs). GSTM1- and GSTT1-null genotypes were determined using polymerase chain reaction. LPO was significantly (p < 0.05) higher in the workers of SoGR. TAC was significantly lower in SwGR subjects (p < 0.001). TTMs were significantly lower in SoGR and SwGR subjects. Among LFTs, activities of aspartate aminotransferase and alanine aminotransferase but not alkaline phosphatase were elevated significantly (p < 0.001) in SoGR subjects. Multivariate linear regression revealed no association between studied polymorphisms, oxidative stress biomarkers, and LFTs. These results indicate that working in the SoGR and SwGR can lead to oxidative stress and abnormal LFTs. Continuous monitoring of natural gas workers for probable ongoing problems is therefore suggested.

Nutritional status and serum zinc and selenium levels in Iranian HIV infected individuals.

BACKGROUND: Human immunodeficiency virus infected individuals are prone to malnutrition due to increased energy requirements, enteropathy and increased catabolism. Trace elements such as zinc and selenium have major role in maintaining a healthy immune system. This study was designed to evaluate the nutritional status of Iranian subjects who were newly diagnosed with human immunodeficiency virus infection and to compare serum level of zinc and selenium in these patients with those of the sex and aged match healthy subjects. METHODS: After an interview and physical examination, nutritional assessment was done based on clinical and anthropometric parameters. Body mass index (normal range 18.5-27 kg/m2 based on age) of less than 16, 16-16.9 and 17-18.4 kg/m2 were considered as severe, moderate and mild malnutrition respectively. Serum level of zinc and selenium were measured by graphite furnace atomic absorption. RESULTS: Severe, moderate and mild malnutrition were detected in 15%, 38% and 24% of human immunodeficiency virus infected individuals respectively. Compared with the healthy control group, serum level of zinc and selenium in the human immunodeficiency virus infected subjects were significantly lower (P = 0.01 and P = 0.02 respectively). CONCLUSION: Malnutrition found to be prevalent in Iranian human immunodeficiency virus infected individuals and low serum zinc and selenium levels are common in this population.

Perceived competence and school adjustment of hearing impaired children in mainstream primary school settings.

BACKGROUND: Although educational main streaming of children with special needs formally began in Iran since 1992 there is little information whether hearing impaired children feel competent in regular schools. METHODS: To determine the perceived competence and school adjustment of hearing impaired children in mainstream primary school settings, the self-perception profile was administered to 60 mainstreamed hard of hearing children and 60 classmates with normal hearing matched for gender by a single interviewer. The instrument comprised 28 items, 23 of which were similar to those of 'adapted test Image for children with cochlear implants' asking children about their feelings about their own cognitive, physical, socio-emotional and communication competence and school adjustment. The Cronbach alpha coefficient for the instrument was 0.93. RESULTS: Hard of hearing children rated their competence significantly poorer than their hearing classmates for all domains. Mean differences for the five domains ranged from 0.48 (for physical competence) to 0.90 (for school adjustment) on a scale of 1-4. There were no significant differences between girls' and boys' competence, in either the hearing or the hearing impaired groups. Classifying overall scores for perceived competence into four groups ('poor competence', 'low competence', 'moderate competence' and 'high competence'), 23.4% of hearing impaired children but none of the hearing classmates rated themselves as having low or poor competence. On the other hand 85% of hearing children and only 18.3% of hearing impaired children rated themselves as highly competent. CONCLUSION: We suggest that periodical assessments of mainstreamed children might help to identify those children who are having difficulty adapting to their environment.