Formaldehyde is a colorless and highly irritating substance that is used as a preservative and chemical fixative in tissue processing in pathological laboratories. Formaldehyde is mutagenic and is classified by the IARC as the definitive carcinogen (A1 group). This cross-sectional descriptive-analytical study was performed to determine the respiratory exposure of 60 employees of pathology labs with formaldehyde and to estimate carcinogenic and non-carcinogenic risk in Iran in 2018-2019. Occupational exposure to formaldehyde was assessed in summer season using the NIOSH 3500 method and a personal sampler with flow of 1 l/min connected to two Glass Midget Impingers containing 20 ml of 1% sodium bisulfate solution. The respiratory symptoms questionnaire provided by the American Thoracic Society was used to assess the health effects of formaldehyde exposure. The carcinogenic and non-carcinogenic risk assessment of inhaled exposure to formaldehyde was also performed using the USA Environmental Protection Agency (OEHHA) method. The mean respiratory exposure of employees to formaldehyde was 0.64 mg/m 3 (range: 0.1474 to 1.3757). Occupational exposure in 28.3% (n = 17) of employees was above the OSHA recommended range. Wheezing (24%), burning eyes (25%), and cough (21.7%) were the most prevalent health problems. The mean ± SD of the carcinogenic risk among the employees was 3.45 × 10 −4 ± 2.27 × 10 −4 . The highest mean of carcinogenic risk was found in lab workers (4.44 × 10 −4 ). Given the high level of carcinogenic and non-carcinogenic risk of respiratory exposure to formaldehyde in pathological employees, especially lab worker, the use of management controls, engineering controls, and respiratory protection equipment to reduce exposure levels of all workers to less than the allowed exposure limits seems necessary.

Pharmaceutical wastewater is one of the major complex and toxic industrial effluents containing little or no biodegradable organic matters. In this study, H2O2/UV based advanced oxidation process (AOP) was used to remove organic materials from pharmaceutical industry effluent. For the chemical oxygen demand (COD) removal radiation of medium pressure mercury vapor UV lamp was used in the presence of hydrogen peroxide (H2O2/UV). Results indicated that the efficiency of COD removal depends on the initial concentration of H2O2, oxidation time and pH. The efficiency of COD removal at low H2O2 concentration was very low even coupled with UV light, which can be attributed to the low generation of hydroxyl radicals (OH •). At high concentration of H2O2 (500 mg/dm 3) and optimum pH (pH = 4), 87.6% removal efficiency could be achieved during 70 min oxidation. For high concentration of H2O2 (500 mg/dm 3) at pH 3 and 7, the maximum COD removal efficiency was 28.5% and 15.2% respectively, indicating significant roles of pH and H2O2 concentration in the process of COD removal.

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Riedel's thyroiditis is a rare inflammatory disease of the thyroid gland and has been reported in 0.05% of thyroid surgeries. Herein we report two cases of Riedel's thyroiditis with variable clinical presentations. One of these cases was a 51-year-old man who was presented with hypothyroidism and the other a 17-year-old young male with thyrotoxicosis. In these cases, age may be a determining factor in presenting symptoms and signs, disease process, and response to treatment.

Our results suggest that HFE mutations C282Y and H63D are more frequent in Iranian BTM patients than in the normal population, causing no significant changes in serum ferritin level.

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