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Background and purpose: Due to the considerable increase in the environmental pollution, especially with oil, during the last 50 years, the international community and international organizations have made remarkable efforts to reduce this pollution. The result was regulating of at least 200 international conventions on environmental issues. The purpose of this study was to evaluate the oil pollution process despite the international conventions on the elimination of oil pollution (1992-2009). Materials and methods: Oil pollution levels were obtained from official sources meanwhile, the production of crude oil per day was calculated and then was compared with the amount of oil pollution in the same period. Comparing the two types of data, the percentage of pollution was calculated. For drawing graphs and describing statistical data, the Microsoft Excel spreadsheet software (Version 2007) was used. Results: Changes in the pollution were investigated between 1992 and 2009 during which 16-fold international conventions for the elimination of oil pollution were approved by the international community. Pollution rate in these years indicated a decline with weak swing and oil pollution percentage has reduced from 9.56 percent of the total oil production in 1992 to 0.08 in 2009. Conclusion: Although international conventions and countries membership has had a positive effect on reducing oil pollution, it was not enough to completely eliminate the pollution and needs safeguards in international agreements as well as monitoring performed by international bodies.

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Background and purpose: Fish is an important source of protein for human and is an important part of the diet, so, studying the concentration of heavy metals in commercial fish could be helpful in evaluating the risk of fish consumption.
Materials and methods: A total of 60 fish samples from four different species including anchovy, white, perch, and trout was randomly collected in fall 2016 from Rast Fish Market. After sample preparation and microwave digestion, the amount of heavy metals were determined by inductively coupled plasma optical emission spectrometer (ICP-OES). The US Environmental Protection Agency's (EPA) method was used to estimate the health risks associated with exposure to heavy metals in fish samples.
Results: The highest concentrations of heavy metals included mercury in whitefish (1.29 ± 0.23 μg/g), lead in whitefish (4.54 ± 0.75 μg/g), cadmium in salmon (0.07 ± 0.01 μg/g), arsenic in whitefish (1.36± 0.15 μg/g), nickel in whitefish (0.61 ± 0.07 μg/g), tin in whitefish (0.63 ± 0.05 μg/g), and chromium in fish perch (1.52 ± 0.04 μg/g). Non-cancer risk for all heavy metals in all the species was less than 1.
Conclusion: The concentration of metals in species studied was in acceptable level, indicating no risk of toxicity. According to current results, fish consumption does not lead to adverse health effects.