Shark meat is used as sacrificial food in Gyeongsangbuk-do, and is a major source of dietary mercury. This study aimed to evaluate the effects of shark meat intake or the ritual of Jesa on blood mercury levels within workers living in Gyeongsangbuk-do.

This study was conducted from September 2016 to October 2016 in two cities of Gyeongsangbuk-do. To compare the differences between urban and rural areas, two workplaces each in Daegu as the urban area and Yeongcheon as the rural area were selected. General characteristics and characteristics related to shark meat consumption of the workers were acquired by personal interviews during their health examination. Blood mercury concentrations were analyzed by the gold amalgamation method using a direct mercury analyzer (DMA-80; Milestone Inc., Shelton, CT, USA).

The shark consumption group had a higher blood mercury concentration than the non-consumption group. The levels of blood mercury increased with the frequency, annual intake, as well as most recent date of shark meat consumption. Moreover, the levels of mercury in blood increased according to the annual frequency of participation in Jesa (times per year) and the annual frequency of shark meat consumption during Jesa (times per year).

Shark meat intake and the ritual of Jesa contributed to an increase in the blood mercury levels of workers in Gyeongsangbuk-do. Therefore, it is necessary to evaluate dietary exposure, occupational as well as other factors that may influence blood mercury concentrations in workers during their health examination, particularly in regions with high mercury exposures.

It is thought that computer familiarity has increased significantly since 2004 as well as the use of computers. This study aimed to evaluate the effects of computer familiarity and types of keyboard and computer on the performance of the Korean computerized neurobehavioral test (KCNT), and to identify which parameters of KCNT were affected by aforementioned factors.

A total of 85 subjects were classified into three groups of computer familiarity by Korean typing speed. Their age, gender and the level of education were also collected. The parameters of KCNT included simple reaction time, choice reaction time, addition, symbol digit, and finger tapping speed. The test was conducted using three types of computers: a laptop computer, a laptop computer with a simplified keyboard, and a desktop computer with a simplified keyboard.

Parameters including the simple reaction time, choice reaction time, addition, and symbol digit, and the finger tapping speed of non-dominant hand showed no significant differences in the results among the three groups by computer familiarity after age and educational years were controlled as covariates. The mean reaction time of the simple reaction time and the choice reaction time with a simplified keyboard was significantly shorter compared to that with a typical keyboard. With regard to type of computer, the mean reaction time of the simple reaction time and the choice reaction time was significantly reduced when performed with the desktop computer with a simplified keyboard.

Unlike previous study results, the choice reaction time, the addition, and the finger tapping speed of dominant hand were the only parameters affected by the computer familiarity. Both the type of keyboard and the type of computer significantly influenced the simple reaction time and the choice reaction time. Therefore, it is recommended to use a desktop computer with a simplified keyboard for such parameters.

Gejang (marinated crab) is a favorite traditional food and a main source of crab intake among Koreans. The present study aimed to identify the possibility of cadmium inflow to the body through gejang; accordingly, the relationship between gejang intake frequency and amount, and blood cadmium concentrations was investigated.

Using data from the first Korea National Health and Nutrition Examination Survey in the sixth period in 2013, means and standard errors of blood cadmium concentrations in relation to gejang intake frequency and amount, as well as the monthly intake of gejang, were obtained from 1381 participants for whom data regarding blood cadmium concentration measurements was available.

After adjustment for confounding factors, a gejang intake frequency of four or fewer times per week and a monthly intake of 200 cm³ or less had no significant effect on blood cadmium concentrations. However, participants with gejang intake of at least five times per week had a weighted mean cadmium concentration of 2.12 μg/L (p < 0.001), and participants who had a gejang monthly intake of more than 200 cm³ had a weighted mean cadmium concentration of 1.76 μg/L (p < 0.001).

These results suggest that to minimize the effect of gejang consumption on blood cadmium level, gejang intake should be limited to four or less times per week and 200 cm³ or less per month. Weekly intake of at least five times and monthly intake of more than 200 cm³ may increase blood cadmium levels.