Internet addiction and college students depression:an analysis of moderating mediating effects / 中国学校卫生

Objective@#To explore the mediating role played by college students social anxiety and social support in the relationship between internet addiction and depression.@*Methods@#A cluster random sampling method was used to conduct a questionnaire survey among 3 536 college students in three higher vocational colleges in Anhui Province. The content included general demographic characteristics, depression, Internet addiction, social support, and social anxiety. The Process program was used to mediate and analysis of regulation.@*Results@#Among the survey subjects, 1 552(43.90%) had depressive symptoms, including 561(45.65%) boys and 991(42.96%) girls.The total score of Internet addiction was significantly positively correlated with depression score(r=0.30, P<0.01); social anxiety(social fear, social avoidance) was positively correlated with depression(r=0.24, 0.27, P<0.01); social support(subjective support, objective support, support utilization) was significantly negatively correlated with depression(r=0.25, -0.23, -0.17, P<0.01). Conditional process analysis shows that social anxiety had a mediating role between internet addiction and depression(c'=0.06, P<0.01), and that Internet addiction and social anxiety were regulated by social support(β=-0.00，P=0.02).@*Conclusion@#By increasing the social support of college students to improve social anxiety, it might help to reduce the depression of college students caused by Internet addiction.

Estimated assessment of cumulative dietary exposure to organophosphorus residues from tea infusion in China

BACKGROUND@#China has the world's largest tea plantation area in the world. To sustain high yields of the tea, multiple pesticides are used on tea crops to control pests. Organophosphorus (OP) pesticides are among the most widely used types of agricultural pesticides in China. As tea is a significant potential source of exposure to pesticide residues, the public concern has increased in relation to pesticide residues found in tea in China. The aim of the study was to estimate cumulative dietary exposure to OP residues from tea infusion for Chinese tea consumers to determine whether exposure to OP residues from tea infusion is a cause of health concern for tea consumers in China.@*METHODS@#OP residue data were obtained from the China National Monitoring Program on Food Safety (2013-2014), encompassing 1687 tea samples from 12 provinces. Tea consumption data were obtained from the China National Nutrient and Health Survey (2002), comprising 506 tea consumers aged 15-82 years. The transfer rates of residues from tea leaves into tea infusions were obtained from the literature. The relative potency factor (RPF) approach was used to estimate acute cumulative exposure to 20 OP residues from tea infusion using methamidophos as the index compound. Dietary exposure was calculated in a probabilistic way.@*RESULTS@#For tea consumers, the mean and the 99.9th percentile (P99.9) of cumulative dietary exposure to OP residues from tea infusion equalled 0.08 and 1.08 μg/kg bw/d. When compared with the acute reference dose (ARfD), 10 μg/kg bw/d for methamidophos, this accounts for 0.8 and 10.8% of the ARfD.@*CONCLUSIONS@#Even when considering OP residues from vegetables, fruits and other foods, there are no health concerns based on acute dietary exposure to OP residues from tea infusion. However, it is necessary to strengthen the management of the OP pesticides used on tea in China to reduce the risk of chronic dietary exposure to OPs from tea infusion.

Probabilistic assessment of dietary exposure to both deoxynivalenol and zearalenone from cereal-based products in Chinese populations / 中华预防医学杂志

<p><b>OBJECTIVE</b>To elucidate the dietary exposure to deoxynivalenol (DON) and zearalenone (ZEN) from cereal-based products in Chinese populations using the probabilistic assessment approach.</p><p><b>METHODS</b>A total of 292 wheat flours and 347 corn-based products were collected from sampling sites of 107 supermarkets or farmers markets, which were randomly selected from 44 cities of 13 provinces in 2009 by the stratified cluster random sampling method. Then, DON and ZEN contamination levels in these samples above analyzed by UPLC-MS/MS in combination with the food consumption data of 68 959 respondents, who were divided into group 1 aged 3 to 13 years old, and group 2 aged 14 and over 14 years old (≥14 years old), obtained by China National Nutrition and Health Survey in 2002 were investigated. A probabilistic assessment model using Monte Carlo simulation was applied to derive the intake distribution of P(1)-P(99) percentile of dietary exposure to DON and ZEN. Meanwhile, all parameters related to dietary exposure to both toxins were compared with either the provisional maximum tolerable daily intake (PMTDI) of 1 µg·kg(-1)·d(-1) for DON, or the tolerable daily intake (TDI) of 0.25 µg·kg(-1)·d(-1) for ZEN in order to evaluate the risk of dietary intake of two toxins and find the minimum percentile of dietary exposure to these two toxins. The statistical differences of dietary exposure to these two toxins between two groups were achieved by t test.</p><p><b>RESULTS</b>The detection frequencies of DON in wheat flours and corn-based products were 100% (292/292) and 97.4% (338/347), respectively. A total of 21 out of 639 samples (wheat flours: 5/292, corn-based products: 16/347) were positive for DON at the levels exceeding the Chinese regulatory limit of 1 000 µg/kg for DON. And the detection frequencies of ZEN in wheat flours and corn-based products were 53.4% (156/292) and 87.6% (304/347), respectively.54 out of 347 corn-based products and no wheat flours were positive for ZEN at the levels exceeding the Chinese regulatory limit of 60 µg/kg for ZEN. Meanwhile, the mean values (95% CI) of the P(50), P(75), P(90), P(95), P(97.5) and P(99) percentile of dietary exposure to DON in populations of 3 to 13 years old were 0.170 (0.170-0.171), 0.762 (0.759-0.765), 2.066 (2.038-2.069), 3.515 (3.501-3.530), 5.342 (5.314-5.372), and 9.220 (9.155-9.279) µg · kg(-1)·d(-1), which were higher than those in populations of ≥14 years old (0.131 (0.130-0.131), 0.500 (0.498-0.501), 1.280 (1.276-1.285), 2.138 (2.128-2.14), 3.510 (3.494-3.527), and 5.512 (5.474-5.546) µg·kg(-1)·d(-1)), with t values of 87.19, 163.87, 164.66, 157.78, 105.47 and 96.31, and all P values less than 0.001. And the mean values (95% CI) of the P(50), P(75), P(90), P(95), P(97.5) and P(99) percentile of dietary exposure to ZEN in populations of 3 to 13 years old were 0.001 (0.001-0.001), 0.006 (0.006-0.006), 0.039 (0.038-0.039), 0.101 (0.100-0.101), 0.195 (0.194-0.197) and 0.378 (0.374-0.381) µg · kg(-1)·d(-1), which were also higher than those in populations of ≥14 years old (0.001 (0.001-0.001), 0.004 (0.004-0.004), 0.026 (0.026-0.026), 0.061 (0.060-0.061), 0.115 (0.115-0.116) and 0.232 (0.231-0.235) µg·kg(-1)·d(-1)) with T-values of 151.11, 73.80, 96.81, 100.81, 91.93 and 76.13, and all P values less than 0.001. Besides, the minimum percentile of dietary exposure to DON in populations of 3 to 13 years old and ≥14 years old exceeded the corresponding PMTDI of 1 µg·kg(-1)·d(-1) was found in the probability distribution of P(76) (99% percentile = 1.03 µg·kg(-1)·d(-1)) and P(84) (95% percentile = 1.01 µg·kg(-1)·d(-1)) percentile, respectively. And the minimum percentile of dietary exposure to ZEN in populations of 3 to 13 years old and ≥14 years old exceeded the corresponding TDI of 0.25 µg·kg(-1)·d(-1) was found in the probability distribution of P(97) (95% percentile = 0.25 µg·kg(-1)·d(-1)) and P(98) (90% percentile = 0.26 µg·kg(-1)·d(-1)) percentile, respectively.</p><p><b>CONCLUSION</b>The contamination levels of DON and ZEN in wheat flours and corn-based products and the risk of dietary exposure to both DON and ZEN in populations in Chinese populations were at relatively low levels. The dietary exposure to both DON and ZEN in populations of 3 to 13 years old was higher than those in populations of ≥14 years old . Populations of 3 to 13 years old were the populations at the high risk of dietary exposure to both mycotoxins.</p>