| Objective: This study estimated the levels of heavy metal contents in vegetables in Pingquan County and the resultant health risks posed to the population through consumption, with the aim of providing a scientific framework for management and supervision of food safety to protect the health of the residents.Methods:1Four major areas were chosen from Pingquan County（including the Pingquan County） for the research based on the type and availability of the vegetables to be studied.409 samples of vegetables（including 4 kinds and 31 types） were purchased from the market or obtained from farmers; and the sampling site, date, id number, name and species of the vegetable were recorded immediately.2The concentrations of arsenic（As）, cadmium（Cd）, chromium（Cr）, mercury（Hg）, lead（Pb）, copper（Cu）, and zinc（Zn） in the vegetables were analyzed by inductively coupled plasma mass spectrometry and the results were compared with the Chinese food contaminants limitation standards（GB2762-2012）.3The levels of heavy metal contamination in the samples were evaluated using pollution indices and rating standard of green vegetables.4The 2000 US Environmental Protection Agency（USEPA） proposed target risk index（the target hazard quotient, THQ） was used to evaluate the average weight of children and adults within the population under exposure to the health risks of heavy metal pollution.5ICRP（International Commission on Radiological Protection） recommendation based on the health risk hazards of carcinogenic contaminants（heavy metals） was used to assess the carcinogenic risk hazards of the vegetable samples.6SPSS19.0 and Excel were used for the data analyses and processing, thrugh descriptive statistics, and the results were presented as mean and standard deviation.Results:1409 samples were collected from Pingquan County, including 120 leafy vegetables, 195 melon and fruit vegetables, as well as 38 root and alliaceous vegetables. The content of Pb, Hg, Cr and Cd were higher in the studied samples than the national standard, while the levels of the other 3 heavy metals（As, Cu, Zn） were in line with the national standard. Among these samples, the exceeding rate of heavy metals in the leafy, root, fruit and alliaceous vegetables were 7.50%（9/120）, 5.26%（2/38）, 16.41%（32/195） and 19.64%（11/56） respectively.2The individual pollution indices of Cr in cabbages and that of Hg in purple cabbages, cucumbers, chili peppers and cowpeas were beyond 0.7（level 2, safe grade） whiles the pollution indices of alliaceous vegetables and root vegetables were all within the range of 0.7（excellent grade）.The integrated pollution index of 4 kinds of vegetables（the leafy, root, fruit and alliaceous vegetables） were all below 0.7, which indicated that the level of pollution was minimal（safety）.3The following samples were found to have the THQ value of single heavy metal（Cr） greater than 1:total=3.67%（15/409）: 0.73%（3/409） for adults and 2.94%（12/409） for children; leaf vegetables=6.67%（8/120）: 1.67%（2/120）for adults and 5.00%（6/120） for children; melon and fruit=1.54%（3/195）:1.54%（3/195）for children;root vegetables=2.63%（1/38）: 2.63%（1/38） for children; alliaceous vegetables=5.36%（3/56）: 1.79%（1/56） for adults and 3.57%（2/56） for children. On the basis of TTHQ assessment, the number of samples with multiple heavy metal concentration greater than 1 were 190（46.45%）,including 16 samples（3.91%） for adults and 174 samples（42.54%）for children.4 Average annual health risk level for each Pingquan County resident caused by eating vegetables was 5.145×10-5·a-1 due to As pollution, 3.460×10-5·a-1 due to Cd pollution, 4.315×10-7·a-1 due to Cr pollution,6.223×10-8·a-1 due to Hg pollution, 4.043×10-7·a-1 due to Pb pollution,1.579×10-7·a-1 due to Cu pollution and 1.894×10-8·a-1 due to Zn pollution.Conclusions:1The mean concentrations of Pb and Hg in the samples were significantly higher than the standard permissible levels. Comparatively, root and fruit vegetables are more likely to have higher concentrations of heavy metals than leafy and alliaceous vegetables. The result shows that the contents of heavy metals in vegetables analyzed in Pingquan County were found to be within the safe limit based on the national criterion for classification; so the vegetables produced in the survey area can be classified as pollution-free vegetables.2The high concentration of Hg identified in most of the vegetables classifies Hg as the highest single heavy metal pollutant. On the contrary, As was found to be the lowest single heavy metal pollutant because the concentrations of As in all the samples were in line with the national standard. The comprehensive pollution index shows that melon and fruit vegetables have higher score than the other kinds of vegetables.3Four kinds of vegetables produced in Pingquan County tend to be safe for adults and children based on the THQ measurement of the health risks of single heavy metal pollution. Leafy vegetables and alliaceous vegetables were however, found to be dangerous for children based on the THQ assessment of health risks posed by multiple heavy metal pollution. The overall health risks of heavy metals were mainly due to Cr pollution.4Average annual health risk posed to each resident in Pingquan County by heavy metal contamination was within the standard range, so the vegetables produced in Pingquan County were generally found to be safe for human consumption... |
