Hongbin Cao

Heavy metals in rice and garden vegetables and their potential health risks to inhabitants in the vicinity of an industrial zone in Jiangsu, China

Contamination of soil and agricultural products by heavy metals resulting from rapid industrial development has caused major concern. In this study, we investigated heavy metal (Cu, Zn, Pb, Cr, Hg and Cd) concentrations in rice and garden vegetables, as well as in cultivated soils, in a rural-industrial developed region in southern Jiangsu, China, and estimated the potential health risks of metals to the inhabitants via consumption of locally produced rice and garden vegetables. A questionnaire-based survey on dietary consumption rates of foodstuffs showed that rice and vegetables accounted for 64% of total foodstuffs consumed, and over 60% of rice and vegetables were grown in the local region. Average concentrations of Cr, Cu, Zn, Cd, Hg and Pb were 0.75, 2.64, 12.00, 0.014, 0.006 and 0.054 mg/kg dw (dry weight) in rice and were 0.67, 1.18, 4.34, 0.011, 0.002 and 0.058 mg/kg fw (fresh weight) in garden vegetables, respectively. These values were all below the maximum allowable concentration in food in China except for Cr in vegetables. Leafy vegetables had higher metal concentrations than solanaceae vegetables. Average daily intake of Cr, Cu, Zn, Cd, Hg and Pb through the consumption of rice and garden vegetables were 5.66, 16.90, 74.21, 0.10, 0.04 and 0.43 microg/(kg x day), respectively. Although Hazard Quotient values of individual metals were all lower than 1, when all six metal intakes via self-planted rice and garden vegetables were combined, the Hazard Index value was close to 1. Potential health risks from exposure to heavy metals in self-planted rice and garden vegetables need more attention.

Exposure and risk assessment for aluminium and heavy metals in Puerh tea

As the consumption of Puerh tea is booming because of its multiple health-promoting effects, the possible health risks resulting from long-term exposure to metals contained in this tea need to be evaluated. To assess the human risk associated with drinking Puerh tea, concentrations of aluminium, lead, cadmium, mercury, zinc, copper and arsenic were determined in samples of Puerh tea, tea leaves from the plants, and planted soil collected from the Yunnan province, China. Site-specific exposure parameters such as body weight and consumption rate of Puerh tea were investigated in Kunming and Puer cities using face-to-face surveys. Health risks were evaluated for the inhabitants of Kunming and Puer cities by gender and by age groups. Although the Puerh tea plant easily absorbs aluminium from soil, the concentrations of Al and six other elements in Puerh tea were all far below the safety concentration limits of China. Both the HQ (Hazard Quotient) values for single elements and the HI (Hazard Index) value for all seven elements were far below one, indicating no non-carcinogenic risks from these seven elements for inhabitants of Kunming and Puer under the current consumption rates of Puerh tea. However, probabilistic estimation of carcinogenic risk shows that the 95th percentile carcinogenic rate of arsenic in Puerh tea approaches the accepted risk level of 10(-4) for the highest exposure group. Therefore, the arsenic in Puerh tea is of concern.

Arsenic accumulation in Scutellaria baicalensis Georgi and its effects on plant growth and pharmaceutical components

Scutellaria baicalensis Georgi is a traditional Chinese medicinal plant. The effects of arsenic (As) on the growth and the formation of pharmaceutical components of S. baicalensis, and the uptake and accumulation of As by S. baicalensis were investigated using a field pot-culture experiment. The results show that spiking low concentrations of As (</=100mgkg(-1)) into soils can hasten the growth and development of the roots. High levels of As, however, reduced plant growth. The concentrations of five flavone components were not significantly affected by spiking low concentrations of As (</=200mgkg(-1)) into soils. High levels of As inhibited the generation of baicalin and wogoninside, but facilitated the generation of baicalein, wogonin and oroxylin A in S. baicalensis Georgi. The concentration of As in each part of the plant was proportional to the concentration of As spiked into the soil. The application of phosphorus (P) to the soil promoted the uptake and accumulation of As in the roots of the plant, but this synergistic effect became weaker with the incremental addition of P. Dry biomass did not change in response to low levels of P addition (</=200mgkg(-1)) to soils, but it increased significantly under high levels of P. Based on the results of both this pot-culture experiment and human health risk assessments, maximum safety limits of 2.0mgkg(-1) of As in the roots of S. baicalensis Georgi and 70mgkg(-1) of As in cultivated soils are suggested.

Urbanization-related changes in soil PAHs and potential health risks of emission sources in a township in Southern Jiangsu, China

Urbanization, which is characterized by population aggregation, industrial development, and increased traffic load, may change local polycyclic aromatic hydrocarbons (PAH) emissions and their associated health risks. To investigate these changes, we collected soil samples in 2009 and 2014 in a rapidly developing small town in Southern Jiangsu (China) and measured the concentrations of 16 PAHs via gas chromatography-mass spectrometry. Although the total PAHs decreased from 4586.6 to 640.6ng/g, the concentrations of the high-molecular-weight PAHs benzo(b)fluoranthene and benzo(a)pyrene increased due to changes in the PAH sources. Source apportionment by positive matrix factorization indicated that the two sources responsible for the highest soil PAH contributions changed from biomass combustion (42%) and coal combustion (32%) in 2009 to coal, biomass and natural gas combustion (35%) and diesel combustion (33%) in 2014. However, the two sources with the highest associated health risks were diesel and gasoline combustion in both years. The incremental lifetime cancer risk for residents exposed to PAHs in the soil via incidental ingestion and dermal contact decreased from 1.75×10-6 to 1.60×10-6. The ban on open burning of straw and the substitution of coal with natural gas offset the PAH health risks due to increased urbanization.

Determination of the Heavy Metal Levels in Panax notoginseng and the Implications for Human Health Risk Assessment

ABSTRACT High levels of heavy metals in Panax notoginseng (Sanchi), a valued traditional Chinese medicine, have drawn increasing concern regarding the safe usage of Sanchi preparations. Here, we measured the concentrations of six heavy metals in Sanchi samples from 20 major plantations, investigated the pharmaceutical processes and usages of Sanchi preparations, and assessed the associated potential health risks to consumers. The average concentrations of chromium (Cr), copper (Cu), nickel (Ni), zinc (Zn), lead (Pb), and arsenic (As) in the Sanchi samples were 2.7, 3.7, 6.2, 22.1, 2.0, and 1.4 mg/kg, respectively. The hazard quotients (HQs) for these six single metals and the hazard index (HI) of these metals’ combination were all far less than 1, indicating the absence of a non-carcinogenic health hazard to consumers. The carcinogenic risk of As was 2.1 × 10−6, which is higher than the allowable level suggested by the U.S. Environmental Protection Agency but less than the level suggested by the World Health Organization (WHO). The probabilities of consumers’ exposure due to daily medicine consumption exceeding the allowable daily intakes from medicine (ADIsdrug, 1% of the ADI) suggested by the WHO were 0.0%, 0.1%, 0.1%, 0.0%, 1.6%, and 27.3% for Cr, Ni, Cu, Zn, Pb, and As, respectively.

Biochemical and histopathological effects of subchronic oral exposure of rats to a mixture of five toxic elements

Arsenic, cadmium, lead, chromium and mercury are toxic elements that occur with high frequency in the soil and thus in agricultural products in China. To explore their combined effects, thirty male and thirty female Sprague-Dawley rats were orally exposed to a mixture of these elements at high dose (2.11, 6.47, 72.82, 2.26 and 2.71 mg/kg bw/day), medium dose (1/10 of the high dose) and low dose (1/100 of the high dose) via their drinking water for 90 days. The results revealed that BUN increased in all rats given the high dose, and serum creatinine increased in female rats given the medium dose. Decreased ALP levels in all treated male rats accompanied decreased RBC counts. In the high dose group, serum albumin, globulin and total protein content decreased in male rats, whereas serum ALT levels increased in female rats. Pathological changes were observed in the hepatocytes and renal tubules of all rats given the high dose, and the numbers of spermatogenic cells and sperm significantly decreased in both the epididymides and testes of the rats given the high dose. Abnormalities were observed earlier and more clearly in the males than in the females under combined exposure.

Heavy Metals in Food Crops and the Associated Potential for Combined Health Risk due to Interactions between Metals

ABSTRACT Chromium, copper, zinc, cadmium, mercury, and lead are frequently found at high concentrations simultaneously in the soils of contaminated sites. Greater-than-additive and less-than-additive interactions have been found between pairs of these metals of concern. We performed a target-organ toxicity dose (TTD) approach and a weight-of-evidence (WOE) analysis to estimate the potential cumulative health risks of multiple metals accounting for joint toxic effects. As a case study, dietary exposure via consumption of locally planted rice and vegetables was assessed along with the associated combined health risk of the six metals for inhabitants in the vicinity of an industrial zone in southern Jiangsu, China. The Hazard Index (HI) values of each endpoint for neurological, renal, cardiovascular, hematological, testicular, and hepatic effects were 0.61, 0.54, 0.12, 0.48, 0.05, and 0.12, respectively, all less than 1. Interactions between Cd and Pb were greater than additive for testicular effects with relatively high confidence. Given that the HI value for testicular effects was only 0.05 and most interactions between metals were less-than-additive, a non-carcinogenic health hazard from exposure to heavy metals in locally planted rice and garden vegetables is unlikely.

Emission control priority of PM2.5-bound heavy metals in different seasons: A comprehensive analysis from health risk perspective

Source-specific health risks of PM2.5-bound metals were analyzed for emission control by integrating source apportionment with health risk assessments of residents affected via inhalation pathways. A total of 218 daily PM2.5 samples were collected in 2016 in the central urban district of Beijing, China. Analyses showed that the mean annual concentrations of total heavy metals (THMs) and PM2.5 were 0.39 and 104.37 μg m-3, respectively. The heating season had significantly higher concentrations of THMs and PM2.5 (0.61, 134 μg m-3) than the non-heating season (0.27, 88.1 μg m-3) (p < 0.05). Among all metals, arsenic had the largest incremental cancer risk of 7.04 × 10-6. Six sources were identified by positive matrix factorization combined with conditional probability function and potential source contribution function analyses. The order of contribution to PM2.5-bound metal concentrations was resuspended dust (61.0%), traffic emission (16.3%), Cu-related industry (14.1%), coal combustion (3.7%), Cr-related industry (3.4%), and fuel oil combustion (1.6%). During the heating season, the contribution of coal combustion decreased slightly, which may have been due to the countermeasure of substituting coal for gas or electric heat in 2016. However, in terms of cancer risk contribution, coal combustion was the top contributor in both heating (3.5 × 10-6, 51.6%) and non-heating (2.7 × 10-6, 59.6%) seasons due to high attributable contents of the toxic metals, As, Cd and Pb. The Cr-related and Cu-related industries were the next controlled sources in the heating and non-heating seasons, respectively. Thus, these sources should receive priority in the development of control measures.

Impacts of silicon addition on arsenic fractionation in soils and arsenic speciation in Panax notoginseng planted in soils contaminated with high levels of arsenic

Arsenic (As) is a well-known carcinogenic substance whose biological toxicity in soils and plants depends on its concentration and chemical forms. Silicon (Si) generally can alleviate biotic and abiotic stresses, including As stress. However, its effects vary depending on As chemical form, plant species and other factors. A pot experiment was performed to investigate the effects of Si addition on the content and forms of As in red soil and its uptake, transport and speciation in Panax notoginseng. The results showed that additions of 25 and 75 mg kg-1 of Si both significantly decreased the concentrations of water-soluble As and exchangeable As in soil and therefore decreased the bioavailability of soil As. However, the As uptake by Panax notoginseng (PN) was increased, which resulted in increases in As concentration by 18.5% and 2.3% in roots and by 56.7% and 58.3% in shoots, respectively, when compared with the control. Arsenate (As(V)) was the dominant As species in all the treatment soils (99.8-100%), whereas arsenite (As(III)) was prevalent in plant roots (75.2-92.4%), shoots (74.1-87.9%) and leaves (73.9-84.3%). Si addition (25 and 75 mg kg-1) significantly increased As(III) concentration in roots by 167.5% and 83.3%, respectively. Monomethylarsonic acid (MMA) was the only detected methylated As but at low concentrations (0.01-0.29 mg kg-1) and only in PN leaves. Si addition (25 and 75 mg kg-1) significantly increased the copy number of the arsenite methyltransferase (arsM) gene by 31.0% and 47.2% but did not increase the methylated As species content in PN leaves. The detected copy number of the arsM gene did not represent the capacity of soil to methylate As, and the sources of MMA in leaves need to be explored in further research.

The Application of CLEA Model in Accessing Health Risks of PAHs in Soil

The concentrations of PAHs in 29 soil samples in a little town in southern Jiangsu were detected. Based on these soil concentration data and parameters from existing studies for this area, we use contaminated land exposure assessment (CLEA) model developed by Environment Agency of United Kingdom to analyze the Average Daily Exposure (ADE) and subsequent health risks of the local residents for their exposure to PAHs in soil. The health risk assessment shows that oral of and dermal contact to soil are the two main pathways for PAHs exposure. Compared to children and teenagers (0-16), the adults (16-65) have higher accumulative carcinogenic risk. However, the annual mean carcinogenic risk of the children is higher than adults. Generally speaking, women have a little higher carcinogenic risk than men. The health risks of all the groups exceed 10, which need to be concerned.