摘要:【目的】揭示土壤和烟叶中多环芳烃(polycyclic aromatic hydrocarbons,PAHs)的暴露特征及其对人体造成的健康风险。【方法】采集了贵州松桃县长坪(CP)、太平(TP)、平头(PT)、普觉(PJ)、盘信(PX)和孟溪(MX)6个烟区土壤和新鲜烟叶样品各40个,测定样品中16种PAHs含量,分析其经口(ingestion)、皮肤(dermal)和呼吸(inhalation)3种非饮食摄入途径的暴露特征,并评估了PAHs对烟农造成的致癌和非致癌健康风险。【结果】土壤和烟叶中7种致癌性的PAHs[(Chr)、苯并(a)蒽(BaA)、苯并(b)荧蒽(BbF)、苯并(k)荧蒽(BkF)、二苯并(a,h)蒽(DahA)、苯并(a)芘(BaP)和茚并(1,2,3-cd)芘(IP)]的含量分别为70.97~365.71和293.53~1 730.72 μg/kg,平均含量分别为221.13和 707.03 μg/kg;土壤和烟叶中9种非致癌性PAHs[萘(Nap)、蒽(Ant)、菲(Phe)、芘(Pyr)、苊烯(Ane)、二氢苊(Any)、芴(Flu)、荧蒽(Fla)和苯并(g,h,i)芘(BghiP)]的总含量分别为65.6~647.6和108.9~606.1 μg/kg,平均值分别为379.6和304.2 μg/kg。PAHs暴露特征从大到小呈现为:经口摄入 gt; 皮肤摄入 gt; 呼吸摄入,土壤和烟叶中7种致癌性的PAHs对烟农总的平均每日暴露量分别为54.41~280.38和225.04~1 326.87 pg/(kg·d),平均值分别为169.53和542.05 pg/(kg·d);非致癌性的9种PAHs对烟农总的平均每日暴露量分别为146.70~1 448.19和243.41~1 355.33 pg/(kg·d),平均值分别为848.91和680.22 pg/(kg·d);致癌性和非致癌性PAHs的平均每日摄入量最大值均出现在MX烟区。土壤和烟叶中PAHs对烟农产生的非致癌性总危险指数为1.02×10-5~4.31×10-4,平均值为1.92×10-4;PAHs对烟农产生的总致癌风险指数为8.39× 10-7~5.14×10-6,平均值为2.18×10-6。其中,BaP的总致癌风险指数最大(3.69×10-7~4.25×10-6,平均值为1.58×10-6);有26个点位的BaP超过美国环保署建议的临界值,超标率为65%,有90%的取样点7种致癌性PAHs的总量处于低风险水平。【结论】土壤和烟叶中PAHs对烟农的暴露方式主要为经口和皮肤途径,PAHs的非致癌风险值处于美国环保署建议的临界值之下,为可接受水平。绝大多数取样点的致癌性PAHs已经给烟农造成了低风险的健康影响,尤其是BaP应该受到重点关注。
关键词:多环芳烃;土壤和烟叶;烟农;摄入途径;健康风险评估
中图分类号:X53"""""" 文献标志码:A开放科学(资源服务)标识码(OSID):
文章编号:1000-2006(2024)04-0200-09
The exposure characteristic and health risk assessment of polycyclic
aromatic hydrocarbons in soils and tobacco plants
MA Jun1,2, TAN Changyin2, WANG Yong1*, WU Lanyan1, QIN Hangdao1
(1. College of Materials and Chemistry, Tongren University, Tongren" 554300, China;
2. School of Geographic Sciences, Hunan Normal University, Changsha" 410081, China)
Abstract: 【Objective】The aim of this research is to determine the exposure characteristic and health risk of polycyclic aromatic hydrocarbons (PAHs) in soils and tobacco plants. 【Method】 Forty samples of soil and fresh tobacco plants were collected from tobacco-growing areas in Changping (CP), Taiping (TP), Pingtou (PT), Pujue (PJ), Panxin (PX) and Mengxi (MX) in Songtao County of Guizhou Province. A total of 16 PAH species were isolated from the samples. The characteristics of PAHs exposure were analyzed after ingestion, dermal administration, and inhalation. The carcinogenic and non-carcinogenic health risks on" farmers were assessed. 【Result】 The total contents of seven kinds of carcinogenic PAHs [perylene (Chr), benzo(a) anthracene (BaA), benzo(b) fluoranthene (BbF), benzo(k) fluoranthene (BkF), dibenzo(a,h)anthracene (DahA), benzo (a) pyrene (BaP), and indeno(1,2,3-cd) pyrene (IP)] in the soil and tobacco samples were 70.97-365.71 and 293.53-1 730.72 μg/kg," and the mean values were 221.13 and 707.03 μg/kg, respectively. The total contents of nine non-carcinogenic PAHs [naphthalene (Nap), anthracene (Ant), phenanthrene (Phe), pyrene (Pyr), acenaphthylene (Ane), diacenaphthylene (Any), fluorene (Flu), fluoranthene (Fla), and benzo (g,h,i) pyrene (BghiP)] were 65.6-647.6 and 108.9-606.1 μg/kg," and the mean values were 379.6 and 304.2 μg/kg, respectively. Analysis of the exposure characteristics of the PAHs revealed that ingestiongt;dermalgt;inhalation in terms of the exposure risk. The total average daily exposure of the farmers to the seven carcinogenic PAHs in the soil and tobacco samples was 54.41-280.38 and 225.04-1 326.87 pg/(kg·d), and the mean values were 169.53 and 542.05 pg/(kg·d), respectively. The total average daily exposure of the farmers to the nine non-carcinogenic PAHs in the soil and tobacco samples were 146.70-1448.19 and 243.41-1355.33 pg/(kg·d), and the mean values were 848.91 and 680.22 pg/(kg·d), respectively. The average daily intake (ADI) of the carcinogenic and non-carcinogenic PAHs was the" highest in MX. The total non-carcinogenic risk index of the PAHs in the soil and tobacco samples to the farmers ranged from 8.39×10-7 to 5.14×10-6, with a mean value of 2.18×10-6. The total carcinogenic risk index of the PAHs to the farmers varied from 8.39×10-7 to 5.14×10-6, with a mean value of 2.18×10-6. The total carcinogenic risk index of BaP was the" highest among the PAHs, being 3.69×10-7 to 4.25×10-6, with a mean value of 1.58×10-6. The levels of BaP exceeded the recommended threshold published by the United States Environmental Protection Agency (USEPA) at 26 sites (65%), and the total carcinogenic risk of the seven carcinogenic PAHs was low at 90% of the sampling sites. 【Conclusion】" Ingestion and dermal exposure were the main exposure routes of the PAHs in the soil and tobacco samples. The carcinogenic risk of the non-carcinogenic PAHs was below the critical value recommended by the USEPA, and their values were at acceptable range. The carcinogenic PAHs had a" low health risk to farmers at the majority of sampling sites. However, the carcinogenic PAH, BaP, requires further attention.
Keywords:polycyclic aromatic hydrocarbons; soils and tobacco; tobacco farmers; intake way; health risk assessment
多环芳烃(polycyclic aromatic hydrocarbons,PAHs)是含有至少两个苯环的芳香族化合物,通常以稠环以及非稠环的方式形成,有亲脂性和疏水性等特点[1]。PAHs因其性质稳定、毒性强、有致癌、致畸和致突变效应,且能通过食物链进人体而备受关注[2]。多环芳烃可通过大气沉降和其他途径进入土壤[3],也可暴露于作物表面[4],最终对人类健康造成损害[5-6]。有研究指出,多环芳烃暴露与哮喘、支气管炎和肺癌等的发生有关[7],也可通过干扰人体的内分泌功能影响健康[8]。多环芳烃是间接致癌物,通常以苯并(a)芘(Bap)为代表,具有高度致癌性[9]。Bap可通过体内代谢从前致癌物转化为最终致癌物,从而诱发多种癌症,如皮肤癌、白血病和膀胱癌[10]。Lee等[11]发现Bap的代谢氧化物可以与鸟环氨基结合,改变原本与胞嘧啶结合的3个氢键,导致DNA配对异常。此外,嵌入DNA分子中的致癌物可以破坏DNA的碱基序列,也可能导致细胞向癌细胞的转化。此外,最近一项关于多环芳烃的研究报告称,PAHs可引起导致睾丸功能受损,男性的生殖功能障碍[12]。人类接触多环芳烃通常是通过摄入食物和水、吸入空气或烟雾、皮肤接触土壤和油等途径[2]。其中,农民通过土壤接触多环芳烃的频率高于其他途径。因此,对PAHs的暴露特征及其对人体产生潜在风险的研究应引起关注。
烤烟在我国栽培广泛,在烟草类型作物中种植面积最大[13],因此,开展烤烟种植区可持续性有机污染的风险暴露研究和健康风险评估工作,对保障当地居民尤其是烟农的生存环境安全以及人体健康具有重要的意义。2020年中国烤烟产量超过202万t,其中贵州超过21万t。烤烟一度成为农民致富的重要方式,位于贵州东部的松桃县正是烤烟种植的主要区域之一。本研究以松桃县烤烟产区的土壤和烟叶为研究对象,分析16种PAHs在土壤和烟叶中的风险暴露特征,探究其通过非饮食途径对烟农可能的暴露特征,并评估其潜在的致癌和非致癌风险,为全面了解PAHs污染物在土壤和烟叶中暴露的潜在风险,以及进一步研究烤烟种植及管理过程中潜在的健康风险提供参考。
1 材料与方法
1.1 样品采集与制备
样品采集地位于贵州东部的松桃县,于2020年7月在长坪(CP)、太平(TP)、平头(PT)、普觉(PJ)、盘信(PX)和孟溪(MX)采集烤烟成熟期土壤和新鲜烟叶样品各40个(109.16°~109.27°E,27.94°~28.13°N)。土壤和烟叶样品的采集严格按照采样标准进行,用不锈钢铲采集由5~ 6个点位(S形布点法)的混合表层土壤2 kg。同时用不锈钢剪刀分别在3 ~ 5株烤烟的上部、中部和下部叶混合后取约 1 kg烟叶。样品采集后用冰袋盒保存并运回实验室,-20 ℃ 冻存24 h后,转移至冻干机中冷冻干燥96 h,用陶瓷研钵研磨后过0.25 mm不锈钢筛,用棕色玻璃瓶保存于干燥器中待分析。
1.2 样品处理与测定
本研究共测定了萘(Nap)、蒽(Ant)、菲(Phe)、芘(Pyr)、苊烯(Ace)、二氢苊(Acy)、芴(Flu)、荧蒽(Fla)、苯并(g,h,i)芘(BghiP)、(Chr)、苯并(a)蒽(BaA)、苯并(b)荧蒽(BbF)、苯并(k)荧蒽(BkF)、二苯并(a,h)蒽(DahA)、苯并(a)芘(BaP)、茚并(1,2,3-cd)芘(IP)等16种PAHs。样品中PAHs采用二氯甲烷索氏提取24 h,待冷却后,用旋转蒸发仪(Rotavapor R-215,BCHI Labortechnik AG,瑞士)在370 Pa、90 r/min、36 ℃条件下浓缩至干,用环己烷定容待测。土壤样品用正己烷-二氯甲烷(体积比1∶1)作为淋洗液,烟叶样品用正己烷-丙酮(体积比4∶1)作为淋洗液,收集洗脱液旋转蒸发浓缩并定容至1 mL并过0.22 μm的有机滤膜,转移至棕色进样瓶并保存于4 ℃冰箱中待上机测定。
土壤和烟叶样品中PAHs含量采用二氯甲烷索式提取、四通道色谱分离仪[CHRO-400,赛次科技(大连)有限公司]净化、气相色谱-质谱联用仪(GC-MS:Agilent 7890A 5975C,美国Agilent公司)测定[14-15]。GC-MS条件设置:电子(70 eV)轰击EI离子源(230 ℃),传输线和接口设置温度为260和280 ℃,电压设置为1.012 kV,质量扫描范围(m/z)为60~640 amu;高纯He(gt; 99.999%)作为载气,弹性石英毛细管柱(DB-5MS)为30 m×0.25 mm×0.25 μm,设置流速为1 mg/L。升温程序:设置柱室初始温度为50 ℃并保持1 min,然后以15" ℃/min升至200 ℃并保持1 min,再以8" ℃/min升至280 ℃并保持3 min,最终温度至285 ℃。进样口温度保持250 ℃,选择SIM模式定量。
1.3 质量保证
对16种PAHs化合物进行加标回收试验,土壤和样品平均加标回收率大于80.3%,仪器检出限(LOD)lt;2.1 μg/kg。在分析过程中设置程序空白,每10个样品加入空白样品进行抗干扰和污染检测,并减去空白样品中的测定值得到数值。
1.4 暴露方式及健康风险评估
有机污染物是通过饮食和非饮食2种暴露途径威胁人体健康,其中非饮食途径有经口摄入(ingestion)、皮肤摄入(dermal)和呼吸摄入(inhalation)3种方式。根据美国环保署提供的风险评估模型,并参照文献进行修正优化后[16-18],得到植烟土壤和烟叶中PAHs的非饮食途径摄入量和健康风险的计算公式:
IAD,Ingestion=C×RIngestion×F×TW×AAT。(1)
式中:IAD,Ingestion为经口摄入途径的平均每日摄入量, pg/(kg·d);C为PAH在土壤或烟叶中的含量,μg/kg;RIngestion为摄入率,取值为100 mg/d[16];F为暴露频率,取值为350 d/a[16];T为暴露时间,取值为24 a[17];W为体质量,取值为60 kg[17];AAT为持续时间(致癌性PAHs取值为25 550 d,非致癌性PAHs取值为8 760 d[18])。
IAD,Dermal=C×SSA×AAF×AABS×F×TW×AAT×
GGIABS。(2)
式中:IAD,Dermal为通过皮肤摄入途径的平均每日摄入量, pg/(kg·d);SSA为接触介质的皮肤面积,取值为5 700 cm2/d[16-17];AAF为质介对皮肤的黏附系数,取值为0.07 mg/cm2[18];AABS为皮肤吸附系数,取值为0.1[16-18];GGIABS为胃肠道吸附系数,取值为1[16-18]。
IAD,Inhalation=C×RInhalation×F×TW×AAT×PPEF×106。(3)
式中:IAD,Inhalation为通过呼吸摄入的平均每日摄入量,pg/(kg·d);RIngestion为呼吸摄入率,取值为20 m3/d[17];PPEF为扩散因子,取值为1.36×109 m3/kg[16-18]。
土壤和烟叶中非致癌性PAHs通过经口摄入、皮肤摄入和呼吸摄入3种途径对烟农产生的危险指数之和(H)用如下公式计算:
H=∑IAD,iDRfD(RfC)×109。(4)
式中:i为各风险物的第i种暴露途径;DRfD(RfC) 为每日经口和皮肤(经呼吸)暴露参考剂量,mg/(kg·d)。
土壤和烟叶中致癌性PAHs通过经口摄入、皮肤摄入和呼吸摄入3种途径对烟农产生的致癌风险指数之和(CCRI)用如下公式计算:
CCRI=∑[IAD,i×SSFO(IUR)×109]。(5)
式中:SSFO(IUR)为每日经口和皮肤(经呼吸)暴露斜率因子,mg/(kg·d)。
土壤和烟叶中非致癌性PAHs对烟农产生的总危险指数(TH)用如下公式计算:
TH=Hs+Ht。(6)
式中:Hs和Ht分别为土壤和烟叶中的危险指数。
土壤和烟叶中致癌性PAHs对烟农产生的总致癌风险指数(TCRI)用如下公式计算:
TCRI=CCRI,s+CCRI,t。(7)
式中:CCRI,s和CCRI,t分别为土壤和烟叶中的致癌风险指数。
1.5 数据处理
数据整理与分析采用Excel 2016,数据图采用Origin 2019b绘制。
2 结果与分析
2.1 土壤和烟叶中多环芳烃的含量
多环芳烃在土壤和烟叶中的含量如图1所示,土壤样品中16种PAHs的总含量为166.74~989.43 μg/kg,平均值为600.77 μg/kg;烟叶样品中16种PAHs的总含量为502.79~2 217.15 μg/kg,平均含量为1 011.23 μg/kg。土壤和烟叶中9种非致癌性PAHs的总含量分别为65.6~647.6和108.9~606.1 μg/kg,平均值分别为379.6和304.2 μg/kg;而7种致癌性的PAHs的总含量分别为70.97~365.71和293.53~1 730.72 μg/kg,平均含量分别为221.13和 707.03 μg/kg。土壤和烟叶样品中平均含量最高的是菲和苯并(a)芘,分别为达80.03和404.07 μg/kg,最低的分别是苊烯和二氢苊。40个土壤样品中芘、苯并(a)蒽和苯并(g,h,i)芘全部检出,芘、、苯并(a)蒽、苯并(b)荧蒽、苯并(k)荧蒽和苯并(a)芘在40个烟叶样品中也全部检出。说明致癌性PAHs在土壤和烟叶中的大量累积成为对烟农造成健康威胁的主要风险点,尤其表现为具有强致癌性的苯并(a)芘。
2.2 土壤和烟叶中多环芳烃的暴露特征
2.2.1 致癌性多环芳烃的摄入特征
烟农经口途径平均摄入土壤中致癌性PAH最多的是[23.14 pg/(kg·d)],其次是苯并(a)芘[19.84 pg/(kg·d)]。通过皮肤途径的平均最大摄入量为[9.23 pg/(kg·d)](),而通过呼吸途径的平均最摄入量较低,均小于0.004 pg/(kg·d)。烟农平均每日经口、皮肤和呼吸途径摄入土壤中7种PAHs的量分别为38.89~200.39、15.52~79.96 和0.005 7~0.029 5 pg/(kg·d)(表1)。烟叶中PAH单体的经口、皮肤和呼吸的最大值均为苯并(a)芘,烟农通过经口、皮肤和呼吸摄入烟叶中7种致癌性PAHs的量分别为160.84~948.34、64.18~378.39、0.023 7~0.139 5 pg/(kg·d)。表明土壤和烟叶中致癌性的PAHs主要是通过经口摄入和皮肤摄入的形式对烟农造成潜在威胁(表1)。
烟农对7种致癌性PAHs的平均总摄入量分别为54.41~280.38和225.04~1 326.87 pg/(kg·d),平均值分别为169.53和542.05 pg/(kg·d)(图2)。土壤中的总摄入值最高,其次是苯并(a)芘,而烟叶中总摄入量最高的是苯并(a)芘,其次为苯并(b)荧蒽。烟农对土壤中致癌性PAH单体的总摄入量从大到小表现为gt;苯并(a)芘gt;苯并(k)荧蒽gt;茚并(1,2,3-cd)芘gt;苯并(b)荧蒽gt;二苯并(a,h)蒽gt;苯并(a)蒽,而在烟叶中从大到小则呈现出苯并(a)芘gt;苯并(b)荧蒽gt;苯并(k)荧蒽gt;gt;茚并(1,2,3-cd)芘gt;二苯并(a,h)蒽gt;苯并(a)蒽的摄入特点,这同样与致癌性PAH在土壤和烟叶中的含量相关。因此,烟农平均每日致癌性多环芳烃摄入量也由其含量决定。
2.2.2 多环芳烃的非致癌摄入特征
烟农对土壤和烟叶中9种非致癌性多环芳烃的摄入量由公式(1~3)计算所得。烟农经口、皮肤和呼吸途径平均摄入土壤中多环芳烃最大的是菲,而最小的是苊烯。烟农平均每日通过3种非饮食途径摄入土壤中9种PAHs的总量分别为1 035.05、412.99和0.152 2 pg/(kg·d)(表2)。
烟叶中PAH单体的经口、皮肤和呼吸途径平均摄入量为24.76~143.53、9.88~57.27和0.021 1~0.003 6 pg/(kg·d)。烟农通过3种非饮食途径摄入烟叶中9种PAHs的平均值分别为486.17、193.98 和 0.071 5 pg/(kg·d)(表2)。以上表明烟农主要是以经口摄入和皮肤摄入方式摄入土壤和烟叶中的非致癌性PAHs。
烟农对土壤中9种非致癌性PAHs的平均总摄入量为146.70~1 448.19 pg/(kg·d),对烟叶中∑9PAHs的平均总摄入量从大到小则为243.41~1 355.33 pg/(kg·d)(图3)。土壤和烟叶中总摄入值最高分别的是菲和萘,而最低的分别是苊烯和二氢苊。烟农对土壤中非致癌性PAH单体的总摄入量从大到小表现为菲gt;蒽gt;萘gt;芘gt;荧蒽gt;苯并(g,h,i)芘gt;芴gt;二氢苊gt;苊烯,而对烟叶的摄入从大到小则是萘gt;芘gt;菲gt;蒽gt;荧蒽gt;芴gt;苊烯gt;苯并(g,h,i)芘gt;二氢苊,这与非致癌性PAH在土壤和烟叶中的含量相关,因此,烟农平均每日非致癌性多环芳烃摄入量由其含量决定。
2.2.3 不同烟区土壤和烟叶中多环芳烃的暴露特征
土壤和烟叶中致癌性PAHs的平均最大摄入值均出现在MX烟区,从大到小表现为MX gt; TP gt; PT gt; PX 的暴露特征,而在CP和PJ烟区表现出相反的暴露特点(图4a)。非致癌性PAHs的平均最大摄入值也出现在MX烟区,从大到小表现为MX gt; PT gt; PJ gt; TP gt; CP gt; PX,而在烟叶中从大到小呈现出MX gt; CP gt;PJ gt; PT gt; PXgt; TP的暴露特征(图4b)。
2.3 土壤和烟叶中多环芳烃的健康风险
土壤和烟叶中致癌性的苯并(a)蒽、、苯并(b)荧蒽、苯并(k)荧蒽、苯并(a)芘、茚并(1,2,3-cd)芘和二苯并(a,h)蒽对烟农产生的平均致癌风险指数见图5a。在土壤样品中CCRI值最大的是二苯并(a,h)蒽,而烟叶样品中CCRI值最大的为苯并(a)芘。美国环保署建议的PAHs对人体的产生的致癌风险分为特低风险(小于1×10-6)、低风险[1×10-6, 1 ×10-4)、中风险[1×10-4,1×10-3)、高风险[1×10-3, 1 ×10-1)和特高风险(≥1×10-1)5个等级[16-17]。在所有土壤样品中,致癌性PAH单体的CCRI值均小于1×10-6量级,全部处于特低风险水平;烟叶样品中苯并(a)蒽、、苯并(b)荧蒽、苯并(k)荧蒽、茚并(1,2,3-cd)芘和二苯并(a,h)蒽产生的致癌风险指数均小于1×10-6,处于特低风险水平,有23个烟叶样品中苯并(a)芘的致癌风险指数高于1×10-6,但低于1×10-4,处于低风险的烟叶样品率为57.5%。说明有部分烟叶样品的PAHs已经对烟农造成了低健康风险。土壤和烟叶中致癌性的PAH对烟农产生的TCRI值如图5b所示。7种PAH单体的TCRI最大值为4.25×10-6,在40个取样点位中,苯并(a)芘的总致癌风险指数最大,有26个点位超过美国环保署建议的临界值,超标率为65%。有36个取样点的总致癌风险指数介于1×10-6~1×10-4,说明有90%的取样点处于低风险水平。表明本研究烟区土壤和烟叶中致癌性PAHs的残留已经给烟农的健康造成了一定的威胁。
萘产生的平均非致癌危险指数最高,在土壤和烟叶中分别为4.72×10-5和8.99×10-5,而蒽产生的平均非致癌危险指数最低,在土壤和烟叶分别为5.80×10-7和8.37×10-7(图5c)。多环芳烃对烟农产生的TH由公式(6)计算所得。PAH单体的TH为1.02× 10-5~4.31×10-4,平均值为1.92×10-4。萘、苊烯、二氢苊、芴、菲、蒽、荧蒽、芘和苯并(g,h,i)芘的最大TH值分别为3.56×10-4、4.17×10-6、7.17×10-6、1.17×10-5、3.68×10-5、4.19×10-6、1.27×10-5、2.14×10-5和2.28×10-5,PAHs经口暴露、皮肤接触暴露和呼吸暴露途径对烟农产生的总非致癌危险指数均小于10-3数量级,美国环保署制定的非致癌风险临界值为1,当H gt;1时,多环芳烃会对人体造成非致癌的健康影响[16-17],本研究土壤和烟叶中PAHs对烟农产生的非致癌危险指数均未超过美国控制临界值,说明PAHs给烟农带来的非致癌性健康风险处于可接受的范围。
3 讨 论
本研究中,16种多环芳烃在40个土壤样品中的平均含量低于Ambade等[19]对印度东部城市土壤开展调查得出的结果,也低于王飞等[20]调查位于太原的农田土壤中16种PAHs的总含量以及严青云等[9]研究南方某地塑料厂土壤时的结果。但高于李文静等[21]研究油田居住区附近的土壤、张秀秀等[22]在调查南京农田土壤和Jia等[23]在研究上海农业土壤时的PAHs含量。同时,本次土壤样品中有部分样品的PAHs的含量超过欧洲农业土壤的控制标准[24](中度污染,600~1 000 μg/kg;轻度污染,200~600 μg/kg)处于轻度到中度污染水平。烟叶样品中16种PAHs总含量平均值低于Tesi等[25]在对尼日利亚市场的苦叶菜和南瓜叶中PAHs含量的检测结果,以及赵体跃等[26]对广西水生蔬菜中PAHs的含量开展研究时所检测的含量,而高于Jia等[23]在研究上海本地蔬菜中PAHs的含量、葛蔚等[27]在研究叶类和瓜果类蔬菜时和龙明华等[28]对南宁市市售菜心进行研究时得出的结果。这可能是因为PAHs可通过大气沉降吸附于植物表面[25],新鲜的烟叶有比蔬菜更为宽大的表面积而易于附着污染物。
而多环芳烃可能被输送到远离其来源的地方并在土壤中积累,随后通过食物链或各种其他暴露途径转移至人体[29],最终对人类健康构成长期危害[30]。烟农对土壤和烟叶中多环芳烃的摄入量表现为经口摄入途径最大,3种暴露途径造成的致癌和非致癌摄入量总体呈现出经口摄入gt;皮肤摄入gt;呼吸摄入的特点。这与严青云等[9]对典型塑料厂土壤中PAHs对人体产生的健康风险时得出的结论一致。Chen等[31]研究指出饮马河流域土壤中PAHs的暴露以经口摄入途径为主和Hu等[32]在评估三峡水库区土壤PAHs对人体的暴露特征时得出经口摄入途径大于皮肤摄入途径的结果与本研究结论保持一致。不同烟区烟农对土壤和烟叶中PAHs的摄入特征不同,最大摄入值出现在孟溪采样区域,这可能是因为松桃有丰富的锰矿资源[33],在进行资源开采利用等工业活动中[34],PAHs进入环境介质中并通过大气沉降进入土壤[35]和植物表面[25],而孟溪离锰矿开采场较近,故烟农对PAHs的摄入量较高。
本研究中,土壤和烟叶中PAHs的非致癌风险值均处于美国环保署建议的临界值之下,同样,从长春市玉米-土壤体系中[36]和天津农村土壤[37]采集的中多环芳烃的暴露水平。除了有90%的取样点中苯并(a)芘处于低风险水平以外(CCRIlt;1×10-4),其余致癌性的PAHs产生的致癌风险值均处于特低风险水平。这与沈阳城市土壤[38]、武汉农业土壤[39]、胜利油田的周边居住区土壤[21]以及日照市化工园区土壤中致癌性PAHs产生的风险值处于同一水平[40]。
综上,松桃烟区土壤中16种PAHs轻度到中度污染水平。烟区土壤和烟叶中16种PAHs对烟农的暴露方式主要为经口和皮肤摄入途径;PAHs在土壤和烟叶中对烟农产生的非致癌风险值处于美国环保署建议的临界值之下,处于可接受水平,但这并不意味着没有任何风险;绝大多数取样点位的致癌性PAHs已经给烟农造成了低风险的健康影响,尤其是苯并(a)芘应该受到重点关注。本研究结果有助于了解土壤和烟叶中多环芳烃的危害特征,以及非食品类作物中PAHs的主要暴露特点,从而为提高烟农的自我防范意识,并为监管者制定环境介质中多环芳烃的控制标准提供参考。
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(责任编辑 孟苗婧 郑琰燚)
收稿日期Received:2022-04-12""" 修回日期Accepted:2022-05-11
基金项目:铜仁市科技计划项目(铜市科研〔2023〕43号);国家自然科学基金项目(22166031);湖南省研究生科研创新项目(CX20220514);贵州省科技计划项目(黔科合基础-ZK〔2021〕一般224)。
第一作者:马军(junma2015@qq.com),讲师。*通信作者:王勇(wy7185299@126.com),副教授。
引文格式:马军,谭长银,王勇,等.
土壤和烟叶中多环芳烃的暴露特征及健康风险评估[J]. 南京林业大学学报(自然科学版),2024,48(4):200-208.
MA J,TAN C Y,WANG Y,et al.
The exposure characteristic and health risk assessment of polycyclic aromatic hydrocarbons in soils and tobacco plants
[J]. Journal of Nanjing Forestry University (Natural Sciences Edition),2024,48(4):200-208.
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