ARSENIC POISONING IN BANGLADESH: A GEOGRAPHIC ANALYSIS1

ABSTRACT: Drinking of arsenic‐contaminated tubewell water has become a serious health threat in Bangladesh. Arsenic contaminated tubewells are believed to be responsible for poisoning nearly two‐thirds of this country's population. If proper actions are not taken immediately, many people in Bangladesh will die from arsenic poisoning in just a few years. Causes and consequences of arsenic poisoning, the extent of area affected by it, and local knowledge and beliefs about the arsenic problem — including solutions and international responses to the problem — are analyzed. Although no one knows precisely how the arsenic is released into the ground water, several contradictory theories exist to account for its release. Initial symptoms of the poisoning consist of a dryness and throat constriction, difficulty in swallowing, and acute epigastric pain. Long‐term exposure leads to skin, lung, or bladder cancer. Both government and nongovernmental organizations (NGOs) in Bangladesh, foreign governments, and international agencies are now involved in mitigating the effects of the arsenic poisoning, as well as developing cost‐effective remedial measures that are affordable by the rural people.     

Genotoxicity at Low Level Dose of Inspirable Urban Ambient Air Particulate in a Semiarid Regime

Samples of inspirable air particulate(inhalable + ingestable) were obtained at two urbanlocations in southern Argentina which differ in theirexposure to pollution by class B2 polynuclear aromatichydrocarbons (PAHs). Sample extracts were tested in vitro for induction of chromosomal aberrations incultured rat hepatocytes. The average induced amountof chromosomal aberrations did not vary amonggeographic locations, but significant differences wereidentified in samples near known emitting sources. Thedifferences were analyzed in the frame of a model ofthe emissions and their subsequent distribution andre-suspension from the soil and other surfaces. Theresults show that the rat hepatocyte test is sensitiveto genotoxic activity of the urban air particulate inthe low dose range of the tested fractions. Adequatemodels of human exposure to these materials shouldconsider emissions and re-suspension of pollutants bywind. The implications of these results on theformulation of policies of emission reduction, urbansoil management and the design of cancer epidemiologystudies are discussed.     

甲醛致骨髓造血细胞遗传毒性研究展望

甲醛是我国目前最主要的室内空气污染物.相当一部分新装修的房屋室内甲醛浓度超过安全标准,室内甲醛污染已成为中国的环境污染公害.2004年6月15日世界卫生组织下属的国际癌症研究局确认甲醛是人类致癌物,然而甲醛是否能导致人类白血病?该公报指出:虽然有流行病学的证据,但是由于致病机制并不清楚,需要做进一步的研究,才能得出结论.问题的关键是:甲醛或其衍生成分经血液向骨髓转移的分子机制,以及这些成分在骨髓中对微环境组分的作用机制.     

Pendrin mediates uptake of perchlorate in a mammalian in vitro system

Perchlorate is a known endocrine disruptor present in groundwater, vegetables and dairy food products in many regions of the United States. It interferes with the uptake of iodide into the thyrocyte by the sodium-iodide symporter at the basolateral surface, thus potentially disrupting the synthesis of thyroid hormone. Because transport of iodide from the thyroid follicular cells to the follicular lumen is mediated by the protein pendrin at the apical surface, we hypothesized that perchlorate may also interact with this protein. Therefore, HeLa cells were transfected with the human SLC26A4 gene, which encodes pendrin, to generate an in vitro mammalian system expressing the recombinant pendrin protein (HeLa-PDS). The HeLa-PDS cells, along with untransfected cells, were then cultured in presence of iodide and/or perchlorate. Intracellular levels of these two chemicals were measured by ion chromatography tandem mass spectrometry. Results from this study show that iodide and perchlorate uptake increases significantly in HeLa-PDS cells as compared to untransfected cells. Thus, recombinant HeLa cells expressing pendrin protein accumulate iodide and perchlorate intracellularly, indicating that pendrin is involved in the uptake of perchlorate. Additional results from this study suggest that iodide and perchlorate competitively inhibit each other for uptake by pendrin. The ability of perchlorate to compete with iodide for uptake by both basal and apical transporters may increase the potential of perturbation of thyroid homeostasis and therefore the estimated risk posed to susceptible human populations.     

Pesticide exposure and serum organochlorine residuals among testicular cancer patients and healthy controls

The incidence of testicular cancer (TC) has been increasing worldwide during the last decades. The reasons of the increase remains unknown, but recent findings suggest that organochlorine pesticides (OPs) could influence the development of TC. A hospital-based case-control study of 50 cases and 48 controls was conducted to determine whether environmental exposure to OPs is associated with the risk of TC, and by measuring serum concentrations of OPs, including p,p’-dichlorodiphenyldichloroethylene (p,p’-DDE) isomer and hexachlorobenzene (HCB) in participants. A significant association was observed between TC and household insecticide use (odds ratio [OR] = 3.01, 95 % CI: 1.11-8.14; OR_adjusted = 3.23, 95 % CI: 1.15-9.11). Crude and adjusted ORs for TC were also significantly associated with higher serum concentrations of total OPs (OR = 3.15, 95 % CI: 1.00-9.91; OR_adjusted = 3.34, 95 % CI: 1.09-10.17) in cases compared with controls. These findings give additional support to the results of previous research that suggest that some environmental exposures to OPs may be implicated in the pathogenesis of TC.     

双酚-A和17β-雌二醇对人乳腺癌细胞生长的影响

通过MTT-细胞增殖活性测定法和双参数流式细胞光度术研究了双酚-A和17b-雌二醇对人乳腺癌细胞株MCF-7增殖、细胞周期以及核酸和蛋白合成的影响.结果表明,在310^-16～310^-8mol/L范围内,双酚-A和17b-雌二醇都能促进细胞增殖;在310^-14mol/L时,细胞增殖活性达到最高值.当作用浓度为310^-14mol/L时,细胞周期的S期比例增加,细胞总蛋白表达量明显增加.统计结果表明,双酚-A和17b-雌二醇对MCF-7细胞生长特性的雌激素效应非常相似.     

Do disinfection byproducts in drinking water have an effect on human cancer risk worldwide? A meta‐analysis

In the present study, a meta‐analysis was carried out to clarify the association between disinfection byproducts (DBPs) in drinking water and human cancer risk worldwide. Kidney, colorectal, esophagus, urinary bladder, brain, breast, leukemia, lung, and rectum cancers were selected to perform this analysis. According to preferred reporting items for systematic review and meta‐analysis protocol (PRISMA) guidelines, the relevant studies were identified and selection criteria (inclusion and exclusion criteria) were applied. Next, effective subgroups in these studies (gender, type of drinking water source, and type of DBPs) were analyzed. The quality of the studies was evaluated using the Newcastle‐Ottawa Scale. In addition, this overall study included analyses of 16 case–control and 3 cohort studies. The overall odds ratio (OR) with 95% confidence intervals (CI) between DBPs and cancer risk was 1.01 (95% CI, 0.94–1.09). The summary ORs of cancer risk were 1.04 (95% CI, 0.89–1.19) for kidney; 0.98 (95% CI, 0.87–1.09) for colorectal; 1.07 (95% CI, 0.84–1.29) for esophagus; 0.93 (95% CI, 0.80–1.06) for pancreatic; 1.00 (95% CI, 0.83–1.18) for brain; 1.13 (95% CI, 0.99–1.26) for breast; 0.93 (95% CI, 0.72–1.13) for leukemia; and 1.18 (95% CI, 1–1.36) for lung cancers. The results of this meta‐analysis suggested that there is not a significant association between DBPs in water and cancer risk. In addition, subgroup analysis shows a positive association with colorectal and kidney cancer risk in men, as well as colon and breast cancers in females. Studies of both genders have shown a significant association between lung and pancreatic cancers. Moreover, this study finds a significant relationship between cancer rate and consumers of city water and bottled water sources. In analyzing different types of DBPs in water, chlorine and trichloromethane show a significant association in increasing cancer risk.     

石河子市采暖季和非采暖季住宅中邻苯二甲酸酯的污染特征及婴幼儿健康风险评估

为了解石河子市住宅中邻苯二甲酸酯(Phthalates,PAEs)的污染特征及PAEs对婴幼儿产生的健康风险.本研究对石河子市采暖季和非采暖季50户住宅降尘中的7种PAEs物质进行检测,利用蒙特卡洛(Monte Carlo)模拟和生理提取实验(PBET)评估了PAEs暴露对0～3岁婴幼儿产生的生殖和癌症风险.结果表明:①不同时期石河子市卧室和客厅降尘中邻苯二甲酸二异丁酯(diisobutyl phthalate,DIBP)、邻苯二甲酸二正丁酯(Dibutyl phthalate,DBP)和邻苯二甲酸二(2-乙基)己酯[Bis(2-ethylhexyl)phthalate,DEHP]均为室内PAEs的主要组成物质,占总PAEs的99.5%以上,其中DEHP为首要PAEs物质(浓度中位数值为361～462μg·g~(-1)),DBP次之(浓度中位数值为94.9～166μg·g~(-1));②除DIBP外,采暖季卧室和客厅降尘中各PAEs的浓度均高于非采暖季,且差异具有统计学显著性(p0.05),此趋势对小分子质量的邻苯二甲酸二甲酯(Dimethyl phthalate,DMP)和邻苯二甲酸二乙酯(Diethyl phthalate,DEP)而言更明显,DMP采暖季浓度中位数值:0.36～0.42μg·g~(-1)非采暖季:nd,DEP采暖季:0.65～0.71μg·g~(-1)非采暖季:nd～0.03μg·g~(-1);③利用风险指数(HQ)进行健康风险评估表明,采暖季和非采暖季DBP暴露可能会对0～3岁婴幼儿产生较大的生殖风险(HQ_(DBP )=2.62～5.79);DEHP暴露可能会对0～2岁婴幼儿产生较大的癌症风险(HQ_(DEHP)=3.51～5.22).当考虑生物可及性后,仍有8%～37%的婴幼儿可能存在生殖风险,几乎所有婴幼儿无癌症风险.     

某聚氯乙烯分厂的氯乙烯职业健康风险评价

以某化工企业的聚氯乙烯分厂为研究对象,引入美国环境保护署(EPA)推荐的健康风险评价四步法,即危害鉴定、剂量-反应评价、暴露评价和风险表征,对不同作业任务(清釜、看釜、巡检和配料)工人的氯乙烯职业暴露进行健康风险评价。结果表明,从非致癌效应来看,看釜、巡检和配料岗位工人暴露于VC引起肝细胞多态性的HI值均高于安全阈值1,其中看釜工的危害指数最大,引起的不利健康效应最严重。从致癌效应来看,清釜工暴露于VC引起肝血管肉瘤的风险处于可接受水平;而看釜工患肝血管肉瘤的风险值R,达到可接受上限10-4对应的工作年限ED=1.91 a,因此,需要尽可能地采用安全防护措施减少该岗位的职业暴露。巡检和配料岗位的肝血管肉瘤风险达到可接受水平上限10-4时,对应的工作年限分别为4.36 a和9.33 a。由于健康风险评价更侧重长期暴露危害物质对人体健康的影响,即使工作场所满足国标规定的浓度阈值,仍然存在工人长期暴露于低浓度致癌物的风险。     

中美固体废物污染环境防治法律制度比较

对中美两国的固体废物法律制度进行了全面系统地比较，得出了中美两国的社会制度和经济发展水平虽然不同，但因美国的固体废物立法较早，管理制度比较全面，有些地方值得我国固体废物立法、监督管理借鉴。