珠三角某市管网末梢水中化学污染物健康风险评价

目的 初步评估珠三角某市管网末梢水中化学污染物对人体健康产生的潜在风险。方法 于2015年1-12月,对珠三角某市160份管网末梢水中5种基因毒物质(砷、六价铬、镉、三氯甲烷和四氯化碳)和12种躯体毒物质(铅、汞、硒、氰化物、氟化物、硝酸盐、铁、氨氮、锰、铜、锌和挥发酚)进行检测,采用美国国家环境保护局(US EPA)推荐的健康风险评价模型对上述17种化学污染物通过饮水途径所引起的健康风险做出初步评价。结果 珠三角某市管网末梢水中化学污染物所引起的致癌风险介于3.10×10-10/a~2.92×10-5/a之间,非致癌风险介于0.08×10-11/a~95.24×10-11/a之间,总健康风险为3.66×10-5/a。个人致癌风险由高至低分别为六价铬＞砷＞三氯甲烷＞镉＞四氯化碳,个人非致癌风险由高至低分别为氟化物＞硝酸盐＞铅＞铜＞汞＞硒＞氨氮＞铁＞锌＞氰化物＞锰＞挥发酚。结论 珠三角某市管网末梢水中17种化学污染物对人体健康产生的个人健康风险水平均在国际辐射防护委员会(ICRP)规定的最大可接受风险水平(5.0×10-5/a)范围内。     

肇庆市农村地区饮用水健康风险评价

目的 初步评估肇庆市农村地区饮用水部分项目健康风险,为饮用水风险管理和决策提供依据。方法 于2016年对全市农村饮用水铬、砷、镉、三氯甲烷、四氯化碳、铅、铜、汞、铁、锌、铝、硒、锰、氰化物、氨氮、氟化物、硝酸盐17个项目进行检测,应用美国环保署推荐的风险评估模型对上述项目通过饮水途径所引起的健康风险进行评价。结果 17个项目通过饮水途径引起的总健康风险为2.92×10-5/年,水中化学致癌物所致的健康风险度大于非致癌物质所致的风险度,占总风险的99.96%。化学致癌物所致健康风险由高至低依次为铬（VI）＞砷＞镉＞四氯化碳＞三氯甲烷,产生的平均个人年风险在2.59×10-5/年 - 3.92×10 - 9/年之间。非化学致癌物所致健康风险由高至低依次为铝＞铜＞氟化物＞铅＞硝酸盐＞锰＞汞、铁＞锌＞硒＞氰化物＞氨氮,产生的平均个人年风险在6.32×10 - 9/年 - 6.52×10 - 12/年之间。结论 肇庆市农村地区饮用水健康总风险低于国家辐射防护委员会推荐的5×10 - 5/年,应把饮用水中致癌物,特别是铬（VI）作为优先管理对象。     

某非规范垃圾填埋场地下水中污染物的健康风险评价

目的评价华北某非规范垃圾填埋场地下水中污染物的健康风险。方法于2007年5月,采集华北某市附近一非规范垃圾填埋场附近5口有代表性的民用水井(即采样点1～5)水样,按照GB/T 5750—2006《生活饮用水标准检验方法》测定样品中的氨氮、硝酸盐氮、亚硝酸盐氮、挥发酚、锌、六价铬、汞、锰、pH值、氟化物、总硬度指标,并进行健康风险评价。结果仅采样点2的水样中检出化学致癌性污染物(六价铬),其由饮水途径所导致健康危害的个人年风险为7.60×10-4/a。水样中非致癌污染物饮水途径健康危害的风险平均为16.060×10-9/a。不同采样点各种非致癌性污染物由饮水途径所致健康危害的个人年风险比较,由高至低依次为:采样点2(24.861×10-9/a)>采样点4(17.753×10-9/a)>采样点3(17.701×10-9/a)>采样点5(11.718×10-9/a)>采样点1(8.265×10-9/a)。各种非致癌性污染物由饮水途径所致健康危害的个人年风险比较,由高至低依次为:汞(5.694×10-9/a)>硝酸盐氮(5.178×10-9/a)>氟化物(3.186×10-9/a)>挥发酚(0.869×10-9/a)>锰(0.532×10-9/a)>氨氮(0.344×10-9/a)>锌(0.250×10-9/a)>亚硝酸盐氮(0.006×10-9/a)。结论采样点2地下水受致癌性污染物和非致癌性污染物污染比较严重,不宜作为饮用水源。     

武汉市农村生活饮用水化学污染物健康风险评价

目的 了解武汉市农村生活饮用水中污染物浓度水平,并通过健康风险评价初步评估水体污染物对成人及儿童身体健康的潜在危害度。 方法 对2017年武汉市农村饮用水中17个指标的浓度进行调查,并利用美国环保局推荐的风险评估模型进行健康风险评价。 结果 武汉市农村饮用水中5种化学致癌物和12种非致癌物所引起的成人和儿童总健康风险分别为2.58×10^-5/a和3.61×10^-5/a,其中化学致癌物的健康风险值大于非致癌物的健康风险值,占总健康风险的99.99%。化学致癌物所致成人和儿童的健康风险值由高到低均依次为铬(六价)＞砷＞镉＞三氯甲烷＞四氯化碳,非致癌物所致成人和儿童的非致癌健康风险值由高到低均依次为铅＞氟化物＞铜＞汞＞硝酸盐＞锰＞铁=锌＞硒＞氰化物＞氨氮＞挥发性酚。化学致癌物和非致癌物对儿童的健康风险均高于成人。 结论 武汉市农村饮用水中污染物所致成人和儿童总健康风险在美国环保局和国际放射防护委员会推荐的最大可接受风险度(1×10^-4/a和5×10^-5/a)范围内。     

抓住根本 夯实基础 不断深化初保内涵

广州市辖9个区、4个县级市,666.49万人。1991年初级卫生保健工作在全市铺开,1996年5区4市的农村初保规划目标全部通过省级审评达标;1996年越秀区的城市初保规划目标通过了卫生部、广东省的联合审评;1998年海珠区、东山区、白云区、荔湾区的城市初保规划目标通过了省级审评验收达标。至此,广州市除黄埔区、芳村区、天河区的城市初保规划目标未经审评外,城乡初保全部通过审评达标,跻身于广东省     

广东省十城市饮用水中部分元素健康风险评价

目的对广东省10城市饮用水中元素的健康风险进行评估。方法于2011年2—4季度,对各监测点市政水厂的出厂水中砷、铬（六价）、镉、铅、汞、硒、锰、铜、锌9种元素浓度进行检测。采用美国环保署推荐的健康风险评价模型,计算上述9种元素经口途径暴露的健康风险。结果广东省10个城市出厂水中除汞的合格率为98.8%（169/171）外,其他指标均全部合格。3种基因毒金属所引起的健康危害的个人年风险水平由高至低依次为铬（六价）(3.71×10^-5/a)>砷(1.04×10^-5/a)>镉(0.16×10^-5/a),总健康风险值为4.91×10^-5/a。6种躯体毒金属健康危害的个人年风险水平由高至低依次为铜(11.82×10^-10/a)>铅(6.41×10^-10/a)>汞(3.06×10^-10/a)>硒(1.04×10^-10/a)>锰(0.58×10^-10/a)>锌(0.24×10^-10/a)。结论广东省10城市饮用水中9种元素的单指标个人年风险水平分别在国际辐射防护委员会（ICRP）的最大可接受风险水平(5.0×10^-5/a)范围内。     

广州市儿科医疗资源配置的效率研究

目的分析广州市儿科医疗资源配置效率,促进广州市儿科医疗资源的合理配置。方法 2014年3月至6月对广州市12个区63所开展儿科业务的医疗机构进行调查,调查表采用自制的《儿科人力资源现状调查表》,并运用DEA模型对广州儿科医疗资源配置效率进行分析。结果儿科医疗资源配置为DEA有效的区域有越秀区、海珠区、天河区、荔湾区、番禺区、萝岗区、花都区、从化区、南沙区;DEA弱有效的区域是增城区;非DEA有效的区域是黄埔区、白云区。结论广州市儿科医疗资源配置效率存在明显地域差异,部分区域投入的医疗资源没有得到充分利用。     

南昌市主城区饮用水中消毒副产物含量及其健康风险评价

目的 了解南昌市主城区饮用水中消毒副产物种类、分布,并评价其潜在健康风险。方法 于 2015年枯水期（11月）、2016年丰水期（6月）采集南昌市主城区 8家市政出厂水水样 16份 ,依据《生活饮用水标准检验方法》（GB/T5750 - 2006）检测水样中 13种消毒副产物含量;运用美国环保局健康风险评价模型评价消毒副产物通过饮水途径引起的健康风险。结果 出厂水中消毒副产物浓度均符合《生活饮用水卫生标准》（GB5749 - 2006）,卤乙酸（二氯乙酸、三氯乙酸）和三卤甲烷（三氯甲烷、二溴一氯甲烷）是南昌市主城区饮用水中主要消毒副产物。消毒副产物在丰水期浓度是枯水期浓度的4.16倍,丰水期二氯乙酸、三氯乙酸、三氯甲烷浓度高于枯水期,枯水期二溴一氯甲烷浓度高于丰水期（均P＜0.05）。消毒副产物引起的致癌风险为2.83×10 - 5/年～7.98×10 - 5/年,中值5.91×10 - 5/年,非致癌风险为6.21×10 - 2/年～1.86×10 - 1/年,中值为1.22×10 - 1/年。致癌风险主要来自二氯乙酸、三氯乙酸和二氯一溴甲烷,丰水期以三氯乙酸和三氯甲烷贡献最大;枯水期以二溴一氯甲烷和二氯一溴甲烷贡献最大;而二氯乙酸对非致癌风险贡献最大。结论 卤乙酸和三卤甲烷是南昌市主城区饮用水中的主要消毒副产物,出厂水中消毒副产物引起的致癌风险在可接受的范围,但需提出风险控制措施,丰水期消毒副产物浓度应该得到控制。     

广州主城区土壤砷元素污染及健康风险评价

[目的]了解广州主城区土壤砷(As)含量、空间变异性及其影响因素,评价土壤As污染程度和人体健康风险. [方法]采用网格布点法选择广州主城区土壤为研究对象,采用原子荧光光谱法测定土壤As含量;基于ArcGIS地统计模块研究土壤As空间变异性;采用单因子污染指数评价As污染程度以及美国环保署(EPA)风险评价模型评价人体健康风险. [结果] 广州主城区土壤As平均含量(23.40 mg/kg)高于广州市、广东省和中国土壤背景值(P＜0.05),不同城区土壤As分布差异无统计学意义(P＞0.05);土壤As呈中等空间相关关系,主要受结构性因素和随机性因素的影响;土壤As含量与土壤有机质、pH不呈相关关系(P＞0.05);土壤As污染程度从无污染到中度污染范围变化,66.13％土样遭受污染,平均污染程度为轻度污染;广州主城区土壤As的儿童平均非致癌风险值大于风险限值1,成人平均非致癌风险值小于风险限值1;儿童和成人土壤As致癌风险指数在1×10-5～1×10-6范围,均在致癌风险阈值1×10-6～1×10-4范围. [结论]广州主城区土壤As遭受不同程度污染;广州主城区土壤As对儿童非致癌风险存在潜在健康风险;对儿童和成人致癌风险均在致癌风险阈值范围内,对人体健康不会造成明显危害.     

武汉市农村地区地下水健康风险评价

目的了解武汉市农村地区地下饮用水中化学污染物的健康风险。方法于2009年9—12月对武汉市A、B、C、D、E五个区所辖的1945个行政村进行地下水抽样调查,并采用美国环保局(USEPA)推荐的健康风险评价模型对地下水中砷、氟化物、硝酸盐、铁和锰经饮水途径所引起的健康风险作出初步评价。结果武汉市农村地区地下水总健康风险为2.87×10-6/a。B区、A区、C区、D区、E区地下水中砷的个人年致癌风险分别为0、2.86×10-7、2.00×10-7、1.07×10-6、1.50×10-6/a。个人年均健康风险排列顺序为E区(4.83×10-6/a)D区(3.45×10-6/a)A区(9.24×10-7/a)C区(6.40×10-7/a)B区(2.41×10-9/a)。结论 D和E农村地区地下水中的砷具有一定的致癌风险。     

Labile nitrogen reserves and plasma nitrogen fractions in growing cattle.

The existence and magnitude of labile nitrogen (N) reserves were studied in growing cattle using a dietary N depletion-repletion technique. Blood parameters and urinary N excretion patterns were monitored. Blood hematocrit (Ht) did not respond to reduced ingested N until after week 3 of depletion at which time it began to fall. About 3 weeks of repletion regime was required before Ht values increased again. Plasma protein and albumin decreased from 6.05 and 2.70 g during standardization to 5.44 and 2.44 g/100 ml after 5 weeks of depletion and did not approach predepletion levels until week 6 of repletion. Plasma urea N decreased from 16 mg in standardization to 0.08 mg/100 ml in depletion and required 3 weeks of repletion treatment to attain a peak of 18 mg/100 ml. Labile N reserves were determined by integrating the areas from total urinary N excretion curves obtained during depletion and repletion periods. On a live body weight basis labile N represented 5.6% of total body N. When computed on an empty body weight basis (does not include weight of gastrointestinal tract), labile N totalled 6.0%. The magnitude of labile N stroes as a percentage of total body N was 44% greater in steers with a mean body weight of 280 kg compared with animals weighing 144 kg.     

Interval nitrogen excretion and maintenance nitrogen requirements for parenteral nutrition in primates

This paper discusses a regression technique for determining maintenance nitrogen requirements in well-nourished primates (M fascicularis) on total parenteral nutrition. Animals were administered a continuous glucose infusion, and parenteral nitrogen intake was varied at constant time intervals in a random order (from 0 to 1 g nitrogen/kg/day). Interval nitrogen balance (intake minus urinary nitrogen output) was plotted against interval nitrogen intake. The x-intercept was defined as the maintenance nitrogen requirement. First, 24-h intervals were used at a nonprotein caloric intake of 85 kcal/kg/day (approximately 175% of primate resting energy expenditure) and the nutritional adequacy of the estimated requirement evaluated prospectively. Next, 8-h balance intervals were used and the maintenance nitrogen requirements predicted by this abbreviated technique were compared to those obtained using the longer method. Finally, the short-interval technique was repeated at two other levels of continuous glucose infusion (60 kcal/kg/day and 8 kcal/kg/day) and the effect on predicted nitrogen requirement examined. Maintenance parenteral nitrogen requirements for primates may be determined in 48 h using the abbreviated techniques.     

Relationship between fasting urinary nitrogen loss and obligatory nitrogen loss in rats

The relationship between obligatory nitrogen loss (ONL) and fasting urinary nitrogen loss (FUNL) was investigated in a longitudinal study in rats aged 30–430 days. Although both measurements increased with body size, when scaled allometrically they showed a decline. The rates of decline were parallel, such that at all ages the relationship between the two was FUNL=1.5 ONL. At any age inter-individual variability in this ratio was relatively small, the coefficient of variation being <7%. We propose that FUNL may be used as a proxy for the measurement of ONL and hence protein requirements. The reported relationship may also provide a theoretical basis for the well known but enigmatic relationship between BMR and ONL.     

Effects of corticosterone administration on nitrogen excretion and nitrogen balance in adrenalectomized rats.

Adrenalectomized rats were implanted with pellets containing corticosterone in proportions varying from 0% to 100%, plus cholesterol. Stable concentrations of plasma corticosterone resulted, varying from subnormal (A) to physiologic (B) to supraphysiologic (C). When food was ingested ad libitum, weight gain was maximal in B at plasma corticosterone concentrations of 0.14-0.20 mumol/L; weight loss occurred in C, despite higher food intake. Even when rats had constant limited food intake, weight gain and positive nitrogen balance were significantly reduced in A compared with B because fecal nitrogen rose significantly and the retention of absorbed nitrogen for growth decreased. In C, weight decreased despite constant intake, and nitrogen balance became negative because urinary nitrogen increased markedly. We conclude that glucocorticoid insufficiency reduces nitrogen balance by impairing intestinal absorption of dietary protein and the utilization of absorbed nitrogen, whereas glucocorticoid excess reduces nitrogen balance by augmenting urinary nitrogen despite constant nitrogen intake.     

Minimum nitrogen requirement from glandless cottonseed protein for nitrogen balance in college women

Seven women, 18 to 23 years of age, were fed cooked cottonseed products for 42 days in order to determine the minimum nitrogen requirements for glandless cottonseen flour after baking. The women consumed from 81 to 213 mg N/kg body weight from cottonseed protein. Nitrogen intake from each experimental period was calculated from the average nitrogen content of the cottonseed products consumed each day of the experiment period. Nitrogen excretion was determined from the measurement of nitrogen in a total collection of urine and feces for each experimental period plus an obligatory loss of 5 mg/kg body weight. Fasting blood samples were taken prior to the study and at the end of each 7-day experimental period thereafter. The minimum requirement for cottonseed protein to maintain a positive nitrogen balance was 106 mg N/kg body weight. For the "reference woman," weighing 58 kg, at least 6.1 g of cottonseed flour nitrogen would be required to maintain nitrogen equilibrium. Plasma amino acid values of threonine, proline, valine, isoleucine, leucine, tyrosine, and lysine decreased significantly from day 0 to day 7 of the study. There were no significant differences in these plasma amino acids thereafter. Cottonseed flour incorporated into baked products maintained nitrogen balance in college women with no change in their nutritional status.