新生鼠PFOS低剂量慢暴露对成年后神经行为的影响

为观察新生鼠全氟辛烷磺酸(PFOS)低剂量慢暴露对其成年后神经行为和海马组织影响,选取出生后5-7 d雄性SD幼鼠80只,按体重随机分为4组,分别为对照组(Con)、低剂量组(P5)、中剂量组(P10)、高剂量组(P20),每组各20只。从PND7开始染毒,共染毒12周,动态记录体重,并进行水迷宫、旷场实验、滚轮实验观察神经行为变化,同时取材进行HE染色,观察海马形态学改变。结果显示与Con组比较,P20组染毒8 d后出现体重增长减缓(P0.05),4周时P10和P20组死亡率明显升高;并且P10、P20组在4周,P5组在8周时,水迷宫实验逃逸潜伏期延长,目标象限停留时间缩短;P10、P20组大鼠在4周,P5组在8周时,旷场实验中央格停留时间延长,站立次数减少,行走总距离缩短;滚轮试验中,对照组和P5组肢体运动协调能力无显著性差异。P5组在染毒12周时出现海马神经元排列紊乱,胞核固缩及胞体胀大,CA1区细胞和齿状回闩区神经前体细胞数量明显少于Con组(P0.01)。上述结果表明,大鼠幼年PFOS低剂量慢暴露可损害其成年后空间学习记忆及自主探究能力,这种损害可能与海马神经元发生不足有关     

职业危害因素混合接触综合评价方法概述

作业场所同时接触多种职业危害因素的综合危害性日益引起广泛关注，如何对其进行科学的评价成为职业危害研究者面临的重要课题。本文对不同危害因素的混合危害作用的评价方法进行了系统的总结与归纳，探讨了混合作用的描述方法，分析了毒理学、流行病学、风险评价三大类方法应用于混合危害作用评价时的基本原理、核心思路和实施流程，此外对三种方法的特点进行了对比分析。     

Fathead Minnow and Bluegill Sunfish Life‐Stage Responses to 17β‐Estradiol Exposure in Outdoor Mesocosms

Developmental and reproductive effects of 17β‐estradiol (E2) exposure on two generations of fathead minnows and one generation of bluegill sunfish were assessed. Fish were exposed to E2 for six continuous weeks in outdoor mesocosms simulating natural lake environments. First generation fish were exposed while sexually mature. Second generation fathead minnows were exposed either during early development, sexual maturity, or both stages. Multiple endpoints were measured to assess effects of E2 exposure on fecundity and fish health and development. Plasma vitellogenin concentrations were highly variable in all fish. Differences in egg production timing for both species indicate differences in fecundity between females exposed to E2 and controls. First generation fathead minnows exposed to E2 had lower body condition factors and reduced secondary sexual characteristic expression by males. Only a difference in relative liver weight was observed in second generation fathead minnows. First generation bluegill males exposed to E2 had significantly smaller testes compared to controls. Although fish response was highly variable, results indicate that exposure to E2 at environmentally relevant concentrations affect fathead minnow and bluegill sunfish health and development, which may have implications for the health and sustainability of fish populations. Furthermore, exposure timing and environmental factors affect fish response to E2 exposure.     

Double exposure and the climate gap: changing demographics and extreme heat in Ciudad Juárez,Mexico

Scholars have recognised a climate gap, wherein poor communities face disproportionate impacts of climate change. Others have noted that climate change and economic globalisation may mutually affect a region or social group, leading to double exposure. This paper investigates how current and changing patterns of neighbourhood demographics are associated with extreme heat in the border city of Juárez, Mexico. Many Juárez neighbourhoods are at-risk to triple exposures, in which residents suffer due to the conjoined effects of the global recession, drug war violence, and extreme heat. Due to impacts of the recession on maquiladora employment and the explosion of drug violence (2008–2012), over 75% of neighbourhoods experienced decreasing population density between 2000 and 2010 and the average neighbourhood saw a 40% increase in the proportion of older adults. Neighbourhoods with greater drops in population density and increases in the proportion of older residents over the decade are at significantly higher risk to extreme heat, as are neighbourhoods with lower population density and lower levels of education. In this context, triple exposures are associated with a climate gap that most endangers lower socio-economic status and increasingly older-aged populations remaining in neighbourhoods from which high proportions of residents have departed.     

Occupational exposure to synthetic musks in barbershops,compared with the common exposure in the dormitories and households

Synthetic musks (SMs) have been widely used as fragrance ingredients in personal care and sanitary commodities. Due to their high volatility and particle-binding affinity, the indoor dust is a major reservoir of SMs, and dust ingestion could be an important exposure way to special populations, such as hairdressers. In spite of the known toxicity of SMs, there is no information regarding the occurrence of SMs in barbershop dusts and the exposure of hairdressers through indoor dust ingestion. In the present study, the levels of two nitro musks and five polycyclic musks were measured from indoor dust samples collected from barbershops, and some other indoor dust samples were also collected from dormitories, bathhouses and households for comparison. The concentrations of ∑SMs in barbershop dusts were 10–100 times higher than those from the other three indoor microenvironments. Polycyclic musks accounted for 89.4% of ∑SMs on average in all samples, of which two compounds, HHCB and AHTN jointly dominated 97.9% of polycyclic musks. The levels of HHCB and AHTN varied from 12.2 to 8.39 × 10⁵ and from 13.2 to 3.49 × 10⁵ ng g⁻¹, respectively. The daily intakes (DIs) of ∑SMs through house dust ingestion were estimated using the model of high dust ingestion and worst-case exposure (P95), and the corresponding exposure rates were 2791, 135 and 727 ng d⁻¹ for the hairdressers, general population and toddlers. SMs were also detected in blood samples collected from the hairdressers and normal adults (n = 50 and 10, respectively). There was no significant difference between these two groups. Despite the absence of higher SM concentrations in hairdresser’s blood, we should not overlook the potential occupational health risks due to their high SMs ingestion rate.     

Particle size distributions and health-related exposures of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) of sinter plant workers

This study measured particle size distributions of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in two workplace atmospheres of the sintering grate and rough roll shredder in a sintering plant, and to assess their workers’ health-related exposures. We found that the PCDD/F concentration of the sintering grate (site A = 14.47 pg m⁻³) was lower than that of the rough roll shredder (site B = 17.20 pg m⁻³). Particle size distributions of PCDD/Fs were in the form of the unimodal with the mass median aerodynamic diameter (MMAD) of 4.74 μm and 5.23 μm, and geometric standard deviation (σ_g) of 3.15 and 2.15 for the site A and B, respectively. The above results suggest that the workplace of the site A had a less fraction of coarse particles than that of the site B. The estimated PCDD/F concentrations of the inhalable fraction (11.0 pg m⁻³) and thoracic fraction (8.89 pg m⁻³) of the site A were lower than those of the site B (12.4 and 9.39 pg m⁻³, respectively). But to the contrary the estimated respirable fraction of the site A (5.05 pg m⁻³) was slightly higher than that of the site B (4.93 pg m⁻³). Our results clearly indicate the importance to conduct particle size segregating samplings for assessing human PCDD/F exposures.     

Hepatic and immune biological effect assays in C57BL/6 mice to measure polycyclic aromatic hydrocarbon bioavailability under laboratory exposures with increasing environmental relevance

Background Monitoring biological responses that are mediated via the aryl-hydrocarbon receptor (AhR) in animals exposed to environmental contaminants can indicate both the presence to chemicals that act through this biochemical pathway and whether these chemicals are bioavailable. Objectives The use of an ex-situ method that incorporated biological responsiveness monitoring in mice for determining the presence of ‘biologically active’ hydrocarbons in contaminated soils was investigated. Methods The use of C57BL/6 as a test organism was validated by determining hepatic and immune responsiveness to two polyaromatic hydrocarbons (PAHs): 3,4 benz[a]pyrene (B[a]P) and 1,2 benz (a)anthracene (BA) administered via intraperitoneal (i.p.) injection. The responsiveness of mice exposed to soils spiked with hydrocarbons or ex situ exposures to soil removed from two contaminated sites was also investigated. Results and Discussion Mice that were exposed to B[a]P via i.p. injections showed a 14-fold increase in liver microsomal ethoxyresorufin O-deethylase (EROD) activity compared to the control group. In contrast EROD activity following BA exposure at the same level was not significantly enhanced. Mouse immune response was significantly inhibited in a dose-dependent manner by i.p. injections of B[a]P. No significant inhibition occurred with the same doses of BA. Following i.p. exposure, the retention of B[a]P in mouse carcasses was greater than BA. Mice exposed to clean soils spiked with environmentally relevant concentrations of B[a]P and BA failed to show any significantly different hepatic or immune responses. Carcass residue data indicated a limited uptake of PAH from the soil. In contrast, EROD activity in mice exposed (ex situ) to hydrocarbon-contaminated soils removed from a fuel-loading depot and decommissioned gas works was significantly enhanced (4- and 2-fold respectively). However, this increase in EROD activity did not appear to correlate with either soil or carcass PAH concentrations. Conclusions and Outlook These results support the assumption that B[a]P has a higher affinity for the aryl hydrocarbon receptor (AhR) compared to BA. Soil parameters such as organic carbon content, structure and particle size distribution can modulate the bioavailability of contaminants to biological receptors. These factors are implicated in the lack of responsiveness demonstrated in the spiked soil experiments. However the responsiveness of EROD activity in mice exposed (ex situ) to soil contaminated with complex mixtures of hydrocarbon compounds confirms the potential usefulness of this model to determine the presence of ‘biologically active’ compounds in aged soils removed from contaminated sites.     

An approach to comparative assessments of potential health risks from exposure to radionuclides and hazardous chemicals

The need to compare potential health risks to the public associated with different activities that can result in releases of hazardous substances to the environment is becoming increasingly important in decision-making. In making such comparisons, it is desirable to use equivalent indicators of potential health risks for radionuclides, chemical carcinogens, and noncarcinogenic hazardous chemicals. Current approaches to risk assessment that were developed for purposes of protecting human health do not provide equivalent indicators of potential risks from exposure to radionuclides and hazardous chemicals. Comparisons of environmental concentrations or calculated exposures or risks with standards for protection of public health also do not provide equivalent indicators of potential risks. We propose a simple approach to comparative risk assessments in which calculated exposures to any hazardous substances are expressed relative to no-observed-effect levels (NOELs) or, preferably, lower confidence limits of benchmark doses (BMDLs) in humans. This approach provides an equivalent, science-based indicator of the relative risks posed by different exposures to any hazardous substances.     

A pharmacokinetic modeling of inorganic arsenic: a short-term oral exposure model for humans

This study presents a pharmacokinetic modeling of inorganic arsenic disposition in human body for short-term oral exposures. Effort on the development of the model is directed toward the prediction of the kinetic behavior of inorganic arsenic and its metabolites in the body. The current model considers the 4 circulating species; As^III, As^v, and two metabolites such as monomethylarsenic (MMA) and dimethylarsenic (DMA) in the blood and tissue groups. While it is difficult to estimate some parameters used in the models at this time, the current model assumptions and predictions seem to be consistent with the experimental observations found in the literature. Hence, the current model, when more fully developed, is expected to provide insight into the behavior of inorganic arsenic and its methylated metabolites within the body, and may help increase the understanding of risk assessment issues associated with inorganic arsenic in drinking water.     

A comparison of lead exposures in industrial “hot spots” in Jordan and Israel

The aim of this study was to compare two hot spots of lead (Pb) exposure in Israeli and Jordanian occupational settings. The study also sought to assess whether any differences in regulations and legislation regarding occupational health could be identified as a source of exposure disparities. Blood and hair specimens were collected from workers in a battery factory in Jordan and a secondary Pb smelter in Israel and compared. About 33% of the currently exposed group showed blood lead (BPb) levels above the internationally recommended concentration of 40 µg dL^?1. Although the differences of BPb levels between Israel and Jordan were not statistically significant, average levels were lower in Jordan. Beyond the difference in the factory types, disparity in exposure levels might be explained due to a combination of proclivities of factory management, public policies, existing medical surveillance and insurance, as well as cultural differences. Results reveal that despite existing regulations and the growing attention that is dedicated to Pb and metal occupational exposures, there are still hot spots for Pb exposure in Israel and Jordan. The contrasting experience found in the current study raises the possibility that information and technology exchange between the two countries Israel and Jordan, may be beneficial for improving occupational health policy in these two neighboring countries.