Human Health Effects Of Exposure Research Articles

Measurement in the study of human exposure to animal feces: A systematic review and audit.

Human exposure to animal feces is increasingly recognized as an important transmission route of enteric pathogens. Yet, there are no consistent or standardized approaches to measurement of this exposure, limiting assessment of the human health effects and scope of the issue. To inform and improve approaches to the measurement of human exposure to animal feces, we audited existing measurement in low- and middle-income countries. We systematically searched peer-reviewed and gray literature databases for studies with quantitative measures of human exposure to animal feces and we classified measures in two ways. First, using a novel conceptual model, we categorized measures into three 'Exposure Components' identified a priori (i.e., Animal, Environmental, Human Behavioral); one additional Component (Evidence of Exposure) inductively emerged. Second, using the exposure science conceptual framework, we determined where measures fell along the source-to-outcome continuum. We identified 1,428 measures across 184 included studies. Although studies overwhelmingly included more than one single-item measure, the majority only captured one Exposure Component. For example, many studies used several single-item measures to capture the same attribute for different animals, all of which were classified as the same Component. Most measures captured information about the source (e.g. animal presence) and contaminant (e.g. animal-sourced pathogens), which are most distal from exposure on the source-to-outcome continuum. We found that measurement of human exposure to animal feces is diverse and largely distal from exposure. To facilitate better assessment of the human health effects of exposure and scope of the issue, rigorous and consistent measures are needed. We recommend a list of key factors from the Animal, Environmental, and Human Behavioral Exposure Components to measure. We also propose using the exposure science conceptual framework to identify proximal measurement approaches.

Health risks of environmental exposure to microplastics

Plastics are materials widely used in all sectors. The subject of interest in recent years has become so-called microplastics, whose composition and structure are causing new environmental hazards. The presence and accumulation of microplastics in the environment threaten the ecological balance, the water environment, food sustainability and safety, and ultimately human health. Human exposure to microplastics is primarily through the oral route, so the main source of human exposure to microplastics is diet. Despite many studies focusing on microplastic contamination in seafood, fish, and shellfish, estimating total human exposure to microplastics via the oral route is difficult, due to the lack of research on other foods in this area. The risks to human health from inhaling microplastics remain unclear. According to the WHO, there is no reliable evidence of the harmful effects of microplastic on the human body, but the phenomenon requires further research. Likely health effects of human exposure to microplastic include respiratory and gastrointestinal effects, oxidative stress, and cancer. There is a need to raise public awareness about environmental exposure to microplastics and effective waste management.

Comparative modelling of inspiratory airflow and micron particle deposition patterns in monkey and human nasal airways

Laboratory animals have historically performed a vital function in evaluating health effects of human exposure to ambient particulate matter (PM). Due to the complexity of particle-laden flows and airway interactions that involve multiple species, in-depth knowledge of airflow and particle transport in both the non-human primate surrogates and human airways is still lacking. To advance the understanding in this field, this paper presents a numerical study that investigated the airflow and particle deposition characteristics of inhaled PMs in monkey and human nasal airways. Anatomically accurate macaca fuscata monkey and human nasal cavity models were reconstructed from CT images, micron particles with diameters less than 10 μm were included to conduct in silico exposure studies. Resultant particle deposition patterns were quantified by deposition enhancement factor (DEF) and deposition intensity (DI) along the airways to provide profound understanding of the similarities and differences in particle inhalation exposure characteristics across species. Anatomy comparison showed that the convoluted nasal passage of the monkey airway possessed higher level of complexity in terms of the surface-area-to-volume ratio compared to the two human nasal models, which could lead to higher evaluated nasal exposure to airborne particulate matter. Similar airflow patterns were observed from streamlines and wall shear stress distributions in all three nasal cavities of two species, with bulk air concentrated mainly in the middle and inferior meatuses in the nasal chambers. Despite the evidenced inter-subject deposition variations presented in all considered nasal cavity models, strong and similar micron particle deposition preferences with comparable DEF and DI levels were observed along the floor region of middle and inferior meatuses for both species. The methods and research findings presented in this work represent critical, initial steps towards establishing high-fidelity qualitative and quantitative linkages between the two species that enable more effective laboratory data extrapolations, improve study design, and facilitate validations of in vitro techniques currently being developed as part of international efforts to reduce or replace the use of animals in toxicity assessments for aerosol exposures.

Global public health implications of human exposure to viral contaminated water.

Enteric viruses are common waterborne pathogens found in environmental water bodies contaminated with either raw or partially treated sewage discharge. Examples of these viruses include adenovirus, rotavirus, noroviruses, and other caliciviruses and enteroviruses like coxsackievirus and polioviruses. They have been linked with gastroenteritis, while some enteric viruses have also been implicated in more severe infections such as encephalitis, meningitis, hepatitis (hepatitis A and E viruses), cancer (polyomavirus), and myocarditis (enteroviruses). Therefore, this review presents information on the occurrence of enteric viruses of public health importance, diseases associated with human exposure to enteric viruses, assessment of their presence in contaminated water, and their removal in water and wastewater sources. In order to prevent illnesses associated with human exposure to viral contaminated water, we suggest the regular viral monitoring of treated wastewater before discharging it into the environment. Furthermore, we highlight the need for more research to focus on the development of more holistic disinfection methods that will inactivate waterborne viruses in municipal wastewater discharges, as this is highly needed to curtail the public health effects of human exposure to contaminated water. Moreover, such a method must be devoid of disinfection by-products that have mutagenic and carcinogenic potential.

Interspecies comparison of heat and mass transfer characteristics in monkey and human nasal cavities

Air conditioning in the nasal airways plays an important role in regulating ambient atmospheric temperature and humidity conditions of the inhaled air. Inevitably, it may alter the behaviour and fate of inhaled ambient aerosols within the human respiratory airways due to hygroscopic growth and droplet evaporation, which is a phenomena of variations in particle sizes due to physical and chemical reactions on particle surfaces in different temperature and humidity fields. Although laboratory animals have been widely used to predict health effects of human exposure to ambient substances, the nasal temperature and humidity responses in animal surrogates and human nasal cavities are still less-investigated. This paper provides a comparative study between two monkey and two human nasal subjects under the same ambient temperature and humidity conditions, where nasal models were reconstructed from CT images and the heat and mass transfer process incorporating with the intricate nose anatomy were modelled by the computational fluid dynamics (CFD) approach. Present model comparison revealed that the monkey nasal models can reach equilibrium temperature and moisture state for inhaled ambient air in a much shorter distance compared to the human models. This indicate that heat transfer in the monkey models is more effective compared to the human models due to having a higher complexity coefficient and a smaller hydraulic radius. Hence, in order to achieve comparable or similar inhalation exposure patterns in animal surrogates, corresponding adjustments such as changing the size of released particles, or the inhalation flow rates, to achieve comparable particle Stokes number are needed. The outcomes of this study would provide informative insights for future inhalation toxicology studies related to hygroscopic materials and targeted drug delivery through nasal airways.

Residential proximity to agricultural glyphosate use and neurobehavior in the CHAMACOS study

BACKGROUND AND AIM: Glyphosate herbicides are the most widely used pesticides in the world. In California, agricultural use and total sales of glyphosate have more than doubled in the past 20 years. However, few studies have evaluated the human health effects of exposure. Our aim was to assess the relationship of agricultural glyphosate use within 1 km of residences with cognition and behavior in adolescence and young adulthood. METHODS: We collected residential history information during pregnancy and childhood in the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) birth cohort. Using California Pesticide Use Report data, we estimated agricultural glyphosate use within 1 km of residences during the prenatal period and from 0-5 years of age, weighted for wind direction. We estimated associations with: Full-scale Intelligence Quotient, Verbal Comprehension, Working Memory, Processing Speed and Perceptual Reasoning from the Wechsler Intelligence Scale for children, 4th edition at 7 and 10.5y; internalizing (anxiety and depression) and externalizing behaviors (hyperactivity and attention) from the Behavior Assessment System for Children-2 at 16 and 18y; and police encounters, delinquent acts, and risk-taking behaviors at 18y. RESULTS:A two-fold increase in glyphosate use within 1 km of postnatal residences was associated with more youth-reported depression (β=1.3, 95% Credible Interval (CrI): 0.2, 2.5), and maternal-reported internalizing behaviors (β=1.3, 95% CrI: 0.2, 2.7), driven by associations with anxiety (β=1.2, 95% CrI: 0.2, 2.3) at 16 and 18y. Residential proximity to glyphosate use during pregnancy or early childhood was not associated with other behavioral or cognitive domains. CONCLUSIONS:Though we observed associations of early childhood residential proximity to agricultural glyphosate use with a slight increase in internalizing behaviors, overall associations were null for most cognitive and behavioral outcomes. Future studies of neurodevelopment and glyphosate biomarkers would integrate exposure from diet, agricultural and home use. KEYWORDS: glyphosate, agriculture, cognition, behavior, children, adolescents

Exposure to e-cigarette aerosol over two months induces accumulation of neurotoxic metals and alteration of essential metals in mouse brain

Despite a recent increase in e-cigarette use, the adverse human health effects of exposure to e-cigarette aerosol, especially on the central nervous system (CNS), remain unclear. Multiple neurotoxic metals have been identified in e-cigarette aerosol. However, it is unknown whether those metals accumulate in the CNS at biologically meaningful levels. To answer this question, two groups of mice were whole-body exposed twice a day, 5 days a week, for two months, to either a dose of e-cigarette aerosol equivalent to human secondhand exposure, or a 5-fold higher dose. After the last exposure, the olfactory bulb, anterior and posterior frontal cortex, striatum, ventral midbrain, cerebellum, brainstem, remaining brain tissue and spinal cord were collected for metal quantification by inductively coupled plasma mass spectrometry and compared to tissues from unexposed control mice. The two-month exposure caused significant accumulation of several neurotoxic metals in various brain areas - for some metals even at the low exposure dose. The most striking increases were measured in the striatum. For several metals, including Cr, Cu, Fe, Mn, and Pb, similar accumulations are known to be neurotoxic in mice. Decreases in some essential metals were observed across the CNS. Our findings suggest that chronic exposure to e-cigarette aerosol could lead to CNS neurotoxic metal deposition and endogenous metal dyshomeostasis, including potential neurotoxicity. We conclude that e-cigarette-mediated metal neurotoxicity may pose long-term neurotoxic and neurodegenerative risks for e-cigarette users and bystanders.

Towards guidelines for time-trend reviews examining temporal variability in human biomonitoring data of pollutants

In the last few decades, a plethora of studies have focused on human biomonitoring (HBM) of chemical pollutants. Reviewing the copious HBM data reported in these studies is essential for evaluating the effectiveness of pollution management efforts, for example by evaluating time-trends. Nevertheless, guidance to systematically evaluate time trends in published HBM data has never been developed. In this study, we therefore present a proposal for guidelines to conduct “time-trend reviews” (TTRs) that examine time trends in published large HBM datasets of chemical pollutant concentrations. We also demonstrate the applicability of these guidelines through a case study that assesses time-trends in global and regional HBM data on mercury. The recommended TTR guidelines in this study are divided into seven steps: formulating the objective of the TTR, setting up of eligibility criteria, defining search strategy and screening of literature, screening results of search, extracting data, analysing data, and assessing certainty, including the potential for bias in the evidence base. The TTR guidelines proposed in this study are straightforward and less complex than those for conducting systematic reviews assessing datasets on potential human health effects of exposure to pollutants or medical interventions. These proposed guidelines are intended to enable the credible, transparent, and reproducible conduct of TTRs.

The current status of studies of human exposure assessment of microplastics and their health effects: a rapid systematic review.

This rapid systematic review aims to summarize studies of human exposure to microplastics (MPs) and their health effects. For the systematic literature review, we separately searched for review articles and original articles published from 2000 to 2019 in the PubMed, NDSL, KMBASE, and Cochrane databases. A total of 276 review articles and 475 original articles were independently evaluated and eligibility of each article was assessed by two researchers. Finally, 8 review articles and 13 original articles were selected for analysis. There was no standardized methodology for determining human exposure to MPs. Therefore, the size, shape, color, and chemical composition of MPs were considered as factors that affected human exposure to MP. We ascertained that human exposure to MPs occurs through two major routes: inhalation and ingestion. The general population can be exposed to MPs through the food chain, food, and mineral water. Thus, there are multiple scenarios for the exposure process. The only exposure marker in humans is the detection and measurement of MPs in feces. Health effects of human exposure to MPs include respiratory effects from inhalation, digestive effects from ingestion, oxidative stress, and cancer. However, there are few studies of the effects of MP exposure in the general population. Based on a systematic review, we propose a standardized methodology to identify various exposure scenarios to facilitate studies of human exposure to MPs and their health effects.

Human Exposure to Glyphosate and Methods of Detection: A Review

Glyphosate is a broad-spectrum herbicide used extensively worldwide. The carcinogenic potential of glyphosate has been debated. This review aimed to describe human exposure, report environmental air concentrations in relation to occupational exposure, and identify the methods used to analyze glyphosate or AMPA concentrations. We searched, Google Scholar, Science Direct and PubMed for relevant papers in Thai or English, published from 2004 to 2017. Thus, 16 studies were identified. The results show that glyphosate and aminomethylphosphonic acid (AMPA) are markers of both internal and external exposure dose. Glyphosate is generally detected at concentrations comparable to or higher than AMPA. Human exposure has been assessed with measured levels of glyphosate ranging from 0.02 to 233 µg/L and a range of AMPA of 0.15 to 2.63 µg/L in human urine. The highest concentrations of glyphosate and AMPA found in blood were 171.1×103 and 2,600 µg/L, respectively, from acute poisonings and intentional self-harm. Environmental air concentrations of glyphosate ranged from less than 0.01 to 46.80 µg/m3 in the working field areas. Four methods used to analyze glyphosate and AMPA were identified: ELISA, HPLC-fluorescence/MS, GC-MS, LC-MS. While these results indicate the level of human exposure to glyphosate, the resulting human health effects of exposure are still uncertain. Therefore, there is a need for more investigation into human health risk assessment and application of health surveillance programs, particularly among glyphosate applicators.

Systematic review and meta-analyses of putative human health effects of exposure to per- and polyfluoroalkyl substances in children and adults

Systematic review and meta-analyses of putative human health effects of exposure to per- and polyfluoroalkyl substances in children and adults

Human health effects of traffic-related air pollution (TRAP): a scoping review protocol

BackgroundTraffic-related air pollution (TRAP) is one of the major sources of exposure in urban areas and has been associated with a wide range of adverse human health effects. Much of the Canadian population is regularly exposed to TRAP as a result of daily activities (e.g., commuting) and a significant portion of the population resides in close proximity to major roadways. The objective of this scoping review is to develop an evidence map of the epidemiological literature of the human health effects of exposure to TRAP, to support future reviews and assessments by Health Canada.MethodsLiterature searches will be conducted in Ovid EMBASE and Ovid MEDLINE database. DistillerSR will be used to manage the review process. Two reviewers will independently screen the studies in a two-part process (title and abstract; full text) for eligibility. Epidemiological studies and reviews will be included if they report on the human health effects of exposure to TRAP. Data collection will include study design parameters and human health outcomes evaluated in the study. A descriptive analysis will be used to provide a high-level summary of the number of studies evaluating the different types of health effects and cross-tabulations by study design parameters.DiscussionThe scoping review will be used to identify subject areas for more detailed review and evaluation of the human health effects of TRAP by the Air Health Effects Assessment Division of Health Canada.

Environmental Health Sciences in a Translational Research Framework: More than Benches and Bedsides.

Background:Environmental health scientists may find it challenging to fit the structure of the questions addressed in their discipline into the prevailing paradigm for translational research.Objective:We aim to frame the translational science paradigm to address the stages of scientific discovery, knowledge acquisition, policy development, and evaluation in a manner relevant to the environmental health sciences. Our intention is to characterize differences between environmental health sciences and clinical medicine, and to orient this effort towards public health goals.Discussion:Translational research is usually understood to have evolved from the bench-to-bedside framework by which basic science transitions to clinical treatment. Although many health-related fields have incorporated the terminology and context of translational science, environmental health research has not always found a clear fit into this paradigm. We describe a translational research framework applicable to environmental health sciences that retains the basic structure that underlies the original bench-to-bedside paradigm. We propose that scientific discovery (T1) in environmental health research frequently occurs through epidemiological or clinical observations. This discovery often involves understanding the potential for human health effects of exposure to a given environmental chemical or chemicals. The practical applications of this discovery evolve through an understanding of exposure–response relationships (T2) and identification of potential interventions to reduce exposure and improve health (T3). These stages of translation require an interdisciplinary partnership between exposure sciences, exposure biology, toxicology, epidemiology, biostatistics, risk assessment, and clinical sciences. Implementation science then plays a crucial role in the development of environmental and public health practice and policy interventions (T4). Outcome evaluation (T5) often takes the form of accountability research, as environmental health scientists work to quantify the costs and benefits of these interventions.Conclusion:We propose an easily visualized framework for translation of environmental health science knowledge–from discovery to public health practice–that reflects the crucial interactions between multiple disciplines in our field. https://doi.org/10.1289/EHP4067

A restatement of the natural science evidence base concerning the health effects of low-level ionizing radiation.

Exposure to ionizing radiation is ubiquitous, and it is well established that moderate and high doses cause ill-health and can be lethal. The health effects of low doses or low dose-rates of ionizing radiation are not so clear. This paper describes a project which sets out to summarize, as a restatement, the natural science evidence base concerning the human health effects of exposure to low-level ionizing radiation. A novel feature, compared to other reviews, is that a series of statements are listed and categorized according to the nature and strength of the evidence that underpins them. The purpose of this restatement is to provide a concise entrée into this vibrant field, pointing the interested reader deeper into the literature when more detail is needed. It is not our purpose to reach conclusions on whether the legal limits on radiation exposures are too high, too low or just right. Our aim is to provide an introduction so that non-specialist individuals in this area (be they policy-makers, disputers of policy, health professionals or students) have a straightforward place to start. The summary restatement of the evidence and an extensively annotated bibliography are provided as appendices in the electronic supplementary material.

A cross-sectional study of changes in markers of immunological effects and lung health due to exposure to multi-walled carbon nanotubes

Background: Multi-wall carbon nanotubes (MWCNTs) are manufactured nanomaterials to which workers and the general population will be increasingly exposed in coming years. Little is known about potential human health effects of exposure to MWCNTs, but effects on the lung and the immune system have been reported in animal and mechanistic studies.Objectives: We conducted a cross-sectional study to assess the association between occupational exposure to MWCNTs and effects on lung health and the immune system.Methods: We assessed 51 immune markers and three pneumoproteins in serum, complete blood cell counts (CBC), fractional exhaled nitric oxide (FENO), and lung function among 22 workers of a MWCNT producing facility and 39 age- and gender-matched, unexposed controls. Measurements were repeated four months later among 16 workers also included in the first phase of the study. Regression analyses were adjusted for potentially confounding parameters age, body mass index, smoking, and sex, and we explored potential confounding by other factors in sensitivity analyses.Results: We observed significant upward trends for immune markers C-C motif ligand 20 (p = .005), basic fibroblast growth factor (p = .05), and soluble IL-1 receptor II (p = .0004) with increasing exposure to MWCNT. These effects were replicated in the second phase of the study and were robust to sensitivity analyses. We also observed differences in FENO and several CBC parameters between exposed and non-exposed, but no difference in lung function or the pneumoproteins.Conclusions: We observed indications of early effects of occupational exposure to MWCNTs on lung health and the immune system.

An Updated Review of Ciguatera Fish Poisoning: Clinical, Epidemiological, Environmental, and Public Health Management.

Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world. It causes substantial human health, social, and economic impacts. The illness produces a complex array of gastrointestinal, neurological and neuropsychological, and cardiovascular symptoms, which may last days, weeks, or months. This paper is a general review of CFP including the human health effects of exposure to ciguatoxins (CTXs), diagnosis, human pathophysiology of CFP, treatment, detection of CTXs in fish, epidemiology of the illness, global dimensions, prevention, future directions, and recommendations for clinicians and patients. It updates and expands upon the previous review of CFP published by Friedman et al. (2008) and addresses new insights and relevant emerging global themes such as climate and environmental change, international market issues, and socioeconomic impacts of CFP. It also provides a proposed universal case definition for CFP designed to account for the variability in symptom presentation across different geographic regions. Information that is important but unchanged since the previous review has been reiterated. This article is intended for a broad audience, including resource and fishery managers, commercial and recreational fishers, public health officials, medical professionals, and other interested parties.

CALCULATION OF THE SAFE TIME OF GSM MOBILE PHONES USAGE

A cellular mobile radio technology has become an important part of our everyday life as it provides a convenient communication services during user’s mobility. These facilities result in increasing the user numbers of this technology at an extra ordinary rates. Widespread usage of cellular mobile communication systems has generated public concern about the possible environmental, and health effects of human exposure to electromagnetic energy emitted by base stations and cellular phones as an amount of this energy is absorbed by the human body which works as an efficient receiving antenna.This paper discusses the probable health effects of cellular mobile system emissions, and presents two proposed methods to calculate the time of the safe usage of the mobile phones that operate under the Global System for Mobile Communications (GSM).

Effects of Neonicotinoid Pesticide Exposure on Human Health: A Systematic Review.

Background:Numerous studies have identified detectable levels of neonicotinoids (neonics) in the environment, adverse effects of neonics in many species, including mammals, and pathways through which human exposure to neonics could occur, yet little is known about the human health effects of neonic exposure.Objective:In this systematic review, we sought to identify human population studies on the health effects of neonics.Methods:Studies published in English between 2005 and 2015 were searched using PubMed, Scopus, and Web of Science databases. No restrictions were placed on the type of health outcome assessed. Risk of bias was assessed using guidance developed by the National Toxicology Program’s Office of Health Assessment and Translation.Results:Eight studies investigating the human health effects of exposure to neonics were identified. Four examined acute exposure: Three neonic poisoning studies reported two fatalities (n = 1,280 cases) and an occupational exposure study of 19 forestry workers reported no adverse effects. Four general population studies reported associations between chronic neonic exposure and adverse developmental or neurological outcomes, including tetralogy of Fallot (AOR 2.4, 95% CI: 1.1, 5.4), anencephaly (AOR 2.9, 95% CI: 1.0, 8.2), autism spectrum disorder [AOR 1.3, 95% credible interval (CrI): 0.78, 2.2], and a symptom cluster including memory loss and finger tremor (OR 14, 95% CI: 3.5, 57). Reported odds ratios were based on exposed compared to unexposed groups.Conclusions:The studies conducted to date were limited in number with suggestive but methodologically weak findings related to chronic exposure. Given the wide-scale use of neonics, more studies are needed to fully understand their effects on human health.Citation:Cimino AM, Boyles AL, Thayer KA, Perry MJ. 2017. Effects of neonicotinoid pesticide exposure on human health: a systematic review. Environ Health Perspect 125:155–162; http://dx.doi.org/10.1289/EHP515

Investigating the Health Effects of Exposure to Criteria Pollutants Using AirQ2.2.3 in Shiraz, Iran

ABSTRACTThe quality of air is one of the main environmental issues related to human health. The aim of this study was to evaluate the effects of air pollution on the health of residents in Shiraz, as one of the major cities in Southern Iran, with population of 1500000 people. In this study, AirQ2.2.3 model developed by the WHO European Centre for Environment and Health was used. Daily concentration of particulate matter less than 10 microns in diameter (PM10), sulfur dioxide, nitrogen dioxide and maximum 8-hour average ozone concentration were used to evaluate the health effects of human exposure to these pollutants. The total number of excess deaths, Cardiovascular Disease (CVD) mortality, mortality from respiratory diseases, hospital admissions for CVD and hospital admissions for respiratory disease (RD) were calculated. In 2012 and 2013, hospital admissions for respiratory disease for the WHO baseline incidence of PM10 were respectively 54.6% and 38.6% of the total hospital admissions for respiratory disease. That was the highest short-term health effects on 1500000 Shirazi residents. The assessments carried out indicated the possibility that CVD mortality can play a major role in mortality due to PM10, SO2 and O3 pollutants. Overall, the results showed that health effects resulting from exposure to pollutants are directly related to their concentration. Therefore, immediate action to prevent pollution and reduce emissions from various sources, such as transport and energy production industries, is required to reduce the concentration of pollutants in Shiraz.

Carcinogenic potential of PAHs in oil-contaminated soils from the main oil fields across China.

The concentrations, composition profiles, and sources of polycyclic aromatic hydrocarbons (PAHs) were analyzed in 55 surface soil samples collected from four oil fields across China (Daqing, DQ; Shengli, SL; Xinjiang, XJ; and Huabei, HB). The total 16 priority PAHs concentrations of DQ, SL, XJ, and HB ranged from 857 to 27,816; 480 to 20,625; 497 to 43,210; and 12,112 to 45,325 ng/g, respectively, with means of 9160; 6394; 13,569; and 22,954 ng/g and the seven possible carcinogenic PAHs accounted for 8-25.7 % of the total PAHs. Almost all the samples were heavily contaminated, and phenanthrene, chrysene, and pyrene were the most dominant components. The PAH isomeric ratios indicated that PAHs in oil fields mainly originated from petroleum. The toxic assessment illustrated that people living and working in oil fields would suffer low carcinogenic risk, which was somehow coincided with the results of epidemiological survey on cancer incidence. It seems essential to pay more attention to the chronic human health effects of exposure to oil fields and to focus new studies on the public health field that involves a large number of people all over the world.