Lifetime Cancer Risk Assessment Research Articles

Source apportionment and risk assessment of polycyclic aromatic hydrocarbons in the atmospheric environment of Alexandria, Egypt

In this study, three receptor models [factor analysis/multiple linear regression (FA/MLR), positive matrix factorization (PMF) and UNMIX] were applied seasonally to investigate the source apportionment of PAHs in the atmospheric environment of Alexandria, and a lifetime cancer risk was assessed. ∑44 (gas+particle) PAH concentrations varied from 330 to 1770ngm−3 and 170–1290ngm−3 in the summer and winter seasons respectively. PAH concentrations at the industrial sites were significantly higher than at the traffic and residential sites during the winter season (p<0.001). Summer PAH concentrations were significantly higher than the winter season at the traffic sites (p=0.027). Results obtained from the three receptor models were comparable. Vehicle emissions, both diesel and gasoline contributed on average 36.0–49.0% and 19.0–34.0% respectively, natural gas combustion 11.0–27.0% and, during the summer only, also evaporative/uncombusted petroleum sources 8.00–18.0%. Seasonal trends were found for the gasoline emission source. Overall, PMF and UNMIX models afforded better source identification than did FA/MLR. The lifetime cancer risk assessment showed that incremental lifetime cancer risks (ILTCRs) were greater than the acceptable level of 10−6 through dermal and ingestion routes at all the investigated sites and through the inhalation route at the industrial and traffic sites only. Total ILTCRs (6.64×10−3–4.42×10−2) indicated high potential risks to the local residents.

Cancer and non-cancer risk assessment of trihalomethanes in urban drinking water supplies of Pakistan

This study aims at monitoring and risk assessment of trihalomethanes (THMs) such as chloroform, bromodichloromethane, dibromochloromethane and bromoform, in the drinking water supplies of Rawalpindi and Islamabad. THMs were monitored at twenty locations in these twin cities using solid phase micro extraction-gas chromatography (SPME-GC). Total concentration of THMs was ranged between 21 and 373μg/L, whereas both cities had an average total THMs concentration of 142 and 260μg/L, respectively. Chloroform was found as one the major contributor to the THMs concentration (>85%). The occurrence of THMs followed the given order: chloroform, bromodichloromethane>dibromochloromethane>bromoform. Lifetime cancer risk assessment of THMs was carried out using prediction models via different exposure routes (ingestion, inhalation and dermal). An average lifetime cancer risk was found to be 0.74×10−4 and 1.24×10−4 for Rawalpindi and Islamabad, respectively. The number of expected cancer cases per year could reach two cases for each city. Hazard index values were found below unity for both the cities implying that there would be no considerable non-cancer risk. Oral ingestion was found to be one of the main routes of exposure for both types of risk which was followed by inhalation and dermal routes.

A statistical regression model for the estimation of acrylamide concentrations in French fries for excess lifetime cancer risk assessment

Human exposure to acrylamide (AA) through consumption of French fries and other foods has been recognized as a potential health concern. Here, we used a statistical non-linear regression model, based on the two most influential factors, cooking temperature and time, to estimate AA concentrations in French fries. The R2 of the predictive model is 0.83, suggesting the developed model was significant and valid. Based on French fry intake survey data conducted in this study and eight frying temperature–time schemes which can produce tasty and visually appealing French fries, the Monte Carlo simulation results showed that if AA concentration is higher than 168 ppb, the estimated cancer risk for adolescents aged 13-18 years in Taichung City would be already higher than the target excess lifetime cancer risk (ELCR), and that by taking into account this limited life span only. In order to reduce the cancer risk associated with AA intake, the AA levels in French fries might have to be reduced even further if the epidemiological observations are valid. Our mathematical model can serve as basis for further investigations on ELCR including different life stages and behavior and population groups.

Health risk assessment of polycyclic aromatic hydrocarbons and heavy metals via dietary intake of vegetables grown in the vicinity of thermal power plants

Six different vegetables grown in the vicinity of three thermal power plants and a background site in Delhi, India were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) and 7 heavy metals (Cd, Cu, Cr, Ni, Zn, Fe and Mn). Annual mean concentrations of PAHs and all metals were found to be significantly higher (ANOVA, p<0.001) at power plant sites as compared to the background site. Higher abundances of coal tracer PAHs such as Phen, Anth, Flan, Pyr and Chry in power plant vegetables suggested possible impacts of coal combustion emissions. Higher ratios of polluted sample-to-background sample of vegetables were found especially for Cr, Cd, Ni and Zn. Spinach and radish showed greater accumulation of PAHs and metals on a mass basis at the power plant sites while vegetables belonging to the gourd family showed highest relative enrichment. Power plant samples showed 184–475% greater metal pollution index (MPI) values as compared to the background location while health risk indices (HRI) for Cd and Ni exceeded the safe limit for most vegetables. Incremental lifetime cancer risk (ILCR) assessment showed that up to 58 excess cancer cases are likely in Delhi for lifetime ingestion exposure to PAHs at their observed concentrations.

Airborne inhalable metals in residential areas of Delhi, India: distribution, source apportionment and health risks

The inhalable fraction of ambient particles (particulate matter with aerodynamic diameter less than 10μm, denoted by PM10) collected at three residential sites in Delhi, India during December 2008–November 2009 were characterized with respect to 8 major and trace metals (Fe, Mn, Cd, Cu, Ni, Pb, Zn and Cr). Mean annual 24–h PM10 levels varied from 166.5–192.3μg m–3 at the sites (8–10 times of the WHO limit). Weekday/weekend effects on PM10 and associated metals were investigated. Significant seasonal variations (ANOVA, p<0.001) in species concentrations were observed with PM10 and crustal metals peaking in summer while anthropogenic metals peaked in winter. Spatial distributions of metals were influenced mainly by proximity to traffic and industrial areas. Influence of meteorological parameters on ambient metal distributions was also studied. Source apportionment by principal component analysis–multiple linear regression (PCA–MLR) identified three major sources: crustal (49–65%), vehicular (27–31%) and industrial (4–21%). As a part of health risk assessment, calculated theoretical estimates of blood lead levels in children varied from 10.2–13.3μg dL–1, indicating some degree of lead toxicity. Incremental lifetime cancer risk (ILCR) assessment showed that up to 2 908 excess cancer cases (102 for Cd, 2 559 for Cr (VI) and 247 for Ni) are likely in Delhi for lifetime inhalation exposure to these species at their current concentrations.

Organochlorines and heavy metals in wild caught food as a potential human health risk to the indigenous Māori population of South Canterbury, New Zealand

Increasing concentrations of anthropogenic contaminants in wild kai (food) of cultural, recreational and economic importance to the indigenous Māori of New Zealand is a potential human health risk. Contaminants that are known to bioaccumulate through the food chain (e.g., organochlorine pesticides (OCPs), PCBs and selected heavy metals) were analysed in important kai species including eel ( Anguilla sp.), brown trout ( Salmo trutta), black flounder ( Rhombosolea retiaria) and watercress ( Nasturtium officinale) from important harvesting sites in the region of South Canterbury. Eels contained relatively high wet weight concentrations of p,p′-DDE (8.6–287 ng/g), PCBs ( 32Σ PCB; 0.53–58.3 ng/g), dieldrin (< 0.05–16.3 ng/g) and Σchlordanes (0.03–10.6 ng/g). Trout and flounder contained lower concentrations of organochlorines than eels, with p,p′-DDE wet weight concentrations ranging from 2.2 to 18.5 ng/g for trout and 6.4 to 27.8 ng/g for flounder. Total arsenic wet weight concentrations were below detection limits for eels but ranged from 0.27 to 0.89 μg/g for trout and 0.12 to 0.56 μg/g for flounder. Mercury concentrations ranged from 0.02 to 0.56 μg/g, 0.11 to 0.50 μg/g and 0.04 to 0.10 μg/g (ww) for eel, trout and flounder respectively. Lifetime excess cancer risk was calculated through established risk assessment procedures, highlighting dieldrin, ΣPCBs and p,p′-DDE in eels and arsenic in trout and flounder as primary contaminants of concern. A second non-cancer chronic health risk assessment indicated that mercury and PCBs were a potential concern in eels and mercury in trout. A cumulative lifetime cancer risk assessment showed potential health risk for consumption of some species, even at low consumption rates and provided the basis for establishing recommended dietary consumption limits for harvest sites within the study region.

Animal studies of life shortening and cancer risk from space radiation

The U. S. Air Force study of the delayed effects of single, total body exposures to simulated space radiation in rhesus monkeys is now in its 21st year. Observations on 301 irradiated and 57 age-matched control animals indicate that life expectancy loss from exposure to protons in the energy range encountered in the Van Allen belts and solar proton events can be expressed as a logarithmic function of the dose. The primary causes of life shortening are cancer and endometriosis (an abnormal proliferation of the lining of the uterus in females). Life shortening estimates permit comparison of the risk associated with space radiation exposures to be compared with that of other occupational and environmental hazards, thereby facilitating risk/benefit decisions in the planning and operational phases of manned space missions. Calculations of the relative risk of fatal cancers in the irradiated subjects reveal that the total body surface dose required to double the risk of death from cancer over a 20-year post exposure period varies with the linear energy transfer (LET) of the radiation. The ability to determine the integrated dose and LET spectrum in space radiation exposures of human is, therefore, critical to the assessment of life-time cancer risk.