Central Tendency Exposure Research Articles

Evaluation of fluoride exposure using disability-adjusted life years and health risk assessment in south-western Iran: A novel Monte Carlo simulation

Consumption of fluoride-contaminated water is a worldwide concern, especially in developing countries, including Iran. However, there are restricted studies of non-single-value health risk assessment and the disease burden regarding fluoride intake nationwide. Prolonged exposure to excessive fluoride has been linked to adverse health effects such as dental and skeletal fluorosis. This can lead to under-mineralization of hard tissues, causing aesthetic concerns for teeth and changes in bone structure, increasing the risk of fractures. As such, we aimed to implement probability-based frameworks using Monte Carlo methods to explore the potential adverse effects of fluoride via the ingestion route. This platform consists of two sectors: 1) health risk assessment of various age categories coupled with a variance decomposition technique to measure the contributions of predictor variables in the outcome of the health risk model, and 2) implementing Monte Carlo methods in dose-response curves to explore the fluoride-induced burden of diseases of dental fluorosis and skeletal fractures in terms of disability-adjusted life years (DALYs). For this purpose, total water samples of 8053 (N=8053) from 57 sites were analyzed in Fars and Bushehr Provinces. The mean fluoride concentrations were 0.75 mg/L and 1.09 mg/L, with maximum fluoride contents of 6.5 mg/L and 3.22 mg/L for the Fars and Bushehr provinces, respectively. The hazard quotient of the 95th percentile (HQ>1) revealed that all infants and children in the study area were potentially vulnerable to over-receiving fluoride. Sobol’ sensitivity analysis indices, including first-order, second-order, and total order, disclosed that fluoride concentration (Cw), ingestion rate (IRw), and their mutual interactions were the most influential factors in the health risk model. DALYs rate of dental fluorosis was as high as 981.45 (uncertainty interval: UI 95 % 353.23–1618.40) in Lamerd, and maximum DALYs of skeletal fractures occurred in Mohr 71.61(49.75–92.71), in Fars Province, indicated severe dental fluorosis but mild hazard regarding fractures. Residents of the Tang-e Eram in Bushehr Province with a DALYs rate of 3609.40 (1296.68–5993.73) for dental fluorosis and a DALYs rate of 284.67 (199.11–367.99) for skeletal fractures were the most potentially endangered population. By evaluating the outputs of the DALYs model, the gap in scenarios of central tendency exposure and reasonable maximum exposure highlights the role of food source intake in over-receiving fluoride. This research insists on implementing defluoridation programs in fluoride-endemic zones to combat the undesirable effects of fluoride. The global measures presented in this research aim to address the root causes of contamination and help policymakers and authorities mitigate fluoride's harmful impacts on the environment and public health.

Health Risk Assessment of Indoor Formaldehyde Exposure in Facilities for Medically Vulnerable People

A health risk assessment was conducted using indoor formaldehyde concentrations measured during a four-year period from 2019 to 2022 for 322 facilities within Busan Metropolitan City. In the facilities, the average concentration of formaldehyde was 26.7 <i>μg</i>/m3 for general hospitals, 27.4 <i>μg</i>/m3 for nursing hospitals, 17.8 <i>μg</i>/m3for daycare centers, 42.9 <i>μg</i>/m3 for postpartum care centers, and 14.1 <i>μg</i>/m3 for elderly care facilities. As for the health risk of formaldehyde, workers in hospitals, daycare centers, postpartum care centers, and elderly care facilities had ECR (excess cancer risk) values of 3.54 × 10-5, 2.84 × 10-5, 6.84 × 10-5, and 1.86 × 10-5 for CTE (central tendency exposure), respectively. Based on the Busan City ordinance seven out of 322 facilities in this study were found to be non-compliant. When the risk was calculated for individual data according to the exposure of workers in each facility, 303 ECR values (94%) exceeded 1.0 × 10-5. If excess cancer risk is calculated by assuming a gradual change in formaldehyde concentration, the current maintenance standard (70 <i>μg</i>/m3) is insufficient to provide appropriate safety for workers, patients and residents. Therefore, higher stringent values than 50 <i>μg</i>/m3 are required to obtain indoor air quality standards for formaldehyde that meet an ECR of 1.0 × 10-4.

Arsenic toxicity, biomarkers of exposure and risk assessment among different aged young population from endemic areas of West Bengal, India

Arsenic exposure and associated risks in various age groups, including toddlers (1–6 years), children (7–11 years) and adolescents (12–17 years) have been evaluated through ingestion of drinking water (134 and 23.1 μg/l), rice grain (209 and 180 μg/kg) and vegetables (206 and 80.6 μg/kg) from two respective arsenic exposed villages namely Jamdani in Gaighata and Bade Khantura in Habra-I block from the North 24 Parganas district of West Bengal. ‘Spearman correlation’ found a significant association between arsenic intake particularly from drinking water and biomarkers exposure. Statistical analysis, employing ‘ANOVA’ followed by ‘Bonferroni correction’, demonstrated a strong correlation between age and arsenic deposition in biomarkers. Notably, age-dependent drop in urinary arsenic level and rise in hair and nail was observed among the studied age groups. Based on the SAMOE (Risk Thermometer), drinking water poses the highest risk for Jamdani (class 5) than Bade Khantura (class 4), while rice grains and vegetables both were classified as risk class 4 for the studied age groups. The cumulative estimated-daily-intakes (EDICumulative) of arsenic in central tendency exposure (CTE) for Jamdani and Bade Khantura were observed to be 1.09 × 10−2 and 2.7 × 10−3 mg/kg bw/day; 1.01 × 10−2 and 2.53 × 10−3 mg/kg bw/day; 9 × 10−3 and 2.46 × 10−3 mg/kg bw/day for respective age groups. Likewise, the EDICumulative for possible reasonable maximum exposure (RME) for two villages were observed to be 1.67 × 10−2 and 5.18 × 10−3 mg/kg bw/day; 1.56 × 10−2 and 4.91 × 10−3 mg/kg bw/day; 1.42 × 10−3 and 4.76 × 10−3 mg/kg bw/day for respective age groups. Furthermore, arsenic exposure was higher in all the age groups from Jamdani compared to Bade Khantura and calculated health risk (cancerous and non-cancerous) was more in toddlers followed by children and adolescents. It is highly recommended to prioritize the consumption of arsenic-safe drinking water and ensure access to a nutritious food supply to effectively combat the arsenic toxicity.

From trihalomethanes chronic daily intake through multiple exposure routes to cancer and non-cancer health risk assessment: Evidence from public Portuguese indoor swimming pools facilities using a probabilistic approach

This study aimed to estimate chronic daily intake (CDI) and to predict the attributable lifetime cancer risk (LCR) and hazard index (HI) from concurrent exposure to four trihalomethanes (THMs; chloroform, bromodichloromethane, dibromochloromethane and bromoform), via multiple exposure routes (oral ingestion, dermal contact and inhalation), among 238 non-competitive attendees of 10 Portuguese public indoor swimming pools (SPs), using a probabilistic approach based on Monte Carlo simulations. Exposure parameters of study participants were collected via questionnaires and THMs levels in SPs water were determined according the respective normative standards. The CDI for total THMs calculated for male and female participants considering all routes was 7.52 and 8.97 mg/kg/day, respectively. SP attendees presented higher CDI through inhalation than via the other two exposure routes, and chloroform was the compound contributing the most to total THMs CDI. The risk analysis indicated that the total LCR and HI from the targeted THMs were higher than the negligible risk levels (1 × 10−6 and 1, respectively) in the scenarios examined (central tendency exposure and reasonable maximum exposure), and the health risk for females was slightly higher than for males. This study suggests that there are possible adverse health risks, thus, to protect pool attendees, adequate mitigation measures, and comprehensive regulatory guidelines on individual THMs concentrations are needed.

Exploring a variance decomposition approach integrated with the Monte Carlo method to evaluate groundwater fluoride exposure on the residents of a typical fluorosis endemic semi-arid tract of India

This study appraised the groundwater fluoride (F−) endemicity and the exposure levels under the Central Tendency Exposure (CTE) condition and the Reasonable Maximum Exposure (RME) condition on the residents of the semi-arid parts of the Birbhum district of Peninsular India using a Variance Decomposition (Sobol Sensitivity Indices) approach combined with Monte Carlo Simulations. The study finds the national scale drinking water standard limit for F− (1.5 mg L−1) is inappropriate for the present survey area where F− concentration in groundwater varied between 0.26 and 11.82 mg L−1 and ~54.5% of the samples (N = 400) exceeded this limit. Therefore, estimated the optimum F− concentration of 0.733 mg L−1 for the region using the method recommended by the World Health Organization (WHO) to calculate the optimum F− limit at a regional scale. The average value of F− concentrations for this region (1.71 mg L−1) is considerably higher than the estimated optimum concentration or even the maximum permissible limits recommended for the subtropical regions (0.5–0.7 mg L−1). The exposure analysis revealed the infants and children as potentially vulnerable populations compared to adolescents and adults of the study area for CTE and RME scenarios. The multi-exposure pathways indicated oral intake as the main exposure pathway whereas exposure through dermal contact was insignificant for the residents of all age groups of this region. Based on the first, second and total order Sobol Sensitivity Indices, F− concentration (C) in groundwater, the groundwater ingestion rate and their combined interaction are the greatest significant parameters for the oral exposure model whereas C and its interaction effects with the proportion of the skin surface area in contact with groundwater as the utmost sensitive variables for the dermal health risks assessment model. The present study insists the inhabitants to intake defluoridated groundwater.

An investigation into uncertainties within Human Health Risk Assessment to gain an insight into plans to mitigate impacts of arsenic contamination

The topical research on Human Health Risk Assessment (HHRA) is investigated in this paper but in the context of uncertainty using Monto Carlo Simulation (MCS) tools. This study aims to capture some of the inherent uncertainties by implementing MCS in two dimensions: Dimension 1 considers the variability within the prescribed parameters; and Dimension 2 captures the uncertainty due to functional definitions of some of the moments of the selected distributions and interdependency of correlated parameters at a higher level. The 2D MCS model of HHRA is applied to risk assessment of a study area contaminated by arsenic, a challenging case in which arsenic has a geogenic origin but the risk is triggered by human activities. The results indicate that (i) the uncertainty in the results for the site reflects a probability distribution of risk with a positive skew; and (ii) the uncertainty increases by increasing arsenic concentration, as indicated by whisker box diagrams. The study sheds light on identifying remedial strategies since risk corresponding to Reasonable Maximum Exposure (RME Risk) is higher than the concern level of risk recommended by USEPA. The risk corresponding to the central tendency exposure is also higher than the concern level of risk in most of the samples. The paper investigates current water supply sources in the residential areas and their risk values and accordingly identifies a set of possible action plans to mitigate risk. However, the formulated 2D MCS can be extended by employing local data for deriving probability distributions and different uncertainty techniques.

Characterization of groundwater nitrate exposure using Monte Carlo and Sobol sensitivity approaches in the diverse aquifer systems of an agricultural semiarid region of Lower Ganga Basin, India

Prevalence of nitrate in different aquifer systems is a growing environmental and public health concern. Efforts were made for the first-time to achieve a higher accuracy in health risks characterization associated with the nitrate in groundwater of the diverse aquifer systems on the residents of a semi-arid rural tract of Lower Ganga Basin using Monte Carlo Simulations and Sobol Sensitivity analyses. The nitrate levels in groundwater varied between 0 and 508.3 mg/L with a mean of 19.79 ± 32.78 mg/L and 0–435.0 mg/L with a mean of 24.44 ± 35.15 mg/L during the pre-monsoon and post-monsoon periods, respectively. About 847.12–1000.25 km2 area of the survey area (total area 4545 km2) exhibited nitrate concentrations (C) > the pre-intervention limits (45–50 mg/L). Minor populations, especially the infants from the granite gneiss, Rajmahal traps, laterite, recent alluvial and old alluvial aquifer zones under the Central Tendency Exposure (CTE) condition and all the aquifer zones (including the Gondwana supergroup aquifer zone) under Reasonable Maximum Exposure (RME) scenarios, were characterized as being at high risks of methemoglobinemia, primarily due to ingestion of untreated nitrate contaminated groundwater. Residents of the alluvial aquifer zones of the study area were found to the most vulnerable to the groundwater nitrate toxicity through oral and dermal exposures. The study validated the prediction accuracies of different interpolation methods including the Spline, Kriging, polynomial and Inverse Distance Weighted and revealed that Kriging predicted the Spatio-seasonal variations of groundwater nitrate of the district more accurately. Sobol Sensitivity analysis revealed C and the interaction effects of C and groundwater Ingestion Rate (IR), and C and Fraction of skin area contacted with groundwater (F) as the influential parameters for oral and dermal health risks exposure models. Therefore, the study recommends to residents of the study area to consume treated groundwater to mitigate nitrate related health morbidities.

Health risk assessment of co-occurrence of toxic fluoride and arsenic in groundwater of Dharmanagar region, North Tripura (India)

The present study assessed the co-occurrence of fluoride and arsenic in groundwater of Dharmanagar region (Tripura, India). Co-occurrence of the two toxicants was observed in 59% of the analyzed groundwater samples (n = 71), out of which concentrations of both the toxicants exceeded the World Health Organization drinking water standards in 30% samples. Significant positive correlation (r = 0.6) was observed between groundwater fluoride (<0.005–4.8 mg/l) and arsenic (<0.003–0.044 mg/l) contents. The range of cumulative estimated daily intakes (EDI) in the studied population was: 0.07–0.1 and 0.13–0.18 mg/kg-day for the Central Tendency Exposure (CTE) and the Reasonable Maximum Exposure (RME) scenarios, respectively. The EDI (fluoride) for the children of the study area was already found to reach the ‘Tolerable Upper Intake Level’ (UL) value (0.1 mg/kg-day), and the children are thus at high risk from developing dental fluorosis. Irrespective of the CTE or RME scenario, the hazard index of fluoride (HIFluoride = 1.2–3) and that of arsenic (HIArsenic = 1.5–5) were always found to be unsafe (HI > 1) in the studied population. The estimated Cumulative Noncancerous Lifetime Hazard Index for simultaneous fluoride and arsenic exposures was calculated to be prominently high (10 and 22 for the CTE and RME scenarios, respectively). The average urinary fluoride and arsenic contents of the studied population was observed to be correlated (r = 0.46 and 0.69) with the groundwater fluoride and arsenic concentrations, respectively. The observed content of urinary fluoride (mean = 3.1 ± 1.2 mg/l) of the studied population was determined to be 65–163% of their total fluoride intakes (1.9–7.2 mg/day). The obtained results are highly alarming and thus for reducing threats to human health, the government should immediately take necessary action for supplying safe drinking water for the residents.

Prioritizing Type of Industry through Health Risk Assessment of Occupational Exposure to Dimethylformamide in the Workplace.

The purpose of this study was to classify hazards at an industrial level and evaluate the exposure risks of workers exposed to dimethylformamide (DMF) used as a solvent in the workplace and to determine industries that need priority measures in managing DMF exposure. We calculated hazard quotients at an industrial level. The exposure data of DMF in the workplace were obtained from the work environment monitoring program provided by the Korea Occupational Safety and Health Agency. The evaluation was conducted on textile manufacturing, leather manufacturing, chemical manufacturing, pharmaceutical manufacturing, and rubber manufacturing industries, which have many unit work sites handling DMF. The highest central tendency exposure and reasonable maximum exposure were 2.13 and 18.66 mg/m3 for the rubber product manufacturing industry, respectively. A total of 63.8% of workplaces in the textile manufacturing sector had a hazard quotient higher than 1. The highest risk for exposure to DMF is in the rubber and plastic manufacturing industry, and the lowest risk was in the medical materials and pharmaceutical manufacturing sector. Based on this study, effective management of DMF exposure could be achieved by establishing priority management measures for the textile and rubber and plastic product industries.

Exposure to toxicants in soil and bottom ash deposits in Agbogbloshie, Ghana: human health risk assessment.

Recycling of e-waste using informal or crude techniques poses serious health risk not only to the workers but also to the environment as whole. It is against this background that this paper sought to measure health risk faced by informal e-waste workers from exposure to toxicants such as lead, cadmium, chromium, copper, arsenic, tin, zinc and cobalt via oral and dermal contact with bottom ash and soil. Using random sampling techniques, 3 separate sites each (where burning and manual dismantling of e-wastes are usually carried) were identified, and a total of 402 samples were collected. The samples were analysed using standard methods for chemical analysis prescribed by the American Water Works Association (AWWA). Concentrations of Pb, Cd, Cr, Cu, As, Sn, Zn and Co in bottom ash samples from location ASH1 are 5388±0.02mg/kg (Pb), 2.39±0.01mg/kg (Cd), 42±0.05mg/kg (Cr), 7940±0.01mg/kg (Cu), 20±0.07mg/kg (As), 225±0.04mg/kg (Sn), 276±0.04mg/kg (Zn) and 123±0.04mg/kg (Co), while concentrations of the aforementioned toxicants in soil samples at location ASG1 are as follows: 1685±0.14mg/kg (Pb), 26.89±0.30mg/kg (Cd), 36.86±0.02mg/kg (Cr), 1427±0.08mg/kg (Cu), 1622±0.12mg/kg (As), 234±0.25mg/kg (Sn), 783±0.31mg/kg (Zn) and 135±0.01mg/kg (Co); used as input parameters in assessing health risk faced by workers. The results of cancer health risk faced by e-waste workers due to accidental ingestion of As in bottom ash at ASH1 is 4.3×10-3 (CTE) and 6.5×10-2 (RME), i.e. approximately 4 out of 1000 e-waste workers are likely to suffer from cancer-related diseases via central tendency exposure (CTE parameters), and 7 out of every 100 e-waste worker is also likely to suffer from cancer cases by reasonable maximum exposure (RME) parameters, respectively. The cancer health risk results for the other sampling sites were found to have exceeded the acceptable USEPA cancer risk value of 1×10-4 to 1×10-6 (i.e. 1 case of cancer per every 10,000 people to 1 case of cancer per every 1,000,000 people). The non-cancer health risk results for all the toxicants were higher in all the locations for both adult and children working the e-waste site. From the findings of this study, the government of Ghana has to immediately put in place policies that would address the safety of the e-waste workers as well as protect the environment.

Health risk assessment of occupational exposure to styrene depending on the type of industry: Data from the Workplace Environmental Monitoring Program in Korea

ABSTRACTData from the Workplace Environmental Monitoring Program was used to evaluate the concentrations and risk of occupational exposure to styrene in different industries to identify which industries should be prioritized for styrene exposure management. Risk assessments were conducted for the five industries with several workplaces that mostly use styrene: motor vehicle and motorcycle maintenance and repair services, other chemical product manufacturing, ship and boat building, basic chemical manufacturing, and plastic products manufacturing. The highest central tendency exposure was found in the plastic products manufacturing industry (10.14 mg/m3). In addition, the hazard quotient (HQ) for central tendency exposure exceeded 1 only in the plastic products manufacturing industry. Almost two-thirds (62.2%) of workplaces in the plastic products manufacturing industry have an HQ exceeding 1. We conclude that workers in the plastic products manufacturing industry are at the highest risk for styrene exposure, and those in motor vehicle and motorcycle maintenance and repair service and basic chemical manufacturing are at the lowest risk. These results show that styrene exposure could be most effectively managed by prioritizing control measures in the plastic products manufacturing industry.

Human Health Risk Assessment of Artisanal Miners Exposed to Toxic Chemicals in Water and Sediments in the Prestea Huni Valley District of Ghana.

A human health risk assessment of artisanal miners exposed to toxic metals in water bodies and sediments in the PresteaHuni Valley District of Ghana was carried out in this study, in line with US EPA risk assessment guidelines. A total of 70 water and 30 sediment samples were collected from surface water bodies in areas impacted by the operations of artisanal small-scale gold mines in the study area and analyzed for physico-chemical parameters such as pH, TDS, conductivity, turbidity as well as metals and metalloids such as As, Cd, Hg and Pb at CSIR—Water Research Institute using standard methods for the examination of wastewater as outlined by American Water Works Association (AWWA). The mean concentrations of As, Cd, Hg and Pb in water samples ranged from 15 μg/L to 325 μg/L (As), 0.17 μg/L to 340 μg/L (Cd), 0.17 μg/L to 122 μg/L (Pb) and 132 μg/L to 866 μg/L (Hg), respectively. These measured concentrations of arsenic (As), mercury (Hg), cadmium (Cd) and lead (Pb) were used as input parameters to calculate the cancer and non-cancer health risks from exposure to these metals in surface water bodies and sediments based on an occupational exposure scenario using central tendency exposure (CTE) and reasonable maximum exposure (RME) parameters. The results of the non-cancer human health risk assessment for small-scale miners working around river Anikoko expressed in terms of hazard quotients based on CTE parameters are as follows: 0.04 (Cd), 1.45 (Pb), 4.60 (Hg) and 1.98 (As); while cancer health risk faced by ASGM miners in Dumase exposed to As in River Mansi via oral ingestion of water is 3.1 × 10−3. The hazard quotient results obtained from this study in most cases were above the HQ guidance value of 1.0, furthermore the cancer health risk results were found to be higher than the USEPA guidance value of 1 × 10−4 to 1 × 10−6. These findings call for case-control epidemiological studies to establish the relationship between exposure to the aforementioned toxic chemicals and diseases associated with them as identified in other studies conducted in different countries as basis for developing policy interventions to address the issue of ASGM mine workers safety in Ghana.

Exposure monitoring and risk assessment of biphenyl in the workplace.

This study was performed to assess exposure to and the risk caused by biphenyl in the workplace. Biphenyl is widely used as a heat transfer medium and as an emulsifier and polish in industry. Vapor or high levels of dust inhalation and dermal exposure to biphenyl can cause eye inflammation, irritation of respiratory organs, and permanent lesions in the liver and nervous system. In this study, the workplace environment concentrations were assessed as central tendency exposure and reasonable maximum exposure and were shown to be 0.03 and 0.12 mg/m3, respectively. In addition, the carcinogenic risk of biphenyl as determined by risk assessment was 0.14 × 10−4 (central tendency exposure) and 0.56 × 10−4 (reasonable maximum exposure), which is below the acceptable risk value of 1.0 × 10−4. Furthermore, the central tendency exposure and reasonable maximum exposure hazard quotients were 0.01 and 0.06 for oral toxicity, 0.05 and 0.23 for inhalation toxicity, and 0.08 and 0.39 for reproduction toxicity, respectively, which are all lower than the acceptable hazard quotient of 1.0. Therefore, exposure to biphenyl was found to be safe in current workplace environments. Because occupational exposure limits are based on socioeconomic assessment, they are generally higher than true values seen in toxicity experiments. Based on the results of exposure monitoring of biphenyl, the current occupational exposure limits in Korea could be reviewed.

Exposure Monitoring and Health Risk Assessment of 1-Bromopropane as a Cleaning Solvent in the Workplace

ABSTRACTThis study was conducted to estimate the health risk to workers exposed to 1-bromopropane (1-BP) used as a cleaning solvent in their workplaces. Fifty samples from 10 workplaces that use 1-BP as a cleaning solvent were obtained to assess 1-BP concentrations. An exposure assessment revealed central tendency exposure (CTE) and reasonable maximum exposure (RME) levels of 82.1 and 214.8 mg/m3, respectively. For risk characterization, the 1-BP exposure concentrations for reproductive and developmental toxicities were calculated as 2.8 and 8.5 mg/m3, respectively, and compared with the reference concentrations in the workplace. The CTE and RME hazard quotients (HQ) were, respectively, 29.4 and 77.0 for reproductive toxicity and 9.6 and 25.2 for developmental toxicity. The results of our 1-BP risk assessment indicated that the CTE-HQs for both categories were higher than the acceptable risk value of 1, indicating that 1-BP may be considered as harmful to workers.

Health Risks to Children and Adults Residing in Riverine Environments where Surficial Sediments Contain Metals Generated by Active Gold Mining in Ghana

The purpose of this study was to investigate the current status of metal pollution in the sediment from rivers, lakes, and streams in active gold mining districts in Ghana. Two hundred and fifty surface sediment samples from 99 locations were collected and analyzed for concentrations of As, Hg, Cr, Co, Cu, Fe, Zn, Pb, Cd, Ni, and Mn using inductively coupled plasma-mass spectroscopy (ICP-MS). Metal concentrations were then used to assess the human health risks to resident children and adults in central tendency exposure (CTE) and reasonable maximum exposure (RME) scenarios. The concentrations of Pb, Cd, and As were almost twice the threshold values established by the Hong Kong Interim Sediment Quality Guidelines (ISQG). Hg, Cu, and Cr concentrations in sediment were 14, 20, and 26 times higher than the Canadian Freshwater Sediment Guidelines for these elements. Also, the concentrations of Pb, Cu, Cr, and Hg were 3, 11, 12, and 16 times more than the Australian and New Zealand Environment and Conservation Council (ANZECC) sediment guideline values. The results of the human health risk assessment indicate that for ingestion of sediment under the central tendency exposure (CTE) scenario, the cancer risks for child and adult residents from exposure to As were 4.18 × 10−6 and 1.84 × 10−7, respectively. This suggests that up to 4 children out of one million equally exposed children would contract cancer if exposed continuously to As over 70 years (the assumed lifetime). The hazard index for child residents following exposure to Cr(VI) in the RME scenario was 4.2. This is greater than the United States Environmental Protection Agency (USEPA) threshold of 1, indicating that adverse health effects to children from exposure to Cr(VI) are possible. This study demonstrates the urgent need to control industrial emissions and the severe heavy metal pollution in gold mining environments.

Assessment of cancer and noncancer health risks from exposure to PAHs in street dust in the Tamale Metropolis, Ghana

This study is part of a broader initiative to characterize, quantify and assess the human health risk associated with exposure to polycyclic aromatic hydrocarbons (PAHs) in street dust along the Trans-ECOWAS highway in West Africa. In the first part, PAHs were characterized and quantified in low- and high-traffic zones. In this study, cancer and noncancer human health risks from exposure to (PAHs) in street dust in the Tamale metropolis, Ghana were assessed in accordance with the USEPA risk assessment guidelines. The results of the study as obtained from inhalation of benzo [a] anthracene (BaA), benzo [a] pyrene (BaP), benzo [k] fluoranthene (BkF) and chrysene via central tendency exposure parameters (CTE) by trespassers (street hawkers including children and adults) in street dust within low traffic zones in the Tamale metropolis are 1.6E-02, 4.7E-02, 1.8E-03, and 1.6E-04 respectively. For reasonable maximum exposure parameters (RME), risk values of 1.2E-01, 3.5E-01, 1.3E-02 and 1.2E-03 respectively were obtained for benzo [a] anthracene, benzo [a] pyrene, benzo [k] fluoranthene and chrysene. Hazard index for acenaphthene, anthracene, fluoranthene, fluorine, naphthalene and pyrene in the CTE and RME scenarios were 2.2, 3.E-01, 2.6, 2.6, 100, 38 and 12, 1.7,15, 14, 550, 210 respectively. Generally, the cancer health risk associated with inhalation of benzo [a] anthracene, benzo [a] pyrene, benzo [k] fluoranthene and chrysene revealed that resident adults and children in the Tamale metropolis are at risk from exposure to these chemicals. The results of this preliminary assessment that quantified PAH related health risks along this part of the Trans-ECOWAS highway revealed that, there is the need for regulatory agencies to put in comprehensive measures to mitigate the risks posed to these categories of human receptors.

English

The study assessed non-cancer human health risk from exposure to mecury (Hg), cadmium (Cd), arsenic (As), copper (Cu), and lead (Pb) in surface and groundwater in Tinga, in the Bole-Bamboi District. A total of 42 water samples were collected for a period of six months. Mean concentration of Hg, Cd, and Pb were found to be (0.050 ± 0.04 mg/L), (0.031 ± 0.02 mg/L) and (0.07 ± 0.05 mg/L), respectively. These were all above the World Health Organization (WHO) recommended guideline values for drinking water. Non-cancer human health risk as a result of exposure to Hg and Cd through ingestion of borehole water was found to be high. Hazard quotients (HQ) as a result of exposure to mercury for adults and children ranged from 2.5 to 30 through central tendency exposure (CTE) and 4.6 to 60 through reasonable maximum exposure (RME). For Cd, CTE ranged from 0.96 to 2.7 and RME ranged from 1.8 to 5.4. The HQ for exposure to Hg and Cd through ingestion of ground water exceeded the acceptable United States Environmental Protection Agency (USEPA) value of 1.0. This implies that resident children and adults are likely to develop diseases (such as low intelligent quotient, tremor, kidney failure, increased hypertension and cardiovascular diseases) associated with long term exposure to Hg and Cd. Key words: Small-scale mining, Tinga, non-cancer, health risk, hazard quotient, borehole, surface water.

Screening-Level Risk Assessment for Styrene-Acrylonitrile (SAN) Trimer Detected in Soil and Groundwater

A screening-level risk assessment was conducted for styrene-acrylonitrile (SAN) Trimer detected at the Reich Farm Superfund site in Toms River, NJ. Consistent with a screening-level approach, on-site and off-site exposure scenarios were evaluated using assumptions that are expected to overestimate actual exposures and hazards at the site. Environmental sampling data collected for soil and groundwater were used to estimate exposure point concentrations. Several exposure scenarios were evaluated to assess potential on-site and off-site exposures, using parameter values for exposures to soil (oral, inhalation of particulates, and dermal contact) and groundwater (oral, dermal contact) to reflect central tendency exposure (CTE) and reasonable maximum exposure (RME) conditions. Three reference dose (RfD) values were derived for SAN Trimer for short-term, subchronic, and chronic exposures, based upon its effects on the liver in exposed rats. Benchmark (BMD) methods were used to assess the relationship between exposure and response, and to characterize appropriate points of departure (POD) for each RfD. An uncertainty factor of 300 was applied to each POD to yield RfD values of 0.1, 0.04, and 0.03 mg/kg-d for short-term, subchronic, and chronic exposures, respectively. Because a chronic cancer bioassay for SAN Trimer in rats (NTP 2011a) does not provide evidence of carcinogenicity, a cancer risk assessment is not appropriate for this chemical. Potential health hazards to human health were assessed using a hazard index (HI) approach, which considers the ratio of exposure dose (i.e., average daily dose, mg/kg-d) to toxicity dose (RfD, mg/kg-d) for each scenario. All CTE and RME HI values are well below 1 (where the average daily dose is equivalent to the RfD), indicating that there is no concern for potential noncancer effects in exposed populations even under the conservative assumptions of this screening-level assessment.

Human Health Risk Assessment of Trichloroethylene from Industrial Complex A

This study investigated the human health risks of trichloroethylene from Industrial Complex A. The excessive carcinogenic risks for central tendency exposure were 1.40 × 10?5 for male and female residents in the vicinity of Industrial Complex A. The excessive cancers risk for reasonable maximum exposure were 2.88 × 10?5 and 1.97 × 10?5 for males and females, respectively. These values indicate that there are potential cancer risks for exposure to these concentrations. The hazard index for central tendency exposure to trichloroethylene was 1.71 for male and female residents. The hazard indexes for reasonable maximum exposure were 3.27 and 2.41 for males and females, respectively. These values were over one, which is equivalent to the threshold value. This result showed that adverse cancer and non-cancer health effects may occur and that some risk management of trichloroethylene from Industrial Complex A was needed.

Ecological Health Status of the Fosu Lagoon, Southern Ghana II: Environmental and Human Health Risk Assessment

This study set out to assess the levels, distribution and human health risk of Pb, As, Cd, Mn and polycyclic aromatic hydrocarbons (PAHs) in sediments from the Fosu Lagoon in Ghana. This was coupled with environmental fate modeling to investigate biodegradation behaviour of PAHs in sediment. Generally, the order of heavy metal enrichment for the sampling locations was Mn>Cd>Pb>As respectively. Only Mn showed significant enrichment at all sites. The observed PAH contamination demonstrated potential anthropogenic impact. The phenanthrene-anthracene ratio was less than 10 indicating that the PAHs originate from combustion. Benzo[b]fluoranthrene is the only carcinogenic PAH that was detected in the study. Regarding heavy metals in children, the total Hazard Index (HI) for ingestion and dermal route was 3.4×10-2 and 8.2×10-3 respectively for Central Tendency Exposure (CTE) whereas it was 2.1×10-1 and 1.0×10-1 for the Reasonable Maximum Exposure (RME) scenario. In adults, the total HI was 1.0×10-3 and 1.2×10-3, for ingestion and dermal routes respectively under the CTE scenario. For RME scenario, ingestion and dermal exposure had risk values of 2.2×10-2 and 3.1×10-2, respectively. Regarding PAHs, the total carcinogenic risk (RME) for children and adults were estimated as 1.02×10-5 and 8.38×10-6 respectively. The carcinogenic risk derived from the ingestion and dermal absorption of metals exceeded the generally acceptable risk level of 10-6 for individual chemicals, being slightly above 10-4. That risk level, basically due to the ingestion of As and Mn through sediments suggests potential harm to human health. The concentrations of PAHs in sediments did not present signii¬cant non-carcinogenic and carcinogenic risk for the local population. The fate modelling however, suggests that naphthalene, anthracene, benzo[b]fluoranthene, pyrene, fluorene and phenanthrene tend to sorb onto soil or sediment in the environment and biologically ‘‘do not degrade fast’’. This implies the need to implement long term monitoring of these compounds in order to sustain this fragile ecosystem.