Tag Archives: risk assessment

Cryptosporidium Risks Associated with Potable Reuse

Amoueyan E, Ahmad S, Eisenberg JNS, Pecson B, Gerrity D. Quantifying pathogen risks associated with potable reuse: A risk assessment case study for Cryptosporidium. Water research 2017 Apr 19;119:252-266. doi: 10.1016/j.watres.2017.04.048.

This study evaluated the reliability and equivalency of three different potable reuse paradigms: (1) surface water augmentation via de facto reuse with conventional wastewater treatment; (2) surface water augmentation via planned indirect potable reuse (IPR) with ultrafiltration, pre-ozone, biological activated carbon (BAC), and post-ozone; and (3) direct potable reuse (DPR) with ultrafiltration, ozone, BAC, and UV disinfection. A quantitative microbial risk assessment (QMRA) was performed to (1) quantify the risk of infection from Cryptosporidium oocysts; (2) compare the risks associated with different potable reuse systems under optimal and sub-optimal conditions; and (3) identify critical model/operational parameters based on sensitivity analyses. The annual risks of infection associated with the de facto and planned IPR systems were generally consistent with those of conventional drinking water systems [mean of (9.4 ± 0.3) × 10-5 to (4.5 ± 0.1) × 10-4], while DPR was clearly superior [mean of (6.1 ± 67) × 10-9 during sub-optimal operation]. Because the advanced treatment train in the planned IPR system was highly effective in reducing Cryptosporidium concentrations, the associated risks were generally dominated by the pathogen loading already present in the surface water. As a result, risks generally decreased with higher recycled water contributions (RWCs). Advanced treatment failures were generally inconsequential either due to the robustness of the advanced treatment train (i.e., DPR) or resiliency provided by the environmental buffer (i.e., planned IPR). Storage time in the environmental buffer was important for the de facto reuse system, and the model indicated a critical storage time of approximately 105 days. Storage times shorter than the critical value resulted in significant increases in risk. The conclusions from this study can be used to inform regulatory decision making and aid in the development of design or operational criteria for IPR and DPR systems.

Selenium Health Risk Assessment

Vinceti M, Filippini T, Cilloni S, Bargellini A, Vergoni AV, Tsatsakis A, Ferrante M. Health risk assessment of environmental selenium: Emerging evidence and challenges (Review). Mol Med Rep. 2017 Mar 24. doi: 10.3892/mmr.2017.6377.

New data have been accumulated in the scientific literature in recent years which allow a more adequate risk assessment of selenium with reference to human health. This new evidence comes from environmental studies, carried out in populations characterized by abnormally high or low selenium intakes, and from high-quality and large randomized controlled trials with selenium recently carried out in the US and in other countries. These trials have consistently shown no beneficial effect on cancer and cardiovascular risk, and have yielded indications of unexpected toxic effects of selenium exposure. Overall, these studies indicate that the minimal amount of environmental selenium which is source of risk to human health is much lower than anticipated on the basis of older studies, since toxic effects were shown at levels of intake as low as around 260 µg/day for organic selenium and around 16 µg/day for inorganic selenium. Conversely, populations with average selenium intake of less than 13-19 µg/day appear to be at risk of a severe cardiomyopathy, Keshan disease. Overall, there is the need to reconsider the selenium standards for dietary intake, drinking water, outdoor and indoor air levels, taking into account the recently discovered adverse health effects of low-dose selenium overexposure, and carefully assessing the significance of selenium-induced proteomic changes.

Probablistic risk assessment of perchlorate in drinking water

Lumen A, George NI. Evaluation of the risk of perchlorate exposure in a population of late-gestation pregnant women in the United States: Application of probabilistic biologically-based dose response modeling. Toxicology and applied pharmacology. 2017 Mar 2. pii: S0041-008X(17)30098-4. doi: 10.1016/j.taap.2017.02.021.

The risk of ubiquitous perchlorate exposure and the dose-response on thyroid hormone levels in pregnant women in the United States (U.S.) have yet to be characterized. In the current work, we integrated a previously developed perchlorate submodel into a recently developed population-based pregnancy model to predict reductions in maternal serum free thyroxine (fT4) levels for late-gestation pregnant women in the U.S. Our findings indicated no significant difference in geometric mean estimates of fT4 when perchlorate exposure from food only was compared to no perchlorate exposure. The reduction in maternal fT4 levels reached statistical significance when an added contribution from drinking water (i.e., 15μg/L, 20μg/L, or 24.5μg/L) was assumed in addition to the 90th percentile of food intake for pregnant women (0.198μg/kg/day). We determined that a daily intake of 0.45 to 0.50μg/kg/day of perchlorate was necessary to produce results that were significantly different than those obtained from no perchlorate exposure. Adjusting for this food intake dose, the relative source contribution of perchlorate from drinking water (or other non-dietary sources) was estimated to range from 0.25-0.3μg/kg/day. Assuming a drinking water intake rate of 0.033L/kg/day, the drinking water concentration allowance for perchlorate equates to 7.6-9.2μg/L. In summary, we have demonstrated the utility of a probabilistic biologically-based dose-response model for perchlorate risk assessment in a sensitive life-stage at a population level; however, there is a need for continued monitoring in regions of the U.S. where perchlorate exposure may be higher.

Health Risk Assessment of Cadmium Pollution, Foshan City, China

Dou M, Zhao P, Wang Y, Li G. Health risk assessment of cadmium pollution emergency for urban populations in Foshan City, China. Environmental science and pollution research international. 2017 Jan 30. doi: 10.1007/s11356-017-8437-3.

With rapid socioeconomic development, water pollution emergency has become increasingly common and could potentially harm the environment and human health, especially heavy metal pollution. In this paper, we investigate the Cd pollution emergency that occurred in the Pearl River network, China, in 2005, and we build a migration and transformation model for heavy metals to simulate the spatiotemporal distribution of Cd concentrations under various scenarios of Cd pollution emergency in Foshan City. Moreover, human health hazard and carcinogenic risk for local residents of Foshan City were evaluated. The primary conclusions were as follows: (1) the number of carcinogen-affected people per year under scenario 1 reached 254.41 when the frequency was 0.1 year/time; specifically, the number of people with cancer per year in the area of the Datang, Lubao, and Nanbian waterworks was 189.36 accounting for 74% of the total number per year; (2) at the frequency of 5 years/time, the Lubao waterwork is the only one in extremely high- or high-risk grade, while besides it, the risk grade in the Datang, Nanbian, Xinan, Shitang, and Jianlibao waterworks is in the extremely high or high grade when the frequency is 0.1 year/time; (3) when Cd pollution accidents with the same level occurs again, Cd concentration decreases to a low level in the water only if the migration distance of Cd is at least 40-50 km. Based on the health risk assessment of Cd pollution, this study gives the recommendation that the distance should keep above 50 km in tidal river network of the Pearl River Delta between those factories existing the possibility of heavy metal pollution and the drinking water source. Only then can the public protect themselves from hazardous effects of higher levels of heavy metal.

Dose-Response Assessment of Inorganic Arsenic and Lung Cancer, Taiwan

Hsu KH, Tsui KH, Hsu LI, Chiou HY, Chen CJ. Dose-Response Relationship between Inorganic Arsenic Exposure and Lung Cancer among Arseniasis Residents with Low Methylation Capacity. Cancer Epidemiol Biomarkers Prev. 2016 Dec 22. pii: cebp.0281.2016. doi: 10.1158/1055-9965.EPI-16-0281.

Background: Exposure to inorganic arsenic (InAs) has been documented as a risk factor for lung cancer. This study examined the association between InAs exposure, its metabolism, and lung cancer occurrence.

Methods: We followed 1300 residents from an arseniasis area in Taiwan, determined urinary InAs metabolites, and identified 39 lung cancer cases. Cox proportional hazard model was performed.

Results: The results demonstrated that participants with either the primary methylation index (monomethylarsonic acid [MMA]/InAs) or the secondary methylation index (dimethylarsinic acid[DMA]/MMA) lower than their respective median values were at a higher risk of lung cancer (hazard ratios from 3.41 to 4.66) than those with high methylation capacity. The incidence density of lung cancer increased from 79.9/100000 (year-1) to 467.4/100000 (year-1) for residents with low methylation capacity and from 0 to 158.5/100000 (year-1) for residents with high methylation capacity when the arsenic exposure dose increased from 2-10 ppb to ≥200 ppb, respectively. The analyses revealed a dose-response relationship between lung cancer occurrence and increasing arsenic concentrations in drinking water as well as cumulative arsenic exposure (monotonic trend test; P < .05 and P < .05, respectively) among the residents with low methylation capacity. The relationship between arsenic exposure and lung cancer among high methylaters was not statistically significant.

Conclusions: Hypomethylation responses to InAs exposure may dose-dependently increase lung cancer occurrence.

Impact: The high-risk characteristics observed among those exposed should be considered in future preventive medicine and research on arsenic carcinogenesis.

Health Risk of Arsenic in Groundwater, Taiwan

Liang CP, Wang SW, Kao YH, Chen JS. Health risk assessment of groundwater arsenic pollution in southern Taiwan. Environ Geochem Health. 2016 Dec;38(6):1271-1281.

Residents of the Pingtung Plain, Taiwan, use groundwater for drinking. However, monitoring results showed that a considerable portion of groundwater has an As concentration higher than the safe drinking water regulation of 10 μg/L. Considering residents of the Pingtung Plain continue to use groundwater for drinking, this study attempted to evaluate the exposure and health risk from drinking groundwater. The health risk from drinking groundwater was evaluated based on the hazard quotient (HQ) and target risk (TR) established by the US Environmental Protection Agency. The results showed that the 95th percentile of HQ exceeded 1 and TR was above the safe value of threshold value of 10-6. To illustrate significant variability of the drinking water consumption rate and body weight of each individual, health risk assessments were also performed using a spectrum of daily water intake rate and body weight to reasonably and conservatively assess the exposure and health risk for the specific subgroups of population of the Pingtung Plain. The assessment results showed that 0.01-7.50 % of the population’s HQ levels are higher than 1 and as much as 77.7-93.3 % of the population being in high cancer risk category and having a TR value >10-6. The TR estimation results implied that groundwater use for drinking purpose places people at risk of As exposure. The government must make great efforts to provide safe drinking water for residents of the Pingtung Plain.

Trace Element Induced Risk in Bay County, Xinjian, China

Turdi M, Yang L. Trace Elements Contamination and Human Health Risk Assessment in Drinking Water from the Agricultural and Pastoral Areas of Bay County, Xinjiang, China. Int J Environ Res Public Health. 2016 Sep 23;13(10). pii: E938. doi: 10.3390/ijerph13100938.

Tap water samples were collected from 180 families in four agricultural (KYR: Keyir, KRW: Kariwak, YTR: Yatur, DW: Dawanqi) and two pastoral areas (B: Bulong and Y: Yangchang) in Bay County, Xinjiang, China, and levels of seven trace elements (Cd, Cr, As Ni, Pb, Zn, Se) were analyzed using inductively-coupled plasma mass spectrometry (ICP-MS) to assess potential health risks. Remarkable spatial variations of contamination were observed. Overall, the health risk was more severe for carcinogenic versus non-carcinogenic pollutants due to heavy metal. The risk index was greater for children overall (Cr > As > Cd and Zn > Se for carcinogenic and non-carcinogenic elements, respectively). The total risk index was greater in agricultural areas (DW > KYR > YTR > KRW > B > Y). Total risk indices were greater where well water was the source versus fountain water; for the latter, the total health risk index was greater versus glacier water. Main health risk factors were Cr and As in DW, KYR, YTR, KRW, and B, and Zn, Cr, and As in the Y region. Overall, total trace element-induced health risk (including for DW adults) was higher than acceptable (10(-6)) and lower than priority risk levels (10(-4)) (KYR, YTR, KRW, Y, and B). For DW children, total health risk reached 1.08 × 10(-4), higher than acceptable and priority risk levels (10(-4)).