Tag Archives: disinfection byproducts

Geonotoxicity of Drinking Water Treated with Disinfectants; China

Nie X, Liu W, Zhang L, Liu Q. Genotoxicity of drinking water treated with different disinfectants and effects of disinfection conditions detected by umu-test. Journal of environmental sciences (China). 2017 Jun;56:36-44. doi: 10.1016/j.jes.2016.07.016.

The genotoxicity of drinking water treated with 6 disinfection methods and the effects of disinfection conditions were investigated using the umu-test. The pretreatment procedure of samples for the umu-test was optimized for drinking water analysis. The results of the umu-test were in good correlation with those of the Ames-test. The genotoxicity and production of haloacetic acids (HAAs) were the highest for chlorinated samples. UV+chloramination is the safest disinfection method from the aspects of genotoxicity, HAA production and inactivation effects. For chloramination, the effects of the mass ratio of Cl2 to N of chloramine on genotoxicity were also studied. The changes of genotoxicity were different from those of HAA production, which implied that HAA production cannot represent the genotoxic potential of water. The genotoxicity per chlorine decay of chlorination and chloramination had similar trends, indicating that the reaction of organic matters and chlorine made a great contribution to the genotoxicity. The results of this study are of engineering significance for optimizing the operation of waterworks.

DBP Compliance Data are Poor Proxies for Short-Term Exposure

Parvez S, Frost K, Sundararajan M. Evaluation of Drinking Water Disinfectant Byproducts Compliance Data as an Indirect Measure for Short-Term Exposure in Humans. Int J Environ Res Public Health. 2017 May 20;14(5). pii: E548. doi: 10.3390/ijerph14050548.

In the absence of shorter term disinfectant byproducts (DBPs) data on regulated Trihalomethanes (THMs) and Haloacetic acids (HAAs), epidemiologists and risk assessors have used long-term annual compliance (LRAA) or quarterly (QA) data to evaluate the association between DBP exposure and adverse birth outcomes, which resulted in inconclusive findings. Therefore, we evaluated the reliability of using long-term LRAA and QA data as an indirect measure for short-term exposure. Short-term residential tap water samples were collected in peak DBP months (May-August) in a community water system with five separate treatment stations and were sourced from surface or groundwater. Samples were analyzed for THMs and HAAs per the EPA (U.S. Environmental Protection Agency) standard methods (524.2 and 552.2). The measured levels of total THMs and HAAs were compared temporally and spatially with LRAA and QA data, which showed significant differences (p < 0.05). Most samples from surface water stations showed higher levels than LRAA or QA. Significant numbers of samples in surface water stations exceeded regulatory permissible limits: 27% had excessive THMs and 35% had excessive HAAs. Trichloromethane, trichloroacetic acid, and dichloroacetic acid were the major drivers of variability. This study suggests that LRAA and QA data are not good proxies of short-term exposure. Further investigation is needed to determine if other drinking water systems show consistent findings for improved regulation.

Chlorine Dioxide DBPs in Drinking Water, Qatar

Al-Otoum F, Al-Ghouti MA, Ahmed TA, Abu-Dieyeh M, Ali M. Disinfection by-products of chlorine dioxide (chlorite, chlorate, and trihalomethanes): Occurrence in drinking water in Qatar. Chemosphere. 2016 Sep 13;164:649-656. doi: 10.1016/j.chemosphere.2016.09.008.

The occurrence of chlorine dioxide (ClO2) disinfection by-products (DBPs) in drinking water, namely, chlorite, chlorate, and trihalomethanes (THMs), was investigated. Two-hundred-ninety-four drinking water samples were collected from seven desalination plants (DPs), four reservoirs (R), and eight mosques (M) distributed within various locations in southern and northern Qatar. The ClO2 concentration levels ranged from 0.38 to <0.02 mg L-1, with mean values of 0.17, 0.12, and 0.04 mg L-1 for the DPs, Rs, and Ms, respectively. The chlorite levels varied from 13 μg L-1 to 440 μg L-1, with median values varying from 13 to 230 μg L-1, 77-320 μg L-1, and 85-440 μg L-1 for the DPs, Rs, and Ms, respectively. The chlorate levels varied from 11 μg L-1 to 280 μg L-1, with mean values varying from 36 to 280 μg L-1, 11-200 μg L-1, and 11-150 μg L-1 in the DPs, Rs, and Ms, respectively. The average concentration of THMs was 5 μg L-1, and the maximum value reached 77 μg L-1 However, all of the DBP concentrations fell within the range of the regulatory limits set by GSO 149/2009, the World Health Organization (WHO), and Kahramaa (KM).

Does Aluminum Ion Inhibit or Promote Disinfection Byproducts?

Shen H, Chen X, Chen H. Influence on the generation of disinfection byproducts in a tannic acid solution by aluminum ions. Environmental Technology. 2016 Aug 17:1-11.

Aluminum (Al) commonly exists in natural waters, and its salts are often used as coagulants in drinking water treatment. Therefore, associated with the security of drinking water, functions of Al ions (Al3+) on generation of disinfection byproducts (DBPs) should not be ignored. This study focuses on DBPs and the carcinogenic factor of chlorinated water samples after the addition of Al3+ with different Al3+/initial tannic acid molar ratios. The results imply that Al3+ acts as a promoter of haloacetic acids (HAAs) and an inhibitor of trihalomethanes (THMs) when tannic acid is selected as model compound of natural organic matter during chlorination. Depending on the results of size exclusion chromatography and ultraviolet spectrophotometer, an equilibrium system can be assumed between hydrolysis and flocculation in tannic acid solution with Al3+. Furthermore, influences on the equilibrium system for Al3+ addition may result in various effects on generation and distribution ratios of THMs and HAAs during chlorination. Finally, according to the analyses of a fluorescence spectrophotometer, it is demonstrated that the presence of Al3+helps to increase precursors of DBPs (humic acid-like organics) and then improve the generation of DBPs.

Disinfection Byproduct Formation During Biofiltration

Delatolla R, Seguin C, Springthorpe S, Gorman E, Campbell A, Douglas I. Disinfection byproduct formation during biofiltration cycle: Implications for drinking water production. Chemosphere 2015 Oct; Vol. 136, pp. 190-7.

The goal of this study was to investigate the potential of biofiltration to reduce the formation potential of disinfection byproducts (DBPs). Particularly, the work investigates the effect of the duration of the filter cycle on the formation potential of total trihalomethanes (TTHM) and five species of haloacetic acids (HAA5), dissolved oxygen (DO), organic carbon, nitrogen and total phosphorous concentrations along with biofilm coverage of the filter media and biomass viability of the attached cells. The study was conducted on a full-scale biologically active filter, with anthracite and sand media, at the Britannia water treatment plant (WTP), located in Ottawa, Ontario, Canada. The formation potential of both TTHMs and HAA5s decreased due to biofiltration. However the lowest formation potentials for both groups of DBPs and or their precursors were observed immediately following a backwash event. Hence, the highest percent removal of DBPs was observed during the early stages of the biofiltration cycle, which suggests that a higher frequency of backwashing will reduce the formation of DBPs. Variable pressure scanning electron microscopy (VPSEM) analysis shows that biofilm coverage of anthracite and sand media increases as the filtration cycle progressed, while biomass viability analysis demonstrates that the percentage of cells attached to the anthracite and sand media also increases as the filtration cycle progresses. These results suggest that the development and growth of biofilm on the filters increases the DPB formation potential.

Atrazine in Drinking Water Not Associated with Overian Cancer, Iowa

Inoue-Choi M, Weyer PJ, Jones RR, Booth BJ, Cantor KP, Robien K, Ward MH Atrazine in public water supplies and risk of ovarian cancer among postmenopausal women in the Iowa Women’s Health Study. Occupational and Environmental Medicine. 2016 Jul 1. pii: oemed-2016-103575. doi: 10.1136/oemed-2016-103575.

BACKGROUND: Few studies have evaluated environmental chemical exposures in relation to ovarian cancer. We previously found an increased risk of ovarian cancer among postmenopausal women in Iowa associated with higher nitrate levels in public water supplies (PWS). However, elevated nitrate levels may reflect the presence of other agricultural chemicals, such as atrazine, one of the most commonly detected pesticides in Iowa PWS.

METHODS: We evaluated the association between atrazine in drinking water and incident ovarian cancer (N=145, 1986-2010) among 13 041 postmenopausal women in the Iowa Women’s Health Study who used their PWS for ≥11 years as reported in 1989. Average levels of atrazine (1986-1987), nitrate-nitrogen (NO3-N, 1955-1988) and estimated levels of total trihalomethanes (TTHM, 1955-1988) from PWS monitoring data were linked to the participants’ cities of residence. We computed HRs and 95% CIs by categories of the average atrazine level (not detected, ≤ or >0.37 parts per billion=median) using Cox proportional hazards regression adjusting for ovarian cancer risk factors.

RESULTS: Atrazine was detected in water samples from 69 cities where 4155 women (32%) lived and levels were moderately correlated with NO3-N (ρ=0.35) and TTHM (ρ=0.24). Atrazine levels were not associated with ovarian cancer risk with or without adjusting for NO3-N and TTHM levels (p-trend=0.50 and 0.81, respectively). Further, there was no evidence for effect modification of the atrazine association by NO3-N or TTHM levels.

CONCLUSIONS: In our study with low atrazine detection rates, we found no association between atrazine in PWS and postmenopausal ovarian cancer risk.

Spain, Italy THM Exposure and Colorectal Cancer; No Association Found

Villanueva CM, Gracia-Lavedan E, Bosetti C, Righi E, Molina AJ, Martín V, Boldo E, Aragonés N, Perez-Gomez B, Pollan M, Gomez Acebo I, Altzibar JM, Jiménez Zabala A, Ardanaz E, Peiró R, Tardón A, Chirlaque MD, Tavani A, Polesel J, Serraino D, Pisa F, Castaño-Vinyals G, Espinosa A, Espejo-Herrera N, Palau M, Moreno V, La Vecchia C, Aggazzotti G, Nieuwenhuijsen MJ, Kogevinas M. Colorectal Cancer and Long-Term Exposure to Trihalomethanes in Drinking Water: A Multicenter Case-Control Study in Spain and Italy. Environmental Health Perspectives. 2016 Jul 6.

BACKGROUND: Evidence on the association between colorectal cancer and exposure to disinfection by-products in drinking water is inconsistent.

OBJECTIVES: We assessed long-term exposure to trihalomethanes (THMs), the most prevalent group of chlorination by-products, to evaluate the association with colorectal cancer.

METHODS: A multicentre case-control study was conducted in Spain and Italy in 2008-2013. Hospital-based incident cases, population-based (Spain) and hospital-based (Italy) controls were interviewed to ascertain residential histories, water type consumed in each residence, frequency and duration of showering/ bathing, and major recognized risk factors for colorectal cancer. We estimated adjusted odds ratios (OR) for colorectal cancer in association with quartiles of estimated average lifetime THM concentrations in each participant’s residential tap water (μg/L, from age 18 to two years before the interview) and estimated average lifetime THM ingestion from drinking residential tap water (μg/day).

RESULTS: Subjects analyzed were 2047 cases and 3718 controls. Median values (ranges) for average lifetime residential tap water concentrations of total THMs, chloroform, and brominated THMs were 30 (0-174), 17 (0-63), and 9 (0-145) μg/L, respectively. Total THM concentration in residential tap water was not associated with colorectal cancer (OR=0.92, 95%CI: 0.66-1.28 for highest vs. lowest quartile), but chloroform concentrations were inversely associated (OR=0.31, 95%CI: 0.24-0.41 for highest vs. lowest quartile). Brominated THMs concentrations showed a positive association among men at the highest vs. lowest quartile (OR=1.43, 95%CI: 0.83-2.46). Patterns of associations were similar for estimated average THM ingestion through residential water consumption.

CONCLUSIONS: We did not find clear evidence of an association between detailed estimates of lifetime total THM exposures and colorectal cancer in our large case-control study population. Negative associations with chloroform concentrations and ingestion suggest differences among specific THMs, but these findings need confirmation in other study populations.