Comparative Cytotoxicity of Six Iodinated ... - ACS Publications

Mar 21, 2017 - Institute of Orthopaedics and Musculoskeletal Sciences, University College London, Royal National Orthopaedic Hospital, Brockley...
0 downloads 0 Views 900KB Size
Subscriber access provided by University of Colorado Boulder

Letter

Comparative cytotoxicity of six iodinated disinfection byproducts on non-transformed epithelial human colon cells Rassil Sayess, Ahmed Khalil, Mittal Shah, David A Reckhow, and Krystal Juliette Godri Pollitt Environ. Sci. Technol. Lett., Just Accepted Manuscript • DOI: 10.1021/acs.estlett.7b00064 • Publication Date (Web): 21 Mar 2017 Downloaded from http://pubs.acs.org on March 27, 2017

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

Environmental Science & Technology Letters is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 17

Environmental Science & Technology Letters

1

Comparative Cytotoxicity of Six Iodinated Disinfection By-Products

2

on Non-Transformed Epithelial Human Colon Cells

3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

Rassil Sayess1, Ahmed Khalil2, Mittal Shah3, David A. Reckhow1, Krystal J. Godri Pollitt2,* 1

Department of Environmental and Water Resources Engineering, School of Civil and Environmental Engineering, University of Massachusetts, Amherst, United States 01003 2 Department of Environmental Sciences, School of Public Health and Health Sciences, University of Massachusetts, Amherst, United States 01003 3 Institute of Orthopaedics and Musculoskeletal Sciences, University College London, Royal National Orthopaedic Hospital, Brockley Hill, Stanmore, HA7 4LP

*Corresponding author: E-mail: [email protected] Key words: DBPs; Iodinated DBPs; cytotoxicity; epithelial colon cells, nontransformed human cells, drinking water

19 20 21 22 23 24 25 26 27

1

ACS Paragon Plus Environment

Environmental Science & Technology Letters

28

Abstract

29

Exposure to disinfection by-products (DBPs) in chlorinated drinking water has been positively

30

associated with increased risk of colon, bladder, and rectum cancers. Iodinated DBPs (I-DBPs)

31

are of concern as this class exhibits enhanced cytotoxicity and genotoxicity compared to

32

chlorinated and brominated equivalents in Chinese Hamster Ovary (CHO) cells. We tested the

33

impact of six I-DBPs on immortalized normal human colon epithelial cells, CCD 841 CoN. Our

34

assay showed the rank order for cytotoxicity of the I-DBPs was as follows: iododacetic acid

35

(IAA) > iodoacetamide (IAcAm)> bromoiodoacetamide (BIAcAm)> chloroiodoacetamide

36

(CIAcAm)> bromoiodoacetic acid (BIAA)≈ diiodoacetic acid (DIAA). The enhanced

37

cytotoxicity for IAA compared with other haloacetic acids agrees with studies conducted on

38

CHO cells. IAcAm was found to be 3.5 times more cytotoxic than BIAcAm and 9.4 times more

39

cytotoxic than CIAcAm. The cytotoxicity of both dihaloacids (i.e., BIAA, DIAA) was less than

40

1% of that of the monohaloacid IAA. Apart from IAA, the nitrogenous I-DBPs demonstrated

41

greater cytotoxicity than the carbonaceous I-DBPs. The results are consistent with previous CHO

42

studies of dihalogenated I-DBPs but not monohalogenated ones. This study has implications for

43

drinking water management strategies aimed at minimizing the formation of I-DBPs associated

44

with enhanced cytotoxicity.

45 46 47 48 49 50

2

ACS Paragon Plus Environment

Page 2 of 17

Page 3 of 17

51 52

Environmental Science & Technology Letters

1. Introduction Exposure to disinfection byproducts (DBPs) through chlorinated drinking water is a

53

major public health concern given the increased risk of colon, bladder, and rectum cancers.1-12

54

There are twenty compounds that have been identified as iodinated I-DBPs, fifteen of which

55

have been detected in chlorinated and chloraminated waters (Supporting Information, Table

56

S1).13-23 These compounds are of particular concern because of the twenty compounds that have

57

been identified, all but one have shown enhanced cyto- and genotoxicity compared to their

58

brominated and chlorinated analogues.18,20,24-30

59

Published studies of I-DBPs have primarily evaluated toxicity using Chinese Hamster

60

Ovary (CHO) cell models.18,21,24,26,30-32 Given that the toxicological response of a chemical will

61

vary between species due to natural heterogeneity, the response in CHO cells cannot necessarily

62

be extended to humans. While we appreciate the limitations in extending results from in vitro to

63

epidemiological studies, the use of a healthy human cell line to evaluate DBP toxicity offers a

64

model system to investigate the biological mechanisms underlying the outcomes reported in the

65

population wide studies. Across the twenty I-DBPs of interest, only iodoacetic acid (IAA) has

66

been the subject of cytotoxicity evaluation in human cell lines (Supporting Information, Table

67

S1), of which only two used non-transformed human cells.33,34 Given the position of I-DBPs in

68

drinking water as a public health concern, it is important to further assess the toxicity of other I-

69

DBPs. In this study, we evaluated the cytotoxicity of a group of nitrogenous and carbonaceous I-

70

DBPs on a non-transformed human colon cell line.

3

ACS Paragon Plus Environment

Environmental Science & Technology Letters

71

2. Materials and Methods

72

2.1. Reagents and Chemical

73

Dulbecco’s Phosphate Buffer Saline (D-PBS; 30-2200TM stored at 4 °C), Eagle’s

74

Minimum Essential Medium (EMEM; 30-2003TM stored at 4 °C), Penicillin-Streptomycin

75

Solution (30-2300TM stored at -20 °C), dimethylsulfoxide (DMSO, 4-XTM stored at 4 °C),

76

Trypsin-EDTA Solution (1X, 30-2101TM stored at -20 °C), and fetal bovine serum (FBS) (30-

77

2020 TM stored at -20 °C) were purchased from American Type Culture Collection (ATCC).

78

PrestoBlue® Cell Viability Reagent was obtained from ThermoFisher Scientific and stored at 4

79

°C. Diiodoacetic acid (DIAA, >90%), bromoiodoacetic acid (BIAA, >85%),

80

bromoiodoacetamide (BIAcAm, >85%), and chloroiodoacetamide (CIAcAm,>99%) were

81

purchased from CanSyn Chemical Corporation (Toronto, Canada). Iodoacetamide (IAcAm,

82

>99%) and iodoacetic acid (IAA, >98%) were purchased from Sigma-Aldrich. Triton® X-100

83

(Molecular Biology Grade) was obtained from Promega.

84

2.2. Preparation of Solutions

85

Table 1 presents the six tested I-DBPs. IAA stock solution was prepared by dissolving

86

IAA in EMEM solution containing 10% FBS and 1% Penicillin-Streptomycin. For the other five

87

compounds, stock solutions were prepared by dissolving each compound in EMEM containing

88

10% FBS, 1% Penicillin-Streptomycin, and 0.1% DMSO. The prepared EMEM solutions

89

containing each of the six I-DBPs had a pH between 7 and 7.5, were stored at 4 °C, and were

90

used within 4 weeks. I-DBPs were assumed to be stable within that range of pH and timeline.

91

This was further confirmed by similar cell counts between the first cytotoxicity assay and the last

4

ACS Paragon Plus Environment

Page 4 of 17

Page 5 of 17

Environmental Science & Technology Letters

92

for every tested concentration. Serial dilutions in the appropriate media were used to make a total

93

of 6 concentrations for each compound to be analyzed for cytotoxicity.

94

Table 1: Summary of the concentration ranges for each of the six I-DBPs Compound

Abbreviation

Molecular structure

Iodoacetic Acid

Iodoacetic acid Iodoacetic Acid

Diiodoacetic acid

IAA Bromoiodoacetic Acid

BIAA

Bromoiodoacetamide Bromoiodoacetic Acid

IAcAm Iodoacetic Acid Bromoiodoacetamide

264.84

Chloroiodoacetamide Diiodoacetic Acid

95

Bromoiodoacetamide

Diiodoacetic Acid Chloroiodoacetamide

25 - 2000

Chloroiodoacetamide

184.96

50 - 5000

219.41

0.1 - 4000

263.86

10 - 5000

Chloroiodoacetamide

CIAcAm

Iodoacetamide

Bromoiodoacetamide

Diiodoacetic Acid

Diiodoacetic Acid

Bromoiodoacetic Acid Bromoiodoacetamide

Iodoacetamide

Chloroiodoacetamide

Bromoiodoacetic Acid

Bromoiodoacetic Acid

Iodoacetamide

Iodoacetamide

5 - 2000

Bromoiodoacetamide

Iodoacetic Acid

Chloroiodoacetamide

311.84

DIAA Iodoacetic Acid

Iodoacetamide

Tested Concentration range (µM) 0.1 - 50

Diiodoacetic Acid

Iodoacetamide

Bromoiodoacetic Iodoacetamide acidIodoacetic Acid

Molecular weight Diiodoacetic Acid (g/mol) 185.95

Bromoiodoacetic Acid

Bromoiodoacetamide

Chloroiodoacetamide

BIAcAm

2.3. Cell Culture

96

Immortalized (non-neoplastic) normal human colon epithelial cells, CCD 841 CoN

97

(CRL-1790), were obtained from ATCC at passage 13 and were used in all experiments between

98

passage 15 and 17. The CCD 841 CoN cells were isolated from a 21-week gestation fetus that

99

did not show any abnormalities.35 This cell line was selected given the positive association

100

reported by epidemiological studies between exposure to chlorinated water and increased risk of

101

colon cancer.6,9,10 The cells were cultured and maintained in T75 tissue culture flasks with

102

EMEM-C containing 10% non-heat inactivated FBS and 1% Penicillin-Streptomycin Solution at

103

37 °C in a humidified 5% CO2 incubator. Cells were maintained until 80% confluence before

104

subsequent assays described below.

5

ACS Paragon Plus Environment

Environmental Science & Technology Letters

105 106

2.4. Human Cell Cytotoxicity Assay CCD 841 CoN cells were seeded (12,500 cells per well) in clear, sterile, 96-well

107

microplates with EMEM-C media and cultured at 37 °C in a humidified 5% CO2 incubator.

108

Upon reaching 80% confluence, the media was replaced with fresh media containing different

109

concentrations of the six compounds (exposure media), EMEM-C (positive control for IAA), or

110

EMEM-C with 0.1% DMSO (positive control for five other compounds). The plates were then

111

incubated for 12 hours at 37 °C in the humidified 5% CO2 incubator. At hour 11, Triton® X-100

112

(1 µL) was added to the positive controls and incubated for one hour. Following the exposure

113

period, cells were washed with D-PBS. EMEM-C (90 µL) and PrestoBlue (10 µL) were added to

114

each well and incubated for 1 hour at 37 °C in the humidified 5% CO2 incubator. A

115

SpectraMax® MiniMax™ Imaging Cytometer (Molecular Devices) was used to measure the

116

fluorescence at 535 nm for excitation and 615 nm for emission at 52 points per well. For each

117

compound, 2 to 5 biological replicates were tested at each concentration. Exposures were

118

repeated on 3 or 4 separate days (experimental replicates), yielding a total of 9 to 15 replicates

119

per concentration per compound. The negative control for IAA was EMEM-C while that for the

120

other five compounds was EMEM-C with 0.1% DMSO. Cell viability was evaluated as the

121

number of viable cells while cell cytotoxicity was evaluated as the reduction in the number of

122

viable cells compared to the negative control.

123

2.5. Data Analysis

124

Cytotoxicity data was normalized to the averaged percent of the corresponding negative

125

controls from individual experiments. The average mean viability values obtained from the

126

biological and experimental replicates from all the experiments were used to construct a cell

127

viability concentration-response curve. The data from each compound were used to generate

6

ACS Paragon Plus Environment

Page 6 of 17

Page 7 of 17

Environmental Science & Technology Letters

128

Four-Parameter Logistic nonlinear regression functions using the “log(inhibitor) vs. response”

129

equation (Eq. 1).

130

𝑌 = 𝐵𝑜𝑡𝑡𝑜𝑚 + (𝑇𝑜𝑝 − 𝐵𝑜𝑡𝑡𝑜𝑚)/(1 + 10(𝐿𝑜𝑔𝐼𝐶50 −𝑋)×𝐻𝑖𝑙𝑙𝑆𝑙𝑜𝑝𝑒) )

131

where Y is the percent of cells that are viable, X is the tested concentration, and HillSlope is the

132

slope of the sigmoidal curve. The Top and Bottom values were constrained to 100 (all cells are

133

viable) and 0 (all cells are not viable), respectively.

134

Eq. 1

To fit the curve for each compound, the parameters were adjusted to minimize the mean

135

square error between the fitted values and observations. The root mean squared error was then

136

calculated for each of the fitted curves to reflect every compound. The optimized curves were

137

used to calculate the LC50 and LC10 values, or the lowest concentration at which 50% and 10%

138

reduction in cell density is observed as compared to control cells, respectively. The LC50 value

139

was used to rank the cytotoxicity of the six I-DBPs for this cell line. All data were analyzed

140

using the programming language R.

141

3. Results and Discussion

142

3.1. CCD 841 CoN cytotoxicity

143

Figure 1 presents a dose-response curve for the six I-DBPs. The viability of CCD 841

144

CoN cells was found to decrease in a concentration-dependent manner within the tested range of

145

concentrations for the six compounds (Supporting Information, Table S2). The LC10

146

concentrations were 2.4 µM for IAA, 3.2 µM for IAcAm, 13.4 µM for BIAcAm, 21.3 µM for

147

CIAcAM, 5.5 µM for DIAA, and 332.1 µM for BIAA. The LC50 values ranged from 8.6 µM for

148

IAA to about 1 mM for DIAA and BIAA. In CCD 841 CoN cells, the rank order for cytotoxicity 7

ACS Paragon Plus Environment

Environmental Science & Technology Letters

149

of the six I-DBP compounds based on their LC50 values was as follows: IAA > IAcAm >

150

BIAcAm > CIAcAm > DIAA ≈ BIAA (Table 2).

151 152

Figure 1: Concentration-response curves of the six I-DBPs on CCD 841 CoN cells.

153

Table 2: Summary of the CCD 841 CoN cell cytotoxicity of the I-DBPs I-DBP

154 155 156 157 158 159 160

LC10a

LC50b (µM)

R2 c

Toxic rank order IAA 2 8.6 0.83 1 IAcAm 3 39.1 0.76 2 BIAcAm 13 136.3 0.52 3 CIAcAm 21 369.0 0.69 4 DIAA 6 954.7 0.51 5 BIAA 332 982.2 0.81 6 a the concentration at which the cell viability was reduced by 10% as compared to the negative control determined by the non-linear Four-Parameter Logistic nonlinear regression functions b the concentration at which the cell viability was reduced by 50% as compared to the negative control determined by the non-linear Four-Parameter Logistic nonlinear regression functions c the root mean squared error for the non-linear curve fitting

IAA exhibited the highest cytotoxicity to CCD 841 CoN cells among the six I-DBPs.

161

This finding is in line with published literature which reports enhanced cytotoxicity for IAA

162

compared with other haloacetic acids in CHO cells.18,26,30-32 The increased cytotoxicity of IAA

8

ACS Paragon Plus Environment

Page 8 of 17

Page 9 of 17

Environmental Science & Technology Letters

163

has been attributed to the length of the carbon-halogen bond and the number of halogens per

164

atom. 26 As the size of the halogen increases, the dissociation energy declines making iodine an

165

excellent leaving group compared to the other halogens; this consequently leads to higher

166

cytotoxicity. The pattern of decreasing toxicity of I>Br>Cl has been previously observed for all

167

identified I-DBPs except for iodoacetaldehyde.18,21,26,30-32 Enhanced toxic potency is also

168

attributable to fewer halogens per atom.34 However, previous studies showed that the haloacids

169

was less cytotoxic than the haloamides in CHO-AS52 cells.21,27 These results were consistent

170

with the results of the dihalogenated compounds in this study but not for the mono-halogentated

171

ones: IAA was two times more cytotoxic than IAcAm in CCD 841 CoN cells. This may indicate

172

that human colon cells are more sensitive to IAA than IAcAm. Since haloamides were not

173

explored in other cell lines than CHO cells, the significance is unclear.

174

3.2. Comparative cytotoxicity of CCD 841 CoN cells and other cell lines

175

Differences across cytotoxicity assays, as well as inherent sensitivity across cell lines to

176

particular compounds, will affect the overall response of a cell line to a compound.37 Although it

177

is not ideal to relate the sensitivity of human cells with mouse or hamster cells because of their

178

characteristic and species specific differences, a comparison of the toxicity rank of different cell

179

lines to a toxicant could potentially offer some useful insight to these cell lines. IAA is the only

180

compound where such comparison is possible since it has been studied in hamster (CHO-AS52

181

and CHO-K1), mouse (NIH3T3), and human (HepG2, Caco-2, and CCD 841 CoN) cell lines

182

(Figure 2).24,26,32,37,38,39 NIH3T3 cells, CHO-AS52 cells, and CHO-K1 cells were exposed for 72

183

hours, 24,26,32,38 HepG2 cells were exposed for 24 hours, 39 and Caco-2 cells were exposed for 4

184

hours to IAA, 37 compared to a 12-hour exposure period in this study. The results demonstrate

185

comparable LC50 between CCD 841 CoN cells from this study and HepG2 liver cells, 39 while

9

ACS Paragon Plus Environment

Environmental Science & Technology Letters

186

the LC50 was about two times more than that for the Caco-2 cells. 37 Compared to cell lines of

187

mouse and hamster origins (CHO-AS52, CHO-K1, and NIH3T3), CCD 841 CoN cells were less

188

impacted by IAA. 24,26,32,38 One explanation for the observed differences in LC50 between human

189

and other cell lines could be the higher resilience of human cells in comparison to small animal

190

(e.g., mice and hamster) cells. Another reason could be the difference in exposure times whereby

191

the exposure to the human cell lines (4 hours to 24 hours) was lower than that of the small

192

animals (72 hours).

193 194 195 196 197 198

Figure 2: Comparison of the LC50 calculated from the cytotoxicity of IAA on different mammalian cell lines from the literature 24,26,32,37,38,39 and the present study. The grey bars indicate an animal (CHO and mouse) cell line (72-hour exposure). The white bar indicates human cancer liver (24-hour exposure) and cancer colon (4-hour exposure) cell lines. The black bar indicates the human healthy colon cell line used in this study (12-hour exposure).

10

ACS Paragon Plus Environment

Page 10 of 17

Page 11 of 17

199

Environmental Science & Technology Letters

The cytotoxicity of DIAA, BIAA, IAcAm, BIAcAm, and CIAcAm have previously only

200

been tested using CHO-AS52 cells.21,30 A comparison of the LC50 for these five compounds on

201

CCD 841 CoN cells (this study) and on CHO-AS52 cells from the literature is presented in

202

Figure 3. The three iodoamides were associated with lower LC50 values (39.1 - 369 µM)

203

compared to the dihaloacids (~1000 µM) indicating that apart from IAA, nitrogenous-DBPs were

204

more cytotoxic than carbonaceous-DBPs. The trend across DBPs for both cell lines was found to

205

be similar. It is worth noting that the exposure period for CHO-AS52 cells was 72 hours

206

compared to 12 hours in our study. Furthermore, the range of exposure concentrations evaluated

207

in our study (Table 1) extended beyond those evaluated in CHO-AS52 cells.21,30 The results from

208

our study shows that the sensitivity of CCD 841 CoN cells to these five compounds was lower

209

than those reported in the literature despite the higher exposure concentrations.21,30 This may

210

indicate a higher resilience of human colon cells to these toxicants than CHO cells, leading to the

211

decrease in observed sensitivity. However, since the exposure period is lower for the CCD 841

212

CoN cells (12 hours) compared to the CHO-AS52 cells (72 hours), this observation is not

213

conclusive.

11

ACS Paragon Plus Environment

Environmental Science & Technology Letters

214 215 216 217

Figure 3: Comparison of the LC50 between five I-DBPs on CCD 841 CoN cells (this study; 12hour exposure) and CHO-AS52 cells (72-hour exposure). 21,30 The LC50 is shown on a log scale. To the best of our knowledge, the data presented here is the first to study the impact of

218

DBPs on a cell line known to be associated with epidemiological evidence. We have shown that

219

apart from IAA, the three tested iodoamides were more cytotoxic in CCD 841 CoN cells than the

220

haloacids. Given their enhanced cytotoxicity observed in a human cell line, IAA and the three

221

iodoamides (IAcAm, BIAcAm, and CIAcAm) should be prioritized when developing strategies

222

to control DBP formation in treated drinking water.

223

12

ACS Paragon Plus Environment

Page 12 of 17

Page 13 of 17

Environmental Science & Technology Letters

224 225 226 227 228

Supporting Information Available:

229

References

230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262

S1. Occurrence of I-DBPs in treated water, the cytotoxicity models used, and information inferred from cytotoxicity assays S2. Viability of CCD CoN 841 cells for the 6 I-DBPs at different concentrations

1. Bove, G. E., Rogerson, P. A., & Vena, J. E. (2007). Case-control study of the effects of trihalomethanes on urinary bladder cancer risk. Arch. Environ. Occup. Health, 62 (1), 39−47. 2. Bull, R. J., Birnbaum, L. S., Cantor, K., Rose, J., Butterworth: B. E., Pegram, R., & Tuomisto, J. (1995). Water chlorination: essential process or cancer hazard? Fundam. Appl. Toxicol., 28, 155. 3. Cantor, K. P., Villanueva, C. M., Silverman, D. T., Figueroa, J. D., Real, F. X., GarciaClosas, M., Malats, N., Chanock, S., Yeager, M., Tardon, A., Garcia-Closas, R., Serra, C., Carrato, A., Castano-Vinyals, G., Samanic, C., Rothman, N., Kogevinas, M. (2010). Polymorphisms in GSTT1, GSTZ1, and CYP2E1, disinfection by-products, and risk of bladder cancer in Spain. Environ. Health Perspect, 118, 1545− 1550. 4. Costet, N., Villanueva, C. M., Jaakkola, J. J., Kogevinas, M., Cantor, K. P., King, W. D., Lynch, C. F., Nieuwenhuijsen, M. J., & Cordier, S. (2011). Water disinfection byproducts and bladder cancer: Is there a European specificity? A pooled and meta-analysis of European case- control studies. Occup. Environ. Med., 68 (5), 379−385. 5. King, W. D., & Marrett, L. D. (1996). Case-control study of bladder cancer and chlorination byproducts in treated water (Ontario, Canada). Cancer Causes Control, 7:596-604. 6. King, W. D., Marrett, L. D., & Woolcott, C. G. (2000). Case-control study of colon and rectal cancers and chlorination by-products in treated water. Cancer Epidemiol. Biomarkers Prev., 9: 813–818. 7. Koivusalo, M., Pukkala, E., Vartiainen, T., Jaakkola, J. J. K., & Hakulinen T. (1997). Drinking water chlorination and cancer-a historical cohort study in Finland. Cancer Causes Control, 8:192-200. 8. McGeehin, M. A., Reif, J. S, Becher, J. C., Mangione, E. J. (1993). Case-control study of bladder cancer and water disinfection methods in Colorado. Am. J. Epidemiol., 138:492501. 9. Morris RD, Audet AM, Angelillo IF, Chalmers TC, Mosteller F. Chlorination, chlorination byproducts, and cancer: a meta-analysis. Am J Public Health, 82:955-963 (1992). 10. Rahman, M. B., Driscoll, T., Cowie, C., & Armstrong, B. K. (2010). Disinfection byproducts in drinking water and colorectal cancer: A meta-analysis. Int. J. Epidemiol., 39 (3), 733−745.

13

ACS Paragon Plus Environment

Environmental Science & Technology Letters

263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307

11. Villanueva, C. M., Cantor, K. P., Cordier, S., Jaakkola, J. J., King, W. D., Lynch, C. F., Porru, S., & Kogevinas, M. (2004). Disinfection byproducts and bladder cancer: A pooled analysis. Epidemiol., 15 (3), 357−367. 12. Villanueva, C. M., Cantor, K. P., Grimalt, J. O., Malats, N., Silverman, D., Tardon, A., Garcia-Closas, R., Serra, C., Carrato, A., Castaño-Vinyals, G., Marcos, R., Rothman, N., Real, F. X., Dosemeci, M., & Kogevinas, M. (2007) Bladder cancer and exposure to water disinfection by-products through ingestion, bathing, showering, and swimming in pools. Am. J. Epidemiol., 165: 148–156. 13. Bichsel, Y. & von Gunten, U (1999). Oxidation of iodide and hypoiodous acid in the disinfection of natural waters. Environ. Sci. Technol., 33, 4040–4045. 14. Brass, H.J., Feige, M.A., Halloran, T., Mello, J.W., Munch, D., & Thomas, R.F. (1977). The national organic monitoring survey: samplings and analysis for purgeable organic compounds. In: Drinking Water Quality Enhancement through Source Protection: Ann Arbor, MI, pp. 393-416. 15. Cancho, B., Ventura, F., Galceran, M., Diaz, A., & Ricart, S. (2000). Determination, synthesis and survey of iodinated trihalomethanes in water treatment processes. Water Res., 34 (13), 2784-2791. 16. Chu, W., Gao, N., Yin, D., Krasner, S.W., & Templeton, M.R. (2012). Trace determination of 13 haloacetamides in drinking water using liquid chromatography triple quadrupole mass spectrometry with atomic pressure chemical ionization. J. Chromatogr. A., 1235, 178-181. 17. Glaze, W. E., Henderson, J. E., & Smith, G. Analysis of new chlorinated organic compounds formed by chlorination of municipal wastewater. In Water Chlorination: Environmental Impact and Health Effects; Jolley, R. J., Ed.; Ann Arbor Science: Ann Arbor, MI, 1975; Vol. 1, pp 139-159. 18. Jeong, C.H., Postigo, C., Richardson, S.D., Simmons, J.E., Kimura, S.Y., Marinas, B.J., Barcelo, D., Liang, P., Wagner, E.D., & Plewa, M.J. (2015). Occurrence and comparative toxicity haloacetaldehyde disinfection byproducts in drinking water. Env. Sci. Technol., 49, 13749-13759. 19. Krasner, S.W., Weinberg, H.S., Richardson, S.D., Pastor, S.J., Chinn, R., Sclimenti, M.J., Onstad, G.D., & Thruston, A.D. Jr. (2006). Occurrence of a new generation of disinfection byproducts. Environ. Sci. Technol., 40, 7175-7185. 20. Plewa, M.J., Wagner, E.D., & Jazwierska, P. (2004a). Halonitromethane drinking water disinfection byproducts: chemical characterization and mammalian cell cytotoxicity and genotoxicity. Environ. Sci. Technol., 38, 62-68. 21. Plewa, M. J., Muellner, M. G., Richardson, S. D., Fasano, F., Buettner, K. M., Woo, Y.T., McKague, B. A., & Wagner, E. D. (2008). Occurrence , Synthesis , and Mammalian Cell Cytotoxicity and Genotoxicity of Haloacetamides : An Emerging Class of Nitrogenous Drinking Water Disinfection Byproducts. Environ. Sci. Technol., 42(3), 955–961. 22. Richardson, S. D. (2003). Disinfection by-products and other emerging contaminants in drinking water. TrAC Trends Anal. Chem., 22(10), 666–684. doi:10.1016/S01659936(03)01003-3 23. Weinberg, H. S., Krasner, S. W., Richardson, S. D., & Thruston, A. D. Jr. (2002). The Occurrence of Disinfection By-Products (DBPs) of Health Concern in Drinking Water:

14

ACS Paragon Plus Environment

Page 14 of 17

Page 15 of 17

308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 351 352

Environmental Science & Technology Letters

Results of a Nationwide DBP Occurrence Study. EPA/600/R02/068; U.S. EPA: Washington, DC, 2002. 24. Cemeli, E., Wagner, E.D., Anderson, D., Richardson, S.D., & Plewa, M.J. (2006). Modulation of the cytotoxicity and genotoxicity of the drinking water disinfection byproduct iodoacetic acid by suppressors of oxidative stress. Environ. Sci. Technol., 40, 1878-1883. 25. Hunter, E. S., III; Rogers, E. H.; Schmid, J. E.; Richard, A. (1996). Comparative effects of haloacetic acids in whole embryo culture. Teratology, 54 (2), 57−64. 26. Plewa, M.J., Wagner, E.D., Richardson, S. D., Thruston, A.D. Jr., Woo, Y.-T., & McKague, B.A. (2004b). Chemical and biological characterization of newly discovered iodoacid drinking water disinfection byproducts. Environ. Sci. Technol., 38(18), 47134722. 27. Plewa, M. J., Simmon, J. E., Richardson, S.D., & Wagner, E. D. (2010). Mammalian cell cytotoxicity and genotoxicity of haloacetic acids, a major class of drinking water disinfection by-products. Environ. Mol. Mutagen., 51, 871-878. 28. Plewa MJ, Wagner ED. 2009. Mammalian cell cytotoxicity and genotoxicity of disinfection byproducts. Denver, CO: Water Research Foundation. 134 p. 29. Richardson, S. D., Plewa, M. J., Wagner, E. D., Schoeny, R., & DeMarini, D. M. (2007). Occurrence, genotoxicity, and carcinogenicity of regulated and emerging disinfection byproducts in drinking water: a review and roadmap for research. Mutat. Res., 636, 178242. 30. Richardson, S. D., Fasano, F., Ellington, J. J., Crumley, F. G., Buettner, K. M., Evans, J. J., Blount, B. C., Silva, L. K., Waite, T. J., Luther, G. W., McKague, B. A., Miltner, R. J., Wagner, E. D., & Plewa, M. J. (2008). Occurrence and mammalian cell toxicity of iodinated disinfection byproducts in drinking water. Environ. Sci. Technol., 42(22), 8330–8338. doi:10.1021/es801169k 31. Muellner, M. G., Wagner, E. D., McCalla, K., Richardson, S. D., Woo, Y.- T., & Plewa, M. J., 2007. Haloacetamides vs. regulated haloacetic acids: are nitrogen-containing DBPs more toxic? Environ. Sci. Technol., 41-645-651. 32. Zhang, S.- H., Miao, D.- Y., Liu, A.- L., Zhang, L., Wei, W., Xie, H., Lu, & W.- Q. (2010). Assessment of the cytotoxicity and genotoxicity of haloacetic acids using microplate-based cytotoxicity test and CHO/HGPRT gene mutation assay. Mutat. Res., 703, 174-179. 33. Attene-Ramos, M. S., Wagner, E. D., Plewa, M. J., 2010. Comparative human cell toxicogenomics analysis of monohaloacetic acid drinking water disinfection byproducts. Environ. Sci. Technol., 44(19), 7206-7212. 34. Escobar-Hoyos, L. F., Hoyos-Giraldo, L. S., Londoño-Velasco, E., Reyes-Carvajal, I., Saavedra-Trujillo, D., Carvajal-Varona, S., Sánchez-Gómez, A., Wagner, E. D., & Plewa, M. J. (2013). Genotoxic and clastogenic effects of monohaloacetic acid drinking water disinfection by-products in primary human lymphocytes. Water Res., 3282-3290. 35. Thompson, A. A., Dilworth, S., & Hay, R. J. (1985). Isolation and culture of colonic epithelial cells in serum-free medium. J. Tissue Cult. Methods., 9, 117-122. 36. Plewa, M. J., Kargalioglu, Y., Vankerk, D., Minear, R. A., & Wagner, E. D. (2002). Mammalian cell cytotoxicity and genotoxicity analysis of drinking water disinfection byproducts. Environ. Molecul. Mutagen., 40, 134-142.

15

ACS Paragon Plus Environment

Environmental Science & Technology Letters

353 354 355 356 357 358 359 360 361 362 363

37. Procházka, E., Escher, B. I., Plewa, M. J., Leusch, F. D. L., 2015. In vitro cytotoxicity and adaptive stress responses to selected haloacetic acid and halobenzoquinone water disinfection byproducts. Chem. Res. Toxicol., 28, 2059-2069. 38. Wei, X., Wang, S., Zheng, W., Wang, X., Liu, X., Jiang, S., Pi, J., Zheng, Y., He, G., & Qu, W. (2013). Drinking water disinfection byproduct iodoacetic acid induces tumorigenic transformation of NIH3T3 cells. Environ. Sci. Technol., 47, 5913-5920. 39. Wang, S., Zheng, W., Liu, X., Xue, P., Jian, S., Lu, D., Zhang, Q., He, G., Pi, J., Andersen, M. E., Tan, H., & Qu, W (2014). Iodoacetic acid activates nrf2-mediated antioxidant response in vitro and in vivo. Environ. Sci. Technol., 48, 13478-13488.

16

ACS Paragon Plus Environment

Page 16 of 17

Page 17 of 17

364 365

Environmental Science & Technology Letters

For Table of Contents Only

366

17

ACS Paragon Plus Environment