Grantee Research Project Results
2004 Progress Report: Aluminum in Drinking Water Induces Neuronal Apoptosis Via Endoplasmic Reticulum Stress
EPA Grant Number: R829782Title: Aluminum in Drinking Water Induces Neuronal Apoptosis Via Endoplasmic Reticulum Stress
Investigators: Savory, John , Boyd, James C. , Herman, Mary M. , Exley, Christopher , Ghribi, Othman
Institution: University of Virginia , National Institute of Mental Health , Keele University
Current Institution: University of Virginia
EPA Project Officer: Page, Angela
Project Period: August 1, 2002 through July 31, 2005 (Extended to July 31, 2006)
Project Period Covered by this Report: August 1, 2004 through July 31, 2005
Project Amount: $821,249
RFA: Health Effects of Chemical Contaminants in Drinking Water (2001) RFA Text | Recipients Lists
Research Category: Drinking Water , Human Health , Water
Objective:
The main goal of this project is to test the hypothesis that aluminum in drinking water can induce neuronal injury, eventually resulting in the death of some neurons via programmed cell death (apoptosis). It also is hypothesized that aging results in increased susceptibility to aluminum in drinking water. Additional experiments will be carried out to study how this neurotoxic effect of aluminum in drinking water is modulated by silicic acid and fluoride.
Progress Summary:
In a previous report (2003 Annual Report), we described some results of Study Group 1, which investigated the effects of a high concentration of aluminum (Al) in drinking water. In Study Group 2, five additional groups of rabbits, 12 animals per group, have now been studied with the following drinking water treatments:
Group 1: 12 New Zealand white rabbits (2-3 years of age) were administered drinking water containing 0.5 mM Al + 1.0 mM silicic acid (Si) treatment. This group is designated AS1.
Group 2: 12 New Zealand white rabbits (2-3 years of age) were administered drinking water containing 0.5 mM Al + 0.1 mM Si treatment. This group is designated AS0.1.
Group 3: 12 New Zealand white rabbits (2-3 years of age) were administered control (low Al concentration; 3.7 μM) drinking water containing 1.0 mM Si treatment. This group is designated S1.
Group 4: 12 New Zealand white rabbits (2-3 years of age) were administered drinking water containing 0.5 mM Al + 0.25 mM Si treatment. This group is designated AS0.25.
Group 5: 12 control New Zealand white rabbits (2-3 years of age) were administered control (low Al concentration; 3.7 μM ) drinking water containing 0.1 mM Si treatment. This group is designated S0.1.
Methods
Drinking Water Formulation
As with the previous study, we prepared the drinking water by formulating a basic drinking water solution, to which we added additional Al nitrate for the high Al formulation and sodium nitrate for the control (low Al) formulation. An aqueous solution of silicic acid freshly prepared was added to obtain the concentrations listed below. The drinking water formulation has been optimized so that precipitation of Al complexes does not occur.
Basic Drinking Water Formulation
1. Aluminum nitrate: 3.70 μM: mw 375: | 1.3875 mg/L | |||
2. Ammonium phosphate: 11.10 μM: mw 115: | 1.2765 mg/L | |||
3. Barium nitrate: 7.30 μM: mw 261: | 1.9053 mg/L | |||
4. Calcium chloride: 1.85 mM; mw 110.00 | 0.2035 g/L | |||
5. Calcium nitrate: 1.85 mM; mw 236.2 | 0.4369 g/L | |||
6. Copper nitrate: 23.6 μM: mw 187.6: | 4.4274 mg/L | |||
7. Iron (III) nitrate: 1.8 μM: mw 404.0 | 0.7272 mg/L | |||
8. Magnesium chloride: 1.028 mM: mw 95.21: | 0.0979 g/L | |||
9. Potassium nitrate: 0.154 mM: mw 101.1: | 0.01557 g/L | |||
10. Sodium chloride: 3.260 mM: mw 58.4: | 0.19038 g/L | |||
11. Sodium borate: 6.40 μM: mw 381.4: | 2.4410 mg/L | |||
12. Zinc nitrate: 38.2 μM: mw 297.4: | 0.01136 g/L |
Preparation of 2 mM Si(OH)4 (prepared in 60L batches)
- Dissolve 22.08 g of Na4SiO4 in 60 L of ultra pure water. When fully dissolved the solution has an alkaline pH, ~ pH 12.
- Rinse 300 g of Amberlite 200 in 4 L of ultrapure water three times. Use a stirrer and stirrer bar to ensure that the resin is fully suspended in each volume. Decant off the water following each wash.
- Convert the resin from the Na+ form to the H+ form by suspending it in 17.14 L of 1% v/v concentrated nitric acid (14N). Leave stirring for 30 minutes and decant off the acidic solution.
- Rinse the converted resin in 4 L of ultra pure water three times. Use a stirrer and stirrer bar to ensure that the resin is fully suspended in each volume. Decant off the water each time.
- Add the resin to the 60 L of Na4SiO4 solution. Use a stirrer and stirrer bar to ensure that the resin is fully suspended in the solution. The pH of the solution will begin to fall as the Na+ ions are replaced by H+. The reaction is complete when the pH has stabilized, usually at about pH 4-5. This could take 30-60 minutes. Filter the solution to remove all of the resin.
- This solution is 2 mM Si(OH)4 and must be prepared fresh on the day that the drinking water is formulated.
High Al Concentration Water
To prepare the high Al concentration solution, we adjusted the concentration of Al to bring the concentration to 0.5 mM by adding 0.1875 g/L Al(NO3)3 and 1.5 mM NaOH (0.0600 g/L) to each liter of the basic solution. The NaOH was added to obtain the same Na+ concentration achieved when NaNO3 was used in the control drinking water formulation.
Control Drinking Water
We added 0.1275 g/L NaNO3 to the basic solution to adjust the concentration to 1.5 mM.
Silicic Acid-Containing Drinking Water Preparations
In order to achieve the correct concentration of silicic acid in the treatment water, the aqueous solution of silicic acid was added to the various drinking water formulations to bring the final volume to 45 L.
S0.1: | 2.25 L | |||
S1: | 22.5 L | |||
AS1: | 22.5 L | |||
AS0.1: | 2.25 L | |||
AS0.25: | 5.625 L |
All drinking water was prepared 1 week before it was administered to the animals and was stored at 4°C until use. We prepared water every week and each batch was analyzed for its Al and Si content.
Treatment With These Drinking Water Formulations
The treatment time was 36 weeks and was done in two batches. The first three groups began on March 31, 2003, and were sacrificed beginning on December 8, 2003. The last two groups began on September 8, 2003, and were sacrificed beginning on May 17, 2004.
Clinical Outcomes
One rabbit in the S0.1 group died on October 23, 2003, from unknown causes.
Weight
The rabbits were weighed at the onset of the experiment and every month thereafter. They were handled to a minimal extent in order to avoid undue stress.
Necropsy, Tissue Preparation, and Histology
Rabbits were sacrificed and blood samples for the biochemical analysis were collected via heart puncture. The animals were promptly perfused with Dulbecco’s phosphate buffered saline. We then removed the brain and tissue samples from kidney, liver, spleen, and lung. Urine samples were obtained from the bladder using a 10 ml sterile syringe. Brainstem and cerebellum were separated from the cerebrum with a cut through the uppermost midbrain, and a mid-cerebral coronal segment (containing the entire hippocampus) was cut and bisected to yield two symmetrical segments, one for histology and immunochemistry, and the other for Western blot analysis. Tissue specimens from each brain hemisphere, intended for immunohistochemistry, were rapidly frozen on a liquid nitrogen-cooled surface, placed into a zipper-closure plastic bag, and buried in dry ice pellets until transferring to -80°C before sectioning. For immunoblot analysis, fresh tissue from the hippocampus and adjacent cortex was rapidly dissected and homogenized. Residual fresh tissue from cerebrum, brainstem, and cerebellum, as well as segments of kidney, liver, and spleen, were fixed in 10% buffered formalin, processed with standard methods into paraffin blocks, and examined.
Western Blot Analysis
The technique described in the original proposal was followed, although we have performed this analysis only on whole tissue homogenates, because it appears from our studies in the earlier groups that this procedure can provide us with a satisfactory assessment of endoplasmic reticulum stress.
TUNEL Staining for DNA Fragmentation
Terminal transferase-mediated dUTP nick-end labeling (TUNEL) for DNA fragmentation is a marker of apoptosis. We have performed this fluorescence staining as described in the original proposal.
Aluminum Measurements
Drinking water, chow, blood, urine, and tissue specimens have been sent to Dr. Exley for aluminum analysis, which is being performed using electrothermal atomic absorption spectrometry in Dr. Exley’s laboratory at Keele University in the United Kingdom. Some results are now available and are summarized later. Several of the results of the analyses are not yet available.
Statistical Analysis
Statistical evaluations of the differences between experimental and control groups were conducted using nonparametric Mann-Whitney tests. The Bonferroni method was used to adjust p-values for multiple comparisons.
Results
Clinical Observations
No evidence of neurological symptoms as manifested by head tilt, motor dysfunction, hypersensitivity, photophobia, or loss of appetite was noted. A summary of drinking water consumption and weight changes are as follows in Tables 1 and 2.
Table 1. Drinking Water Consumption in the Groups of Rabbits Studied in the Present Phase of the Project
Group |
Daily water consumption (L) |
Range |
AS1 |
3.85 +/- 0.60 |
2.69-5.21 |
AS0.1 |
4.66 +/- 0.53 |
3.29-5.93 |
S1 |
4.38 +/- 0.49 |
3.36-5.71 |
AS0.25 |
4.43 +/- 0.27 |
3.89-5.05 |
S0.1 |
5.01 +/- 0.62 |
3.89-6.07 |
Weight Changes
The animals slowly gained some weight with no differences between the five groups of animals studied.
Histology
No significant changes were observed between the groups of animals studied so far. A comprehensive study has been made of various brain regions plus liver, kidney, spleen, and lung of all animals sacrificed so far. These histologic studies have been carried out on blinded slides by two pathologists in a semi-quantitative manner using a numbering system of 0-3. No evidence of the formation of intraneuronal filamentous aggregates, other neuritic pathology, or vasculitis have been seen in any of the groups.
This phase of the project has resulted in a massive amount of data that remains to be analyzed statistically.
Western Blot Analysis
The results of the Western blot analyses on the groups of rabbits studied during the period covered by this present report are incomplete. However, an analysis of gadd 153, an endoplasmic reticulum stress pathway marker, has been carried out.
Because no translocation of gadd 153 into the nucleus was observed in any of the initial studies, this marker was measured in total tissue homogenates; this approach would detect any upregulation of the protein. No distinct changes in gadd 153 were observed, suggesting zero or minimal endoplasmic reticulum stress. A typical western blot of gadd 153 is shown in Figure 1. Additional studies of endoplasmic reticulum stress, particularly activation of caspase-12, are underway.
Table 2. Monthly Details of the Weights of the Rabbits (weights given in kilograms).
Month 1 is the Starting Weight.
AS1 (kg) |
AS0.1 (kg) |
|||||
Mean |
S.D. |
Range |
Mean |
S.D. |
Range |
|
Month 1 |
5.23 |
0.68 |
4.31-6.58 |
5.03 |
0.11 |
4.81-5.17 |
Month 2 |
5.46 |
0.55 |
4.54-6.58 |
6.05 |
0.73 |
5.35-7.94 |
Month 3 |
5.16 |
0.76 |
4.2-6.8 |
6.45 |
0.83 |
5.43-8.61 |
Month 4 |
5.57 |
0.59 |
4.76-6.69 |
6.45 |
0.9 |
5.33-8.62 |
Month 5 |
5.91 |
0.6 |
4.99-7.03 |
6.5 |
0.74 |
5.67-8.39 |
Month 6 |
5.9 |
0.59 |
4.99-7.03 |
6.26 |
0.9 |
5.67-8.62 |
Month 7 |
6 |
0.56 |
5.1-7.26 |
6 |
1.1 |
4.76-9.07 |
Month 8 |
5.88 |
0.59 |
5.1-7.03 |
6.41 |
0.8 |
5.22-8.16 |
Month 9 |
5.7 |
0.59 |
4.77-6.82 |
6.16 |
0.83 |
4.77-7.8 |
S1 (kg) |
AS0.25 (kg) |
|||||
Mean |
S.D. |
Range |
Mean |
S.D. |
Range |
|
Month 1 |
5.11 |
0.05 |
5.05-5.21 |
5.28 |
0.51 |
4.54-5.9 |
Month 2 |
6.5 |
0.59 |
5.51-7.68 |
5.92 |
0.6 |
4.99-7.03 |
Month 3 |
6.82 |
0.68 |
6-8.38 |
6.21 |
0.66 |
5.1-7.37 |
Month 4 |
6.85 |
0.69 |
6.01-7.94 |
6.28 |
0.67 |
4.99-7.48 |
Month 5 |
6.92 |
0.74 |
5.44-8.16 |
5.85 |
0.73 |
4.31-6.8 |
Month 6 |
6.64 |
0.8 |
4.99-7.94 |
6.59 |
0.8 |
5.56-7.71 |
Month 7 |
6.35 |
0.93 |
4.54-7.82 |
5.89 |
0.66 |
5.22-7.03 |
Month 8 |
6.91 |
0.9 |
5.22-8.62 |
6.21 |
0.87 |
4.99-7.26 |
Month 9 |
6.45 |
0.93 |
4.3-7.92 |
6.67 |
0.91 |
5.44-7.71 |
S0.1 (kg) |
|||
Mean |
S.D. |
Range |
|
Month 1 |
5.26 |
0.34 |
4.76-5.9 |
Month 2 |
5.74 |
0.46 |
5.1-6.35 |
Month 3 |
5.86 |
0.45 |
4.99-6.8 |
Month 4 |
6.15 |
0.43 |
5.44-7.03 |
Month 5 |
6.05 |
0.64 |
4.99-7.06 |
Month 6 |
6.55 |
0.68 |
5.44-7.48 |
Month 7 |
6.23 |
0.52 |
5.44-6.92 |
Month 8 |
6.12 |
0.55 |
4.99-6.92 |
Month 9 |
6.42 |
0.62 |
5.1-7.37 |
Note: There is some variability in the starting weights of the rabbits. Aged rabbits are difficult to obtain and there were differences in the weights of the animals delivered from the vendor. However, all animals studied were guaranteed to be mature (at least 2-3 years of age) and, thus, fulfill the requirements of the project.
Figure 1. Representative Western Blot of the Endoplasmic Reticulum Stress Marker, Gadd 153, in Homogenized Hippocampal Tissue. No evidence of increased activation was observed.Bcl-2 and Bax, anti-apoptosis and pro-apoptosis regulatory proteins, respectively, show no distinctive changes between any of the groups of animals studied so far (Figure 2). NF-κB, which is an apoptosis regulatory protein but also an indicator of inflammation, shows no apparent changes between the groups of animals studied in Year 2 of the project (Figure 3).
Figure 2. Representative Western Blot of the Pro-Apoptotic Bax and Anti-Apoptotic Bcl-2 Markers in Hippocampal Tissue. No significant changes were observed.
Figure 3. Representative Western Blot Analysis of Hippocampal Tissue of the Endoplasmic Reticulum and/or Inflammation Marker, NFκB. No significant changes were seen between the treatment groups.
TUNEL Staining
TUNEL staining for DNA fragmentation, which is a marker of apoptosis, was performed on the groups of rabbits studied in this phase of the project. These representative results are depicted in Figure 4 and show no apparent differences between the various drinking water treatment groups.
8-Hydroxyguanine immunostaining,which is a measure of oxidation of DNA and hence a marker of oxidative stress, shows no evidence of increased oxidative stress in any of the high-Al groups compared to the controls (Figure 5).
Aluminum Measurements
The results of the aluminum analyses of drinking water and brain tissue are given in Table 3. The drinking water analyses were carried out for quality assurance purposes to ensure that the preparation of the water was of the highest quality. The result of these analyses confirms that the preparation of the drinking water meets the standards necessary for the purposes of the study.
Table 3A. Al Measurements on Brain Tissue (μM/g)
S1 |
AS1 |
AS0.1 |
S0.1 |
AS0.25 |
|
Mean |
0.101 |
0.156 |
0.203 |
0.17 |
0.07 |
SD |
±0.081 |
±0.17 |
±0.18 |
±0.116 |
±0.98 |
Table 3B. Quality Assurance Analysis of Drinking Water
S1 |
AS1 |
AS0.1 |
S0.1 |
AS0.25 |
|
Mean Al content (μM/L) |
6.06 |
503.95 |
471.86 |
3.88 |
504.14 |
SD |
±2.89 |
±63.37 |
±42.73 |
±2.51 |
±48.02 |
Mean Si content (μM) |
771.5 |
760.2 |
131.65 |
88.57 |
202 |
SD |
±45.79 |
±138.85 |
±102.23 |
±19.6 |
±35.89 |
AS1 |
S1 |
AS0.1 |
S0.1 |
AS0.25 |
Figure 4. Representative Slidesof TUNEL Staining for Evidence of DNA Fragmentation and, Hence, Apoptosis, for the Five Groups of Rabbits Studied in the Present Phase of the Project. These slides are of hippocampus showing that very few scattered TUNEL-positive neurons were detected and that no discernable differences existed between the treatment groups.
AS1 |
S1 |
AS0.1 |
S0.1 |
AS0.25 |
Figure 5. Representative Slides of 8-Hydroxyguanine Immunostaining for Evidence of Oxidative Damage as Determined by DNA Oxidation for the Five Groups of Rabbits Studied in the Present Phase of the Project. These slides are of hippocampus, showing that little evidence of 8-hydroxyguanine-positive neurons were detected and that no discernable differences existed between the treatment groups.
Complete analyses of Al content have been performed on brain, liver, spleen, bone, and plasma of all animals studied so far. Statistical analyses remain to be carried out, but at this time it does not appear that there are differences between the groups of animals studied.
Clinical Chemistry and Hematology Results
The results of the clinical chemistry and hematology tests are given in Table 4. No statistical differences were observed between the various groups of animals studied in the present phase of the project.
Table 4. Clinical Chemistry and Hematology Results on Blood and Urine Specimens
Analysis |
unit |
S1 |
AS1 |
||||
Mean |
S.D |
Range |
Mean |
S.D |
Range |
||
Sodium |
mmol/L |
145.89 |
16.86 |
125-182 |
144.25 |
6.77 |
126-152 |
Potassium |
mmol/L |
6 |
1.10 |
4.7-7.4 |
5.6 |
0.64 |
4.9->10 |
Chloride |
mmol/L |
97.67 |
10 |
81-109 |
99.67 |
10.35 |
79-110 |
CO2 |
mmol/L |
24.5 |
1.12 |
23-26 |
20.78 |
5.31 |
8-26 |
Urea Nitrogen |
mg/dL |
17.5 |
2.69 |
13-20 |
22.33 |
3.83 |
17-28 |
Creatinine |
mg/dL |
1.33 |
0.19 |
1.1-1.7 |
1.11 |
0.21 |
0.8-1.5 |
Glucose |
mg/dL |
153.09 |
57.59 |
80-253 |
159.17 |
36.14 |
107-216 |
Calcium |
mg/dL |
10.63 |
2.16 |
6.6-12.9 |
11.23 |
1.98 |
7-13.3 |
WBC |
k/μL |
13.61 |
28.31 |
.471-88.3 |
1.76 |
0.59 |
<0.1-2.68 |
RBC |
M/μL |
4.69 |
1.09 |
2.09-5.9 |
4.25 |
1.45 |
0.89-5.49 |
Hemoglobin |
g/dL |
11.91 |
0.73 |
11.1-13.4 |
10.92 |
0.84 |
9-11.9 |
Hematocrit |
% |
33.74 |
10.25 |
8.4-43.2 |
29.37 |
11.4 |
6.1-47.9 |
MCV |
fL |
70.16 |
14.39 |
40.3-90.7 |
68.25 |
7.63 |
52.5-87.2 |
MCH |
pg |
28.06 |
12.3 |
21.2-60.3 |
33.45 |
24.72 |
21.7-108 |
MCHC |
g/dL |
46.65 |
39.21 |
25.6-150 |
50.14 |
37.67 |
24.9-158 |
RDW |
% |
15.74 |
3.63 |
11.3-23.1 |
16.98 |
10.07 |
11.4-49.4 |
PLT |
k/μL |
196 |
161.75 |
<10-552 |
370.73 |
215.72 |
<10-653 |
Urine Creatinine |
mg/dL |
180.31 |
71.86 |
81.1-277.3 |
198.53 |
38.71 |
120.2-253.8 |
Analysis |
unit |
AS0.1 |
S0.1 |
||||
Average |
S.D |
Range |
Average |
S.D |
Range |
||
Sodium |
mmol/L |
140.82 |
17.91 |
126-194 |
137.56 |
3.13 |
130.141 |
Potassium |
mmol/L |
7 |
1.2 |
5.8->10 |
8.47 |
1.17 |
7.4-10 |
Chloride |
mmol/L |
92.55 |
9.19 |
79-104 |
102.56 |
4.85 |
92-107 |
CO2 |
mmol/L |
22 |
4.55 |
22-27 |
23 |
2.87 |
17-26 |
Urea Nitrogen |
mg/dL |
21.33 |
2.5 |
18-24 |
20.38 |
3.25 |
17-27 |
Creatinine |
mg/dL |
1.36 |
0.18 |
1.1-1.6 |
1.43 |
0.18 |
1.2-1.8 |
Glucose |
mg/dL |
156.55 |
48.01 |
86-220 |
180.56 |
34.55 |
148-246 |
Calcium |
mg/dL |
10.25 |
2.31 |
5.4-13.7 |
12.27 |
0.98 |
9.8-13.1 |
WBC |
k/μL |
3.75 |
1.19 |
2.45-5.33 |
|||
RBC |
M/μL |
5.13 |
0.24 |
4.78-5.32 |
|||
Hemoglobin |
g/dL |
11.58 |
0.67 |
10.6-12.1 |
|||
Hematocrit |
% |
35.95 |
2.3 |
32.6-37.7 |
|||
MCV |
fL |
70.13 |
2.15 |
68.3-72.7 |
|||
MCH |
pg |
22.58 |
0.56 |
22-23.3 |
|||
MCHC |
g/dL |
32.2 |
0.28 |
32-32.6 |
|||
RDW |
% |
12.6 |
0.18 |
12.4-12.8 |
|||
PLT |
k/μL |
189 |
96.35 |
<10-238 |
|||
Urine Creatinine |
mg/dL |
163.87 |
47.68 |
104.4-246.3 |
Analysis |
unit |
AS0.25 |
||
Average |
S.D |
Range |
||
Sodium |
mmol/L |
127.5 |
6.52 |
118-139 |
Potassium |
mmol/L |
|||
Chloride |
mmol/L |
95.13 |
9.72 |
81-106 |
CO2 |
mmol/L |
21.4 |
6.39 |
12-28 |
Urea Nitrogen |
mg/dL |
22.5 |
1.29 |
21-24 |
Creatinine |
mg/dL |
1.3 |
0.06 |
1.2-1.4 |
Glucose |
mg/dL |
131.75 |
42.45 |
66-184 |
Calcium |
mg/dL |
10.44 |
1.81 |
7.1-12.5 |
WBC |
k/μL |
|||
RBC |
M/μL |
|||
Hemoglobin |
g/dL |
|||
Hematocrit |
% |
|||
MCV |
fL |
|||
MCH |
pg |
|||
MCHC |
g/dL |
|||
RDW |
% |
|||
PLT |
k/μL |
|||
Urine Creatinine |
mg/dL |
201.46 |
101.75 |
82-467.5 |
Preliminary Conclusions
At this time, seven groups of animals have been treated—two in the first year of the project and five in this second year. So far, there is no marked evidence of neuronal injury from any of the drinking water formulations by careful neuropathological studies, by markers of endoplasmic reticulum and oxidative stress, or by tests for apoptosis. No suggestion of Al accumulation has been observed.
Future Activities:
The following groups of animals, as included in the original proposal, will be studied as they are sacrificed. The timetable for the future studies is outlined in Table 5.
Table 5. Timetable for Future Studies
Group 3: Aluminum and fluoride treatment |
Starting date |
Date of sacrifice |
1. 0.5 mM Al + 0.05 mM fluoride treatment |
6/7/04 |
2/14/05 |
2. 0.05 mM fluoride treatment |
6/7/04 |
2/14/05 |
3. 0.5 mM Al + 0.5 mM fluoride treatment |
7/12/04 |
3/21/05 |
4. 0.5 mM fluoride treatment |
7/12/04 |
3/21/05 |
Supplemental Keywords:
drinking water, risk assessment, exposure, metals, aluminum, fluoride, silicic acid, apoptosis, endoplasmic reticulum, drinking water contaminants, human health effects,, RFA, Health, Scientific Discipline, Waste, Water, Hydrology, Contaminated Sediments, Environmental Chemistry, Risk Assessments, Environmental Microbiology, Drinking Water, other - exposure, groundwater disinfection, pathogens, monitoring, ecological risk assessment, aquifer characteristics, human health effects, water quality parameters, exposure and effects, exposure, contaminated sediment, aluminum, chemical contaminants, neurotoxicity, drinking water distribution system, treatment, human exposure, apoptosis, water quality, drinking water contaminants, drinking water treatment, water treatment, aluminum toxicokineticsProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.