Author’s information (optional)
Url Link
The hyperlink to my paper’s website.
Methods
Based on a preliminary assessment, two groups of “index” subjects were selected: those initially designated as exposed at birth and those initially designated as unexposed at birth. Subjects who were initially designated as “exposed” had a birth residence that was either directly adjacent to a VL/AC pipe or adjacent to a pipe connected to a VL/AC pipe and the only possible water flow to the residence was through the VL/AC pipe (N = 1,910).
The 1,910 subjects of this study were categorized into two groups. One group were those who were exposed at birth while the other group were those who were not. Those who were exposed at birth lived either directly beside a VL/AC pipe or beside a pipe that was connected to a VL/AC pipe, with the VL/AC pipe serving as the only source of water to their home.
Introduction
PCE is a well-recognized animal and human neurotoxicant [3]. Many epidemiologic studies have reported mood changes, including increases in anxiety and depression among adults with occupational exposure to PCE and other solvents [4-10].
Tetrachloroethylene, or PCE, is a known toxin which harms the brain and nervous system of both animals and humans. Many large population studies have found that adults who are exposed to PCE, or other similar chemicals, at work experience changes in their mood, such as anxiety and depression.
Results
Analyses of the association between PCE exposure and reports of mental illness did not reveal any meaningful increases in the risk of depression among subjects exposed during gestation and early childhood (RR:1.1 for any exposure, 95% CI 0.9-1.4, Table 3). However, subjects with any exposure during gestation and childhood had a 1.8-fold increased risk of bipolar disorder (95% CI: 0.9-3.5), a 1.5-fold increased risk of post-traumatic stress disorder (95% CI: 0.9-2.5), and a 2.1-fold increased risk of schizophrenia (95% CI: 0.2-20.0).
When looking at the effects of PCE to having a mental illness, there was no clear increase in the risk of depression to people who were exposed to PCE before birth or in early childhood. However, people exposure during this time were 1.8 times more likely to develop bipolar disorder, 1.5 times more likely to develop post-traumatic stress disorder, and 2.1 times more like to develop schizophrenia.
Discussion
The observed associations should be judged in light of the study limitations. First, the results are likely affected by exposure misclassification. Because historical exposure measurements were unavailable, we estimated the mass of PCE delivered to each subject’s residence using EPANET water distribution modeling software that incorporated a leaching and transport model [13,15].
The results of this study should be interpreted carefully because of its limits. First off, exposure to PCE may not have been classified accurately. Since past measurements of PCE in the water were not available, the researchers had to estimate how much PCE reached each home using EPANET, a computer model of the water system.
Future Directions
More information should be collected on other mental-health risk factors to better control for confounding factors. For example, for those who were found to have elevated risks of bipolar disorder and PTSD with exposures to PCE, were there other variables that could have contributed (i.e. genetics or socioeconomic status)?
Difficult Material
I found that the most challenging to understand was the methods section. Specifically, understanding how the researchers assessed PCE exposure via algorithms and other computer models was difficult to interpret.
BIOL 1593 – Assignment 2 Worksheet
Your Name:
URL link:
Paste the hyperlink to the website containing the original posting about the paper, NOT to the scientific paper itself (provide hyperlink to either the public posting webpage, or the Moodle forum webpage): https://biol1592.trubox.ca/2026/01/24/aschengrau-weinberg-janulewicz-2012/
Additional Translation:
From which section of the paper is this passage?
The discussion section
Paste quoted text on the next line. Do not include quotation marks or a bullet mark:
The observed associations should be judged in light
of the study limitations. First, the results are likely
affected by exposure misclassification. Because historical
exposure measurements were unavailable, we estimated
the mass of PCE delivered to each subject’s
residence using EPANET water distribution modeling
software that incorporated a leaching and transport
model [13,15]. The model did not incorporate information
on water consumption and bathing habits due to
poor maternal recall of these behaviors. While the
model also necessitated many assumptions about the
water distribution system (for example, that all users
drew the same amount of water), results from validation
studies show good correlation between our exposure
estimates and PCE concentrations in historical
water samples (Spearman correlation coefficient (r) =
0.65, P < 0.00010) [21].
Write your translation on the next line:
When drawing conclusions from this study, it is important to note that the results may not be accurate due to the assumptions the authors had to make. For example, the authors had to estimate how much PCE exposure each household had. An algorithm called EPANET was used. This software had to assume how much water each household used, but it could not estimate how much water was used for bathing or drinking. Despite these assumptions, it was found that similar studies produced similar results when estimating PCE exposure.
Additional Future Directions:
What future research do you think should follow up on this work?
Future research should look at whether subsequent generations, such as grandchildren from those who were exposed and not exposed to PCE, have a higher incidence of mental illness.
Difficult Material (from original poster or subsequent student):
What did the previous poster state was difficult to understand? (Copy and paste their statement here.):
I found that the most challenging to understand was the methods section. Specifically, understanding how the researchers assessed PCE exposure via algorithms and other computer models was difficult to interpret.
Try to explain the difficult materials to the original poster as best as you can. (This is where you can help them understand what they found difficult.)
The poster is referring to the use of the Webler and Brown algorithm. This algorithm is used to determine water flow rate and direction based on the direction of water pipes and how many people are using the water. This algorithm is important because it helps the authors determine how much PCE each person was exposed to based on how much water they used.
New Difficult Material (according to you):
What did you not understand about this paper that someone else may be able to help you with? Or, if you understood everything, what did you find most challenging to understand?
I found it difficult to understand exactly how PCE can make one more susceptible to mental illness. The discussion notes how PCE can cross the blood-brain barrier and is attracted to the lipophilic tissue of the central nervous system, but not how this can bring on mental illness.