Aschengrau Weinberg Janulewicz 2012

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.

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.

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.

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.

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)?

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.