C8 Science Panel Newsletter
C8 Science Panel Quarterly Newsletter #4
1. Science Panel studies update
1. Science Panel studies update
Nearly all the data on health and exposure have now been collected and the teams led by the three members of C8 Science Panel are working on the large amount of data we have assembled. We are still awaiting some more information, for example, the validation of medical records for new diseases reported in the telephone interviews and the last round of the Half-life Study, which is charting the speed of clearance of PFOA from people's blood. This information will be collected in the first half of this year.
As we complete the statistical analysis and reporting of results from these various studies, we will be able to start the evaluation phase of the Science Panel work, to determine if there are probable links between C8 exposure and various diseases. In each case we have to wait for all the results to be available before we can complete the evaluation and for most categories of disease we expect to have the results complete in early 2012. However, some will be earlier and we will issue probable link findings sooner where possible, starting later this year.
2. Report on ADD/ADHD and PFOA
This quarter, a status report was filed with the Wood County Court. The following is a summary.
Association of perfluorinated compounds with Attention Deficit/Attention Deficit Hyperactivity Disorder and Learning Disorder among children aged 5-18 years with elevated community exposure to PFOA
From Cheryl Stein
The purpose of this study was to examine the association between C8 exposure and report of a diagnosis with Attention Deficit/Attention Deficit Hyperactivity Disorder (ADD/ADHD) or Learning Disorder among children aged 5-18 years who participated in the C8 Health Project. Children with ADD/ADHD have trouble paying attention, controlling impulsive behaviors (acting without thinking about the results), and sometimes are overly active.
ADD/ADHD is very common in the United States, with almost 10% of parents reporting that their child was diagnosed, and almost 5% of parents reporting that their child was diagnosed with ADD/ADHD and takes medication for it. A Learning Disorder refers to different types of specific learning disabilities, such as disabilities in listening, speaking, basic reading skills, reading comprehension, written expression, mathematical calculation, and mathematical reasoning. Learning Disorders are also common in the United States, with almost 9% of parents reporting that their child was diagnosed with a Learning Disorder.
We were interested in this research question because one study measured levels of C8 and similar perfluorinated chemicals in children's blood and looked at whether a doctor told the parent the child had ADD/ADHD. This previous study found that children with higher levels of these chemicals in their blood were more likely to have ADD/ADHD.
In our study, we included 10,546 children aged 5-18 years old who participated in the C8 Health Project to examine the relationship between C8 (PFOA) and parent's report of ADD/ADHD or Learning Disorder. A parent's report of a medical diagnosis of ADD/ADHD is commonly used in research studies and national surveys. We also examined the relationship between ADD/ADHD or Learning Disorder and the perfluorinated chemical PFOS, PFHxS, and PFNA because these four chemicals are the chemicals that were detected in 100% of blood samples, plus these are the chemicals that were examined in the previous ADD/ADHD study mentioned above. We included children aged 5-18 years old because most children are not diagnosed with ADD/ADHD or a Learning Disorder until they start school.
Of the children aged 5-18 years, 12.4% (n=1,303) were reported to have had a diagnosis with ADD/ADHD and 5.1% (n=542) were reported to have had a diagnosis with ADD/ADHD plus current use of a medication commonly used to treat ADD/ADHD. 12.1% (n=1,281) of children were reported to have had a Learning Disorder diagnosis. We examined ADD/ADHD and Learning Disorder separately, although there may be some children who have both conditions.
As levels of PFOA in the blood increased, reports of ADD/ADHD decreased slightly. As levels of PFHxS in the blood increased, report of ADD/ADHD increased slightly. There was no clear pattern between levels of PFOS or PFNA in the blood and ADD/ADHD. Overall, the associations for a diagnosis with ADD/ADHD and a diagnosis with ADD/ADHD plus medication use were similar. There appears to be no association between PFOA, PFOS, or PFHxS and reports of Learning Disorder. For PFNA, as levels of PFNA in the blood increased, report of Learning Disorder decreased slightly.
Overall our results do not provide a clear indication of an association between PFOA and either ADD/AHDH or Learning Disorder. Higher PFOA levels were associated with fewer ADD/ADHD diagnoses. However, because there is no biological explanation for why increased levels of PFOA could protect children against ADD/ADHD, we think that this finding is related to how PFOA exposure varied in the region, how the characteristics of the population vary across the region, and how different schools and health care providers in the region may be more or less likely to make ADD/ADHD diagnoses. We also found little support for a possible relationship between the other perfluorinated chemicals and ADD/ADHD or Learning Disorder. Higher PFHxS levels were associated with more ADD/ADHD diagnoses. However, the elevation in risk with PFHxS was small, and the finding may be due to chance.
3. New publications
In the last quarter three journal articles of work in progress from the C8 Science Panel team have gone online. These are now available to subscribers on the journal websites. Below we summarise each of them. (In each case, because of journal copyright, only the summary for the article is freely available online. This means that a photocopy or an online pdf document version of the full text of the article can only be obtained from the authors, from a library/individual who has subscribed to the journal, or by paying online to the journal.)
Association of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) with age of puberty among children living near a chemical plant
Lopez-Espinosa MJ, Fletcher T, Armstrong B, Genser B, Dhatariya K, Mondal D, Ducatman A, Leonardi G.
This paper describes the relationship between exposure to perfluorooctanoic acid (PFOA) or perfluorooctane sulfonate (PFOS) and delay in puberty in children aged 8-18 years. All participants (3,076 boys and 2,931 girls) were residents for at least a year in the six water districts contaminated with PFOA in the Mid-Ohio Valley.
This study examines the relationship between blood serum concentrations of PFOA and PFOS in child participants and the chance of reaching puberty, and calculates the number of days' delay in the average age of puberty. Determinations were made as to whether a young person had reached puberty using the test results of male and female hormones which change at puberty and, for the girls, also asking whether menstrual periods had begun. For boys, there was a pubertal delay of about six months when higher exposure groups were compared with lower PFOS exposure groups. In girls, there was a delay of about four months in having menarche associated with high PFOA and PFOS exposed groups compared with lower ones.
Environmental fate and transport modeling for perfluorooctanoic acid emitted from the Washington Works Facility in West Virginia
Shin HM, Vieira VM, Ryan PB, Detwiler R, Sanders B, Steenland K, Bartell SM.
Perfluorooctanoic acid (PFOA) has been detected in environmental samples in Ohio and West Virginia near the Washington Works Plant in Parkersburg, West Virginia. This paper describes retrospective fate and transport modeling of PFOA concentrations in local air, surface water, groundwater, and six municipal water systems based on estimates of historic emission rates from the facility, physicochemical properties of PFOA, and local geologic and meteorological data beginning in 1951.
We linked several environmental modeling systems to model PFOA air dispersion, transit through the vadose zone, surface water transport, and groundwater flow and transport. Several thousand PFOA measurements in municipal well water have been collected in this region since 1998. Our linked modeling system performs better than expected, predicting quite well the measured average water concentrations for each of the six municipal water districts. In the final model, the Spearman's rank correlation coefficient for predicted versus observed water concentrations is 0.87, which indicates it very successfully fits with the observed measurements. These models are useful for estimating past and future public well water PFOA concentrations in this region.
Comparison between free serum thyroxine levels, measured by analog and dialysis methods, in the presence of perfluorooctane sulfonate and perfluorooctanoate
Lopez-Espinosa MJ, Fitz-Simon N, Bloom MS, Calafat AM, Fletcher T.
We carried out this study of thyroid hormone measurement methods, as a check on the quality of these measurents in the presence of PFOA and PFOS. Thyroid hormones play an important role in regulating metabolism, growth, and development in the human body. Animal and human studies have suggested that perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA) may alter thyroid hormone levels in serum. However, animal studies have suggested that this apparent association may be due to bias in techniques used to determine levels of hormones in the presence of PFOS. These findings have led to concern that the same bias may affect any associations between exposure to PFOS or PFOA and hormone levels in humans.
The present study does not indicate any observable bias in results due to the use of certain analytical methods in the presence of PFOS and PFOA in 50 adults from Mid-Ohio Valley living nearby a polytetrafluoroethylene manufacturing facility.