Navigation Links
Large human study links phthalates, BPA and thyroid hormone levels
Date:7/11/2011

ANN ARBOR, Mich.---A link between chemicals called phthalates and thyroid hormone levels was confirmed by the University of Michigan in the first large-scale and nationally representative study of phthalates and BPA in relation to thyroid function in humans.

The U-M School of Public Health study also reported suggestive findings consistent with a previously reported link between a chemical called bisphenol-A and thyroid hormone levels. BPA is best known for its use in certain plastic water bottles and in the linings of canned foods.

Researchers used publicly available data from the U.S. National Health and Nutrition Examination Survey to compare urine metabolites and serum thyroid measures from 1,346 adults and 329 adolescents. Generally speaking, greater concentrations of urinary phthalate metabolites and BPA were associated with greater impacts on serum thyroid measures, said John Meeker, assistant professor at U-M SPH and lead study author.

Specifically, researchers found an inverse relationship between urinary markers of exposure and thyroid hormone levels, meaning as urinary metabolite concentrations increased, serum levels of certain thyroid hormone levels decreased.

Phthalates and BPA are chemical compounds that appear in solvents, plasticizers and common household products. These latest results were consistent with findings from previous smaller studies by Meeker and others that suggested the relationship.

The current study showed the strongest relationship between thyroid disruption and DEHP, a phthalate commonly used as a plasticizer. Research has shown that the primary exposure to DEHP is through diet. Urine samples in the highest 20 percent of exposure to DEHP were associated with as much as a 10 percent decrease in certain thyroid hormones compared to urine samples at the lowest 20 percent of exposure.

"This seems like a subtle difference," Meeker said, "but if you think about the entire population being exposed at this level you'd see many more thyroid related effects in people."

Researchers looked at another phthalate called DBP but overall, didn't find a significant relationship between exposure and thyroid measures. DBP is also a plasticizer, and is also used in solvents and personal care products.

Thyroid hormones play an important role in many body functions, from reproduction to metabolism and energy balance.

While the study focused primarily on adults, these findings underscore the need for more research on adults, pregnant women, and children, Meeker said, because fetal and child development may be particularly vulnerable to disruptions in thyroid hormone levels associated with exposure to environmental chemicals.

Meeker pointed out that the study had limitations. Since urine and serum samples were collected at a single point in time, researchers couldn't conclude a cause-and-effect relationship; it would be better to follow people over time and collect several samples, especially since these chemicals metabolize quickly and one snapshot may not represent the true chemical exposure.

The group has several ongoing studies on the potential impacts of phthalate and BPA exposure on pregnancy outcomes and child development.


'/>"/>

Contact: Laura Bailey
baileylm@umich.edu
734-764-1552
University of Michigan
Source:Eurekalert

Related biology news :

1. Large numbers of birth defects seen near mountaintop mining operations
2. College scientist cites enlarged skeletal muscles as reason birds exist
3. Landsat 5 satellite helps emergency managers fight largest fire in Arizona history
4. Major flooding on the Mississippi River likely to cause large Gulf of Mexico dead zone
5. Glaciations may have larger influence on biodiversity tan current climate
6. Glaciations may have larger influence on biodiversity than current climate
7. Caltech researchers build largest biochemical circuit out of small synthetic DNA molecules
8. EUREKA, the largest European network for industrial R&D and innovation, launches E!NNOVEST
9. Scientists discover the largest assembly of whale sharks ever recorded
10. The Pantanal: A book on the ecology of the largest contiguous wetland in the world
11. Undergraduate institutions should play larger research role
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/9/2016)... 2016 Elevay is currently known ... freedom for high net worth professionals seeking travel for ... connected world, there is still no substitute for a ... sealing your deal with a firm handshake. This is ... advantage of citizenship via investment programs like those offered ...
(Date:4/28/2016)... First quarter 2016:   , Revenues amounted ... quarter of 2015 The gross margin was 49% (27) ... the operating margin was 40% (-13) Earnings per share ... operations was SEK 249.9 M (21.2) , Outlook   ... M. The operating margin for 2016 is estimated to ...
(Date:4/19/2016)... -- The new GEZE SecuLogic access control ... system solution for all door components. It can be ... interface with integration authorization management system, and thus fulfills ... dimensions of the access control and the optimum integration ... considerable freedom of design with regard to the doors. ...
Breaking Biology News(10 mins):
(Date:5/25/2016)... ... May 25, 2016 , ... Scientists at the University ... being tried for mesothelioma may be hampering the research that could lead to one ... Click here to read it now. , The team evaluated 98 mesothelioma ...
(Date:5/24/2016)... ... May 24, 2016 , ... ... and traumatic injuries, will be accelerated by research at Worcester Polytechnic Institute (WPI) ... of wound healing and tissue regeneration. , The novel method, developed by WPI ...
(Date:5/23/2016)... ... May 23, 2016 , ... The need for blood donations in South Texas and across the ... Texas Blood & Tissue Center, blood donations are on the decline. In fact, donations across ... down 21 percent in South Texas in the last four years alone. , There is ...
(Date:5/23/2016)... BOSTON and LONDON , May 23, ... 10 Could See Frontage Boost Efficiency by 40% - ... - Frontage Enforce Quality, Compliance and Traceability Within the ... (CRO) with labs in the United States ... 10 to be deployed across its laboratory facilities. In addition ...
Breaking Biology Technology: