Obesogens left out of article on causes of childhood obesity.

Posted by Thea M. Edwards at Mar 31, 2010 06:00 AM |

A New York Times article “Baby fat may not be so cute after all” written by reporter Roni Caryn Rabin explains that critical developmental events before birth and during infancy and the toddler years may determine whether or not a child becomes obese. 

Rabin identifies several environmental conditions that are known to increase obesity risk, including maternal smoking, obesity or diabetes during pregnancy; formula feeding during infancy; and excess eating, TV watching, or not enough sleep during toddlerhood.
 
But Rabin fails to mention that exposure to chemical obesogens in the environment is an additional risk factor. A growing body of research studies points to how this can happen. Two widespread chemicals implicated in animal studies as obesogens are bisphenol A (BPA) and tributyltin (TBT). 
 
BPA is found in many consumer products and is used heavily in industrial applications. It is a building block of polycarbonate plastics used in food packaging and some baby bottles. Food and beverage cans, dental sealants and thermal paper can contain BPA. Environmentally, BPA is found almost everywhere scientists have looked, from the ocean and beaches, to drinking-water and food, to the human body, where it circulates through tissues, passes to babies through breastmilk and crosses the placenta
 
Several animal studies have identified BPA as an obesogen. For instance, rats exposed to BPA as fetuses and newborns had larger fat cells, increased gene expression associated with fat accumulation and increased tendency to become overweight after weaning. The effects were stronger in female rats and in rats eating a high fat diet. Moreover, BPA seems to affect metabolic rate and underlying tendency to store fat. In that study, the mice exposed to BPA during development did not eat more than unexposed mice.
 
TBT is the active ingredient in certain disinfectants and in fungicides used on food crops. It has been found in disposable diapers, plastic PVC products, anti-mildew paints used in homes, and antifouling paints used on boats to prevent the growth of marine organisms like barnacles and algae (TBT is now banned in marine paints).   
 
TBT exposure has been shown to cause fat accumulation and weight gain in mice and frogs.  One reason is that prenatal exposure to TBT causes more embryonic stem cells than usual to become fat cells.  This increases the number of fat cells in the animal's body.  Having more fat cells is a well-known risk factor for obesity.  This effect of obesogens on stem cells has been confirmed in animal experiments and human cell experiments.
 
Taken together, studies like these suggest that prenatal and infant exposures to obesogens, like BPA and TBT, can program the baby’s metabolic rate and promote fat cell development and tendency to store fat. This scenario increases a child’s risk of obesity and could explain why losing weight is much harder for some people than others. 
 
Reporters can inform their readers by including in their articles that some environmental chemicals are known to influence obesity.