Research Roundup: Plastic Bottle, Celiac Disease and Antibiotics
The Latest Medical News for People With Allergies and Food Sensitivities
Plastic Bottle Alert
A widely used chemical, bisphenol A, or BPA, has been making headlines recently. BPA is used to make polycarbonate plastics and epoxy resins. Polycarbonate plastics are used in food and beverage packaging, including water bottles and baby bottles; epoxy resins are used to line metal food cans and in some dental materials, such as sealants and composites. It's a difficult chemical to avoid; in a study published in 2005, researchers from the U.S. Centers for Disease Control found BPA in the urine of 95 percent of the participants.
Many animal studies suggest an association between BPA and numerous health concerns. These include insulin resistance and early puberty, as well as problems with the immune system, fertility and other (male and female) reproductive tract issues.
A California-based environmental group, Environment California, issued a report finding that BPA was leaching from five different brands of plastic baby bottles. The study results, according to several news accounts, caused a run on glass baby bottles.
Another organization, the Environmental Working Group (EWG), spearheaded a study of 97 cans of commonly eaten foods, such as soups, soft drinks and fruit. Findings showed "widespread contamination" with BPA. According to results posted on the group's website, all six cans of spaghetti and ravioli tested contained measurable levels of BPA, averaging 63.5 parts per billion. Five of six cans of baked beans had measurable levels, averaging 9.7 parts per billion. And two of six cans of infant formula tested contained the chemical. The EWG then contacted major manufacturers of formula sold in the United States; all said that they use BPA to line the metal portions of their containers, including those holding powdered formula.
In August 2007, a team of more than three dozen scientists reviewed some 700 animal studies and released a consensus statement outlining concerns about BPA exposure and issues needing further research. The statement was published in the journal Reproductive Toxicology.
Also in August, the National Institutes of Health National Toxicology Program's Center for the Evaluation of Risks to Human Reproduction convened an expert panel of 12 scientists and expressed "negligible concern" that BPA exposure in utero causes birth defects and "some concern" that BPA exposure causes neural and behavioral problems in infants and children.
For those concerned about BPA, the EWG suggests switching to glass, stainless steel and/or polypropylene or polyethylene baby and water bottles; avoiding #7 plastics (not all of which are polycarbonate, however); and using glass or ceramic dishes when microwaving food. The group also suggests breastfeeding or using powdered (rather than liquid) formula.
DNA of Celiac Disease
Scientists are another step closer to understanding the genetic causes of celiac disease, a condition which affects 1 in 133 people in the United States. Researchers led by David van Heel, professor of gastrointestinal genetics at Queen Mary, University of London, have found a gene that appears to be associated with susceptibility to the disease. Their work was funded by British charity, Coeliac UK, and the Wellcome Trust, a British group that supports medical research.
Researchers looked at genomic data from people with and without celiac disease. They found that people without the disease tend to have a protective DNA sequence in the genes that control messenger proteins related to inflammation. The scientists believe that the protective DNA sequence in people without celiac might help the body defend against intestinal inflammation.
More research clearly is needed to better understand the exact mechanisms at work. Multiple genes, as well as environmental factors, play a role in celiac susceptibility. Van Heel expects that additional genes and risk factors will emerge from further analysis of the genomic data.
Antibiotics, Dogs and Asthma Risk
A study published in the journal CHEST found that children who take antibiotics before their first birthday are significantly more likely to develop asthma by the time they reach their seventh birthday. The risk of developing asthma by age 7 was doubled for kids who took antibiotics for non-respiratory infections. The risk also doubled for those who took multiple courses of antibiotics and who did not live with a dog in their first year. Broad spectrum antibiotic use was more common among some of the groups of children studied.
"Dogs bring germs into the home and it is thought that this exposure is required for the infant's immune system to develop normally," says Anita Kozyrskyj, Ph.D., from the University of Manitoba in Canada in a press release. "Other research has shown that the presence of a dog in early life protects against the development of asthma. Exposure to germs is lower in the absence of a dog. The administration of an antibiotic may further reduce this exposure and increase the likelihood of asthma development," she continues.
The study neither proves nor disproves a role for antibiotics in asthma development, and further studies are needed before drawing conclusions. In the meantime, the authors point out, it would be prudent to avoid unnecessary use of broad-spectrum antibiotics in young children when other antibiotics are available.
British researchers recently published a study in the American Journal of Respiratory and Critical Care Medicine that surprised the authors themselves. The group found that among people with asthma who also had allergies, exposure to cat allergen was linked to a greater airway reaction even if they weren't specifically allergic to cats. The study looked at data from almost 2,000 people across Europe.
The study supports earlier research indicating that indoor allergens are strongly related to asthma and that people with certain allergies show greater bronchial reactions when exposed to those particular allergens.
"We presupposed that we would find increased responsiveness only in those individuals who were exposed to cat allergen and whose blood tests showed that they were allergic to cats. But our study suggests that all allergic individuals have signs of asthmatic responses if exposed to cat allergen, even if blood tests show they are not allergic to cats," says lead author Susan Chinn, DSc, of the Imperial College of London.
The authors conclude that all allergic people with asthma might benefit from reduced cat exposure. Chinn points out, however, that because the results were unexpected, they need to be replicated by other studies before any recommendations can be made. LW