Researchers are reporting an association between phthalate exposure, asthma and allergies in children.
Exposure to, 'phthalates,' substances used as plasticizers in a large variety of consumer goods may occur through ingestion, skin contact, or inhalation.
Children, who are uniquely vulnerable to negative health effects of environmental exposures due to their developing immunological, neurological and respiratory systems, may receive especially high exposures because of more frequent hand-to-mouth activity in combination with contact with, 'polyvinyl chloride (PVC),' surfaces and dust in a home, which collects phthalates and other chemicals.
Researchers are reporting an association between phthalate exposure and asthma and allergic disease in a group of children.
The researchers conducted a cross-sectional analysis of urine sample data from more than 600 children who participated in the 10-year follow-up to the prospective, 'Environment and Childhood Asthma,' study in Oslo.
The follow-up included structured interviews with the parents of the children, as well as:
Samples of the children's first morning urine were collected and assessed for 3 metabolites of low-molecular-weight phthalates commonly used in personal care products, as well as 8 metabolites of high-molecular-weight phthalates commonly used in PVC applications such as:
The researchers used logistic regression modeling to estimate associations between current asthma and phthalate metabolite concentrations.
Prior animal studies showed an association between high-molecular-weight phthalates and allergic disease development, while epidemiological studies showed exposure to house dust containing a number of these chemicals was associated with both asthma and allergic disease. The current analysis revealed an association between asthma in children and the highest quartiles of exposure to the metabolites, 'mono-carboxyoctyl phthalate,' and, 'mono-carboxynonyl phthalate.' The parent compounds of these metabolites are high-molecular-weight phthalates used mainly as plasticizers in PVC products. No association was found between asthma and the 9 other metabolites, nor was any association found between any metabolites and allergic sensitization.
A Study by Columbia University
Children exposed in the womb to moderate levels of 2 plasticizers had a 72-78% higher chance of developing asthma according to a study by Columbia University. The study is the first one to link childhood asthma to prenatal exposure to phthalates. Asthma has been increasing in recent decades. Robin Whyatt, an Environmental Health Scientist at Columbia University stated, "These results suggest that phthalates may be one of the factors associated with that increase." She also said that more studies are needed in order to understand how important a risk factor these chemicals might be.
Phthalates are used in the manufacture of some cosmetics and vinyl and have been connected to several health effects in laboratory animals and in human studies, to include altered male genitalia, airway inflammation, attention and learning issues and premature births. Across America, 1 in every 11 children experiences asthma according to the U.S. Centers for Disease Control and Prevention. Asthma rates more than doubled between 1980 and 1995 and have remained elevated. Asthma rates among black children rose by approximately 50% between 2001 and 2009.
Dr. David Bernstein, an Allergist at the University of Cincinnati and spokesperson for the American College of Allergy, Asthma and Immunology stated, "We don't have a good answer for why asthma and allergies have increased dramatically. Looking at the role of environmental exposures is an interesting and important question." Previous studies revealed an association between childhood exposure to phthalates and asthma, yet no one until this point had examined risk related exposures before birth. Robin Whyatt said, "The prenatal period is likely the greatest window of susceptibility for lung development."
Researchers measured 4 phthalate metabolites in the urine of 300 women who were pregnant in Northern Manhattan and the South Bronx between 1998 and 2006. All of the women in the study were African-American or of Dominican descent. Dr. Bernstein stated, "We don't have a good answer for why asthma and allergies have increased dramatically. Looking at the role of environmental exposures is an interesting and important question." More than half of the children in the study visited a doctor for asthma-related symptoms between the ages of 5-11.
Of these children, 94 - or 31% of the entire study population of children, were diagnosed with asthma. The children in the study experienced asthma at a rate 3 times higher than the U.S. average and roughly double the national average for black children. They most likely have such a high rate for many reasons - to include vehicle exhaust and cigarette smoke. Robin Whyatt said, "We don't know how applicable these [phthalate] findings are to groups with much lower rates of asthma."
Children whose mothers had the highest levels of, 'di-n-butyl phthalate (DnBP),' were 78% more likely to experience an asthma diagnosis than children whose mothers had the lowest levels. Children with mothers who had high levels of, 'butyl benzyl phthalate (BBzP),' were 72% more likely to have asthma. Children also were 39-44% more likely to have asthma symptoms such as wheeze if their mothers had higher levels of DnBp and BBzP during pregnancy. No association was found between asthma and 2 other phthalates used in food packaging and cosmetics.
The phthalate levels measured in mothers involved in the study were comparable to levels found in adults across America, according to Robin Whyatt. The findings raise new concerns that the presence of fairly ubiquitous environmental exposures might have deleterious respiratory effects according to the study. BBzP, used to soften plastics, is commonly found in PVC plastics such as artificial leather and vinyl floor tiles. DnBP is used in some cosmetics and food packaging.
The Results Remain Unclear
A study from 2013 reported that levels of both chemicals are decreasing in people in America. They were banned from some children's products in the year 2008. DnBP was once widely used in nail polishes, but has been removed from most formulations.
The new study builds on studies from 2012 of the same group that reported that children exposed to BBzP or, 'diethyl phthalate (DEP),' experienced elevated risk of asthma-related airway inflammation. Prenatal exposure to BBzP was also associated with increased risk of childhood eczema. Taken by itself, the new study is not conclusive, yet there is mounting evidence linking phthalates to several diseases and chronic conditions, according to Kenneth Spaeth, Director of the Occupational and Environmental Medicine Center at the North Shore University Hospital in Manhasset, N.Y.
It is unclear how phthalates might be increasing asthma risk. One theory, according to Robin Whyatt, is that they may make airways overly sensitive. They might program airways to respond to common environmental stimuli such as animal dander or pollen.
Perhaps unsurprisingly, representatives of the chemical and plastics manufacturers declined to comment on the new findings. Based on a handful of studies conducted between 2003 and 2009, the American Chemistry Council - which represents manufacturers of phthalates and other chemicals, concluded that, "phthalates do not cause, and are not likely to exacerbate, asthma." Yet Robin Whyatt said that conclusion is, "remarkably incomplete," and misses more recent findings.
Almost everyone in America is exposed to phthalates. Robin Whyatt said pregnant women can reduce their exposure by avoiding numbers 3 and 7 plastics. She said to store food in glass containers and never microwave food in plastic containers.
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