US scientists have challenged ways of assessing the safety of food contact chemical bisphenol A (BPA) in a fresh research article.
Some studies claim intake of the substance, used in coating and manufacturing plastic and metal packaging, is a contributing factor in the development of diseases ranging from various cancers to asthma.
The researchers use data from four National Health and Nutrition Examination Surveys (NHANES) detailing urinary BPA levels to deliver findings that do not link BPA to heart disease and diabetes.
But they go on to say that using such information alone to assess health risks associated with intake of BPA in the human diet is questionable.
They assert that NHANES data is based on one-time measurements of levels of food contact materials in urine and so is inconclusive in determining the effect of long term exposure to such substances.
This is because chemicals such as BPA often have a short half-life in the human body and may not be reliably measured by urinary excretion, they claim.
“Whether one-time measurements of chemicals with short physiologic half-lives can or should be used to ascertain chronic exposures must be carefully explored on a chemical-by-chemical basis. However, it is clear that for many chemicals we cannot be confident that one-time measurements represent long-term exposures.”
Regression models were adjusted for creatinine, age, gender, race/ethnicity, education, income, smoking, heavy drinking, BMI, waist circumference, calorie intake, family history of heart attack, hypertension, sedentary time, and total cholesterol.
“Using scientifically and clinically supportable exclusion criteria and outcome definitions, we consistently found no associations between urinary BPA and heart disease or diabetes,” the scientists state.
“These results do not support associations and causal inferences reported in previous studies that used different criteria and definitions.”
They claim datasets such as NHANES have limited value when conducting such risk assessments.
“We are not drawing conclusions regarding whether BPA is a risk factor for these diseases. We are stating the opposite–that using cross-sectional datasets like NHANES to draw such conclusions about short-lived environmental chemicals and chronic complex diseases is inappropriate.
“We need to expend resources on appropriately designed epidemiologic studies and toxicological explorations to understand whether these types of chemicals play a causal role in chronic diseases.
The study was funded by the Polycarbonate/BPA Global Group of the American Chemistry Council and two of the authors had previously published articles with the support of this group.
Source: ‘Use of NHANES Data to Link Chemical Exposures to Chronic Diseases: A Cautionary Tale’. PLoS ONE 7(12): e51086. Doi:10.1371/journal.pone.0051086
Authors: Lakind JS, Goodman M, Naiman DQ (2012)