Latest BPA study “flawed” says American Chemistry Council

06-Oct-2009 - Last updated on 07-Oct-2009 at 08:55 GMT

“Many limitations but no clear conclusions,” is the verdict of the American Chemistry Council (ACC) on the latest study claiming to link exposure to the chemical bisphenol A with risks to human health.

The council has rebuffed the conclusions of a study published in the journal Environmental Health Perspectives which claims to link prenatal exposure to the chemical, commonly found in plastic bottles and sipper cups, with aggressive behaviour in two-year old girls.

Commenting on the study Steven Hentges, of the council’s Polycarbonate/BPA Global Group said: “Inherent in the design of this small-scale study is the inability to establish cause-effect relationships. The study can only evaluate parameters measured in the study for statistical associations, which may be neither real nor meaningful.

Limited reliability

“The limited reliability of the associations reported in this study is characterized by the authors in their concluding paragraph: ‘The reported associations and interactions … should be viewed cautiously since these results could be biased from exposure misspecification or residual confounding.’

Hentges confirmed the council’s belief that research should be based on sound scientific principles in order to be meaningful for human health. But there are significant limitations in the study design, highlighted by the authors themselves, which limit its usefulness, he added.

The council picked out comments from the study’s authors that “… it is ‘difficult to accurately characterize exposure from a single measurement.’ However statistical associations based on inaccurate exposure measurements cannot be meaningful, said the council.

Also, the authors did not recognize that BPA is efficiently converted to a biologically inactive metabolite after exposure, said the council. “What was measured was not BPA, but the metabolite.”

Since BPA exposure is mainly from the diet, said the council, differences in BPA levels among the study participants may indicate significant dietary differences. Diet and nutrition were not evaluated, but are important in fetal development, it said.

Human health

Hentges concluded: “In light of its limitations, there is significant potential for this study to be misconstrued. The results of this preliminary, and severely limited, study cannot be considered meaningful for human health unless the findings are replicated in a more robust study."

The study, Prenatal Bisphenol A Exposure and Early Childhood Behavior, was conducted by researchers at the University of North Carolina and British Columbia's Simon Fraser University (SFU).

The study measured BPA levels in urine samples taken from 249 pregnant women in Cincinnati, Ohio, at 16 and 26 weeks of pregnancy, then again at birth. The children were assessed for behavioural problems at two years of age through questionnaires completed by their parents.