Issue 23 – Engagement

Issue 23, February 2010 (scroll down for this month’s articles): How to make environmental health science relevant to clinicians; US companies volunteer to phase out controversial chemicals; and researchers uncover link between BPA exposure and heart disease. Plus 5 Stories / 5 studies, our new round up of the best news and science from January.

Rules of Engagement: Making environmental health science relevant to clinicians

The differences between approval process for pharmaceuticals and chemicals before they enter the market. Since 2007, the EU has begun implementing REACH legislation in an effort to manage how potentially biologically-active compounds may enter the marketplace. Source: Adapted from Navigating the Scientific Evidence to Improve Prevention. (2009) Discussion Document to Participants for Navigation Guide Workshop August 10-11, 2009. p10. Click to enlarge.

by Paul Whaley

Tracey Woodruff MPH, Director of the Program for Reproductive Health at the University of California San Francisco (UCSF), finds it difficult to understand why, after around 1,000 studies, there is still so little action on bisphenol-A (BPA).

Woodruff does not believe that the problem is a lack of evidence of harm – the 1,000 studies provide plenty of evidence – so there must be anther reason why there have been so few moves on BPA in health policy or clinical practice.

She has seen the problem before, pointing to formaldehyde as an example. In this instance, multiple studies were showing increased rates of nasal cancer in rats exposed to formaldehyde 20 years before human observational research confirmed the same health outcome in people. Formaldehyde was then finally restricted, but only after 20 years of arguably preventable cancers.

Woodruff is now coordinating a committee of medical and public health practitioners which believes a major part of the problem is the perception that environmental health science is irrelevant to clinical practice, and that a major cause of this perception is a misunderstanding of the differences in how environmental health and clinical research are conducted.

For example, in the clinical arena randomised controlled trials (RCTs) are considered the “gold standard” of evidence for medical diagnostic testing. However, in environmental health this standard is almost impossible to attain. As is the case for the testing of pharmaceuticals on pregnant or lactating women, for ethical reasons it is not possible to conduct RCTs to determine the health effects of environmental chemicals.

This means experimental data has to come from animal toxicity testing and that human observational studies, rated in the clinical context as less valuable than a well-conducted RCT, are one of the best sources of information available to environmental health researchers.

How, then, does one introduce clinicians to environmental health science if it is not the sort of information they are used to dealing with? Mark Miller MD, Director of the UCSF Pediatric Environmental Health Specialty Unit, says: “The key is sorting out the materials so they are acceptable to the clinical community – they have to meet the standards of that community, be written in a language the community understands, which stands up to the concerns of clinicians.”

Woodruff’s committee is therefore looking at establishing a GRADE-style (“The Grading of Recommendations, Assessment, Development and Evaluation”) standardisation for environmental health science, duplicating GRADE’s transparent methodology for making evidence-based recommendations about the best way to deal with an environmental health issue.

The key concepts here are transparency and trust: clinicians, who are not environmental health specialists, need confidence they are making appropriate recommendations if they are going to make any at all. And at the moment, they are very wary of a science Miller says is sometimes perceived as “wacky”.

Once environmental health science becomes an accepted part of medical knowledge, Miller says clinicians will find it easier to direct some of their attention towards “looking at the causes of problems and getting stuck into the public health issues which lead to them having a patient on the table in the first place.”

US companies volunteer to phase out controversial chemicals

Albemarle, one of the companies agreeing to phase out decaBDE, says it has developed a safer, recyclable polymer-based alternative to flame retardants. Image: nelso47, stock.xchng

Six major baby bottle manufacturers and the three largest flame retardant companies in the US have made deals to phase out controversial chemicals from their products.

Following negotiations with the US Environmental Protection Agency, the largest US importer and the two largest US manufacturers of decaBDE, a common chemical used to prevent objects catching fire, agreed to phase out the chemical from most applications by 2013.

DecaBDE has become increasingly controversial in the past few years. Recent studies have found that toddlers are particularly exposed to the chemical, which migrates from household objects into house dust, while evidence is accumulating of possible harm to the thyroid system, behaviour and brain function.

In 2007 two US states, Washington and Maine, passed legislation aimed at banning decaBDE. Since then, 10 or more states are considering restrictions.

The baby bottle manufacturers will be eliminating bisphenol-A, an endocrine-disrupting chemical which has been the focus of much media attention, especially in the US. Thought to be of special concern for infants, phasing BPA out of baby products has become a priority.

Neither chemical, however, is to be found on the recently-updated EU list of Substances of Very High Concern (SVHCs), which is now 29 chemicals in length. SVHCs are chemicals short-listed for a second selection phase, after which they may prioritised for phase-out in the EU.

Researchers uncover BPA and heart disease link

Americans with higher levels of BPA in their urine were more likely to report cardiac problems. Image: Gray's Anatomy, 1918

In a study which confirms previous findings, researchers from the University of Exeter in the UK have reported a significant association between levels of bisphenol-A (BPA) in human urine and the diagnosis of cardiovascular disease.

The researchers analysed data from US National Health and Nutrition Survey (NHANES), which has been collecting health and nutrition information from a representative subpopulation of the US since the 1960s, in order to provide health statistics to guide public health policy interventions.

The researchers examined data gathered on 1,400 Americans between 2005 and 2006 and found that those with the highest levels of BPA in their bodies were 33% more likely to develop heart disease than those with the lowest levels.

In other research, a French team from the National Institute of Agronomic Research in Toulouse found that rats exposed in the womb to even low levels of BPA were more likely to develop intestinal inflammation in adulthood. They also found in vitro that BPA reduces the permeability of human intestinal tissue.

The research coincides with the US FDA reversing its long-held position that BPA is safe, stating that it is of “some concern” for infants and children, rather than a chemical which poses no risk to humans.

5 Stories / 5 Studies

5 Stories: Five news and opinion items

Assessing Risks from Bisphenol-A: Brilliant piece of science writing on what the animal evidence is telling us about potential health risks from BPA, the obstacles in the way of translating this to humans, and how to deal with them.

Hey FDA, Is it Safe? A solid article defending the merits of the recent study connecting BPA to cardiovascular problems and outlining the regulatory challenges faced by the US FDA.

Disinfectants ‘train’ superbugs to resist antibiotics: More evidence that bacteria seem to be able to adapt to resist antibiotics without even being exposed to them.

Scientists link flame retardants and reduced human fertility: Scientists for the first time have found evidence that flame retardants may be reducing human fertility – California women exposed to high levels of the compounds take substantially longer to get pregnant than women with low levels.

Insecticides May Raise Risk of Lupus, RA: In a study of more than 75,000 women, those who used insecticides six or more times a year had nearly two-and-a-half times the risk of developing autoimmune diseases than women who adopted a live-and-let-live attitude toward bugs

5 Studies: Five new pieces of environmental health research

Residential Pesticides Exposure Elevates Risk of Childhood Leukemia: A new meta-analysis finding a positive association between residential pesticide exposure and childhood leukaemia.

POPs Exposure Leads to Insulin Resistance Syndrome: The first animal study to show that exposure to POPs causes insulin resistance and associated obesity and liver disease.

Phthalates may play a role in ADHD symptoms: Korean children with ADHD have been found to be more likely to have phthalate metabolytes in their urine.

Prenatal Exposure to PBDEs and Neurodevelopment: Epidemiologic study finding that children with higher concentrations of PBDEs in their umbilical cord blood at birth scored lower on tests of mental and physical development between the ages of one and six.

Prenatal phthalate exposure and behavioural issues: Study concludes: “Behavioral domains adversely associated with prenatal exposure to LMW phthalates in our study are commonly found to be affected in children clinically diagnosed with Conduct or Attention-Deficit Hyperactivity Disorders.”

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