January 24, 2012

expert reaction to antibody concentrations in children exposed to perfluorinated compounds (PFCs), as published in JAMA

A paper published in the Journal of the American Medical Association found that exposure to perflourinated compounds (PFCs) was associated with a reduced immune response to vaccinations in children. Along with quotes the SMC sent out a fact sheet and a before the headlines analysis.

Prof David Coggon, Professor of Occupational and Environmental Medicine, University of Southampton, said:

“This an interesting finding, but it needs independent confirmation by further studies; the paper’s own authors point out that the research does not establish a causal link. There might be other reasons for the reduced antibody concentrations. Even if the association were causal, it is reassuring that any impacts on response to vaccination appear to have been minor for most of the children studied. Also, PFCs are now tightly regulated in Europe, and many of their previous uses have been banned; so exposures should be declining.”

Dr Tony Fletcher, Senior Lecturer in Environmental Epidemiology, London School of Hygiene and Tropical Medicine, said:

“The results are relevant to most populations, as the serum levels reported are broadly comparable to levels reported in many countries, though a little higher for this Faroese population for one of the compounds PFOS. Fortunately exposure to PFOS has been controlled and serum levels are falling so if this association is causal the effects should be going down as a consequence. PFOA sources appear to be very diverse and involve other compounds which can break down into PFOA. But although PFOA is used in the manufacture of Teflon, there is little or no PFOA in non-stick pans, and it has long since gone from old pans.

“Most of the results would suggest that vaccine protection is being reduced by these exposures, either exposures during childhood or their earlier exposures prenatally passed on from their mothers. But the picture is not so clear in that for one of the vaccines, tetanus, the opposite effect appears where antibody levels at age 7 go up, not down, with exposure to PFOS. So maybe chance is playing a part here in some of the results.

“This is the first such study so it will be important to see if other studies of exposed populations show consistent findings either on infection disease risk or immune function. My current work on PFOA and PFOS is looking at childhood infection in relation to maternal serum levels of these compounds during pregnancy, whether flu vaccination response in adults is affected by them and other clinical immune function markers in relation to serum levels. Although we are not looking at these same antibodies, I will be interested to see our results in the light of these findings in the Faroe Islands.”

Prof Alastair Hay, Professor of Environmental Toxicology at the University of Leeds, said:

“The work was well conducted. It suggests that perfluorocarbons (PFCs, chemicals comprised of carbon and fluorine) concentrations have an adverse effect on antibody levels for tetanus and diphtheria toxins, two antibodies chosen for investigation. A single birth cohort was followed and PFCs were measured in the mothers before birth and in the children when they were 5 and 7 years of age and before and after antibody booster vaccination.

“Twofold increases in PFC concentrations were associated with significant falls in antibody levels. In other words children with higher PFC concentrations had lower antibody levels. The study authors were careful to assess whether the type of vaccine, be it combination or single, played any role in their observations and this was taken account of in the analysis by the team.

“So what does this mean? Firstly, it must be an alert for all health and environment authorities. The chemicals, although present in low amounts in our bodies, have very long residence times before they are excreted.

“Grandjean and his co-authors say that the effect they observed occurs at PFC levels which also affect immune function in animals. This is even more concerning because it indicates that the effect occurs across species and at levels of the chemicals which are present in our blood. How the chemicals operate on the immune system is not understood.

“Grandjean and his team’s work will have to be replicated in other human studies. In parallel, work should be done to investigate possible mechanisms by which the PFCs may affect cells in the immune system. We also need to know if there is safe exposure to these chemicals and what it might be. Does the effect change as we get older and well past the stage when there are booster vaccinations?

“The implication of this work is that everyday exposure to these chemicals makes us more vulnerable to infections. We cannot afford to ignore the research, but equally we should not panic. What we need is a measured response to test the findings in a robust way and assess their implications for our health and particularly that of our children.”

Prof Anthony Dayan, independent toxicologist, said:

“Exposure of mothers and children is proven as an analytical methodology so this looks OK. But the association between PFC levels in maternal serum taken late pre-birth, and antibody levels to two standard antigens taken in children aged 5 and after a ‘booster’ using a different vaccine (they admit this complicates interpretation), is not strong.

“The statement that the antibody levels were below the level accepted for adequate immunity is not properly referenced. The measured level related to immunity (following immunisation or boosting) falls, and the level taken as ‘protective’ must be justified.

“More to the point there is ample information that polyunsaturated fatty acids (PUFAs) are found in marine organisms and they suppress many immune responses. This paper uses neither a control nor even any mention of that well proven fact. So, as eating is claimed to be the source of PFCs and it is the source of the immunosuppressive PUFAs, the study proves nothing.”

‘Serum Vaccine Antibody Concentrations In Children Exposed to Perfluorinated Compounds’ by Grandjean, P et al, was published in JAMA on Tuesday 24 January 2012. Fact Sheet: PFOA/PFOS Before The Headlines analysis: Serum Vaccine Antibody Concentrations In Children Exposed to Perfluorinated Compounds. Before The Headlines is a service provided to the SMC by volunteer statisticians: members of the Royal Statistical Society and Statisticians in the Pharmaceutical Industry. A list of contributors, including affiliations, is available here.