In a recently published consensus statement, the European Society for
Paediatric Endocrinology and the Pediatric Endocrine Society alert physicians
to the possible dangers of endocrine-disrupting chemicals and encourage them to
participate in research on their effects.
“Experimental animal and wildlife studies have shown that
ubiquitous chemicals can function as disrupters of the endocrine systems,
either by interaction with hormone receptors or with hormone synthesis and
metabolism,” one of the statement’s authors, Niels Erik
Skakkebæk, MD, of Rigshopitalet, University Department of Growth and
Reproduction in Denmark, told Endocrine Today. “However, so far,
clinicians have been less aware of the problem.”
Problems for pediatric patients
Concerns about exposure to
endocrine-disrupting chemicals would be hypothetical, except
for the “many endocrine problems [with] no known etiology,” such as
reproductive issues, certain cases of obesity and some thyroid disorders,
according to Skakkebæk. For example, the statement cites cohort studies
indicating that 2% to 9% of newborns in the United Kingdom and Nordic countries
have cryptorchidism. The authors note that any upward trends in these results
may mirror data on increasing incidence of testicular cancer — a disease
which is now suspected to have fetal origins. In addition, Skakkebæk
noted that animal studies suggest dysgenesis of fetal testis related to
endocrine disrupters may also cause reproductive problems.
“The pediatric endocrine societies are the ideal organizations to
call attention to these problems, as there is growing concern that the fetus
growing child may be particularly vulnerable [to
endocrine-disrupting chemicals],” Skakkebæk said. “In fact, it
appears that several endocrine problems in childhood and adult life have fetal
origin, although [this is] not always noticeable during the first years of
Conflicting data from animal and human epidemiological studies further
complicate the issue. Inconsistent evidence hinders the ability of public
health and government regulatory agencies to make important decisions about
manufacturing of certain chemicals, the document states.
“Exposure to endocrine disrupters is complex. We are all exposed
daily to minute amounts of mixtures of them through our modern
lifestyles,” Skakkebæk said. “The crucial question is whether
they may also be harmful for us. We need commitment from clinicians to unravel
the possible roles of endocrine disrupters.”
For more information:
Disclosure: Dr. Skakkebæk reports no relevant financial
disclosures. One author reports receiving lecture fees from Novo Nordisk and
grant support from the Sigrid Juselius Foundation.
The joint statement by European Society for Paediatric Endocrinology and
the Pediatric Endocrine Society highlights the fact that infants and young
children are particularly susceptible to endocrine-disrupting chemical
exposure, due to their passage across the placenta and into breast milk and
because infants and young children are most prone to mouthing on plastics and
are frequently dressed in flame retardant clothing.
Implicating endocrine-disrupting chemical exposure with endocrine
outcomes in humans is problematic, in that the best we usually have is
cross-sectional data, which is complicated by lack of directionality, and the
fact that most endocrine-disrupting chemicals are lipophilic compounds which
store in adipose tissue, making blood levels difficult to interpret.
Mechanistic and/or prospective data are extremely difficult to come by in
humans, let alone children. However, predictive data are beginning to
accumulate. For instance, the degree of organophosphate or organochlorine
(pesticides) exposure during pregnancy predicts cognitive dysfunction in the
offspring, possibly through effects on thyroid metabolism (Bouchard MF. Environ Health Perspect. 2011;119:1189-1195 and Chevrier J. Am J Epidemiol. 2008;168:298-310). On the obesity
front, intrauterine exposure to DDE (pesticide; a metabolite of DDT, banned in
the U.S. in 1972) and PCBs (coolants and electrical equipment) predict BMI
z-scores in toddlers aged 1 to 3 years (Verhulst SL. Environ Health Perspect. 2009;117:122-126 and Mendez MA. Environ Health Perspect. 2011;119:272-278). Lastly, prenatal exposure to
hexachlorobenzene (fungicide) predicted elevated risk for obesity at 6 years (Smink A. Acta Paediatr. 2008;97:1465-1469).
The implications of these studies are that exposure to
endocrine-disrupting chemicals during pregnancy are particularly egregious for
negative effects on outcomes in children that predict disease, socioeconomic
health disparities and excessive utilization of medical resources. Such
exposures are even more alarming, as these compounds are ubiquitous and persist
in the environment, suggesting that the worst is yet to come.
– Robert H. Lustig, MD
Pediatrics, Division of Endocrinology
University of California, San
Disclosure: Dr. Lustig reports no relevant financial disclosures.