to Dewailly et al., "For many years young native children from
Nunavik have had a high incidence of infectious diseases, in particular
meningitis, bronchopulmonary, and middle ear infections. Otitis
media [middle ear infections] and the damage it can cause to hearing
is a major problem for Inuit children and adults. In fact, Inuit
in Nunavik report hearing loss as their most common chronic health
causes for this unusual pattern of infectious diseases is uncertain,
but plausibly linked to the high levels of organochlorine chemicals
experienced prenatally in the womb by Inuit children. Dewailly et
al. explore this hypothesis by measuring organochlorine (OC)
levels in breast milk shortly after birth and testing whether OCs
are associated with rates of inner ear infections early in life.
They find that higher levels of OCs indeed are associated with
an increased rate of these infections.
did they do?
Dewailly et al. measured levels in mother's milk of 10 PCB
congeners and 8 chlorinated pesticides or metabolites (p,p´-DDE,
mirex, heptachlor epoxide, chlordane, hexachlorobenzene, endrin,
and dieldrin). Milk samples were taken shortly after birth and used
as an index to in utero exposure. Then during the first year
of life they examined participating infants' health status three
times in the first 12 months, paying particular attention to the
incidence of ear infections. Blood samples were also taken during
these examinations and used in immune system assays.
did they find?
ear infections were the most frequent health problem in these infants,
with 81% experiencing at least one episode. The frequency of ear
infections did not differ among breast-fed vs. bottle-fed infants.
ranking higher in organochlorine exposure (as measured in breast
milk) were more likely to experience ear infections than those ranking
lower. None of the measured immunological parameters were related
to OC exposure in breast milk.
et al.'s results do not allow them to identify which OC compounds
could be responsible for the Inuit infants susceptibility to ear
infections. The associations between inner ear and exposures were
most consistent for DDE and HCB, but concentrations of the OCs in
general were highly correlated with one another.