NEUROENDOCRINOLOGY
LETTERS
including
Psychoneuroimmunology, Neuropsychopharmacology,
Reproductive Medicine, Chronobiology
and Human Ethology, ISSN 0172–780X
DDT
in human milk and mental capacities in
children at school age:
An additional view on PISA 2000
by
Günter Dörner & Andreas Plagemann
Submitted:
August 6, 2002 Accepted: August 10, 2002
Key
words: total DDT-levels in human milk, mental capacities, PISA
2000, functional teratology, neuroendocrine prophylaxis
Abstract
OBJECTIVES:
To investigate a possible lasting impact of dichlorodiphenyl
trichloroethane (DDT) exposure in neonatal life on mental
capacities in later life.
MATERIAL
AND METHODS: Relationships were evaluated by correlation and
regression analysis between total DDT concentrations in human
breast milk in the years of birth (1984/1985) and measurements
of mental capacities obtained in pupils of the PISA 2000 studies
as well as percentages of backward children in Germany in
1994/95.
RESULTS:
Comparing total DDT levels in human milk during the years
of birth (1984/85) evaluable for eleven PISA countries with
assessed mental capacities of 15-year-old pupils of PISA International,
a significant inverse correlation was found (p<0.001),
even after adjustment for socioeconomic statuses (p = 0.001).
Furthermore, a significant inverse correlation (p<0.001)
was also obtained between the total DDT concentrations in
human milk in 1984/85 in ten foreign countries of three continents
plus fourteen Federal States of Germany and the mental capacities
of 15 year-old pupils of PISA International plus PISA National
(Germany) 2000. Finally, a significant positive correlation
was observed between total DDT contents in human milk in 1984/85
and the percentages of backward school children in 1994/95
in Federal States of Germany (p<0.001).
CONCLUSIONS:
These data – in association with additional experimental
and epidemiological findings – suggest that DDT is a
“neuroendocrine disrupter” as well as a “functional
teratogen” leading to harmful effects on brain development
and mental capacities in later life. Thus, a neuroendocrine
prophylaxis during critical developmental periods in early
life – as recommended by our group since many years –
appears to be most important for primary preventive medicine
but even for “preventive pedagogics”. The validity
of these theses should be re-tested in future PISA studies.
*
* *
Abbreviations
and Units:
PISA:
Programme for International Student Assessment
DDT: dichlorodiphenyl trichloroethane
DDE: dichlorodiphenyl dichloroethene
NEIS: Neuro-Endocrine-Immune-System
NEIP: Neuro-Endocrine-Immune-Prophylaxis
AUS: Australia
CAN: Canada
FIN: Finland
GER: Germany
ITA: Italy
MEX: Mexico
NOR: Norway
POL: Poland
SWE: Sweden
UK: United Kingdom
USA: United States of America
BA: Bavaria
BB: Brandenburg
BW: Baden Wuerttemberg
BR: Bremen
HA: Hamburg
HE: Hesse
LS: Lower-Saxony
MW: Mecklenburg-Western Pomerania
NW: North Rhine-Westphalia
SA: Saxony-Anhalt
SAX: Saxony
SH: Schleswig-Holstein
SL: Saarland
TH: Thuringia
RP: Rhineland-Palatinate
Introduction
DDT,
which was worldwide used as pesticide, is a chlorinated phenyl
derivative (dichlorodiphenyl trichloroethane). Some indications
for negative long-term effects of chlorinated phenyl compounds
on mental capacities were observed in animal experiments and
studies in human beings (1,2).
In 1992, Eriksson et al. (3) reported that neonatal exposure
to DDT clearly affected the muscarinic cholinergic receptors
of the cerebral cortex in newborn mice, leading to permanent
disturbances of the cholinergic system in the brain combined
with disruption of learning capacity in adult life. Ten years
before, we described that a significant decrease of acetylcholine
in the brain, induced in newborn rats by maternal deprivation,
gave rise to a significantly diminished emotionality, learning
capacity, and memory capacity in later life (4). These permanent
changes could be prevented by neonatal administration of an
acetylcholinesterase inhibitor.
Decreased mental capacities were also observed in children who
spent their first year of life in day-nurseries (5). In addition,
decreased mental performance and psychical adaptability were
demonstrated in pupils who were not breast-fed during their
first months of life (6). Finally, we found in children who
received no human milk but cowmilk formula abnormal blood concentrations
of neutral amino acids which can affect neurotransmitter concentrations
in the developing brain (7). Furthermore, we could demonstrate
a significant increase in the prevalence of backward children
in Berlin between the mid 1950s and the late 1960s (p<0.001),
followed by a significant decrease afterwards (8). Interestingly,
a similar time course was described for the production and application
of DDT in Germany (9).
With regard to these observations, after publication of the
International and National PISA-Studies in 2001 (10) and 2002
(11), respectively, we therefore tried to examine whether and
how far perinatal DDT exposure estimated by maternal milk might
be associated with mental capacities later in life.
