The pesticide DDT [1,1,1-trichloro-2,2-bis(chlorodiphenyl)ethane] is 1 of the 12 persistent
organic pollutants (POPs) under negotiation at the Stockholm Convention to restrict
or ban their production and use because of their toxicity, resistance to breakdown,
bioaccumulation, and potential for being transported over long distances. DDT has
estrogenic potential, and the main metabolite, p,p'-dichlorodiphenyl-dichloroethylene
(p,p'-DDE), is a potent antiandrogen. In response to mounting evidence on the endocrine-disrupting
influence of environmental chemicals on human health, this epidemiological study was
initiated to test the hypothesis that nonoccupational exposure to DDT affects male
reproductive parameters. In a cross-sectional study, healthy male subjects (n=311)
between 18 and 40 years (23+/-5) of age were recruited from 3 communities in an endemic
malaria area in which DDT is sprayed annually. A semen analysis according to World
Health Organization (WHO) standards was performed. The Hamilton Thorne Computer Assisted
Sperm Analysis (CASA) system was simultaneously used to determine additional sperm
motility parameters. Blood plasma samples were assayed for p,p'-DDT and metabolites
as a measure of exposure. The exposure levels were expressed as lipid-adjusted p,p'-DDT
and p,p'-DDE values. The mean p,p'-DDT and p,p'-DDE concentrations were 90.23 microg/g(+/-102.4)
and 215.47 microg/g(+/-210.6), respectively. The multivariate linear regression analyses
indicated that mean CASA motility was lower with a higher p,p'-DDE concentration (beta=-0.02,
P=.001) and the CASA parameter beat cross-frequency (BCF) was higher with a higher
p,p'-DDT concentration (beta=0.01, P=.000). There was also a statistically significant
positive association between percent sperm with cytoplasmic droplets and p,p'-DDT
concentration (beta=0.0014, P=.014). The ejaculate volume (mean 1.9+/-1.33 mL) was
lower than the normal range (>or=2.0 mL) according to WHO, and a significant decrease
with increasing p,p'-DDE values was seen for both square root-transformed volume (beta=-0.0003;
P=.024) and count (beta=-0.003; P=.04). Although there were no associations between
either p,p'-DDT or p,p'-DDE concentrations and the rest of the seminal parameters,
the incidence of teratozoospermia (99%; normal sperm<15%) was high. Twenty-eight percent
of the study group presented with oligozoospermia (<20x10(6) sperm/mL), which had
a significant positive association with p,p'-DDE (odds ratio [OR]=1.001, P=.03). There
was a significant positive association between participants with asthenozoospermia
(32%) and p,p'-DDT (OR 1.003, P=.006) and p,p'-DDE (OR 1.001, P=.02). The results
imply that nonoccupational exposure to DDT is associated with impaired seminal parameters
in men. The high exposure levels of p,p'-DDT and p,p'-DDE are of concern because these
levels could have far-reaching implications for reproductive and general health.