[Abstract below]
Traffic pollution damages sperm and may reduce fertility in young and middle-aged men, reveals an Italian study of motorway tollgate attendants.
The attendants, who spend six hours a day sitting in a roadside booth, showed poorer sperm quality than men of the same age living in the same area but not exposed to the same level of exhaust fumes.
Researchers blamed nitrogen oxides and lead for the adverse effects. Although the sperm counts of tollgate workers were normal, their sperm performed less well in tests measuring the ability to reach and penetrate an egg.
"The sperm of the study group was more feeble and less active, so it has lower fertility potential," says Michele De Rosa, study lead at the University of Naples. "Our study demonstrates that continuous exposure to traffic pollutants impairs sperm quality in young and middle-aged men."
Furthermore, the time taken for the tollgate attendants' wives to become pregnant - 15 months on average - was nearly double that of those whose husbands did not work next to the motorway.
Sitting uncomfortably
However, Gerald Lincoln, an expert on male reproduction at the MRC's Human Reproductive Sciences Unit in Edinburgh, UK, urges caution in interpreting the results. Sitting for prolonged periods of time can also affect sperm because of heat in the pelvic area.
"Posture is absolutely crucial," he told New Scientist. "It could have a much bigger effect on sperm characteristics than atmospheric effects."
This problem is acknowledged by the Italian group, who argue that the men in the control group also had sedentary jobs, as it was comprised of clerks, drivers, students and doctors.
Forward progression
De Rosa and his colleagues examined semen quality in 85 tollgate attendants and compared this with 85 men who did not work near a motorway. Sperm function tests, measuring for example overall motility, forward progression and the lateral movement of the sperm head, reveal tollgate attendants as having less vigorous sperm.
However, they did not have a lower sperm volume or count compared to the control group and hormone levels - including testosterone - did not differ significantly between the groups.
Environmental levels of nitrogen oxide, sulphur oxide and lead exceeded maximum legal limits at the tollgates and attendants showed significantly higher blood concentrations of these pollutants compared to the other men.
In attendants who showed damaged sperm, sperm count and viability went down with increasing lead levels. Sperm function become poorer with increasing blood levels of methaemoglobin - a marker for nitrogen oxide.
"Health authorities should be alert to the insidious health effects of environmental pollution," they conclude.
Michele De Rosa1,4, Stefano Zarrilli1, Luigi Paesano1, Umberto Carbone2, Bartolomeo Boggia1, Mario Petretta3, Antonella Maisto2, Francesca Cimmino2, Giancarmelo Puca2, Annamaria Colao1 and Gaetano Lombardi1
1 Department of Molecular and Clinical Endocrinology and Oncology, 2 Department of Preventive Medical Sciences and 3 Department of Internal Medicine, University of Naples ‘Federico II’, Italy 4 To whom correspondence should be addressed at: Department of Molecular and Clinical Endocrinology and Oncology, University of Naples ‘Federico II’, via S. Pansini 5, 80131 Naples, Italy. e-mail: miderosa@unina.it
BACKGROUND: Given the lack of consensus about the effect of traffic-derived pollutants on male fertility, we evaluated semen quality in men occupationally exposed to traffic. METHODS: Semen quality was investigated in 85 men employed at motorway tollgates and in 85 age-matched men living in the same area. Semen, circulating sex hormones, methaemoglobin, sulphaemoglobin, carboxyhaemoglobin, lead (Pb) and zinc (Zn) protoporphyrin were assayed. Environmental carbonium oxide, nitrogen oxide, sulphur oxide and Pb were also measured. RESULTS: Sperm count, and serum levels of FSH, LH and testosterone were within normal range in both groups. Total motility, forward progression, functional tests and sperm kinetics were significantly lower in tollgate workers versus controls. In a subset of tollgate workers with motility below normal, methaemoglobin was inversely correlated with total motility, viability, the hypo-osmotic swelling test, the acridine orange test, the cervical mucus penetration test, linearity, and amplitude of lateral movement of the sperm head, whereas blood levels of Pb were inversely correlated with viability and sperm count. CONCLUSIONS: The finding that blood methaemoglobin and Pb were inversely correlated with sperm parameters indicates that nitrogen oxide and Pb adversely affect semen quality.
Key words: environmental pollution/lead/methaemoglobin/semen analysis/spermatogenesis
source: http://humrep.oupjournals.org/cgi/content/abstract/18/5/1055 30apr03
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