By MedWire Reporters
Environmental exposure to arsenic significantly reduces semen quality in Chinese men, research shows.
Arsenic is a known carcinogen that contaminates water supplies, food, and processed products.
"In China and throughout Asia, huge populations depend on rice as a staple food, which can concentrate higher levels of inorganic arsenic in the grain than wheat," report Heqing Shen (Chinese Academy of Science, Xiamen) and colleagues in Environmental Health.
Animal studies have shown mixed results regarding the effect of arsenic exposure on male and female fertility.
In the present study, the group monitored the profile of arsenic species in the urine of 96 men of reproductive age who attended an infertility clinic.
As arsenic can be metabolized into different species via different pathways, the researchers measured five urinary arsenic metabolites using high-performance liquid chromatography.
The urinary concentration of inorganic arsenic (Asi) was 4.03 µg per gram of creatinine and the urinary concentrations of the organic arsenic species arsenobetaine, dimethylarsinic acid (DMA), and methylarsonic acid (MMA) were 7.49, 20.9, and 2.77 µg per gram of creatinine.
The team reports that DMA concentrations above the median were significantly associated with below-reference sperm concentrations, raising the odds for this 7.2-fold after accounting for confounders.
"It is unclear whether it is DMA itself or the process of arsenic metabolism that affects sperm production," write Shen and colleagues.
Recent animal model experiments have suggested that arsenic impairs male reproductive functions by inducing oxidative stress. Still, the mechanism in humans is not yet known.
"Because of the spread of arsenic in the environment, further research is urgently needed to fully understand its health effects on the semen quality," say the investigators.
There was no association between the other arsenic metabolites and sperm concentrations, and no association with any of the species and sperm motility and semen volume.
The researchers note that smoking may increase the concentration of arsenic metabolites. Smoking was associated with reduced MMA levels, but this association disappeared after accounting for Asi, and Asi itself was not associated with smoking.
This "may suggest that the urinary As concentration was a consequence of arsenical pesticide used on tobacco," says the team.
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