Foul air hits below the belt - Two-decade study reveals link between male infertility and vehicle pollution

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  • Published 6.04.09

Calcutta’s male population is losing the power to procreate with every breath of foul air, according to an Indo-American study of infertility patterns in the city over two decades.

Toxic fumes belched out by vehicles are not only responsible for sore throats and damaged lungs and hearts but also “a significant decline” in male fertility since the 80s, says the report on the basis of laboratory studies of sperm samples collected more than 20 years apart.

The report — the result of collaboration by researchers from Calcutta University, the Dhakuria-based Advanced Medicare & Research Institute (AMRI) and Cleveland Clinic, Ohio — twice refers to The Telegraph’s campaign against vehicular emission.

“It was a first-of-its-kind study in the subcontinent and has been accepted for publication in Fertility and Sterility, a research journal of the American Society for Reproductive Medicine,” said a scientist associated with the project.

The examination of 3,729 sperm samples — 1,752 in the 80s (1981-85) and 1,977 in the last decade (2000-07) — revealed a nearly 10 per cent drop in semen volume and a corresponding decline in motility (a measure of the percentage of sperm that can move towards an ovum for fertilisation) over 20-odd years.

“In the last two decades, fertility patterns in the city have undergone tremendous changes and we found a strong correlation between the trend and worsening pollution levels in the city,” said Ashok Bhattacharyya, a retired professor of biochemistry at Calcutta University and a co-author of the paper.

Dyutiman Mukhopadhyay, the first author of the paper, and the other scientists had taken care to avoid “regional variation” in the selection of samples. According to the report, the root cause of male infertility was regular inhalation of noxious gases belched out by polluting vehicles and the increasing presence of heavy metals such as lead and cadmium in the environment.

The experts attributed the decrease in semen volume mainly to chemicals that adversely affect male sex hormones. Several studies have established that these toxins — released in the air mainly by polluting vehicles — directly affect the functioning of “accessory sex glands” that help produce sperm.

“Benzopyrene, an extremely toxic and carcinogenic pollutant found in the city’s air, can break through all membranes and damage sperm,” Bhattacharyya said.

Alex C. Varghese, the scientific director of the in-vitro fertilisation division of AMRI and a co-author of the study, said the changes in infertility patterns were significant because “such a decline has taken place in a very short duration”.

The paper quotes a World Bank study as saying that in 2002 Calcutta was the third most polluted city in the world in terms of concentration of particulate matter. “Transport emissions in Calcutta rose from an estimated 1,825 tonnes per annum in 1970 to 25,550 tonnes in 1990.”

The paper quotes from reports in The Telegraph to illustrate how much autorickshaws and adulterated fuel (katatel) have contributed to air pollution.

Sudarshan Ghosh Dastidar, an expert on fertility research, said the “male factor” in infertility had shot up to 45 per cent from 30 per cent about four decades ago. He warned that the male population was more vulnerable to air pollution because of lifestyle and frequent exposure. “Sperms generally take 70 to 80 days to mature and males are extremely vulnerable to air pollution during this particular period,” Ghosh Dastidar added.