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Infertility Linked to Environmental Factors |
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By Mario Osava *
The sperm count is on the decline among the male inhabitants of Sao Paulo, Brazil's largest city. Experts associate the problem with air pollution, chemical substances in food, and the stress of urban life.
RIO DE JANEIRO - A new alarm is sounding in Brazil about the environmental causes behind increased infertility. This time it is coming from Sao Paulo, the country's biggest metropolis, where the Albert Einstein Hospital's semen bank is seeing a shortage of good donors.
The decline in the sperm count of male "paulistas," as the city's residents are known, is the cause for concern. In 1992, when it began operating, the semen bank was taking in samples with 100 to 150 million spermatozoids per milliliter. The average has plunged by one-third, to a concentration of 30 to 50 million per milliliter, the bank's coordinator, Vera Beatriz Brand, told Tierramérica.
That quantity is enough to ensure a man's reproductive capacity, considered fertile to a minimum of 20 million sperm per milliliter of semen.
But a sperm donor must have more than 50 million, because half of the sperm die in the freezing process that is used to preserve the samples, explained Brand, a doctor who has worked at the Einstein Hospital for the past 18 years, and at the semen bank since it opened its doors.
Her data come from simple observation of donors and, "lately, more candidates than true donors," and without the rigors of a true scientific experiment, she clarified. It's a very limited sample, because very few men donate semen, and the practice is relatively new in Brazil.
But the Assisted Fertilization Center, which also maintains a semen bank in Sao Paulo, confirmed the trend of declining sperm counts.
"Each day we are more convinced that environmental factors are contributing to the reduction of spermatozoids, and also affecting the fertility of women," the center's director, Edson Borges Junior, said in a Tierramérica interview.
Air pollution, chemical substances in food, stress and other effects of urban life are "intimately related to this loss of fertility," he said. They are the "gonadotoxic" factors that affect the quality and quantity of the gametes (male and female sex cells, Borges explained.
This trend is more visible in some animals with a shorter reproductive cycle, like many bird species, whose eggs have thinner shells, reducing their ability to survive, Borges cited as an example.
Other revealing cases include the increase in the number of hermaphrodite crocodiles (having both male and female sex traits) in Apopka Lake, in the southern U.S. state of Florida, blamed on contaminants that alter the hormonal system, and the falling reproductive rates of panthers in that same region, he added.
The declining fertility rate is a global problem, but especially in the industrialized countries, and is getting worse, said Maria do Carmo Borges de Souza, president of the Brazilian Assisted Reproduction Society.
At a recent European conference, it was reported that one-third of the male population of Denmark presents with infertility and must rely on artificial methods of reproduction.
Assisted reproduction clinics are in increasing demand in Latin America, a reflection of the widespread use of fertilization techniques that infertile couples were previously unaware of. But experts believe that the rise in demand is also due to more problems with fertility in general.
The Latin American Assisted Reproduction Network had 21 registered centers in its first publication in 1990. By 2002, the total had reached 101, concentrated in Brazil (42), Argentina (19) and Mexico (12).
The number of procedures initiated, using techniques like in vitro fertilization and intracytoplasmatic injection of sperm, grew from 4,496 in 1992 to 18,832 a decade later region-wide.
In Brazil, with a current population of more than 182 million, the 2000 census indicated more than 15 million people of reproductive age had difficulty procreating. The absence of this data in previous censuses makes it impossible to analyze the evolution of the problem.
There is a lack of research into the causes of greater infertility, and investigating it is a difficult challenge, because there are so many factors to consider in the environment, observed De Souza, who is a gynecologist.
The most likely is that the phenomenon is due to a set of factors related to industrialization. Sao Paulo, with its 11 million inhabitants, is "the most industrialized city in Brazil, and is paying the price," she said.
One could say that this reflects "a great imbalance" caused by "the modifications that humanity has imposed on nature, with negative consequences for itself," said De Souza.
A study that she is leading seeks to determine the links between environmental problems and the reproductive health problems of urban residents.
The focus of attention is on water, which is consumed by everyone and therefore has widespread effects. Her concern is based on the fact that the main source of water is the Paraíba do Sul watershed, whose waters are contaminated by numerous industries and where a local university found many fish with biological mutations.
The conclusion of the study, in which scientists from different fields are participating, is slated for 2008. A survey has already been conducted of 100 infertile couples, who will be compared with a group of couples that did not have difficulty producing children.
The comparisons will involve the different sources of water consumed and individuals exposed to critical conditions, such as working with toxins or chemical products, said the expert.
A direct relationship between atmospheric contamination and human reproduction was identified in a recent study by the medical school at the University of Sao Paulo, which found that the greater presence of particulate matter in the air reduces the number of births of male offspring.
To carry out the study, the school's air pollution laboratory divided the city of Sao Paulo into three areas. In the most contaminated zone, from 2001 to 2003, 50.7 percent of the children born were male, while in the relatively cleaner zone the proportion was 51.7 percent in the same period.
Although the difference may seem small, it is significant as an indicator of a trend and important in demographic terms, says biologist Ana Julia Coimbra, who confirmed a greater imbalance in laboratory tests.
In a study of a hundred mice, the half that were kept in a compartment with purified air had 24 percent more male births than the half that were kept in an environment with air as contaminated as it is in Sao Paulo.
* Mario Osava is an IPS correspondent.
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