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Study: Pesticide May Reduce Fertility

Pesticide may reduce fertility, says study

Insecticides May Be Linked in Some Degree to Male Infertility
Date Published: January 12, 2006
Source: Newsinferno News Staff

(read the full study here)

Male infertility is a complex problem with numerous possible causes. Sometimes the cause is related to a single reason and other times it may be associated with a combination of factors. A new study now suggests that exposure to non-persistent, or short-lasting, insecticides may be one of those factors.

According to a statement made to Reuters Health by Dr. John D. Meeker, of the University of Michigan, Ann Arbor, and lead author of the study: "Environmental exposure to chlorpyrifos or its metabolite (TCPY) may be associated with reduced levels of circulating testosterone in adult men. A decline in testosterone throughout a population could potentially lead to adverse reproductive health outcomes."

Previously, a commonly used household insecticide, the Environmental Protection Agency (EPA) restricted the use of chlorpyrifos use in homes in 2000 after research revealed it can be harmful to the central nervous system.

Despite the EPA restrictions, however, there is evidence that individuals are still being exposed to the toxin. In fact, the Second National Report on Human Exposure to Environmental Chemicals found that over 90% of U.S. men had detectable levels TCPY in their urine.

A previous report by Dr. .Meeker and colleagues found that higher levels of 1-naphthol (1N) in men's urine are linked to decreased sperm count and increased DNA damage in sperm cells.

1N is a breakdown product of the compound naphthalene, found in cigarette smoke, diesel fuel and other combustion byproducts, and carbaryl, a lawn and garden insecticide known as Sevin.

Dr. Meeker and researchers from the Harvard School of Public Health and the Centers for Disease Control and Prevention (CDC) in Atlanta looked at the link between TCPY and 1N, and reproductive hormone levels in 268 men from an infertility clinic between 2000 and 2003.

According to the report published in the journal Epidemiology, men with higher urine levels of TCPY and 1N had lower levels of the sex hormone testosterone. Testosterone levels decreased along with increasing levels of TCPY, revealing that the association with TCPY was dose-dependent.

The report also noted that higher TCPY levels were also associated with a decreased free androgen index, an indication of lower testosterone concentrations.

Dr. Meeker noted that: "Although the decrements in testosterone related to TCPY were relatively small they may be of public health concern because of widespread human exposure among men.” He added that: "This is the first human evidence of an association between chlorpyrifos or its metabolite (TCPY) and testosterone levels, so other studies would be needed to substantiate our findings."