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Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892

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BuyFindarrow_forward

Biology: The Dynamic Science (Mind...

4th Edition
Peter J. Russell + 2 others
ISBN: 9781305389892
Textbook Problem

Contamination of water by agricultural chemicals affects the reproductive function of some animals. Are there effects on humans? Epidemiologist Shanna Swan and her colleagues studied sperm collected from men in four cities in the United States (Table). The men were partners of women who had become pregnant and were visiting a prenatal clinic, so all were fertile. Of the four cities, Columbia, Missouri, is located in the county with the most farmlands. New York City represents an area with no agriculture.

Data from a Study of Sperm Collected from Men Who Were Partners of Pregnant Women Who Visited Prenatal Health Clinics in One of Four Cities

Location of Clinic
Columbia, Missouri Los Angeles, California Minneapolis, Minnesota New York, New York
Average age 30.7 29.8 32.2 36.1
Percent nonsmokers 79.5 70.5 85.8 81.6
Percent with history of STD* 11.4 12.9 13.6 15.8
Sperm count (million/ml) 58.7 80.8 98.6 102.9
Percent motile sperm 48.2 54.5 52.1 56.4

*STD stands for sexually transmitted disease.

Aging, smoking, and STDs adversely affect sperm. Could differences in any of these variables explain the regional differences in sperm count?

Source: S. Swan et al. 2003. Geographic differences in semen quality of fertile US males. Environmental Health Perspectives 111:414–420.

Summary Introduction

To review:

The effects of aging, smoking, and STDs (sexually transmitted disease) on sperm count due to the regional difference in these variables.

Introduction:

The quality of semen depends upon the number of sperms present, shape of the sperms, and the motility of the sperms. Sperm count is the number of spermatozoa or sperms present per ejaculation. The sperm count is affected by many factors that include aging, smoking, and STDs. Males with low sperm count may get diabetes, heart stroke, and other problems.

Explanation

The table given below shows the data, which has been collected from a certain study of sperm that has been collected from males who were partners of the pregnant women, who visited the parental health clinic in one of the four mentioned cities:

Location of clinic
Columbia, Missouri Los Angeles, California Minneapolis, Minnesota New York City, New York
Average age 30.7 29.8 32.2 36.1
Percent nonsmokers 79.5 70.5 85.8 81.6
Percent with history of STD 11.4 12.9 13.6 15.8
Sperm count (million/milliliter) 58.7 80.8 98.6 102.9
Percent motile sperm 48.2 54.5 52.1 56.4

Sperm count is affected by aging and smoking...

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