Environmental Signaling

Case 4: Gloom and Doom

Session Objectives

Students will be able to:
  • Describe evidence that endocrine disruption is or is not affecting human health
  • Discuss the industrial processes and by-products which produce potentially disruptive chemicals
This short case requires only that you lead students through the headlines and discussion questions, then have them sign up for groups. The pattern and topics mirror those in Strange Happenings.

Consider the following news headlines:

Sperm counts of men worldwide declining

Rivers and streams filled with estrogen and other drugs

Chemicals from plastics linked to cancer

DDT and Dioxin related to infertility and cancer

Cancers of female reproductive tract linked to pesticide use

Abnormalities in male infants due to fetal exposure

These news stories do not bode well for the future. Is this the whole story? Is there good evidence that environmental contamination is causing reproductive diseases and infertility? Is endocrine disruption causing significant problems for human health? What is evidence and what is hype?

Case Assignment

Each of you will receive a copy of two recent reviews on endocrine disruption and male and female health. Then you will form 5 groups to examine different aspects of this problem.

Put your group’s responses, with images and references necessary on the weblog by next Friday:

1) Is human fecundity declining due to endocrine disruption? What is the evidence for and against the idea that human fertility declining, and that environmental chemicals are causing it?

2) Are hormonally active chemicals prevalent in the environment at levels that might cause problems for human health?

3) What is the evidence that plastics and chemicals involved in plastic manufacturing cause endocrine disruption in humans?

4) What is the evidence that PCB’s and other organohalines cause endocrine disruption in humans?

5) What is the evidence that pesticides cause endocrine disruption in humans?

CAPTION: DDT was widely used as an insecticide, and is now used in parts of the world to prevent mosquito-borne malaria.
(click image to manipulate). CREDIT: PubChem, National Library of Medicine.

CAPTION: Bisphenol A was first synthesized as an artificial estrogen and is now being used to make olycarbonate plastics.
(click image to manipulate). CREDIT: PubChem, National Library of Medicine.

  • Bretveld, RW et al. 2006. Pesticide exposure: the hormonal function of the female reproductive system disrupted? Reproductive Biology and Endocrinology 4:30
  • Maffini, MV, et al. 2006. Endocrine disruptors and reproductive health: The case of bisphenol-a. Molecular and Cellular Endocrinology 254-255: 179-86.
  • Matthiessen, P, et al. 2006. Contamination of headwater streams in the United Kingdom by oestrogenic hormones from livestock farms. Science of the Total Environment 367:616-30.
  • McLachlan, JA et al. 2006. Endocrine disrupters and female reproductive health. Best Practice in Clinical Endocrinology and Metabolism 20(1): 63-75.
  • Nichols, HB, et al. 2006. From menarche to menopause: trends among US women born from 1912 to 1969. American Journal of Epidemiology 164(10): 1003-11.
  • Skakkebaek, NE, et al. 2006. Is human fecundity declining? International Journal of Andrology 29:2-11.
  • Storgaard, L, et al. 2006. Male reproductive disorders and prenatal indicators of estrogen exposure. Reproductive Toxicology 21:4-15.
  • Welshons, WV, et al. 2006. Large effects from small exposures. III Endocrine mechanisms mediating effects of bisphenol-a at levels of human exposure. Endocrinology 147(6):S56-S69.
  • Pederson, JA, et al. 2005. Human pharmaceuticals, hormones, and personal care product ingredients in runoff from agricultural fields with treated wastewater. Journal of Agricultural and Food Chemistry 53:1625-32.
  • Fisher, J. 2004. Environmental anti-androgens and male reproductive health: focus on phthalates and testicular dysgenesis syndrome. Reproduction 127:305-15.
  • Toft, G, et al. 2004. Epidemiological evidence on reproductive effects of persistent organochlorines in humans. Reproductive Toxicology 19:5-26.
  • Eskenazi, B, et al. 2002. Serum dioxin concentrations and endometriosis: a cohort study in Seveso, Italy. Environmental Health Perspectives 110(7):629-34.