Water Education - Water Quality

ENDOCRINE DISRUPTORS Page 3

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Freshwater Fish Became "Feminized" and Developed Impaired Kidneys

A team of British scientists from the University of Exeter, University of Plymouth, and Brunel University found that when freshwater fish (belonging to species Rutilus rutilus) were exposed for 300 days to treated sewage effluent containing phthalates and other endocrine disruptors, the fish experienced the following reproductive, endocrine, immune, genotoxic, and nephrotoxic effects (Liney et al., 2006):

  • Feminization of male fish (with histologically altered gonads)
  • "Statistically significant" changes in kidney development (tubule diameter)
  • Modulated immune function (with differential cell count, total number of thrombocytes)
  • Genotoxic damage (as indicated by micronucleus induction and single-strand breaks in gill and blood cells)

Male Tadpoles Developed Ovaries When Exposed to Dibutyl Phthalates

Japanese scientists from Hiroshima University and Hiroshima Prefectural Women's University studied the effects of dibutyl phthalate (DBP) on male Japanese wrinkled frog (Rana rugosa). This particular phthalate, DBP, is one of the phthalate esters widely used as a plasticizer of polyvinyl chloride resins.

The scientists discovered that "DBP is an environmentally dangerous hormone that disrupts the pathways of testicular differentiation in genetically male animals" (Ohtani et al., 2000). In exposing male tadpoles to tiny amounts of DBP, after 0.1, 1, and 10 µM DBP treatment, 0%, 7%, and 17% of tadpoles, respectively, had developed partial or complete ovarian structure when they should be developing complete testes.

In other words, these male tadpoles developed female reproductive structures (ovaries) when they should be growing male structures (testes). Why does this result occur among male tadpoles? Scientists explained that chemical compounds that mimic estrogenic activity must be directly examined for their estrogenic or antiandrogenic action on living animal species. Therefore, these scientists concluded that DBP is a dangerous chemical and is an environmental endocrine disruptor.

Fewer Eggs and Fewer Surviving Fry in Fish Exposed to Phthalates

Abnormal Calcium Metabolism in Phthalate-Exposed Zebra Fish and Salmon

In as early as 1973, American government scientists working with the U.S. Department of Interior's Bureau of Sport Fisheries and Wildlife have found that fishes exposed to phthalates have fewer eggs and fewer surviving fry. Scientists exposed di-2-ethylhexyl phthalate to zebra fish (Brachydanio rerio) and guppies (Poecilia reticulatus) discovered that fish exposed to phthalates produced fewer eggs per spawn than controlled, non-exposed fish (Mayer Jr. and Sanders, 1973). The researchers also found that fry survival was "significantly reduced (P < 0.05) by phthalate exposure," with an 8 percent incidence of abortions observed among the guppy fry. Water fleas (Daphnia magna) exposed to di-2-ethylhexyl phthalate also suffered "significantly reduced" reproduction.

Additionally, these U.S. government scientists also found that coho salmon (Oncorhynchus kisutch) injected with 3 milligrams of di-2-ethylhexyl phthalate/kg of fish demonstrated increased serum calcium. They noted that "All of the dying [zebra fish] fry exposed to di-2-ethylhexyl phthalate died in tetany; however, tetany did not occur in dying controls." Tetany is an abnormal condition characterized by tetanic spasms of voluntary muscles; tetany is the state of continuous contraction of a muscle, especially caused by a series of rapidly repeated stimuli. What does this finding mean? It means that the tetany observed in zebra fish and the increased serum calcium in coho salmon are indications that di-2-ethylhexyl phthalate "may alter normal calcium metabolism in fish" (Mayer Jr. and Sanders, 1973).

Deformed Genitals and Adverse Spermatogenesis of African Clawed Frog

Scientists from Colorado State University have found that African clawed frogs (Xenopus laevis) exposed to very low concentrations of di-n-butyl phthalate (DBP) suffered numerous problems, as follows (Lee and Veeramachaneni, 2005):

  • Between 4% and 6% of male frogs had only one testis (for those tadpoles that were exposed to very low concentrations DBP, at 0, 0.1, 0.5, 1.0, 5.0, or 10.0 ppm DBP, at the beginning of sexual differentiation).
  • Between 2% and 4% of male frogs had retained oviducts (oviducts are tubes that allow for the passage of eggs from an ovary).
  • For all DBP-treated male frogs, seminiferous tubule diameter and the average number of germ cell nests per tubule were lower. Also, the number of tubules with no germ cells was significantly higher (p < 0.05).
  • The percent of secondary spermatogonial cell nests significantly decreased (p < 0.05) in 1.0, 5.0, and 10.0 ppm groups.
  • Several lesions were observed in DBP-exposed frogs' testes (including denudation of germ cells, vacuolization of Sertoli cell cytoplasm, thickening of lamina propria of seminiferous tubules, and focal lymphocytic infiltration).
  • Entire sections of testes containing almost exclusively mature spermatozoa were found in 1.0, 5.0, and 10.0 ppm DBP-exposed testes, indicating impairment of spermiation.
  • Testicular hypoplasia (a condition of arrested development in which an organ or part remains below the normal size or in an immature state) and seminiferous tubular dysgenesis were observed in DBP-exposed frogs. Dysgenesis is defective development especially of the gonads.

The scientists concluded that "subchronic exposure to low concentrations of DBP impairs spermatogenesis" in African clawed frogs. Spermatogenesis is the process of male gamete formation including formation of a spermatocyte from a spermatogonium, meiotic division of the spermatocyte, and transformation of the four resulting spermatids into spermatozoa. These scientists also attributed DBP to the global decline of frogs and other amphibians, which have made headline news for more than a decade now.

Avoid Phthalates in Your Drinking Water and Food

For your health and your family's health, it is best to avoid all plastic containers—both for water and food—labeled #3 PVC and all containers containing phthalates. It is best to use glass or stainless-steel food and water bottles and containers when bottling your own filtered water at home. It is difficult to avoid phthalates in this world even if you want to, so do not voluntarily ingest more phthalates by using phthalate-containing water bottles and food containers!

Partial List of References: Scientific Literature

  • Ronald A. Hites. 1973. "Phthalates in the Charles and the Merrimack Rivers," in Environmental Health Perspectives, January 1973, pages 17-21.
  • Johan Högberg, Annika Hanberg, Marika Berglund, Staffan Skerfving, Mikael Remberger, Antonia M. Calafat, Agneta Falk Filipsson, Bo Jansson, Niklas Johansson, Malin Appelgren, and Helen Håkansson. 2008. "Phthalate diesters and their metabolites in human breast milk, blood or serum, and urine as biomarkers of exposure in vulnerable populations," in Environmental Health Perspectives, volume 116, number 3, March 2008, pages 334-339.
  • Shannon K. Lee and D. N. Rao Veeramachaneni. 2005. "Subchronic exposure to low concentrations of di-n-butyl phthalate disrupts spermatogenesis in Xenopus laevis frogs," in Toxicological Sciences, volume 84, number 2, pages 394-407. (doi:10.1093/toxsci/kfi087)
  • Katherine E. Liney, Josephine A. Hagger, Charles R. Tyler, Michael H. Depledge, Tamara S. Galloway, and Susan Jobling. 2006. "Health effects in fish of long-term exposure to effluents from wastewater treatment works," in Environmental Health Perspectives, volume 114, supplement 1, April 2006, pages 81-89.
  • Foster L. Mayer Jr., and Herman 0. Sanders. 1973. "Toxicology of phthalic acid esters in aquatic organisms," in Environmental Health Perspectives, January 1973, pages 153-157.
  • Hiromi Ohtani, Ikuo Miura, and Youko Ichikawa. 2000. "Effects of dibutyl phthalate as an environmental endocrine disruptor on gonadal sex differentiation of genetic males of the frog Rana rugosa," in Environmental Health Perspectives, volume 108, number 12, December 2000, pages 1189-1193.
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