Apr/May 2001
Energy
Crisis or greed crisis?
Jackie alan Giuliano, Ph.D.
US
Science And Technology Policy
A New Century, A New Framework
Jill Chopyak
An
Ounce Of Precaution: The "Precautionary Principle" Versus "Risk
Management"
Donella
Meadows
The
Pain of the World Passes Through Us
Gaea Yudron, MRET
Plastic
Softeners in Food & Water Linked to Reproductive Disorders
Rachel’s Bi-weekly
Political money: Like A Big Water Balloon by John Darling
Congress:
The Real Pros At Quid Pro Quo
Arianna Huffington
Citizen
Protests Continue: Worldwide Opposition
Kayla M. Starr
Fiddling
While Rome Burns
Blair Bobier
These
Mountains & Rivers as Home:
The Work of the Siskiyou Field Institute
Let
the Children Move
Jon Bredal, MA
Breastfeeding:
A Simple Choice
Pamela Jorrick
Monthly Prayer by Peter Moore
The
Future of Energy Medicine
Richard Gordon
Shock:
How It Limits Our Lives, What We Can Do About It
Peggy Rubin
Cosmic Calendar by Salina Rain
Plastic
Softeners in Food &
Water Linked to Reproductive Disorders
from Rachel’s Bi-weekly
Several new studies indicate that common industrial chemicals called phthalates (pronounced tha-lates) in food and water may be interfering with development of the reproductive system in both boys and girls.
For 20 years, large numbers of baby girls in Puerto Rico between the ages of six months and 2 years have been experiencing premature breast development, a condition called precocious thelarche (pronounced thee-larky). Since 1970, there have been 4674 cases of precocious thelarche recorded in Puerto Rico, where the condition is now occurring in 8 out of every 1000 baby girls, or just under 1%. Compared to a group of baby girls studied in Minnesota, precocious thelarche in Puerto Rico is 18 times as prevalent.
For 20 years, scientists have tried to link the alarming epidemic in Puerto Rico to artificial hormones in meat, pharmaceutical manufacturing wastes, and infant formula containing high levels of phytoestrogens (plants that contain natural estrogen-like chemicals), but no satisfactory explanation has emerged. Now researchers have found evidence linking precocious thelarche to common phthalates.
Blood samples from two groups of girls in Puerto Rico—41 baby girls with precocious thelarche and 35 with normal development—were examined for pesticides and phthalates. Pesticides were not found in either group. Phthalates were present in the blood of 68% of the precocious thelarche group and 14% of the control group. Phthalates tend not to bioaccumulate, so phthalates measured in blood are likely to reflect current exposures, not past exposures.
Phthalates are common industrial chemicals used in building materials, food packaging and food wrap, toys and other children’s products, medical devices, garden hose, shoes, shoe soles, automobile undercoating, wires and cables, carpet backing, carpet tile, vinyl tile, pool liners, artificial leather, canvas tarps, notebook covers, tool handles, dishwasher baskets, flea collars, insect repellents, skin emollients, hair sprays, nail polish, and perfumes. (The Environmental Health Network in California has petitioned the U.S. Food and Drug Administration to require labeling of perfumes that contain toxic phthalates, such as Calvin Klein’s Eternity.)
One particular phthalate—di-(2-ethylhexyl) phthalate, or DEHP—accounted for 88% of the total phthalates measured in the precocious thelarche group and 80% of the total phthalates in the control group. The average levels of DEHP in the control group were 70 ppb and in the precious thelarche group 450 ppb—more than six times as great.
Some phthalates mimic estrogen (female sex hormone) and others interfere with androgen (male sex hormone). In laboratory animals, some phthalates can cause birth defects and can disrupt hormones, leading to altered sexual development. Regarding reproductive and developmental effects in laboratory animals, phthalates vary in potency, with DEHP being about 10 times as potent as the other phthalates.
The average daily consumption of DEHP by children in the U.S. is estimated to be 5.8 milligrams per day. The most important source of DEHP exposure is contaminated baby formula, food and water contaminated by contact with plastic containers and food wrap, and plastic toys and pacifiers made soft by the addition of DEHP. Because Puerto Rico is an island, above-average quantities of prepared foods are shipped there packaged in phthalate-containing plastics.
This small study does not prove that phthalates are causing premature sexual development among baby girls in Puerto Rico, but, combined with what is known about phthalates from laboratory animal studies, it provides a strong suggestion that phthalates may be contributing to the epidemic.
A very recent study reveals that phthalates are present in the blood of adult Americans "at levels we are concerned about," according to John Brock, a chemist with the federal Centers for Disease Control (CDC) in Atlanta. Brock and his colleagues studied phthalates in the blood of 289 adults and found levels "higher than we anticipated."
Many laboratory products (such as plastic tubing) contain phthalates. As a consequence, phthalates are often found in samples analyzed in laboratories because lab equipment contaminates the samples. For the past decade, scientists have been finding phthalates in human tissue samples, but they have assumed they were measuring lab contamination. Consequently, no one has raised an alarm about phthalates in adult humans, until now.
To measure phthalates
in human urine, Brock and his colleagues developed specialized techniques
for identifying metabolic byproducts of phthalates; in other words, they learned
how to measure the chemicals that are produced when phthalates are processed
by a human liver and kidney. By this means, Brock could be sure his team was
measuring human exposures to phthalates and not merely contamination introduced
into samples from laboratory equipment.
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