It was 18 years ago, in 1978, when a small group of biologists studying
the Elevenmile Creek in Escandia County, Florida, were
"startled" (their word) to find a population of tiny mosquitofish that
all appeared to be males, even though some were pregnant and were
bearing normal offspring. Somehow the female mosquitofish had been
changed to look like males; they had been "masculinized."
Mosquitofish are a small, minnow-like species, rarely exceeding 2
inches (46 mm) in length. In normal mosquitofish, the difference
between males and females is obvious. For one thing, males are about
half the size of females. For another, males have a long specialized
rear fin (called a gonopodium) that females lack, which the males use
to insert semen into females. A few days after a female becomes
fertilized, a dark spot appears on each side of her abdomen and the
spot grows as pregnancy proceeds. Thus under normal circumstances, it
is easy to tell male and female mosquitofish apart because they look
nothing like each other. But in the Elevenmile River in Florida in
1978, the mosquitofish all had a male's gonopodium --even the pregnant
females with the telltale spot. Furthermore, the female mosquitofish
with a gonopodium behaved like males. They tried to copulate with other
females. Further study revealed that a few members of the masculinized
population were fully hermaphroditic --having sex organs of both male
and female in a single individual. In 1981, a population of
mosquitofish on the Fenholloway River in Florida was discovered with
the same odd sexual characteristics.
Odd indeed. During the past 100 years, ichthyologists (scientists who
study fish) have collected and examined thousands of specimens of
mosquitofish and no report has appeared of masculinization,
hermaphroditism, or sex reversal (males turning into females or the
other way around). Yet here in two rivers in the Florida panhandle
were entire populations of mosquitofish with this extraordinary
The cause was easy to find. Both rivers received enormous, dark-
colored discharges from paper mills, discharges about equal to the
entire flow of the rivers (25 million gallons per day (MGD) in the
Elevenmile, and 50 MGD in the Fenholloway). Examining fish above and
below these discharge points revealed immediately that fish above were
all normal and fish below were all masculinized. An open and shut case
of cause and effect.
But what in the paper mill waste was causing the problems? Paper mill
waste contains between 250 and 300 chemicals, including dissolved
organics, methanol, turpenes, acetone, fatty acids, cellulose
decomposition products, lignins and tannins, sulphides, mercaptans,
resin-acids, soaps, chlorine, and caustic soda, among others.
Looking into the problem, researchers found studies dating from 1940
and 1941 in which mosquitofish had been masculinized by exposure to
testosterone, the most common male sex hormone. So they reasoned that
something in the paper mill waste was probably acting like a male sex
hormone. But what? It seems like a simple question, but it is not.
This problem has been a scientific political football for 15 years. Two
parallel tracks of research have been proceeding: dioxin and
chlorinated chemicals have been investigated, and naturally-occurring
hormone-mimicking chemicals from plants (phytoestrogens) have been
By 1970, there were many reports circulating which linked dioxin to
various human reproductive problems, chiefly birth defects. In 1980,
U.S. Environmental Protection Agency [EPA] discovered dioxins and
furans in paper mill waste. In 1983, dioxin was found in fish living
downstream from paper mills.
This was not a welcome finding. The volume of paper mill wastes is
huge: in the 1980s, each ton of pulp produced about 25,000 gallons of
contaminated wastewater from the chlorine-bleaching process. With 73
million tons of paper products produced in 1986, bleaching wastes
totaled approximately 1.83 trillion gallons of chlorinated gunk per
year --a total waste flow of 219 cubic meters per second [cms]. This
flow is larger than some major rivers --larger than the Merrimack in
Massachusetts (flow: 205 cms), larger than the James in Virginia (flow:
184 cms), larger than Brazos in Texas (flow: 207 cms), and larger than
the Rogue in Oregon (flow: 182 cms).
In addition to being immensely wasteful, the paper industry is
politically very powerful, with 674,000 people employed in the industry
(a 1986 figure), with U.S. mills producing products valued at $3.9
billion each year. This powerful force has spent untold millions
diverting attention away from its dioxin-laden discharges.
During the early Reagan years, top EPA officials did their part to
prevent recognition of the nation's dioxin problem; EPA chief Anne
Burford and her assistant, Rita Lavelle, were eventually fired for
dioxin-related shenanigans, and Burford's successor, John Hernandez,
resigned in disgrace after a Congress investigated his role in the
altering of a report on dioxin in the Great Lakes. Congress then
appropriated $4 million for a nationwide study of dioxin in the
environment. Preliminary data from that study, available in 1985,
clearly implicated pulp and paper mills in dioxin contamination of
waterways in Minnesota and Maine, and of fish living downstream from
It was paper industry officials who muscled EPA chief William Reilly in
early 1991, persuading him to initiate a multi-year "scientific
reassessment" of dioxin, which EPA promptly got underway in April,
1991, and which the agency has still not concluded. During the course
of that "reassessment," information has come to light showing beyond
any doubt that dioxin mimics hormones and disrupts the endocrine
(reproductive) system of fish, birds, mammals, and most likely humans
as well. (See REHW #290, #390, #391, #414, AND #457.)
Research on Natural Phytoestrogens
The other line of research proceeded in a less politically-charged
atmosphere. Scientists had first reported naturally-occurring hormone-
mimicking chemicals in plants (phytoestrogens) in 1948 when female
sheep became sterile after grazing on clover pastures for prolonged
periods in Australia.
In 1976, researchers in California had shown that certain desert plants
in dry years produce chemicals that inhibit reproduction in the
California quail. These researchers developed the hypothesis that
plants produce such chemicals as a defense against predators; if
predators eat too much of such substances, they become sterile, thus
reducing the predator population.
In 1979, it was shown that a common estrogen-mimicking chemical in
woody plants --beta-sitosterol --could affect the reproductive system
of rabbits. By the mid-1980s, researchers demonstrated similar
effects of beta-sitosterol on mice and rats.
In 1991, the Wingspread Conference occurred (see REHW #263 and #264),
and studies of paper mill effluent began to multiply, many of them by
Canadian researcher Glen Van Der Kraak, who attended Wingspread.
Van Der Kraak and his colleagues have shown that some wild fish living
downstream from pulp and paper mills reach sexual maturity much later
than normal. Other species such as the lake whitefish can be sterilized
by living below a pulp mill. Others have exceptionally small
reproductive organs and abnormally low levels of sex hormones in the
In 1995, Van Der Kraak pointed out that pulp mill waste contains 280 to
1200 parts per billion (ppb) of beta-sitosterol, from the bark of the
trees being turned into pulp. It is the same beta-sitosterol that has
been shown to affect the reproductive systems of rabbits, mice, rats,
and sheep. Furthermore, in 1995 Van Der Kraak injected goldfish with
beta-sitosterol and showed that the levels of sex hormones in their
blood were significantly altered.
Industry is already arguing that synthetic (human-created)
chemicals couldn't possibly be affecting sexual reproduction and
development in wildlife and humans, as many scientists now believe they
are. (For example, see REHW #446, #447, #448.) No doubt, Van Der
Kraak's 1995 goldfish study, emphasizing the role of naturally-
occurring compounds, will become ammunition for those who need a
rationale for continuing to poison wildlife and people with synthetic
However, even Van Der Kraak doesn't believe naturally-occurring
phytoestrogens explain all the problems seen in wildlife exposed to
paper mill wastes. "I don't think beta-sitosterol is going to explain
the entire picture," Van Der Kraak told Janet Raloff of SCIENCE NEWS.
 Fish downstream from pulp mills frequently exhibit detoxifying
liver enzymes, "and we're not seeing that with beta-sitosterol," he
says. "So there must be other chemicals the fish are exposed to--such
as some chlorinated organics--[activating] those enzymes," he says. In
other words, the trail once again leads back to dioxin and other
 William P. Davis and Stephen A. Bortone, "Effects of Kraft Mill
Effluent on the Sexuality of Fishes: An Environmental Early Warning?"
in Theo Colborn and Coralie Clement, editors, CHEMICALLY-INDUCED
ALTERATIONS IN SEXUAL AND FUNCTIONAL DEVELOPMENT: THE WILDLIFE/HUMAN
CONNECTION [Advances in Modern Environmental Toxicology Vol. XXI]
(Princeton, N.J.: Princeton Scientific Publishing Co., 1992), pgs. 113-
 W. Mike Howell and others, "Abnormal Expression of Secondary Sex
Characters in a Population of Mosquitofish, GAMBUSIA AFFINIS HOLBROOKI:
Evidence for Environmentally-induced Masculinization," COPEIA Vol. 4
(1980), pgs. 676-681.
 W. Mike Howell and Thomas E. Denton, "Gonopodial morphogenesis in
female mosquitofish, GAMBUSIA AFFINIS AFFINIS, masculinized by exposure
to degradation products from plant sterols," ENVIRONMENTAL BIOLOGY OF
FISHES Vol. 24, No. 1 (1989), pgs. 43-51.
 Leena R. Suntio and others, "A Review of the Nature and Properties
of Chemicals Present in Pulp Mill Effluents," CHEMOSPHERE Vol. 17, No.
7 (1988), pgs. 1249-1290.
 See, for example, Nicholas Wade, "Viets and vets fear herbicide
health effects," SCIENCE Vol. 204 (May 25, 1970), pg. 817. Carol Van
Strum, A BITTER FOG (San Francisco: Sierra Club Books, 1983), in
footnotes 6, 9, 10, and 11 (found on pgs. 258 and 259) of chapter 2
lists other reports of dioxin problems known in 1970.
 Carol van Strum and Paul Merrell, NO MARGIN OF SAFETY: A
PRELIMINARY REPORT ON DIOXIN POLLUTION AND THE NEED FOR EMERGENCY
ACTION IN THE PULP AND PAPER INDUSTRY (Washington, D.C.: Greenpeace
USA, 1987). See footnotes 14 and 15 on pg. V-7.
 John Andelin and others, TECHNOLOGIES FOR REDUCING DIOXIN IN THE
MANUFACTURE OF BLEACHED WOOD PULP; BACKGROUND PAPER [OTA-BP-O-54]
(Washington, D.C.: U.S. Congress, Office of Technology Assessment, May
1989). See pg. 55.
 See John Andelin and others, cited above, pg. 5.
 River flows are from Frits van der Leeden and others, editors, THE
WATER ENCYCLOPEDIA [SECOND EDITION] (Chelsea, Michigan: Lewis
Publishers, 1990), pgs. 174-175.
 See John Andelin and others, cited above, pg. 5.
 See Carol van Strum and Paul Merrell, cited above, Chapter V.
 Rami S. Kaldas and Claude L. Hughes, Jr., "Reproductive and
General Metabolic Effects of Phytoestrogens in Mammals," REPRODUCTIVE
TOXICOLOGY Vol. 3 (1989), pgs. 81-89.
 A. Starker Leopold and others, "Phytoestrogens: Adverse Effects on
Reproduction in California Quail," SCIENCE Vol. 191 (January 9, 1976),
 S.A. Ghannudi and others, "Adverse Effects of Phytoestrogens III.
The Effect of Beta-sitosterol on the Ovarian Structures of Immature
Rabbits," THE LIBYAN JOURNAL OF SCIENCE Vol. 9a (1979), pgs. 1-12.
 K.R. Munkittrick and others, "Reproductive Dysfunction and MFO
Activity in Three Species of Fish Exposed to Bleached Kraft Mill
Effluent at Jackfish Bay, Lake Superior," WATER POLLUTION RESEARCH
JOURNAL OF CANADA Vol. 27, No. 3 (1992), pgs. 439-446.
 M.E. McMaster and others, "Changes in hepatic mixed-function
oxygenase (MFO) activity, plasma steroid levels and age at maturity of
a white sucker (CATOSTOMUS COMMERSONI) population exposed to bleached
kraft pulp mill effluent," AQUATIC TOXICOLOGY Vol. 21 (1991), pgs. 199-
 G.J. Van Der Kraak and others, "Exposure to Bleached Kraft Pulp
Mill Effluent Disrupts the Pituitary-Gonadal Axis of White Sucker at
Multiple Sites," TOXICOLOGY AND APPLIED PHARMACOLOGY Vol. 115 (1992),
 K.R. Munkittrick and others, "Changes in Maturity, Plasma Sex
Steroid Levels, Hepatic Mixed-Function Oxygenase Activity, and the
Presence of External Lesions in Lake Whitefish (COREGONUS CLUPEAFORMIS)
Exposed to Bleached Kraft Mill Effluent," CANADIAN JOURNAL OF FISHERIES
AND AQUATIC SCIENCES Vol. 49 (1992), pgs. 1560-1569.
 Deborah L. MacLatchy and Glen J. Van Der Kraak, "The Phytoestrogen
Beta-Sitosterol Alters the Reproductive Endocrine Status of Goldfish,"
TOXICOLOGY AND APPLIED PHARMACOLOGY Vol. 134 (1995), pgs. 305-312.
 Stephen H. Safe, "Environmental and Dietary Estrogens and Human
Health: Is There a Problem?" ENVIRONMENTAL HEALTH PERSPECTIVES Vol.
103, No. 4 (April, 1995), pgs. 346-351.
 Janet Raloff, "How paper mill wastes may imperil fish," SCIENCE
NEWS Vol. 148 (November 4, 1995), pg. 295.
Descriptor terms: paper; pulp and paper industry; chlorine; dioxin;
phytoestrogens; estrogen; reproductive disorders; birth defects; water
pollution; fl; fish; wildlife; endocrine disrupters; hormones; anne
burford; rita lavelle; john hernandez; ronald reagan; epa; dioxin
reassessment; beta-sitosterol; glen van der kraak;