Poison
Valley
Part
1
http://archive.salon.com/tech/feature/2001/07/30/almaden1/index.html
Salon.com
Poison Valley
Is workers' health the price we pay for
high-tech progress? First of two parts.
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By Jim Fisher
July 30, 2001 |
At the south end of Silicon Valley in the foothills of
the Santa Cruz Mountains, beside a creek thick with buckeye and
sycamore, lie the ruins of California's first and richest mine. For over
a century the red ore known as cinnabar, first roasted for its metal in
1845, was burned in furnaces at New Almaden Mine and reduced through a
series of condensation chambers into approximately 100 million pounds of
liquid mercury, used to extract silver in Nevada's Comstock mines and
gold in the mother lode.
The mine is also the single greatest
source of mercury pollution in the San Francisco Bay Area. After the
mining companies sweated the quicksilver from the rock, they dumped an
estimated 800,000 cubic yards of burnt cinnabar into nearby Alamitos
Creek: To this day, drops of liquid mercury and cinnabar slag are
readily found in samples collected anywhere between New Almaden Mine and
the city of San Jose. If you follow that creek into Silicon Valley
you'll pass signs showing a fish on a poker, and the warning:
FISH IN THESE WATERS ARE CONTAMINATED WITH
DANGEROUS LEVELS OF POISONOUS MERCURY. DO NOT EAT FISH CAUGHT IN THESE
WATERS.
The creek flows down through the
serpentine foothills, through blue oak and California laurel, until it
passes under McKean Road at the valley floor. A couple of hundred yards
northeast on McKean takes you past a walnut orchard and across Calero
Creek, also flowing down from the New Almaden hills and contaminated
with mercury, until you hit the foot of the Santa Teresa Hills and the
checkpoint for IBM's Almaden Research Center. IBM ARC, the first
computer research lab west of the Mississippi, is the birthplace of a
host of technological innovations as valuable as mother lode gold, and,
according to a wave of recent lawsuits, as toxic as New Almaden Mine
mercury.
If you make a U-turn at the check gate to
IBM ARC and follow the run of Calero Creek as it flows along Camden
Avenue, the pepper trees and flowering plums thin and shift from the
creek bed to the center divide. After approximately five miles you reach
the stoplight at Blossom Hill Road. To your right is the parking lot for
the Santa Clara Valley Water District, and behind it are the Alamitos
Groundwater Recharge Ponds, where the joined creeks of the eastern New
Almaden hills (Alamitos and Calero) meet the Guadalupe River, flowing in
from the west side of Almaden Quicksilver County Park. The combined
water is then spread across the ponds, seeping through the earth's
porous layers until it reaches underground aquifers, where it is stored
until tapped by the county. Signs posted around the pools warn again of
poisoned fish.
You are now officially in Silicon Valley. A
few blocks ahead is the West Valley Freeway. Go east on the West Valley
Freeway and after five miles you'll have driven over one of the largest
plumes of poisoned groundwater in the United States, over 3 miles long
and 180 feet deep, contaminated with xylene, toluene and other volatile
organic compounds, including the chlorinated solvent trichloroethane (TCA).
Pump-and-treat groundwater cleanup operations continue to this day. The
original source of this poison? Underground Tank Farm No. 1 of IBM's
Cottle Road Disk Drive Manufacturing Facility.
Built just three years after the disk
drive was invented at IBM ARC in 1956, the Cottle Road plant was the
first among dozens of manufacturing facilities -- including those
operated by Intel, Hewlett-Packard, Applied Materials and National
Semiconductor -- discovered in the early 1980s to have collectively
leaked tens of thousands of gallons of organic solvents and other toxic
contaminants into the groundwater of Silicon Valley. Today, the valley
is home to more EPA
Superfund sites (29) than any other county in the nation, with the
most notorious of those sites -- from a leaking tank at a Fairchild
Semiconductor fabrication plant -- poisoning a well that served the
south San Jose neighborhood of Los Paseos. A subsequent study by the
state's Department of Health Services found 2.5 to three times the
expected rate of miscarriages and birth defects among pregnant women
exposed to the contaminated drinking water, leading to a lawsuit and
multimillion-dollar settlement in 1986 with over 250 claimants.
The toxic details of Silicon Valley's
mercury-laden streams and contaminated aquifers are relatively well
known. But another, even more troubling potential vector of deadly
pollution has required more time to come to light -- the "clean
rooms" in which high-tech workers come into direct contact with a
vast array of chemicals as they manufacture semiconductor-laden circuit
boards and computer hard drives. According to a lawsuit filed in 1998 in
Santa Clara County Superior Court on behalf of four cancer-stricken IBM
employees and the families of five deceased workers -- the number of
plaintiffs has since quintupled to 45 -- Big Blue and its chemical
suppliers, including Union Carbide, Shell Oil and Eastman Kodak,
fraudulently concealed from their employees the risks of adverse health
effects, including fetal toxicity and cancer, arising from chronic,
low-level exposures to chemicals used in the manufacture of disk drives
and related circuitry. Solvents named in the complaint include many of
the toxic compounds leaked into the groundwater two decades before.
In January, IBM and two chemical
suppliers (Union Carbide and Ashland Chemical) settled a separate case
in a similar wave of lawsuits involving about 200 current, former and
deceased IBM employees, most of whom worked at a huge chip-making plant
in East Fishkill, N.Y. But the amount of the settlement was not made
public and IBM admitted no guilt.
And yet, IBM's own corporate mortality
statistics, charges the Santa Clara lawsuit, record a death rate from
brain cancer among its employees about 2.5 times that of the general
public. Did the chemicals involved in high-tech manufacturing cause the
cancers? No one, not even experts who have long been critical of the
potential safety hazards associated with clean-room workplaces, can say
for certain. But numerous scientific studies have established that
certain chemicals used in manufacturing semiconductors are statistically
associated with increased rates of reproductive problems and various
types of cancers. And the heart of the Santa Clara suit is the assertion
that IBM repeatedly assured its workers that those workplaces were safe.
To the handful of experts occupied with
the dismayingly difficult challenge of assessing the health threats of
semiconductor manufacturing, IBM's alleged confidence could not possibly
have been merited. There simply hasn't been enough testing and research
into the health hazards posed by low-level exposure to combinations of
toxic chemicals. If anything, the experience of the semiconductor
industry should be sobering -- the complexity of the chemical cocktails
at use in modern high-tech industrial manufacturing is mind-boggling,
and it is always getting more so. There is little chance, warn these
experts, of ever catching up with the public health challenges inherent
in new advances in technology, especially when the rate of change
continues to accelerate. We may know that mercury is deadly, we're
pretty sure that drinking water contaminated with trichloroethane isn't
a good idea and we may finally be waking up to the dangers of making
clean-room workers breathe the same recirculated air, laden with complex
chemicals, all day long. But what do we know about the explosion of
research in biotech, and microelectronic machines, or the next wave of
advances in semiconductor manufacturing?
Is the price of technological
advancement, and its consequent economic growth, to be paid in workers'
health? The legacy evident in Silicon Valley, since at least the 1850s,
might hint at such a conclusion, although it also raises an obvious
question: What alternatives do we have, if we are intent on
technological progress? The lawsuits against IBM -- the consummate
symbol of high-tech prowess -- might also give pause to the Silicon
Valley's more ardent advocates of high-tech progress. But instead of
attempting to help public health officials and their own workers keep up
with the challenges of accelerating technological change, for years the
semiconductor industry has been more interested in investing its dollars
in pretending that problems don't exist.
Cottle Road, which today forms the western
boundary of IBM's disk drive manufacturing facility in San Jose, is
named after one of the valley's pioneer ranching families and forms part
of what was once a vast Spanish land grant rancho. Orchards planted by
the Cottles and dozens of other 19th century growers turned the valley
into a world-famous provider of prunes and apricots, inspiring its first
commercial nickname: the Valley of Heart's Delight.
In the 1950s the prune and apricot
orchards began to disappear to make space for the more than 2,500
electronics manufacturing firms that, by the early 1980s, had come to
dominate the valley and would eventually lend it a new name, after the
most common semiconductor substrate: silicon. The IBM campus, occupying
approximately 1 square mile below Coyote Creek to the north and above
the West Valley Freeway to the south, was built in 1959 on the
commercial promise of the disk drive and solid-state electronics. At its
peak it employed between 10,000 and 15,000 workers.
Virtually every computer currently
manufactured owes something to the research carried out by IBM ARC
scientists and the products then manufactured at the Cottle Road plant.
ARC researchers came up with things like thin-film inductive heads,
rotary actuators and sector servos -- technologies found in most every
modern hard drive, be it Quantum, Western Digital or any other brand
owing its skeleton to IBM patents. Without a hard drive, no computer,
not the IBM Thinkpad 600E on which this story is being typed, nor any of
the rack of high-powered Web servers on which this story is being
served, would be anything more than so much heavy metal and miscellaneous
plastics.
Today, the Cottle Road plant is still the
principal factory transforming the research and development of IBM ARC
into salable product. This is where patented chemical formulations used
in optical
lithography -- a process in which chip circuitry patterns are
transferred onto silicon wafers -- and disk-drive coating are mixed,
packaged and shipped. It is where proprietary microcircuitry and
subassemblies for new generations of disk drives are manufactured in the
famous clean rooms -- the factory floors of high-tech production whose
highly protected environments require that workers take air showers
before entering the "fab," and wear head-to-toe "bunny
suits" to protect the wafers from microscopic debris.
"The tiniest speck of dust on a chip
could ruin thousands of transistors," reads an exhibit at the Intel
Museum in Santa Clara. Nowhere in the museum is it mentioned what
health professionals and activists have attempted to point out since the
late 1970s: that this "clean" environment has very little to
do with safeguarding worker hygiene. The bunny suits may do an excellent
job of preventing particles on employee clothes from damaging silicon
wafers, but they are deplorably inadequate to protect workers against
skin contact with the acids, solvents and other chemicals they use as a
daily part of their job. Even worse, most clean-room ventilation systems
are designed to recirculate the majority of the air used in the
workplace, so as to prevent new infusions of airborne dust -- in effect,
workers are breathing the same chemically suffused air over and over
again throughout the workday.
"Had I known that I was working with
anything that could cause cancer, I would have had second thoughts about
going to work there," says Alida Hernandez, a former IBM employee
and plaintiff in the Santa Clara lawsuit, who began her 14-year career
at IBM washing residue from the surface of disk drives. She never knew
what chemicals were in the wash, but a likely suspect is trichloroethane
(TCA), a so-called safe substitute for the known carcinogen
trichloroethylene (TCE), which itself was once touted as a safe
substitute for the carcinogen perchloroethylene (PERC). In relatively
low doses TCA can damage the liver, nervous system and circulatory
system, and has been associated with brain cancer in gerbils exposed
through inhalation. It is one of the contaminants in the solvent plume
spreading beneath the Cottle Road plant, and shows up in Cottle Road's
Toxic Release Inventory data as late as 1991 -- the year Hernandez left
IBM.
Most of Hernandez's 14-year career,
however, was spent in the disk-coating
operations, where she was exposed on a daily basis to another mix of
solvents and resins that also included known or suspected carcinogens,
in addition to liver and nervous-system toxicants. "We were given
classes as to what to do in case of an explosion, what kind of a fire
extinguisher to use if it was electrical or if it was chemical -- those
were the instructions they gave us. They didn't say anything about the
chemicals being bad for your [biological] system, or possibly cancer
causing, or anything like that."
Before starting each shift, it was
Hernandez's responsibility to inspect the back of her
"operation" -- as the coating
workstations were called -- to ensure the machine was running
properly. If the mixers were running too fast, for example, air bubbles
could end up in the coating formulation and ruin a batch of disk drives,
not to mention an employee's performance record. Workers were also
responsible for cleaning the coating equipment with solvents several
times throughout the workday.
"In coating you could only run 50
disks at a time without having to stop your operation and clean [the
machine]," Hernandez says. Machines were cleaned chiefly with acetone,
a moderately toxic solvent that is rapidly absorbed by the skin and is
narcotic in high concentrations. Symptoms of acute exposure include
convulsions, kidney and liver damage, and coma. Lower exposure symptoms
include "slight intoxication, central nervous system depression,
lassitude, drowsiness, loss of appetite, insomnia, somnolence, loss of
strength, shallow respiration, weakness of the limbs, lightheadedness
and general malaise."
The National Toxicology Program safety
data sheet on acetone recommends that workers wear "a full face
chemical cartridge respirator equipped with the appropriate organic
vapor cartridges" when handling this chemical. Hernandez was never
provided with a respirator, or any other means of scrubbing organic
contaminants from the air.
Hernandez, who was frequently in charge
of running several machines at once, estimates that she passed from 350
to 375 disks through each machine per shift.
"Sometimes the [machine] lines would
plug up and it was up to the operator to unplug those lines. You'd get
coating all over yourself -- I mean, it went right through your
clothing. It went down to your skin. After you finished cleaning you
just went and changed the outside smocks -- the bunny suits -- but your
own clothing was all stained. It went right through the bunny
suits."
After the film had been applied, the
disks were placed in drying machines that spewed mists filled with
acetone and coating. That coating, states the complaint, contained the
organic solvent xylene.
An aromatic hydrocarbon -- like benzene -- xylene has long been
implicated in toxicological literature for its adverse effects on the
peripheral nervous system. Additionally, commercial formulations of
xylene -- at least in the early 1980s -- contained concentrations of up
to a few percent of its carcinogenic cousin benzene, according to a 1986
journal article, "Carcinogens and Cancer Risks in the
Microelectronics Industry." It too is one of the chemicals found in
the Cottle Road groundwater plume.
Epoxy resins were another ingredient in
disk coating, made from the compounds epichlorohydrin
and bisphenol-A.
The former chemical is mutagenic and genotoxic, and the latter is a
known endocrine disruptor. Mutagenic and genotoxic "events" --
in which genetic material is changed or damaged -- are part of the first
stage of cancer development, and may be indicative of cancer-causing
chemicals. Epichlorohydrin is, in fact, a carcinogen. Endocrine
disruptors are associated with reproductive and developmental harm.
Even today, clean-room workers continue
to breathe recirculated air throughout their shifts. Machines are still
cleaned, and metal surfaces degreased, with solvents, the most common
being acetone and isopropyl alcohol, though more than a few companies --
particularly the smaller, less recognizable firms -- still use the
carcinogen trichlorethylene or its cousin trichloroethane, according to
annual Toxic Release Inventory data. To this day, the single most
important chemical formulation in the manufacture of computer chips --
the photoresist -- is almost always a mixture of xylenes, carrier
solvents, formaldehyde-based resins and genotoxic photoactive compounds.
Other potential exposures in modern clean rooms include hydrofluoric
acid, antimony, boron, phosphorous, gallium and arsenic.
Hernandez was diagnosed with breast
cancer in 1993, two years after leaving IBM. Hernandez has no family
history of the disease. At the time of her departure, two of her
immediate colleagues had fallen ill, says Hernandez. One female engineer
was on a leave of absence as a result of breast cancer, and the employee
who had trained Hernandez on disk-coating operations came down with skin
cancer. Another colleague suffered a miscarriage.
Hernandez never connected the illnesses
with the job until she was diagnosed with the disease herself.
"It's something you tell yourself always happens to somebody else,
and never to you. When it happened to me, I started to think something
was wrong."
"My mother's death should not have
happened," says Carmen Navarro, daughter of former IBM worker
Alicia Apodaca, who rinsed and inspected silicon wafers in the clean
rooms of Cottle Road from 1980 through 1989, and died of breast cancer
at age 51. As with Hernandez, and the great majority of women newly
diagnosed with breast cancer, there was no history of the disease in
Apodaca's family. "She was vibrant, healthy. She didn't smoke, she
didn't drink, she took good care of her health. She was loved by her six
children, and by her grandchildren, whom she adored."
"She had friendships with fellow
employees at IBM -- a few of them have also passed away with
cancer," Navarro says. One acquaintance died of lung cancer,
another of brain cancer, says Navarro. "And it's continuing,"
she says. In mid-April, Navarro says she learned of another IBM worker
of more than 20 years who was diagnosed with breast cancer. (IBM
declined to comment on Navarro's and Hernandez's statements, citing
pending litigation.)
"I believe that [IBM] knew that the
chemicals were dangerous to the employees," says Navarro. I do
believe that. This should not have happened."
"Workers are a kind of controlled
experiment," says Dr. Sandra Steingraber, author of "Living
Downstream: An Ecologist Looks at Cancer and the Environment," an
authoritative study of the growing body of evidence linking cancer to
the environment. "We know they work in certain workplaces for a
certain number of hours with certain kinds of exposures. It's considered
unethical to go out and do human experiments on a group of folks who
aren't workers -- but this happens de facto in a lot of workplaces.
Workers are the canaries in the mines."
In the East Fishkill lawsuit, former IBM
workers Michael Ruffing and Faye Calton are the parents of Zachary
Ruffing, 15, who was born blind and with facial deformities so severe he
cannot breathe through his mouth or nose. They originally sued for $40
million in damages. Other Fishkill cases name cancers of the
gastrointestinal and lymphatic systems; of the skin, bone and brain;
and, most commonly, of the breast and testes. The cases filed by Cottle
Road employees reflect a similar suite of cancers, the majority of which
-- like the cancers listed above -- have all shown increased rates over
the past 20 years and show longer-term increases that can be traced back
at least 40 years, megatrends that correspond with the proliferation of
synthetic chemicals following World War II.
In fact, workers' compensation statistics
show that exposure to toxic chemicals -- coded as "systemic
poisoning" in California -- is twice as likely to be a cause of
occupational illness in electronics workers as it is for workers in
other manufacturing industries. National figures from the Bureau of
Labor Statistics show that the percentage of work-loss injuries and
illnesses involving "exposures to caustic, noxious and allergenic
substances" in recent years (1992-1998) was consistently between
three and four times higher for workers in the semiconductor industry
than in manufacturing industries as a whole, a group that includes
manufacturers of petrochemicals, paper, petroleum, coal, steel,
aluminum, plastics and rubber.
The BLS statistics do much to erode the
perception that the high-tech industry is somehow "cleaner"
than its predecessors. But what of the companies themselves? How much
did they know about what they might be subjecting their workers to, and
how hard were they trying to find out?
The simple fact is that it isn't in the
high-tech industry's interest to know too much about the long-term
health consequences of exposing its workers to toxic chemicals: The more
it knows, the greater its legal liability. Of the few industry-funded
studies of clean-room-related worker health problems, the two most
significant examined workers' reproductive problems. One study was
funded by the Semiconductor Industry Association, or SIA, the other by
IBM. Both studies were conducted after activists raised concerns about
the toxicity of a group of chemicals called ethylene glycol ethers, or
EGE, used in photoresist.
The IBM-funded study, whose preliminary
findings were released in 1992, found that pregnant employees at IBM's
Fishkill lab who were exposed to EGE were roughly 1.5 times more likely
to suffer a spontaneous abortion than unexposed workers. The authors
emphasized that no conclusive causative chemical could be identified,
but IBM acknowledged that it could be "inferred" that the
cause of the increased miscarriages was exposure to EGE. Eventually, IBM
and most of the industry stopped using EGE. (The SIA study came up with
the same conclusions.)
What's noteworthy is that the gloomy
results of this study didn't lead the industry to carry out more
research into the long-term health consequences of exposure to other chemicals.
See no evil is a wise corporate strategy.
But the Santa Clara lawsuit declares that IBM should have known that
something was very wrong in its clean rooms, based on trends visible in
its Corporate Mortality File, a database with work history on over
10,000 deceased IBM employees. Public access to the mortality file is
currently restricted by a gag order, but the facts cited in the Santa
Clara complaint are corroborated by statistics in a 1996 article in the
scientific journal Epidemiology, "Brain Tumors Among Electronics
Industry Workers." The file is a substantially complete (99
percent) database of all U.S. IBM workers of five or more years who died
between 1975 and 1989; the records were constructed from death
certificates obtained by IBM "for administrative purposes";
and the cause of death in 149 of the total 10,331 cases was primary
brain cancer. (The article never specifically identifies the subject
company, but a footnote identifies IBM as the funder of the research,
and the mortality statistics are identical to those included in the
complaint.)
That's quite a lot of brain cancer, about
2.5 times that of the general population, without factoring in biases
for gender and age. More significantly, what this study found was an
upward slope in brain cancer deaths among male electronics workers as
duration of employment lengthened.
Because of the gag order, the other
charges in the complaint -- that these records prove IBM knew that
workers involved in manufacturing electronic devices were at a
significant risk not only of brain cancer but of non-Hodgkin's lymphoma,
gastric cancers and leukemia -- cannot be independently confirmed. (IBM
will not comment on pending litigation.) But if one traces the citations
in the Epidemiology article back through the scientific literature a
pattern emerges that raises troubling, unanswered questions about
elevated risks of cancer among workers in the manufacture and repair of
electronics, and particularly among workers with long-term work
histories -- specifically, 10 or more years -- and with probable
exposure to solders and organic solvents.
In 1985, the same year the elevated brain
cancer mortality rates began showing up in the scientific literature,
Gary Adams, a chemist working in the material analysis department in
Cottle Road's Building 13, where IBM disk drive coatings were developed,
wrote a memo to IBM corporate headquarters. The memo alerted IBM
officials to a cluster of cancers in his building. Eight out of his 14
immediate colleagues had fallen ill with some form of cancer.
Brain cancer had killed Adams' colleagues
John Wong and Al Smith; lymphatic and hematopoietic cancers killed his
colleagues Gordon Mol and Dwayne Johnson; and gastric cancers killed his
colleagues Robert Cappell and Ken Hart, states the complaint. When Adams
and another colleague, Fred Tarman, developed bone tumors, they decided
it had to be more than a statistical fluke.
"All of a sudden we began to
worry," Adams told "Dateline NBC" in 1998. "And then
when another one [was diagnosed] and another one, it really began to hit
home." Adams said the response of a staff doctor to his request
that the company monitor its workers' health, particularly in Building
13, was to say such a program would be a waste of time, because
"workers did not get cancer from their jobs."
The official stance of the semiconductor
industry has long been similar. At the end of each year, when the Bureau
of Labor Statistics releases the results of its survey on occupational
health and safety, the Semiconductor Industry Association, which calls
itself "the leading voice for the semiconductor industry," and
whose member companies constitute more than 90 percent of U.S.-based
semiconductor production, issues a press release announcing that the
industry ranks among the safest manufacturing industries in the nation.
(The current SIA chairman, incidentally, is John Kelly III, a senior
vice president at IBM.)
Molly Maar, a spokeswoman for the SIA,
says too little is known about the chemicals involved to point fingers
at any particular industry. "What we're finding," she says,
referring to cancer risks among clean-room workers, "is that
there's not much scientific data out there ... Studies aren't
inexpensive, and when you have many companies coming together, these
things don't happen overnight."
IBM's short, official statement following
the Fishkill settlement admits of no doubt:
"No scientific data supports the
allegations of [the plaintiffs]. No evidence conclusively links the
cause of [the plaintiffs' son's] birth defects to the chemicals in
question or, for that matter, any specific chemical at all."
One of the toxicological literature's
most detailed surveys of health risks in clean rooms, it turns out, was
written by a former IBM industrial physician, Dr. Myron Harrison, in a
1992 article titled "Semiconductor Manufacturing Hazards." If
there is a smoking gun for IBM, showing just how much it knew or should
have known about potential health risks in clean rooms during the late
1980s, it is to be found is this exhaustive analysis of the potential
hazards and exposure pathways of chemicals at every stage of chip
making.
"If you look at the very early
studies of chemical carcinogenesis," says Dr. Steingraber, author
of "Living Downstream," "a lot of them were done by
researchers who were industrial toxicologists, who might have originally
worked for an oil company or something like that. They're right on the
front lines ... When they have the courage and integrity to publish
their findings, that's some of the best science that we have showing the
relationship between chemical carcinogens and cancer."
Harrison's catalog of health risks is
staggering. He lists potential exposures of workers to arsenic in the
manufacture of gallium-arsenide wafers; to acid aerosols in the
"wet etch" stage of chip lithography; and to toxic gases of
arsine and boron in the operation of dopant implantation tools. He
attests to cases of hydrofluoric acid burns during the cleaning of
furnace tubes; of exposure to corrosive solvents in wet-stripping
processes; and of untested photoactive compounds being sprayed by
photoresist spinners. He warns of "catastrophic accidents" in
the replacing of gas cylinders and the draining and refilling of wet
chemical baths; of malfunctioning ventilation systems; and of widespread
respiratory complaints among workers, including sinusitis, laryngitis
and asthma. He documents mercury exposure from arc lamps;
"relatively frequent" chemical fires at storage sinks; and
solvent overflows in tool exhaust systems.
Harrison begins his article with an
extensively diagrammed treatment of what remains the most worrisome --
and least acknowledged -- pathway of exposure in clean rooms: the
vaporized mix of organic chemicals recirculated by the ventilation
systems. A rule of thumb proposed by Harrison is that 90 percent of the
air in a clean room is recirculated per hour, to minimize the
introduction of contaminants that might degrade semiconductors or other
advanced technological fabrications. He also shows how fumes can enter
into circulation through "service cores," where vapors escape
during equipment maintenance and where chemical spills are most likely
to occur.
On top of that, recent evidence suggests
that 15 percent of new fume hoods -- the local exhaust system for
clean-room workstations -- fail to operate properly, potentially blowing
toxic vapors back at the worker and into the clean-room environment.
"The ventilation conditions in clean
rooms are very turbulent, and they cause a lot of problems," says
Tom Smith of Exposure Control Technologies, a business that tests and
evaluates laboratory ventilation systems. "Fume hoods [designed for
the microelectronics industry], when we've tested them in clean rooms,
generally only have a capture effectiveness about six inches above the
work surface. If you get above that, or if you have a very volatile
process, they just spill. And the clean-room airflow is so turbulent
that it competes with these hoods, and the vapors escape from these
hoods and infiltrate the return air system and are recirculated with the
air handler."
And there are, without question, plenty
of chemical vapors that can escape into the air system during the
manufacture of a single computer chip, beginning with the pulling of a
silicon crystal to the apotheosized "metallization" of the
wafer -- the industry's term of art for deposition of electrical
connections of aluminum on silicon. Figures based on a speech by a Texas
Instruments fellow at the International Symposium on Semiconductor
Manufacturing in September 1993 estimate that Intel's state-of-the-art
chip fabrication plant
in Rio Rancho, N.M., consumes, in a single year of manufacturing, 832
million cubic feet of bulk gases, 5.72 million cubic feet of hazardous
gases and 5.2 million pounds of chemicals.
These figures, though prodigal, are
deceptively simple, for they do not indicate the unprecedented spectrum
of chemicals used in semiconductor manufacturing. In his 1992 article,
Harrison prefaces a section titled "Selected Toxic Hazards"
with the disclaimer: "An attempt to review the toxicology of all
the thousands of chemicals in use at a typical fabrication plant is
doomed to be superficial and of little value."
And the acceleration of the use of new
techniques and new chemicals in new combinations in high-tech
manufacturing makes safety evaluation harder all the time.
"Professionals associated with this industry," wrote Harrison,
"have invariably commented on the rapid pace of change in tools and
materials, and on the fact that adequate toxicologic assessment of
chemicals almost never precedes their introduction into manufacturing
settings."
Harrison's frustration is echoed by
Joseph LaDou, director of occupational and environmental health at the
University of San Francisco. LaDou calls chip making "one of the
most chemical-intensive industries ever conceived."
"The air-filtering systems do not
alter chemicals except to dilute and recirculate them; and smocks and
head gear do not protect workers from toxic exposures," LaDou wrote
in 1984. He reiterates the point in an interview 17 years later.
"Not only are you recycling the vaporized chemicals, but you're
presumably allowing them to react with one another and introducing
reactants into the air and recycling those as well."
"Most of our [health] regulations
are predicated on workers being exposed to one chemical, maybe two or
three -- but what do you do when they're exposed to a hundred?"
LaDou asks. "What we have here is a brand-new work setting with an
almost scientifically impossible question to answer -- how do you
determine if a recirculated mix of chemicals is safe? -- and there is no
magic formula."
"The problem with the spectrum of
chemicals used in semiconductor manufacturing is that it could
conceivably cause any cancer anywhere in the body," says LaDou.
"When you find a cancer in a semiconductor worker, it's almost
impossible to find a smoking gun."
