=======================Electronic Edition========================
RACHEL’S ENVIRONMENT & HEALTH WEEKLY #415
—November 10, 1994—
News and resources for environmental justice.
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THE SCIENTIFIC BASIS OF CHEMICAL SAFETY–PART I:
LIMITS ON WORKPLACE CHEMICAL EXPOSURES
In 1990, the American Public Health Association (APHA) estimated
that each year 50,000 to 70,000 Americans die of diseases
developed from toxic exposures on the job. Furthermore, APHA
estimated that 350,000 new cases of occupational disease develop
each year from toxic exposures. [1]
The federal government established standards for chemicals in
workplace air for the first time in 1971, as required by the
Occupational Safety and Health Act [OSH Act] of 1970. Prior to
1971, the U.S. had no enforceable federal standards for workplace
air; instead, guidelines (which could be voluntarily adopted, or
not) were set by a private organization called the American
Conference of Governmental Industrial Hygienists (ACGIH). The
ACGIH is a private group composed of industrial hygienists from
state and local governments, plus academics and industry
consultants.
In 1946 the ACGIH established a Committee on Threshold Limits,
charged with developing “threshold limit values” (TLVs) for
chemical exposures in the workplace. A threshold is an amount
below which no damage is evident. The ACGIH says TLVs are
average concentrations in air for an 8-hour workday, 40 hours per
week, to which “nearly all workers may be repeatedly exposed, day
after day, without adverse effect.” [2]
In 1971 the U.S. government adopted all the ACGIH’s TLVs as
official government standards for workplace air. Since 1950, the
ACGIH’s TLVs have also been used to set government standards in
Belgium, West Germany, Austria, Italy, the Netherlands, Portugal,
Denmark, Sweden, Finland, Norway, Spain, Switzerland, England,
Japan, and probably elsewhere.
Furthermore, during the 15 years after 1971, at least 37 of 50
states in the U.S. used the TLVs as the basis for setting ambient
air pollution standards –not workplace standards, but standards
for the general outdoor air. (“Ambient” means “surrounding” or
“enveloping.”) Often states have taken the TLVs, reduced them by
some arbitrary “safety factor” like 100, and declared them “safe”
for ambient air. Reasons for reducing TLVs by a “safety factor”
are: (a) TLVs are established for only 40 hours of exposure each
week, not continuous exposure 168 hours per week; (b) workers are
assumed to be young, healthy, male, and employed (therefore,
probably eating well, with access to health care) whereas the
general population includes pregnant women, infants, the elderly,
people with chronic ailments, people with special sensitivity to
particular chemicals, and poor people who can’t afford to eat
well and rarely, if ever, see a doctor; (c) TLVs are set based on
exposure to a single chemical, but in the real world everyone is
exposed to numerous chemicals simultaneously. Since the “safety
factor” is an arbitrary number, any “safety” in TLV-based ambient
air standards must rely upon the safety of the underlying TLV
itself. There is evidence that the role of TLVs is now being
extended in the U.S., to setting standards for indoor air,
standards for groundwater contamination, and standards for
cleanup at Superfund [contaminated dump] sites.
For nearly 5 decades, no one critically examined the scientific
data underlying the TLVs. Even the TLV Committee itself seems
to have relied solely on the advice of individual Committee
members who took responsibility for setting a TLV for a
particular chemical. Those individual Committee members, it was
revealed in 1988, were often employed by the same corporations
that were the major producers of the chemicals having their TLVs
set. For example, a Dow Chemical Company representative took
responsibility for setting TLVs for at least 30 of Dow’s
halogenated hydrocarbons, pesticides, and other industrial
chemical products. Furthermore, in 1988 it was learned that at
least 104 TLVs had been set based, in whole or in part, on data
that appeared in unpublished corporate communications. Those
corporate communications were not available from the ACGIH, from
the corporations themselves, or from individual members of the
TLV committee. [3] Thus the basis of those TLVs was secret and
not available for scientific peer review. (The Reagan
administration’s Occupational Safety and Health Administration
[OSHA] responded to this information in 1989 by once again
formally adopting all 600 of the TLVs, wholesale, as federal
regulations. The OSH Act of 1970 had required the federal
government to conduct its own research and set its own workplace
air standards, but between 1971 and 1989 OSHA was able to set
only 12 such standards of its own. Since there are roughly
60,000 chemicals now in commercial use, at this rate, OSHA would
take 90,000 years to set standards for all chemicals.)
Despite the absence of open scientific process underlying many
TLVs, many other TLVs had been set based on published
literature, and in those cases, the TLVs were still assumed to
be valid. However, in 1990, independent researchers compared
many TLVs to the scientific reports upon which these TLVs are
supposedly based. [4] They found that, in numerous cases, the
TLVs had been set at levels higher than the levels shown to
cause effects in humans, ranging from eye and nose irritation to
permanent changes in bodily structure and outright disease.
(They also found TLVs based on data that was 50 years old; TLVs
based on examination of as few as 3 individuals; and TLVs set to
protect against hearing loss, based on studies of eyes, noses
and throats but not ears.)
The 1990 report on the scientific underpinnings of the TLVs is
worth reading. Using a uniform format, it contrasts the effects
that the TLV is supposed to prevent, against the actual
scientific study of those effects in humans which the TLV
Committee says it relied upon. Here we reprint excerpts from
that 1990 report readers can see for themselves the way
scientific information has been used in setting many TLVs. We
are quoting the 1990 report verbatim, including material both
inside and outside quotation marks, and including the original
use of … to indicate omissions; our only editing has been to
remove italics from some words. (In what follows, the notation
m**3 means “cubic meter of air.”)
Acetaldehyde: EFFECT. “The TLV, 100 ppm, is recommended to
prevent excessive eye irritation and potential injury to the
respiratory tract.” [ACGIH, 1976]
VALIDATION? “Several of 12 volunteers objected… strenuously
even at 25 ppm… A majority… experienced… eye irritation at
50 ppm.” [Silverman and others, 1946]
Benzene: EFFECT. “A TLV of 25 ppm is believed low enough to
prevent serious blood changes.” [ACGIH, 1976]
VALIDATION? In “a study… of the benzene exposure of workers in
the rubber coating industry… the measured benzene vapor
concentrations averaged 18 ppm and 6 of 47 employees showed a
lowered hemoglobin of below 13.5 grams.” [Pagnotto and others,
1961]
Butyl Alcohol: EFFECT. “In view of the apparent potential of
n-butyl alcohol to increase hearing loss in the younger age group
of workers and to impair vestibular [ear] function at levels
somewhat below 110 ppm, a TLV of 50 ppm as a ceiling value is
recommended.” [ACGIH, 1976]
VALIDATION? “Butyl alcohol, at 25 ppm irritated the eyes, nose,
and throat of the majority of 10 volunteers… At 50 ppm there
was a unanimous feeling of pronounced throat irritation, in 10
volunteers.” [Nelson and others, 1943]
Chlorine dioxide: EFFECT. “The recommended limit of 0.1 ppm is…
to prevent irritation and possible bronchitis.” [ACGIH, 1976]
VALIDATION? “At a factory for the production of
sulfite-cellulose… extensive investigations… showed the
occurrence of slight bronchitis in 7 of 12 workers exposed to
chlorine dioxide… at concentrations lower than 0.1 ppm.”
[Gloemme and Lundgren, 1957]
Chlorodiphenyl–42% chlorine: EFFECT. “It is believed that this
limit, 1 mg/m**3, will offer reasonably good protection against
systemic intoxication but may not guarantee complete freedom from
chloracne [a disfiguring skin disease].” [ACGIH, 1976]
VALIDATION? “In a chemical plant concerned with organic chemical
production where the chlorinated diphenyls in the actual
breathing zone of the workers were 0.1 mg/m**3 of air… seven
cases of mild to moderate chloracne of the face and head occurred
among 14 chemical operators exposed…” [Meigs and others, 1954]
Ethyl Ether: EFFECT. “Regular exposure at this concentration (400
ppm, the TLV) should cause no demonstrable injury to health nor
produce irritation or signs of narcosis among workers.” [ACGIH,
1976]
VALIDATION? “Complaints of nasal irritation began at 200 ppm in
the majority of 10 volunteers.” [Nelson and others, 1943]
Fluoride as F [Fluorine]: EFFECT. “The limit, 2.5 mg/m**3, is
sufficiently low to prevent irritative effects and to protect
against disabling bone changes.” [ACGIH, 1976]
VALIDATION? At a factory where the concentration of fluorides
ranged from 0.14 to 3.13 mg/m**3, “radiological [x-ray]
examination revealed signs of osteosclerosis [abnormal hardening
of bone] in 48 of 189 workers.” [Largent, 1961]
Isopropyl acetate: EFFECT. “The limit, 250 ppm,… is considered
adequate to prevent significant irritation of the eyes and
respiratory passages.” [ACGIH, 1976]
VALIDATION? “We found that at 200 ppm, the majority of… twelve
subjects of both sexes… experienced some degree of eye
irritation.” [Silverman and others, 1946]
Magnesium oxide fume: EFFECT. “The limit, 10 mg/m**3, is
recommended on the basis that this value represents a maximal
desirable limit for dusts of relatively minor hazard.” [ACGIH,
1976]
VALIDATION? In 1 of 4 subjects exposed to an average
concentration of magnesium oxide at 5.8 mg/m**3 and in 2 of 4
subjects exposed to an average concentration of magnesium oxide
of 4.1 mg/m**3 “was found… a leukocytosis [an abnormally large
number of white blood cells] and a fever resembling those caused
by the heavy metals.” [Drinker and others, 1927]
Mercury: EFFECT. “Following a study of the chlorine industry it
was concluded in general that exposure at 0.1 mg/m**3 [100
micrograms/m**3] produced no significant incidence of mercury
poisoning but contained little or no margin of safety.” [ACGIH,
1976]
VALIDATION? “Symptoms or signs of chronic mercury poisoning were
found in 1 of 9 and in none of 3 men… engaged in repairing D.C.
meters… where the concentration of mercury in the atmosphere
averaged 19 and 40 micrograms/m**3, respectively.” [Bidstrup and
others, 1951]
Mica: EFFECT. “The limit of 20 mppcf [million particles per cubic
foot of air]… should prevent disabling pneumoconiosis, but may
not be sufficiently low to eliminate positive chest x-ray
findings in workers with many years’ exposure.” [ACGIH, 1976]
VALIDATION? “In mica factories… the exposure to dust is
limited to muscovite mica only… which contains less than 1%
free silica. When the dust concentrations to which most workers
were exposed ranged from 2 to 21 mppcf, with an average of 10
mppcf,… 27 of 61 workers examined had ground-glass 2 readings
of their chest x-rays.” [Heimann and others, 1953]
Selenium: EFFECT. “The limit of 0.2 mg/m**3 for elementary
selenium and its common inorganic compounds is believed low
enough to prevent systemic toxicity and to minimize irritation of
eyes and respiratory passages.” [ACGIH 1976]
VALIDATION? In the “manufacture of rectifiers… conjunctivitis
and slight tracheo-bronchitis were present in 9 of 62 workers…
The atmospheric concentrations at different stages of the process
varied from 0.007 to 0.05 mg/m**3, nowhere reaching the
recommended MAC [maximum allowable concentration] of 0.1
mg/m**3.” [Note: 0.007 to 0.5 is 4 to 28 times smaller than 0.2,
the TLV.] [Kinningkeit, 1962]
Turpentine: EFFECT. “A TLV of 100 ppm is… recommended to
prevent chiefly irritative effects.” [ACGIH, 1976]
VALIDATION? “Turpentine at 75 ppm caused nose and throat
irritation in several of 10 volunteers.” [Nelson and others, 1943]
[To be continued.]
                
                
                
                
    
–Peter Montague
===============
[1] Philip J. Landrigan, “Commentary: Environmental Disease–A
Preventable Epidemic,” AMERICAN JOURNAL OF PUBLIC HEALTH Vol. 82
(July 1992), pgs. 941-943.
Descriptor terms: apha; american public health association;
osha; occupational safety and health act; acgih; american
conference of governmental industrial hygienists; committee on
threshold limits; tlvs; Belgium; West Germany; Austria; Italy;
the Netherlands; Portugal; Denmark; Sweden; Finland; Norway;
Spain; Switzerland; England; Japan; great britain; united
kingdom; air quality standards; clean air act; caa; indoor air
pollution; superfund remediation; groundwater; standards; reagan;
acetaldehyde; benzene; butyl alcohol; chlorine dioxide;
chlorodiphenyl; ethyl ether; fluoride; fluorine; isopropyl
acetate; magnesium oxide fume; mercury; mica; selenium;
turpentine;