Facts about hexavalent
chromium (chromium VI)
From the National Institute for Occupational Safety and Health
Hexavalent
chromium (Cr(VI)) compounds are a group of chemical substances that
contain the metallic element chromium in its positive-6 valence (hexavalent)
state. Occupational exposures to Cr(VI) occur during the production
of stainless steel, chromate chemicals, and chromate pigments. Cr(VI)
exposures also occur during other work activities such as stainless
steel welding, thermal cutting, chrome plating, painting, and coating
processes.
NIOSH considers all Cr(VI) compounds to be potential occupational
carcinogens. An increased risk of lung cancer has been demonstrated
in workers exposed to Cr(VI) compounds. Other adverse health effects
associated with Cr(VI) exposure include dermal irritation, skin ulceration,
allergic contact dermatitis, occupational asthma, nasal irritation
and ulceration, perforated nasal septa, rhinitis, nosebleed, respiratory
irritation, nasal cancer, sinus cancer, eye irritation and damage,
perforated eardrums, kidney damage, liver damage, pulmonary congestion
and edema, epigastric pain, and erosion and discoloration of the
teeth.
Cr(VI) compounds vary in solubility from those that are readily
soluble to those which are practically insoluble in water. In 1975
NIOSH documented the carcinogenic effects of water-insoluble Cr(VI)
compounds. The NIOSH 1988 testimony to OSHA on the air contaminants
standard recommended that all Cr(VI) compounds, regardless of their
degree of solubility in water, be considered occupational carcinogens.
NIOSH is currently reviewing and evaluating the available information
on Cr(VI) compounds including the toxicology, health effects, industrial
hygiene, and analytical chemistry literature in order to update its
1975 criteria document on Cr(VI).
Toxicity: Hexavalent chromium in contact with skin acts as both
sensitizer and irritant. After entering the organism, it gets reduced
to trivalent chromium, which then binds to proteins and creates haptens
which trigger immune system reaction. Once developed, chrome sensitivity
becomes fairly persistent; in such cases, even contact with chromate-dyed
textiles or wearing of chromate-tanned leather shoes can cause
or exacerbate contact dermatitis.
Hexavalent chromium compounds are carcinogens. Chronic inhalation
of such compounds increases risk of lung cancer. Zinc chromate is
the strongest carcinogen of the chromates used in industry. Soluble
compounds, like chromic acid, are much weaker carcinogens.
Hexavalent chromium is genotoxic. It appears that the mechanism
of genotoxicity relies on pentavalent or trivalent chromium, an intracellular
reduction product of hexavalent chromium after its penetration into
the cell. According to some researchers, the damage is caused by
hydroxyl radicals, produced during reoxidation of pentavalent chromium
by hydrogen peroxide molecules present in the cell.
In an organism, hexavalent chromium undergoes reduction, first to
metastable pentavalent chromium, then to trivalent chromium. Pentavalent
chromium is a known carcinogen. If the material gets lodged in tissues
(lungs are especially vulnerable here, followed by fine capillaries
in kidneys and intestines), its long-term action may lead to cancerous
growth. In some parts of Russia, pentavalent chromium was reported
as one of the factors of incidence of premature senility.
Environmental Science Issues (From
Environmental Health): While exposure to hexavalent chromium
(Cr(VI)) has been associated with increased lung cancer risk for
more than 50 years, the chemical is not currently regulated by
the U.S. Occupational Safety and Health Administration (OSHA) on
the basis of its carcinogenicity. The agency was petitioned in
1993 and sued in 1997 and 2002 to lower the workplace Cr(VI) exposure
limit, resulting in a court order to issue a final standard by
February 2006. Faced with the threat of stronger regulation, the
chromium industry initiated an effort to challenge the scientific
evidence supporting a more protective standard. This effort included
the use of "product defense" consultants
to conduct post hoc analyses of a publicly-funded study to challenge
results viewed unfavorably by the industry.
For class action inquires, go to WatchStrap-Alert.com
OSHA
findings on Chromium (VI)
NIH
articles on Chromium (VI)
NIH
articles on Chromium (VI) in Leather
NIH
report 2000 on Chromium VI
Other Links about Hexavalent Chromium and OSHA:
Study:
Hexavalent Chromium Industry Kept Health Risks Secret
OSHA
Cuts It Close for Revised Rule on Hexavalent Chromium
Federal
Court Compels OSHA to Issue Hexavalent Chromium Rule
Study:
Hexavalent Chromium Industry Kept Health Risks Secret
Meycauayan,
Philippines
Allergy-provoking
substances in leather goods
Another Person Joins Timex Lawsuit
EPA
Rejects Carcinogenic Wood Preservative for Home Use |