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Ø Physical Properties
Ø Chemical Structure
Ø Preparation Methods
Ø Reactions
Ø Usage
Ø Danger
Ø Manufacturers
Ø Source
Ø Introduction
Basic Information about Formaldehyde
Simplest aldehyde, chemical formula HCHO. Formaldehyde (37%) in water solution
(formalin) is used as a preservative, embalming agent, and disinfectant. Large
amounts of formaldehyde are used in the manufacture of various familiar plastics:
Bakelite (the first plastic) is the trademark name for formaldehyde and phenol
polymer; Formica is the trademark name for formaldehyde and urea polymer. The
reaction of formaldehyde with proteins (called amino formylation) leads to its
use in the tanning industry and for treating various vegetable proteins to render
them fibrous.
Ø Physical Properties
The Physical Properties of Formaldehyde
* The chemical formula for formaldehyde is CH2O and the molecular weight is
30.03 g/mol. (1)
* The vapor pressure for formaldehyde is 10 mm Hg at -88 EC, and its log octanol/water
partition coefficient (Log Kow) is -0.65. (1)
* Formaldehyde is a colorless gas with a pungent, suffocating odor at room temperature;
the odor threshold for formaldehyde is 0.83 ppm. (1,8)
* Formaldehyde is readily soluble in water at room temperature. (1)
* Commercial formaldehyde is produced and sold as an aqueous solution containing
37 to 50 percent formaldehyde by weight. (1)
Physical Data
· Vapor Pressure: 52mm @ 37° C
· Specific Gravity: 1.083
· Vapor Density: 1.03
· Appearance: colorless liquid
Hazardous Decomposition
· Carbon Monoxide
· Carbon Dioxide
Fire Hazard Data
· Flash point: 310° F (154°C)
· Autoignition Temp: 932° F (499° C)
· Extinguishers: Water spray, Carbon dioxide, dry chemical powder or
appropriate foam.
· Special Procedures: Wear self-contained breathing apparatus and protective
clothing to prevent contact with skin and eyes, wear rubber gloves.
· Unusual Fire hazards: Emits toxic fumes under fire conditions.
Disposal
Spill Procedures:
· Evacuate area.
· Wear self-contained breathing apparatus, rubber boots and heavy rubber
gloves.
· Cover with lime or soda ash and place in closed containers for disposal.
· Ventilate area and wash spill site after material pickup is complete.
· Combustible Liquid
Disposal:
· Dissolve or mix the material with a combustible solvent and burn in
a chemical incinerator equipped with an afterburner and scrubber.
· Observe all federal, state, and local environmental regulations.
Ø Chemical Structure
Formaldehyde - H2C=O
H3
\
C1 = O2
/
H4
Atomic Charges and Dipole Moment
C1 charge= 0.358
O2 charge=-0.398
H3 charge= 0.020
H4 charge= 0.020
with a dipole moment of 2.46866 Debye
Bond Lengths:
between C1 and O2: distance=1.220 ang___ between C1 and H3: distance=1.122
ang___ between C1 and H4: distance=1.122 ang___
Bond Angles:
for H3-C1-O2: angle=121.7 deg___ for H4-C1-O2: angle=121.8 deg___
Bond Orders (Mulliken):
between C1 and O2: order=1.870___ between C1 and H3: order=0.940___ between C1 and H4: order=0.940___
Best Lewis Structure
The Lewis structure that is closest to your structure is determined. The hybridization
of the atoms in this idealized Lewis structure is given in the table below.
Hybridization in the Best Lewis Structure
1. A bonding orbital for C1-O2 with 1.9999 electrons
__has 32.04% C1 character in a p-pi orbital ( 99.45% p 0.55% d)
__has 67.96% O2 character in a p-pi orbital ( 99.81% p 0.19% d)
2. A bonding orbital for C1-O2 with 1.9994 electrons
__has 34.65% C1 character in a sp1.84 hybrid
__has 65.35% O2 character in a sp1.49 hybrid
3. A bonding orbital for C1-H3 with 1.9932 electrons
__has 56.45% C1 character in a sp2.04 hybrid
__has 43.55% H3 character in a s orbital
4. A bonding orbital for C1-H4 with 1.9932 electrons
__has 56.45% C1 character in a sp2.04 hybrid
__has 43.55% H4 character in a s orbital
7. A lone pair orbital for O2 with 1.9870 electrons
__made from a sp0.65 hybrid
8. A lone pair orbital for O2 with 1.9069 electrons
__made from a p-pi orbital ( 99.92% p 0.08% d)
-With core pairs on: C1 O2 -
Donor Acceptor Interactions in the Best Lewis Structure
The localized orbitals in your best Lewis structure can interact strongly.
A filled bonding or lone pair orbital can act as a donor and an empty or filled
bonding, antibonding, or lone pair orbital can act as an acceptor. These interactions
can strengthen and weaken bonds. For example, a lone pair donor->antibonding
acceptor orbital interaction will weaken the bond associated with the antibonding
orbital. Conversly, an interaction with a bonding pair as the acceptor will
strengthen the bond. Strong electron delocalization in your best Lewis structure
will also show up as donor-acceptor interactions. Interactions greater than
20 kJ/mol for bonding and lone pair orbitals are listed below.
The interaction of the second lone pair donor orbital, 8, for O2 with the antibonding
acceptor orbital, 59, for C1-H3 is 114. kJ/mol.
The interaction of the second lone pair donor orbital, 8, for O2 with the antibonding
acceptor orbital, 60, for C1-H4 is 114. kJ/mol.
Molecular Orbital Energies
The orbital energies are given in eV, where 1 eV=96.49 kJ/mol. Orbitals with
very low energy are core 1s orbitals. More antibonding orbitals than you might
expect are sometimes listed, because d orbitals are always included for heavy
atoms and p orbitals are included for H atoms. Up spins are shown with a ^ and
down spins are shown as v.
12 ----- 3.090 11 ----- 2.598 10 ----- 1.808 9 ----- -2.949 8 -^-v- -6.276
7 -^-v- -10.19
6 -^-v- -10.98 5 -^-v- -12.14 4 -^-v- -15.60 3 -^-v- -26.43 2 -^-v- -269.1
1 -^-v- -507.0
Total Electronic Energy
The total electronic energy is a very large number, so by convention the units
are given in atomic units, that is Hartrees (H). One Hartree is 2625.5 kJ/mol.
The energy reference is for totally dissociated atoms. In other words, the reference
state is a gas consisting of nuclei and electrons all at infinite distance from
each other. The electronic energy includes all electric interactions and the
kinetic energy of the electrons. This energy does not include translation, rotation,
or vibration of the molecule.
Total electronic energy = -114.5456831412 Hartrees
Ø Preparation Methods
The Photoproduction of Organic Residues in Laboratory Interstellar Ice Analogs
UV (Ultraviolet) radiation probably causes significant photochemistry within
the mixed-molecular ices found in space. We simulate this process in our laboratory
using some high-tech gadgetry. When we simulate the photochemistry of interstellar
and cometary ices in the lab we make a host of organic compounds (i.e. compounds
composed primarily of carbon, the kinds of molecules from which we and all living
things are made). We believe this process may be responsible for the richness
of the organics seen in the Diffuse and Dense Interstellar Medium, comets, and
meteorites.
Many people believe that organic compounds from comets and asteriods helped
to make life on Earth possible, so some of these compounds have potential implications
for the origin of life on the Earth.
Organic Compounds
Since comets and interstellar ices are composed primarily of water we started
with ices of water and other simple compounds known to be in space like methanol
(CH3OH), carbon monoxide (CO) and ammonia (NH3). From such simple starting materials
we were able to make things like methane (CH4), carbon dioxide (CO2), ethanol
(CH3CH2OH), formamide, acetamide, ketones, and alcohols. After these sun-burnt
ices are warmed up and the volatiles sublime away we were able to detect some
larger compounds like polyoxymethylene - based polymers (POMs), and hexamethylene
tetramine (HMT). A number of these compounds have potential implications for
the origin of life on the Earth. For example, hexamethylenetetramine (HMT; C6H12N4)
is a potential source of formaldehyde and ammonia and the acid hydrolysis of
HMT leads to the production of amino acids. Follow these links to see how we
identified HMT and how we think it formed.
More Complex Organic Compounds
Even though HMT and POM have molecular weights over 100 amu these are just the
smaller compounds. There are much larger organic materials produced when we
perform our interstellar/cometary ice simulations. Gas Chromatograph Mass Spectrometry
(GCMS) and Laser Desorption Mass Spectrometry analyses (Richard Zare's Lab)
of our residues show the presence a hundreds of different compounds, most of
which have yet to be identified. Many of these compounds have properties that
are potentially of interest to issues associated with the origin of life. For
example, some of these compounds fluoresce, others spontaneously form membranes
in solution, and so on. To learn a little more about these compounds, click
here.
PAH-related photoproducts (alcohols, ketones, and Hn-PAHs, etc.)
Polycyclic aromatic hydrocarbons (PAHs) represent one of the most abundant forms
of carbon in the interstellar medium. Since most PAHs are relatively non-volatile
compounds, in dense interstellar clouds they are expected to feeze out into
the ice. Indeed, astronomers (such as Kris Sellgren of Ohio State and Jean Chiar
of NASA Ames) have directly observed PAHs frozen into the ices. Since we know
that PAHs will be photoprocessed like all the other molecules in the ices we
studies the photolysis of PAHs in H2O-rich ices and this resulted in a Science
paper (see below). These experiments showed that photoprocessing of PAHs in
water ice leads to the production of a number of new compounds including aromatic
ethers, alcohols, and ketones as well as PAHs that contain excess peripheral
H atoms (Hn-PAHs). These kinds of compounds are all seen in carbon-rich meteorites
and we believe that ice photochemistry is the source of these compounds. Furthermore,
Hn-PAHs explain the infrared emssion at 3.4 microns seen towards energetic environments
such as the Orion Bar (Bernstein, Sandford, & Allamandola, ApJ see below)
The production of quinones is of particular interest since this class of compounds
includes important biomolecules such as the K vitamins which play a key role
in electron transport in living systems.
A Direct Method for Sequencing of Genomic DNA using PCR from Frozen Tumor Tissue
Principle:
Often there is a need for DNA testing on small tissue samples that have been
embedded in OPT.
Procedure
A) Sample Preparation
1. After thawing at room temperature, the excess embedding material is removed
and the sample ground using an autoclaved and cleaned mortar and pestle with 1 ml PBS
(phosphate buffered saline).
2. The mixture is then added to 1 ml of a 2x lysis buffer (Applied Biosystems,
Foster City,
CA) that was preincubated for 10 minutes at 60 °C.
3. Proteinase K is added to a final concentration of 0.1 mg/ml and incubated
overnight at 60 °C with gentle mixing.
4. Genomic DNA was extracted with two washings of phenol-chloroform-isoamyl
alcohol (25:24:1) and ethanol/salt precipitation at room temperature for 60
minutes with each wash.
5. The supernatant is poured off and the pellet was washed with 70% ethanol.
6. The tubes are placed in a centrifugal concentrator and evaporated to dryness.
7. The DNA pellet is resuspended in 10 mM Tris, pH 8.0 and 1 mM EDTA (TE Buffer).
8. Two micrograms DNA are subjected to PCR amplification in 100 µl reaction
mixture containing 50 pmol primers, 200 µM dNTP, 50 MM KCl, 10 mM Tris-HCl pH
8.3, 1.5 mM MgCl2, 0.01% gelatin and 2.5 U Taq DNA polymerase.
9. Mineral oil is laid over the top to prevent evaporation, and the solution
is subjected to
30 cycles of denaturation (94 °C, 1 minute), primer annealing (at calculated
temperature
1.5 minutes) and primer extension (72 °C, 2 minutes) in a thermal cycler.
10. Primers are derived from the p53 gene.
11. Amplification is preceded by denaturation at 94 °C for 1.5 minutes and
followed by extension at 72 °C for 7 minutes.
12. Upon completion of amplification, the sample is extracted once with 100
µl chloroform.
13. A 10 µl sample is then electrophoresed using a 1% agarose gel.
Reference
Sun, Yi, Hegamyer, Glenn and Colburn, Nancy H. National Cancer Institute, Frederick
Cancer Research and Development, Frederick, Maryland. "A simple method
using PCR for Direct Sequencing of Genomic DNA from Frozen Tumor Tissue Embedded
in Optimal Cutting Temperature Compound."
The Use of Centrifugal Concentrators for HPLC Work with Isocyanates
Principle:
Centrifugal concentrator concentrates samples quickly with a minimal amount
of handling and emission to the air.
Procedure
A) Equipment
Three traps are used to protect the vacuum pump. The first is a refrigereated
cold trap (-90° C), the second is a liquid nitrogen (<-100 °C) and
the third is a chemical trap.
B) Isocyanates Preparation
1. Toluenediisocyanate (TDI) is analyzed using the methods by Hakes in "An
Improved HPLC
Method for the Determination of Isocyanates Using Nitro Reagent."
2. Samples are prepared by adding TDI standards at three concentration levels
to nitro reagent (N-4 ntirobenzyl N-n propylamine in toluene).
3. The samples are mixed and the toluene is removed using the concentrator.
4. After evaporation, 2 ml methylene chloride are added and samples are extracted
with
1 ml 0.5 M HCl before injection into the HPLC.
C) HPLC Conditions
1. Flow rate at 1.0 ml/minute.
2. Mobile phase 50% hexane, 47.5% methylene chloride, and 2.5% methanol.
3. Run time is 7 minutes.
4. Oven temperature at 40 °C.
5. U.V. detection at 245 nm.
6. Column Silica 5 µ , 25 cm x 4.6 mm (Dupont, Wilmington, Delaware).
Reference
Gaylord, Anna Maria. "Use of Automated Centrifugal Evaporator in Preparation
of HPLC Sample Extracts," American Environmental Laboratory, 46-49 (October,
1990).
Hakes, D. C. Johnson, G. D., and Marhevka, J. S. "An improved HPLC Method
for the Determination of Isocyanates Using `Nitro Reagent'," American Industrial
Hygiene Association Journal 47(3), 181-184 (1986).
The Use of Centrifugal Concentrators for HPLC Work with Formaldehyde
Principle:
Centrifugal concentrator concentrates samples quickly with a minimal amount
of handling and emission to the air.
Procedure
A) Equipment
Three traps are used to protect the vacuum pump. The first is a refrigerated
cold trap (-90 °C), the second is a liquid nitrogen trap (<-100 °C),
the third is a chemical trap.
B) Formaldehyde Preparation
1. The analysis is done using the EPA, "Method for the determination of
aldehydes and ketones in ambient air using HPLC, method TO5".
2. Samples are prepared by adding formaldehyde and formaldehyde-dinitrophenylhydrazine derivative standards at three concentration levels to 10 ml DHPH reagent and
10 ml isooctane.
3. The samples are mixed and the isooctane layer is removed and saved.
4. The DNPH layer is then extracted with methylene chloride-hexane.
5. The sample is mixed and spun and the methylene chloride-hexane levels removed
and mixed with the isooctane in step 3.
6. This sample is placed in the CentriVap and evaporated to dryness.
7. After evaporation, 5 ml methanol is added and the sample analyzed by HPLC.
C) HPLC Conditions
1. Flow rate at 1.0 ml/minute.
2. Mobile phase: 80% methanol, 20% water.
3. Run time: 10 minutes.
4. Oven temperature at 35 °C.
5. U.V. detection at 370 nm.
6. Column Zorbax*, C18 5 µ , 25 cm x 4.6 mm (*Registered trademark of
E. I. duPont de
Nemours, Wilmington, Delaware).
Reference
Gaylord, Anna Maria. "Use of Automated Centrifugal Evaporator in Preparation
of HPLC Sample Extracts," American Environmental Laboratory, 46-49 (October,
1990). EPA, "Method for the determination of aldehydes and ketones in the
ambient air using HPLC, method TO5."
Recovery of Tetrachlorodibenzodioxin and Furans Using the CentriVap Mobile
Console
Principle:
Using a CentriVap aids in the evaporation and recovery of samples.
Procedure/Sample Preparation
1. Place 10 ml toluene into five 50 ml centrifuge tubes.
2. Add 200 nG of the sample to be tested.
3. Mix and place tubes into rotor in the concentrator.
4. Start condenser and let run for 30 minutes.
5. Close lid and start rotor. Turn on heater.
6. Start vacuum pump. Controls are set at concentrator vacuum and auxiliary
vent.
7. After 15 minutes, turn concentrator control to backfill When vacuum is released
and rotor is stopped, open lid and check samples. If more drying is needed,
repeat steps 5-7.
8. Add 1 ml toluene to vial, cap and vortex. Let stand for 2 minutes and place
10 µl 200 nG/l internal standard.
9. Prepare standard by adding 200 nG of 2, 3, 7, 8-tetrachlorodibenzofuran-13C
and 200 nG of 1, 2, 3, 7: 1, 2, 3, 8-tetrachlorodibenzodioxin to 1 ml toluene. Place 10
µl of this standard into a micro-autosampler vial and add 10 µl
of the 200 nG/ml of internal standard.
10. Analyze by high resolution mass spectroscopy.
Reference
C. S. Parsons, Senior Chemist, Pacific Analytical, Inc., Carlsbad, California
Ø Reactions
Carbon-carbon coupling from formaldehyde reaction on Mo(110).
Formaldehyde (CH2O) reaction on Mo(110) is studied with temperature programmed
reaction and IR reflectance absorbance spectroscopy. We present preliminary
results which demonstrate the evolution of gas-phase ethylene from the formaldehyde
reaction, to the best of our knowledge the first example of carbon-carbon bond
formation on clean Mo(110). This reaction is proposed to proceed via an ethylene
dialkoxide intermediate, analogous to that formed during reaction of ethylene
glycol on Mo(110). Other reactions include hydrogenation of CH2O to form a methoxy
intermediate which subsequently undergoes C-O bond scission to evolve gas-phase
Me radicals at .apprx.600 K.
An important reaction of Formaldehyde is the one for the preparation of Alcohols
when it reacts with R*-MgCl to form an alcohol:
* (R represents an alkane)
H
|
R-MgCl + CH2O Þ H -; C -; OH
|
H
Around 1872, various workers were studying the reactions of phenol with, among
other materials, formaldehyde. The reactions appeared to be difficult to control
and the outcome of the reactions difficult to reproduce.
Between 1900 and 1905 these reactions were investigated again and found to produce
product(s) that ranged in consistency from very sticky, viscous liquids to hard,
resinous solids.
In due course, it was recognised that the former could be used as a substitute
for shellac in varnishes while the latter could replace gutta-percha or ebonite.
In 1907, Leo Bakeland established that the reaction between phenol and formaldehyde
was sensitive to the relative concentrations of the starting materials, pH and
temperature. In the same year he filed his first patent on phenol-formaldehyde
resins which he called Bakelite.
Two years later he filed a patent on the incorporation of mineral fillers in
a resin to form a moulding compound. Altogether, he filed 199 patents.
At the same time Bakeland was engaged on his work on phenol-formaldehyde reactions,
an eminent British chemist, James Swinburn , was working in the same field,
and , in due course, he reached the same conclusions. However he filed his patent
one day after Bakeland's.
The Bakelite company was established in 1926 with Bakeland and Swinburn in partnership.
Ø Usage
The Uses of Formaldehyde
* Formaldehyde is used predominantly as a chemical intermediate. It also has
minor uses in agriculture, as an analytical reagent, in concrete and plaster
additives, cosmetics, disinfectants, fumigants, photography, and wood preservation.
(1,2)
* Formaldehyde (as urea formaldehyde foam) was extensively used as an insulating
material until 1982 when it was banned by the U.S. Consumer Product Safety Commission.
(1,2)
Health Data from Inhalation Exposure
Concentration (mg/m3) Health numbersa Regulatory, advisory numbersb Reference
1000.0
_ ___100.0 * LC50 (mice) (400 mg/m3) * LC50 (rats) (203 mg/m3) 33
_ ___10.0
_ ___1.0 * OSHA PEL (4.5 mg/m3) * ACGIH TLV (1.5 mg/m3) 44
_ ___0.1
_ ___0.01
_ ___0.001
_ ___0.0001
_ ___0.00001 * USEPA Cancer Risk Level (1-in-a-million excess lifetime risk)
= 8 H 10-5 mg/m3 6
ACGIH TLVCAmerican Conference of Governmental and Industrial Hygienists' threshold
limit value expressed as a time-weighted average; the concentration of a substance
to which most workers can be exposed without adverse effects.
LC50 (Lethal Concentration50)CA calculated concentration of a chemical in air
to which exposure for a specific length of time is expected to cause death in
50% of a defined experimental animal population.
OSHA PELCOccupational Safety and Health Administration's permissible exposure
limit expressed as a time-weighted average; the concentration of a substance
to which most workers can be exposed without adverse effect averaged over a
normal 8-h workday or a 40-h workweek. a Health numbers are toxicological numbers from animal testing or risk assessment
values developed by EPA. b Regulatory numbers are values that have been incorporated in Government regulations,
while advisory numbers are nonregulatory values provided by the Government or
other groups as advice.
Ø Danger !
Exposure to Formaldehyde
In 1980, laboratory findings showed that exposure to formaldehyde could cause
nasal cancer in rats. Since then, the question of whether exposure to formaldehyde
increases a person's risk of cancer has been the subject of considerable controversy.
Early concerns focused on the use of formaldehyde in the manufacture of mobile
homes. Soon, however, questions were raised about workers routinely exposed
to the substance: anatomists, embalmers, phatologists, other medical workers,
and industrial workers who produce formaldehyde (and formaldehyde resins and
plastics), plywood, photographic film, and permanent press fabrics.
During the 1980s, many studies, including major ones by the National Cancer
Institute (NCI), were conducted to determine whether these workers had a greater
risk for developing cancer than people in the general population. Much of this
research was intended to help two regulatory agencies, the Environmental Protection
Agency (EPA) and the Occupational Safety and Health Administration (OSHA), develop
regulations, if necessary, to protect the public and workers from unnecessary
risks of cancer because of formaldehyde exposure. Investigations at NCI have
focused on industrial workers and professionals such as anatomists and embalmers.
Results from these two groups were not consistent. Anatomists and embalmers
were at greater risk for leukemia and brain cancer than the general population,
but industrial workers were not. Industrial workers employed in the chemical,
plastics, plywood, and photographic film industries developed nasopharyngeal
cancer more often than the general population. The risk increased sevenfold
for workers with heavy exposure to formaldehyde and formaldehyde-containing
particulates. Studies in the Netherlands and Denmark have shown elevated rates
of nasal cancer in many persons exposed to formaldehyde.
An NCI study that noted a 30-percent increase in lung cancer mortality among
industrial workers generated the most controversy because the rate of lung cancer
did not increase with the level of exposure. The excess was not evident at all
industrial plants and was confined to workers in resin and molding compound
production. This led NCI investigators to conclude that factors other than formaldehyde
might have been involved. Other scientists believe formaldehyde exposure may
be the cause of the lung cancer excess.
By 1987, EPA classified formaldehyde as a "probable human carcinogen”
under conditions of unusually high or prolonged exposure. The International
Agency for Research on Cancer also concluded that formaldehyde is a probable
human carcinogen. The OSHA and EPA concluded that new rules governing exposure
limits were necessary. In November 1987, OSHA proposed that the occupational
standard for formaldehyde exposure be reduced from 3 parts per million (ppm)
to 1 ppm, averaged over an 8-hour workday; this proposal became law the following
month. In May 1992, the law was amended, and the formaldehyde exposure limit
was reduced to 0.75 ppm. (Information is available from the Occupational Safety
and Health Administration, Public Affairs Office, Room N3647, 200 Constitution
Avenue, NW., Washington, DC 20210. You may also contact the Public Affairs Office
by calling 202-;693-;1999.)
Formaldehyde use also has been studied in nonindustrial settings. In February
1982, the Consumer Product Safety Commission (CPSC) ordered a ban on all sales
of urea formaldehyde foam insulation (UFFI) for homes and schools. The CPSC
ruled that because formaldehyde gas often is released from foam after installation,
UFFI presents an "unreasonable health risk." In April 1983, however,
a Federal appellate court struck down this ban. The court ruled that there was
not sufficient scientific evidence to justify the ban. The CPSC still believes
that the evidence shows that risks are associated with UFFI. However, CPSC officials
advise consumers to leave insulation alone if they have not experienced any
health problems.
Please Note: The main sources of information for this fact sheet are EPA's
Health and Environmental Effects Profile for Formaldehyde and the Integrated
Risk Information System (IRIS), which contains information on oral chronic toxicity
and the RfD, and the carcinogenic effects of formaldehyde including the unit
cancer risk for inhalation exposure. Other secondary sources include the Hazardous
Substances Data Bank (HSDB), a database of summaries of peer-reviewed literature,
and the Registry of Toxic Effects of Chemical Substances (RTECS), a database
of toxic effects that are not peer reviewed.
Environmental/Occupational Exposure
* The highest levels of airborne formaldehyde have been detected in indoor air,
where it is released from various consumer products. One survey reported formaldehyde
levels ranging from 0.10 to 3.68 ppm in homes. (1)
* Formaldehyde has also been detected in ambient air; the average concentrations
reported in U.S. urban areas were in the range of 11 to 20 ppb. The major sources
appear to be power plants, manufacturing facilities, incinerators, and automobile
exhaust emissions. (7)
* Smoking is another important source of formaldehyde. (1)
* Formaldehyde may also be present in food, either naturally or as a result
of contamination. (1)
Assessing Personal Exposure
* Blood levels of formaldehyde can be measured. However, these measurements
only appear to be useful when exposure to relatively large amounts of formaldehyde
has occurred. (2)
Health Hazard Information
Acute Effects:
* The major toxic effects caused by acute formaldehyde exposure via inhalation
are eye, nose, and throat irritation and effects on the nasal cavity. (1,2)
* Other effects seen from exposure to high levels of formaldehyde in humans
are coughing, wheezing, chest pains, and bronchitis. (1,2)
* Ingestion exposure to formaldehyde in humans has resulted in corrosion of
the gastrointestinal tract and inflammation and ulceration of the mouth, esophagus,
and stomach. (1,2)
* Acute (short-term) animal tests, such as the LC50 and LD50 tests in rats and
rabbits have shown formaldehyde to have high acute toxicity from inhalation,
oral, and dermal exposure. (3)
Chronic Effects (Noncancer):
* Chronic exposure to formaldehyde by inhalation in humans has been associated
with respiratory symptoms and eye, nose, and throat irritation. (1,2,4,5)
* Repeated contact with liquid solutions of formaldehyde has resulted in skin
irritation and allergic contact dermatitis. (5)
* Animal studies have reported effects on the nasal respiratory epithelium and
lesions in the respiratory system from chronic inhalation exposure to formaldehyde.
(1,2,4,5)
* The RfD for formaldehyde is 0.2 mg/kg/d based on a decrease in bodyweight
gain and effects on the stomach in rats. (6)
* EPA has high confidence in the study on which the RfD was based since it consisted
of an adequate number of animals of both sexes, as well as a thorough examination
of toxicological and histological parameters; medium confidence in the database
as several additional chronic bioassays and reproductive and developmental studies
support the critical effect and study; and, consequently, medium confidence
in the RfD. (6)
* EPA has not established an RfC for formaldehyde. (6)
Reproductive/Developmental Effects:
* An increased incidence of menstrual disorders and pregnancy problems were
observed in women workers using urea-formaldehyde resins. However, possible
confounding factors were not evaluated in this study. (1,2)
* A study of hospital equipment sterilizing workers did not report an association
between formaldehyde exposure and increased spontaneous abortions. (1,2)
* Developmental effects, such as birth defects, have not been observed in animal
studies with formaldehyde. (1,2)
Cancer Risk:
* Occupational studies have noted statistically significant associations between
exposure to formaldehyde and increased incidence of lung and nasopharyngeal
cancer. This evidence is considered to be "limited," rather than "sufficient,"
due to possible exposure to other agents that may have contributed to the excess
cancers. (1,6)
* Animal studies have reported an increased incidence of nasal squamous cell
carcinomas by inhalation exposure. (1,6)
* EPA considers formaldehyde to be a probable human carcinogen (cancer-causing
agent) and has ranked it in EPA's Group B1. (6)
* EPA uses mathematical models, based on animal studies, to estimate the probability
of a person developing cancer from breathing air containing a specified concentration
of a chemical. EPA calculated an inhalation unit risk estimate of 1.3 H 10-5
(m g/m3)-1. EPA estimates that, if an individual were to breathe air containing
formaldehyde at 0.08 Fg/m3* over his or her entire lifetime, that person would
theoretically have no more than a one-in-a-million increased chance of developing
cancer as a direct result of breathing air containing this chemical. Similarly,
EPA estimates that breathing air containing 0.8 Fg/m3 would result in not greater
than a one-in-a-hundred thousand increased chance of developing cancer, and
air containing 8.0 Fg/m3 would result in not greater than a one-in-ten-thousand
increased chance of developing cancer. (6)
EPA's Office of Air Quality Planning and Standards, for a hazard ranking under
Section 112(g) of the Clean Air Act Amendments, has ranked formaldehyde in the
nonthreshold category. The 1/ED10 value is 3 per (mg/kg)/d and this would place
it in the medium category under Superfund's ranking for carcinogenic hazard.
(7)