SIDS INITIAL ASSESSMENT PROFILE

+-----------------------------+----------------------------------------+
| **CAS NO**                  | 123-38-6                               |
+-----------------------------+----------------------------------------+
| **CHEMICAL NAME**           | Propanal                               |
+-----------------------------+----------------------------------------+
| **STRUCTURAL FORMULA**      | O                                      |
|                             |                                        |
|                             | CH3-CH2-CH                             |
+-----------------------------+----------------------------------------+

**[RECOMMENDATION OF THE SPONSOR COUNTRY]{.underline}**

> \[**X**\] currently of low priority for further work
>
> \[ \] currently of low priority for further work, but avoid exposure
>
> to man and the environment
>
> \[ \] requiring further information to assess identified concerns
>
> \[ \] candidate for in-depth risk assessment with a view to possible
>
> risk reduction activities

**[SHORT SUMMARY OF THE REASONS WHICH SUPPORT THE
RECOMMENDATION]{.underline}**

Although propionaldehyde is a high production volume chemical, it finds
use almost solely as a chemical intermediate. The aldehyde itself does
not have uses in consumer products. Production and conversion to other
chemicals necessarily take place in closed systems because of the
extremely volatile nature of this chemical. The material is transported
between site locations by bulk carrier. These practices minimize
exposure within the workplace. This assumption is supported by
industrial hygiene monitoring data which indicate a large portion of
samples are below the detection limit of 0.01 ppm and exposures very
rarely exceed 1 ppm.

U.S. TRI reporting requirements indicate that sizable fugitive emissions
exist. However, propionaldehyde has a relatively short existence in air
(T1/2 ≈ 6 hours). In addition, the chemical will tend to partition from
air into water (Henry\'s Constant 3.32 atms./mole fraction). Aldehydes
are reactive and readily oxidize, propionaldehyde yielding propionic
acid, a natural constituent in nature. Further, if the aldehyde were to
enter the systemic milieu of an organism, it would be rapidly oxidized
to propionic acid and serve as a nutrient.

Basic toxicology studies provide data to sufficiently identify the most
sensitive toxic effect of propionaldehyde, irritation upon direct
contact with tissues. It does not have specific adverse effects on the
reproductive capabilities of either male or female rats and does not
produce specific adverse effects on the developing offspring of
laboratory animals. This aldehyde has exhibited weak genotoxic activity
in some *in vitro* assay systems, this is consistent with what has been
observed with other short-chain alkyl aldehydes.

These considerations, taken in total, demonstrate a low order of
priority for further work.

**Table of Contents**

**1. Exposure Assessment 2**

**1.1 Production Volumes 2**

**1.2 Major Uses 2**

**1.3 Manufacturing Process 2**

**1.4 Distribution 2**

**1.5 Fugitive 2**

**1.6 Workplace Monitoring 2**

**2.0 Summary of Environmental Effects 3**

**2.1 Environmental Fate 3**

**2.2 Toxicity to Aquatic Organisms 3**

**2.3 Toxicity to Plants 3**

**3.0 Summary of Health Effects 3**

**3.1 Acute Toxicity and Primary Irritancy 3**

**3.2 Effects Resulting from Repeated Exposure 4**

**3.3 Effects on Reproductive Capabilities 4**

**3.4 Effects on Developmental Toxicity 4**

**3.5 Genotoxic Effects 4**

**4.0 Conclusions 4**

**1.0** **Exposure Assessment**

**1.1 Production Volumes:**

The estimated annual production of propionaldehyde in the United States
is in the order of 275 million pounds. Worldwide, it is estimated that
405 million pounds of this aldehyde are produced annually. Of this total
production volume, it is believed that greater than 99% is used as an
internal plant chemical intermediate.

**1.2 Major Uses:**

The major uses of propionaldehyde is as a reactive intermediate in the
manufacture of n-propanol, propionic acid, 2-methyl pentanol,
trimethyolethane polyols, polyethylene additives, fragrance chemicals
and fungicides. Propionaldehyde, being a reactive chemical intermediate,
is not directly used in products reaching the consumer. Because of its
reactive nature and volatility, residual concentration of
propionaldehyde in consumer products is very low.

**1.3 Manufacturing Process:**

Typically, propionaldehyde is manufactured by the catalytic
hydroformylation of ethylene with carbon monoxide and hydrogen (Oxo
Process). The reaction is carried out under high pressure in closed
systems. Crude propionaldehyde is stripped of dissolved gasses and heavy
residuals by gas stripping in pressured columns and stored for
downstream derivatives production. Propionaldehyde is stored in
pressured tanks or tanks equipped with internal floating roofs in order
to minimize losses by evaporation. Processes which use propionaldehyde
as a reactive intermediate are conducted in closed manufacturing
systems.

**1.4 Distribution:**

For internal plant uses, propionaldehyde typically is transported by
pipeline. Tank cars (rail cars) and tank trucks are used for shipment to
domestic customers. I

**1.5 Fugitive Emissions:**

In the United States, for the year 1990, there were 18 facilities which
reported environmental release information under provisions of the Super
Fund Amendment Reauthorization Act (SARA). These were facilities either
which manufactured or processed 25,000 pounds or more, or used more than
10,000 pounds of propionaldehyde. The Toxic Release Inventory (TRI)
indicates that these facilities collectively released 988,986 pounds of
propionaldehyde into the air and 34,885 pounds to other segments of the
environment. By 1992, total TRI reported emissions had decreased by ≈25%
from those reported in 1990.

**1.6 Workplace Monitoring:**

In the 17 year period between 1975 and 1992, a total of 73 personnel
samples had been taken within the \"Oxo\" production unit of Union
Carbide. Of these, 62 (»85%) were below the detection limit of 0.01 ppm.
The maximum TWA measured over this interval was 26 ppm and the geometric
mean for all 73 TWA determinations was »0.2 ppm. In the same time frame
16 TWA determinations were made within the In-Plant Distribution
Department. Of these 8 (50%) were below the detection limit of 0.01 ppm.
In one or two instances excursions in the range of 100 ppm were
determined, but the geometric mean for all 16 samples was still in the
range of 1 ppm. We believe that these low personnel exposures are
typical of the industry as a whole. Considering the low concentrations
of propionaldehyde measured within the production unit, air
concentrations at the fence-line and within the surrounding community
must be extremely low.

**2.0 Summary of Environmental Effects**

**2.1 Environmental Fate:**

Based upon the physical and chemical properties, propionaldehyde will
not be a persistent environmental contaminant. This chemical is highly
soluble in water and has an octanol/water partition coefficient of less
than 1. As with most aldehydes, it is a reactive molecule and readily
oxidizes to propionic acid. Propionic acid can be metabolized in
biological organisms by the enzymatic pathways of intermediary
metabolism: Thus, propionic acid serves as a nutrient. The aerobic
Biological Oxidation Demand (BOD) has been shown to be 70% of the
theoretical Chemical Oxidation Demand (COD) in 5 days and 95% in 20 days
using unacclimated domestic sewage microorganisms. Given these
considerations, propionaldehyde does not pose the threat of persistent
environmental contamination.

**2.2 Toxicity to Aquatic Organisms:**

Propionaldehyde is of a moderate degree of toxicity to fish, is of a low
order of toxicity to *Daphnia* and is moderately toxic to algae. These
data suggest that it would pose a moderate environmental threat in the
event of accidental spills into ponds or streams. Finally, the aldehyde
has been shown to be at most only a slight threat to water treatment
plants based on toxicity to bacteria.

**2.3 Toxicity to Plants:**

A single study demonstrated that propionaldehyde can inhibit the
germination of seeds, but only at relatively high concentrations.

**3.0 Summary of Health Effects:**

**3.1 Acute Toxicity and Primary Irritancy:**

Propionaldehyde is of a moderate degree of lethal toxicity by single
dose oral ingestion, only of slight acute lethal toxicity by a single
exposure to vapor, is of slight lethal toxicity by skin contact but is
moderately to severely irritating to the skin and could produce corneal
damage if accidentally splashed into the eyes.

**3.2 Effects Resulting from Repeated Exposure:**

The major effect noted on repeated exposure to high concentrations of
propionaldehyde in a study conducted under the OECD/SIDS Combined
Protocol appeared to be associated with tissues which come in direct
contact with the vapor, particularly the tissues of the nasal septum. In
addition to the nasal lesions, evidence of hematological changes in male
rats, predominantly associated with erythrocytes, and a slight effect on
male relative kidney weight was noted at the 1500 ppm exposure
concentration without histopathological confirmation of tissue damage.
Decreased food consumption was noted in females exposed to vapor
concentrations of 750 and 1500 ppm. No \"No Observable Adverse Effects
Level\" (NOAEL) was established in this study, the NOAEL for systemic
toxicity, however, was 150 ppm.

**3.3 Effects on Reproductive Capabilities:**

The effect of propionaldehyde on reproductive performance of rats was
investigated in the OECD/SIDS Combined Protocol. In that study, no
effects were noted on any reproductive parameter in animals exposed to
vapor at concentrations up to 1500 ppm. Litter size and viability were
similar among exposure groups (150, 750 and 1500 ppm) and the control.
Thus the NOAEL for reproductive toxicity was greater than 1500 ppm.

**3.4 Effects on Developmental Toxicity:**

Information on the effects of propionaldehyde on the developing embryo
and fetus was obtained in a study conducted by the OECD/SIDS Combined
Protocol. In that study there was no evidence of external malformations
in pups from dams exposed to vapor at concentrations up to 1500 ppm over
the entire gestation. The data from the combined SIDS Protocol study
suggest a NOAEL for developmental toxicity of greater than 1500 ppm.

**3.5 Genotoxic Effects:**

The genotoxic activity of propionaldehyde has been investigated in a
number of different model systems. In a bacterial gene mutation assay
using *Salmonella typhinurium* (Ames Test), propionaldehyde consistently
did not produce effects consistent with mutagenic activity. It did
produce evidence of a weak mutagenic effect in an *in vitro* mammalian
cell assay, the CHO V79 model No clastogenic activity was detected when
propionaldehyde was tested in an *in vivo* mouse bone marrow
micronucleus assay. These data are not inconsistent with those obtained
with other short chain alkyl aldehydes such as formaldehyde and
acetaldehyde.

**4.0 Conclusions**

Propionaldehyde is a high production volume chemical which finds almost
sole use as a chemical intermediate. It use is primarily in the
manufacture of n-propanol, propionic acid, 2-methyl pentanol,
trimethyolethane polyols, polyethylene additives, fragrance chemicals
and fungicides. It is produced and used exclusively in closed systems
and transported by bulk carrier. These conditions predicate low exposure
of personnel in the work place. This has been confirmed by industrial
hygiene monitoring data. Considering the very low concentrations of
propionaldehyde measured within production facilities, fence line
concentrations need be negligible.

Based upon physical and chemical properties, propionaldehyde is an
unlikely candidate as a persistent environmental contaminant. It is
calculated to have a short half-life in air and would be scavenged from
air into water. It is easily oxidized to propionic acid, a natural
constituent of nature. The aldehyde itself has been shown to be
moderately toxic to fish and algae and of a low order of toxicity to
daphnia. Episodic accidental spills into ponds and streams would pose a
moderate environmental threat. Considering its rapid oxidation to
propionic acid, this threat would be temporary in nature.

Data is available to sufficiently identify the most sensitive toxic
effect of propionaldehyde, irritation upon direct contact with tissue,
particularly irritation of mucosa of the upper respiratory tract upon
exposure to vapor. This observation is consistent with the known
irritant effects of other short chain alkyl aldehydes including
formaldehyde, acetaldehyde and butyraldehyde. Data generated in the
OECD/SIDS Combined Protocol clearly demonstrate that propionaldehyde
does not have specific adverse effects on the reproductive capabilities
of either male or female rats. Data generated by this protocol and data
from other studies which have been published in the open literature also
clearly demonstrate that propionaldehyde does not produce specific
adverse effects on the developing offspring of laboratory animals.

Considering all of the above, propionaldehyde would be of a low priority
for further investigations.