STS 124 Return Samples: Assessment of Air Quality aboard the Shuttle
(STS-124) and International Space Station (1J)

The toxicological assessment of 2 grab sample canisters (GSCs) from the
Shuttle is reported in Table 1. Analytical methods have not changed from
earlier reports. The recoveries of the 3 surrogates (^13^C-acetone,
fluorobenzene, and chlorobenzene) from the GSCs were 99, 103, and 96%.
The presence of Freon 218 from the ISS atmosphere is obvious in the 6/14
sample.

Table 1: Analytical Summary of Shuttle Samples

+---------------+------+---------+-------+-------+------+-----------+
| Sample        | Date | NMVOCs  | T     | Alc   | F    | For       |
| Location      | of   | ^a^     | Val   | ohols | reon | maldehyde |
|               | Sa   |         | ue^b^ |       | 218  |           |
|               | mple | (m      |       | (mg/  |      | (µg/m^3^) |
|               |      | g/m^3^) | (u    | m^3^) | (    |           |
|               |      |         | nits) |       | mg/m |           |
|               |      |         |       |       | ^3^) |           |
+---------------+------+---------+-------+-------+------+-----------+
| Flight deck   | 5/3  | 0       | 0.45  | 0.09  | 0    | \--       |
| (preflight)   | 1/08 |         |       |       |      |           |
+---------------+------+---------+-------+-------+------+-----------+
| Mid-deck (end | 6/1  | 4       | 0.50  | 0.7   | 230  | \--       |
| of mission)   | 4/08 |         |       |       |      |           |
+---------------+------+---------+-------+-------+------+-----------+

^a ^Non-methane volatile organic hydrocarbons with Freon 218 removed

^b^ Calculated excluding CO~2~, formaldehyde, and siloxanes. The main
contribution to both samples was a trace of propenal.

The toxicological assessment of 13 GSCs and 8 pairs of formaldehyde
badges from the ISS is shown in Table 2. The recoveries of the 3
standards (as listed above) from the GSCs averaged 99, 103 and 92%,
respectively. Recoveries from 3 positive-control formaldehyde badges
ranged from 101 to 113%.

Table 2: Analytical Summary of ISS Results

+--------------+------+---------+--------+-------+-----+------------+
| M            | App  | NM      | T      | Alc   | Fr  | Fo         |
| odule/Sample | rox. | VOCs^a^ | Va     | ohols | eon | rmaldehyde |
|              | Date |         | lue^b^ |       | 218 |            |
|              |      | (m      |        | (mg/  | (mg | (µg/m^3^)  |
|              |      | g/m^3^) | (      | m^3^) | /m^ |            |
|              |      |         | units) |       | 3^) |            |
+--------------+------+---------+--------+-------+-----+------------+
| Lab (FMK)    | 2/2  | \--     | \--    | \--   | \-- | 37         |
|              | 5/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| SM (FMK)     | 2/2  | \--     | \--    | \--   | \-- | 34         |
|              | 5/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| Col          | 3/1  | 5       | 0.39   | 4.3   | 41  | \--        |
|              | 9/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| Lab          | 3/1  | 6       | 0.17   | 4.5   | 36  | 40         |
|              | 9/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| SM           | 3/1  | 6       | 0.38   | 4.8   | 36  | 35         |
|              | 9/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| ATV          | 4/0  | 7       | 0.68   | 4.5   | 6   | \--        |
| Vestibule    | 3/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| ATV (first   | 4/0  | 16      | 0.94   | 4.9   | 4   | \--        |
| entry)       | 3/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| SM           | 4/0  | 8       | **     | 4.9   | 34  | 35         |
|              | 7/08 |         | 1.41** |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| Lab          | 4/0  | 5       | 0.25   | 4.2   | 34  | 40         |
|              | 7/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| JLP          | 4/0  | 7       | **     | 4.4   | 38  | \--        |
|              | 7/08 |         | 1.49** |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| SM (F218     | 4/3  | 2       | 0.20   | 4.4   | 630 | \--        |
| leak)        | 0/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| Lab          | 5/2  | 12      | 0.32   | 4.9   | 620 | 30         |
|              | 2/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| JLP          | 5/2  | 4       | 0.43   | 5.9   | 660 | \--        |
|              | 2/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| SM           | 5/2  | 3       | 0.24   | 5.5   | 590 | 28         |
|              | 2/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| JPM (first   | 6/0  | 110^c^  | 0.77   | 9.4   | 70  | \--        |
| entry)       | 4/08 |         |        |       |     |            |
+--------------+------+---------+--------+-------+-----+------------+
| *Guideline*  |      | *\<25*  | *      | *\<5* | *no | *\<120*    |
|              |      |         | \<1.0* |       | ne* |            |
+--------------+------+---------+--------+-------+-----+------------+

^a ^Non-methane volatile organic hydrocarbons without F218 added into
the total.

^b^ Calculated excluding CO~2~, formaldehyde, and siloxanes.

^c^ Butane and iso-butane were the primary components of this high
value.

***T Values above 1.0:*** The SM and JLP samples on April 7 showed T
values well above 1.0. In both cases a small amount of propenal
(acrolein) in the samples contributed 0.8 T units. The source of this
mucosal irritant is unknown. When combined with the T values from other
irritants (primarily other aldehydes, including formaldehyde), the
T~irritants~ were 1.3 and 1.4 for the SM and JLP, respectively. These
are well above the level we would like to find and suggest that the crew
had some risk of very slight upper airway irritation or eye irritation.
The crew did not report airway or eye irritation.

***Freon 218 values:*** This volatile compound was accidentally released
from the SM air conditioning system. Evidence of this release is obvious
in the data of Table 2. From 3/19 to 4/07 the concentration was
relatively unchanged (34-41 mg/m^3^ in all modules). Much lower values
were observed as the crew entered and sampled the ATV vestibule and then
the ATV itself. The leak occurred on 4/30, and we found that the
concentration of Freon 218 (620-660 mg/m^3^) had not decreased more than
20 days later (5/22). As expected, some of the Freon entered the JLP
before a pristine, first-entry sample could be obtained.

***The Butanes in JPM:*** The finding of butane (43 mg/m^3^) and
iso-butane (52 mg/m^3^) in the first-entry sample of the JPM was totally
unexpected. The primary compound identified with offgassing during the
ground test was trimethylsilanol (TMS). The on-orbit sample showed TMS
and other common offgas products (several light alcohols, ethyl acetate,
and C7-alkanes), but the 4-carbon alkanes were unexpected. These
highly-volatile compounds are sometimes used in mixtures with propane as
heat-exchange fluids, but no such source has been identified in the JPM.
They are of no toxicological significance at these concentrations.

John T. James, Ph.D.

Chief Toxicologist

[Enclosures]{.underline}

Table 1A: [Analytical concentrations of compounds found in the STS-124
GSCs](http://hefd.jsc.nasa.gov/files/STS-124.Conc.xls)

Table 1B: [Analytical concentrations of compounds found in 1J
GSCs](http://hefd.jsc.nasa.gov/files/1J.Rtn.Conc.xls)

Table 2A: [T-values of the compounds in table
1A](http://hefd.jsc.nasa.gov/files/STS-124.T-values.xls)

Table 2B: [T-values of the compounds in table
1B](http://hefd.jsc.nasa.gov/files/1J.Return.T-value.xls)