Cleaning up: Fabrics retain remnants of dry cleaning fluid
- Published: Nov 1, 2011
- Author: Steve Down
- Channels: Base Peak
High school musings on dry cleaning
When US high school student Alexa Dantzler chose to study the persistence of dry cleaning chemicals on clothes for a project in her freshman science class, she decided she needed help. A speculative email to Professor Paul Roepe at Georgetown University, Washington, DC, led to collaboration and some surprising results.
The chemical under investigation was perchloroethylene (PCE), used by 80-85% of dry cleaners in the USA and Europe and brought in as a replacement for trichloroethane which was damaging the Earth's ozone layer. Unfortunately, PCE is not without its own problems.
Although it is more stable to photodegradation than trichloroethane, it is actually more toxic, so the potential health risks for dry cleaning personnel and customers were increased upon its introduction to the industry.
The short-term effects of PCE include dizziness, inebriation, confusion, sleepiness, irritation of the eyes, nose, mouth, throat and respiratory tract, shortness of breath and vomiting. In the long term it can damage the central nervous system, liver and kidneys. As if that were not enough, it has also been classified as probable human carcinogen by the International Agency Ror research on Cancer.
Dantzler had read that PCE has been found in groundwater and soil around dry cleaning establishments and in storage areas for cleaned clothes and wondered whether it would also be retained on the clothes after cleaning. Together with PhD students Katy Sherlach and Alexander Gorka, they devised a novel GC/MS method for measuring PCE in dry cleaned fabric.
Perchloroethylene in fabrics after cleaning
Enlisting the help of Dantzler's mother, small swatches of different types of material were sewn underneath the linings of men's jackets which were sent for dry cleaning. They were collected the same day and the swatches were removed and stored immediately in zip-top plastic bags in a freezer until analysis.
The dry cleaning residues were extracted into methanol over 24 hours before GC/MS analysis on an ion trap mass spectrometer in electron ionisation mode. The presence of PCE, eluting after approximately 5 minutes, was confirmed from the mass spectrum and the concentrations were determined from the integrated peak area against a calibration curve prepared from standard solutions.
Four types of material were tested to see if the type of fabric influenced the amount of PCE retained. No PCE was detected on silk whereas cotton, wool and polyester all contained post-cleaning PCE residues.
For five out of seven dry cleaning establishments, the PCE content ranged from 10-56 nmol/cm2. The remaining two dry cleaners left no traces of PCE, but they were subsequently shown to use other cleaning fluids, namely supercritical carbon dioxide and a petroleum-based hydrocarbon mixture.
Polyester retained the highest amount of PCE after one cleaning cycle but this changed after multiple cleaning cycles. Both cotton and polyester accumulated PCE, levelling off after two and three cycles, respectively, but wool was extremely retentive. It contained two and four times as much PCE as polyester and cotton, respectively, after six cycles.
Exposure to dry cleaning fluid in the home
With an eye on the effects on human health, the research team examined how long it took the PCE to leave the fabric under typical conditions in the home. "We don't really think about dry cleaning as a health issue. Everybody dry cleans clothing and you pick it up, you bring it home, you don't even think about it," said Sherlach.
Wool samples from one cleaner were kept in the open air at room temperature, to simulate being hung up in the home. After seven days, the amount of PCE had reduced by 50% and keeping the garment in the plastic wrap provided by the cleaner made no difference.
So, PCE from dry cleaned clothing could present a health risk due to inhalation and contact with the skin. The research team calculated the amount of PCE in a pair of adult wool trousers to be about 160 mg (1300 µmol). If ten of them were stored in a typical wardrobe then the exposure would be 2.0 mmol/m3 or 50 ppm.
Unfortunately, it is rather more difficult to determine whether or not these levels would be carcinogenic due to a lack of studies in the literature on PCE and its metabolites. The researchers claimed that "skin absorption through dry-cleaned fabrics (particularly wool) is an underappreciated route of potential human PCE exposure."
They recommended that detailed studies should be carried out on the levels of PCE in dry cleaned clothes from different cleaners, its rate of volatilisation and dermal absorption, and the human metabolism of PCE.
"At the end of the day, nobody - I mean nobody - has previously done this simple thing - gone out there to several different dry cleaners and tested different types of cloth for retained PCE," says Roepe.
The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.
Alexa Dantzler and Paul Roepe
Photo: Anita Dantzler