Introduction

Perchloroethylene (aka tetrachloroethylene or PERC) is the main chemical found in products used for dry cleaning worldwide. It acts as a solvent to remove stains from all types of fabrics, since it is an excellent solvent for organic materials. It is volatile, highly stable and non-flammable, reasons for which it is so widely used in this industry. The big selling point of this chemical is that it is quite effective and quite cheap, which means that almost all dry cleaners throughout the globe use it daily. The problem is that PERC is quite toxic, both for humans and the environment. Because of all these reasons, the French government has set up to 2022 the complete banning of PERC from dry cleaning establishments situated close to residential areas. Similar laws had been already passed in Denmark and the USA.

Impact of PERC in Paris' dry cleaners

We interviewed face-to-face all dry cleaners in Paris with the aim of understanding how they would deal with the interdiction of this chemical, as well as assess their level of awareness of the dangers of PERC. We also aimed to understand what were their needs, to try to design a product that would help make their daily life easier.

Our survey (original questionnaire in French or translated version in English) allowed us to create a better suiting product, but it also allowed us to assess the level of awareness of the dry cleaners regarding the dangers of using PERC. The interesting thing about Paris is that the city is divided into 20 neighborhoods, the 20 arrondissements. This division is very interesting for our study because it allows us to make not only a statistical analysis of our data, but also a socio-economical one based on the differences in styles of living in each arrondissement.

250 dry-cleaners and hundreds of kilometres walked after, we got to know which are the most difficult stains to remove and which are the most problematic fabrics.
We also got to know their personal experiences on the use of PERC and the impact that the compulsory change would have on their business. We learnt that the already existing alternatives to PERC are not efficient enough.
Most of the dry cleaners expressed their concern over their business, being afraid that the new methodologies would result in a decrease of the quality of their services. Using the existing alternative to PERC means that it takes longer to remove the stains than it used to take when they used PERC. It also means that for the most difficult stains they need to use pre-washing products to be able to efficiently get rid of the stains.
We learnt that, among the most difficult stains to remove, red wine is a particularly difficult one to get rid off. This type of stains is especially difficult to remove without a trace on white fabrics, since it has very strong pigments. We therefore decided to focus on developing a pre-washing product for getting rid of the verrry Frrrrench red wine stains.

Results

Figure 1: Reported PERC use per arrondissement and observed existing correlations. All data obtained from analysis of the answers to the questionnaire. Original set of data not displayed publicly to preserve the anonymity of the dry cleaners.

On the use of PERC in Paris

The first question we wanted to answer with our questionnaire was the one of how widely spread was the use of PERC in Paris. Our data shows that half the dry cleaners in Paris still use PERC as a solvent in their dry-cleaning facilities (figure 1B), which means that in the followup to 2022, time when the chemical will be prohibited in France, half of the dry-cleaners of Paris will have to make the investment of updating their facilities.
Although we do not have numbers for it because we did not originally include the question in our questionnaire, we found out that many of the dry cleaners that do not use PERC had changed to the alternatives in the previous 5 years.

Looking at figure 1A, we can see that the distribution of the use of PERC in Paris is not homogeneous, with some arrondissements using it much more than others. The 12th and 13th arrondissements were the ones in which the use of PERC was still more prominent, and the north arrondissements, the 17th, 18th, 19th and 20th were the ones in which PERC was most seldom used.

We analysed the socio-economic characteristics of those arrondissements, trying to find some correlation that would help us explain the differences on the use of the chemical.
We initially expected that on the "richest" arrondissements the use of alternatives would be more frequent. We based this hypothesis on the thought that businesses that were located in expensive arrondissements would be able to support the monetary effort of changing their infrastructures easier than those located in poorer arrondissements. Nonetheless, a correlation between the mean income and the use of PERC was not found. We hypothesised that this might be due to the fact that the French Government has made the effort to support monetaryly the dry cleaners that change their infrastructures to be able to use the alternatives, and thanks to this help, the economical differences between arrondissements have been diluted.

We also expected to see a correlation between the awareness of the population that inhabited the arrondissement and the use of PERC. We hypothesised that those arrondissements in which their inhabitants had easier access to high education would be more sensibilised to the dangers of using the chemical, and would therefore pressure their local dry-cleaners to change to the alternatives. Nonetheless, once again, our original premise was completely wrong, since no correlation between white workers and use of PERC was found.
The one correlation that we were able to find was that existing between the use of PERC and the percentage of immigrant population. Those with a higher percentage of immigrant population displayed the lowest values of PERC use. Once we observed this correlation we realised that we had been looking at the data with the wrong perspective all along.
Paris is traditionally a city with a high percentage of immigrant population, and the different populations are well distributed throughout the 20 arrondissements. Nonetheless, the immigrant population is higher in the north districts, which are also the poorer ones. Something that could explain the correlation observed between immigrant population and PERC use is that the people that live in the 17th, 18th, 19th and 20th might both live and work in dry cleaners in these arrondissements. Therefore, a stronger concern would exist on those dry cleaners, since the effects on health of using PERC would be more strongly felt by those both living and working close to PERC-using facilities.
A second explanation could also be that the French Government helps more those who need it the most, and would therefore have begun helping the dry cleaners in those arrondissements first.
A third explanation could also be that the 17th, 18th, 19th and 20th arrondissements have seen an increase in population in the last decades. The new population living there could have started new business, choosing to use the alternatives directly, whereas in the older arrondissements like the 1st and the 6th, with long-stablished dry-cleaning facilities, the change would be slower.

Figure 2: Awareness of the population on the risks of using PERC. All data obtained from analysis of the answers to the questionnaire. Original set of data not displayed publicly to preserve the anonymity of the dry cleaners.

On the awareness of Parisian dry-cleaners

The second question we wanted to answer with our questionnaire was the one of how aware are the dry-cleaners of the risks of working with PERC. Looking at figure 2A, we can see that the majority of dry-cleaners have no perception, or light to moderate perception of the risk of working with PERC. This shows that the information is not reaching the dry-cleaning industry effectively. Moreover, many dry-cleaners answered that they believed there to be no risks of working with PERC, and felt suspicious for the reasons why the French government was taking these measurements. These results are very interesting and show that there needs to be a more effective communication between the authorities and the dry-cleaning industry, and that there has to be a channel for discussion between them, in order for the industry to regain confidence.
Our questionnaire also suggests that, as can be seen in figure 2B, dry-cleaners in which the workers were concerned about the health problems associated with PERC found the transition to new alternatives easier, showing that obviously the concern for health overcomes the economical struggle.

Lastly, we evaluated the concern of Parisian dry-cleaners on the use of enzymes that were produced in GMO. The overall picture is that in the entirety of Paris, there were not many dry cleaners that were preoccupied with the prospect of using GMO enzymes. Our data also shows that amongst the people that reported to have light or no concern on the effect of PERC on human health the percentage of people concerned about the use of GMOs on laundry was lower than that of those that were worried about it.

Figure 3: Most difficult stains and fabrics. All data obtained from analysis of the answers to the questionnaire. Original set of data not displayed publicly to preserve the anonymity of the dry cleaners.

Learning from tradition to innovate

As explained before, we developed our questionnaire with two things in mind; first, to evaluate the impact of PERC on the dry-cleaning industry, and second, to get to know the industry's needs in order to produce a product that could really be useful in real life conditions. In order to do so, we got to know what were the needs and struggles that the dry-cleaners go through. We learnt from what it is traditionally done in order to innovate.

First, we got to know that the most common stains that drive people to take their clothes to the dry cleaners are fat, wine, ink and blood (figure 3A).
We also learnt that red wine stains are particularly challenging to remove, with the great majority of dry-cleaners answering that they were hard to remove. Interestingly, we learnt those dry cleaners that had already made the change from PERC to new alternatives had now to use a pre-washing treatment for demanding stains, such as red wine. This did not happen before with PERC, that was enough to clean the stains on its own.
Lastly, we got to know that the hardest fabric to clean stains from is, without a doubt, silk, mainly because of the fragile nature of the fabric. The fragile nature of silk means that the pre-washing chemicals cannot act for a long time without damaging the fabric, highlighting the need for efficient stain-treatments.

We, therefore, decided to focus on creating an enzymatic pre-washing product for wine stains. In order to make the product very efficient, we decided to fuse our enzymes to Fabric Binding Domains, taking special attention to silk binding domains, since it was the most difficult fabric to clean stains from. By concentrating the enzymatic activity on the fabric we make the process more efficient, hence protecting the fragile nature of this fabric.

Attributions

The Human Practices were designed by the entire team with the help of our advisors. Face-to-face interviews were carried out by Alicia, Allison, Antoine V. and Sébastien (due to the fact that speaking french was necessary to perform them). A big thank you to our advisors Jake and Jason for helping us analyse the results.

References

• The list of the dry cleaners existing in Paris was obtained in the Yellow Pages (Pages Jaunes)
• The statistics for each Arrondissement were obtained in the Mairie de Paris and in the Institut National de la Statistique et des Etudes Economiques