Study on reusable cleanroom clothing

A new study by DuPont Per­son­al Pro­tec­tion which assess­es the per­for­mance of reusable gar­ments for clean­room appli­ca­tions could lead to a rad­i­cal change in con­trolled envi­ron­ment prac­tices.  The results, which the com­pa­ny has pub­lished in a whitepa­per, con­firm that reusable gar­ments are vul­ner­a­ble to dam­age from laun­der­ing and ster­il­iza­tion – and that the evi­dence that a gar­ment has been com­pro­mised is often invis­i­ble to the naked eye.
The results could have far-reach­ing impli­ca­tions, par­tic­u­lar­ly for those work­ing in the med­ical devices man­u­fac­tur­ing, phar­ma­ceu­ti­cal, biotech­nol­o­gy and research indus­tries. Still a rel­a­tive­ly new intro­duc­tion, sin­gle-use tex­tiles such as Tyvek Iso­Clean reduce the risk of con­t­a­m­i­na­tion and will become an increas­ing­ly impor­tant ele­ment of any con­t­a­m­i­na­tion con­trol strategy.
Reusable gar­ments used in ster­ile and asep­tic pro­duc­tion require repeat­ed laun­der­ing and ster­il­iza­tion cycles to main­tain their effec­tive­ness, using such tech­niques as gam­ma radi­a­tion. Phys­i­cal prop­er­ty data are often avail­able for new clean­room gar­ments: how­ev­er, there are less data avail­able through­out the entire gar­ment life. DuPont’s new study is intend­ed to address this infor­ma­tion gap.
Says Jean-François Teneul, Glob­al Busi­ness Man­ag­er for the Con­trolled Envi­ron­ments sec­tion of DuPont Per­son­al Pro­tec­tion: “Most con­t­a­m­i­na­tion with­in asep­tic pro­cess­ing areas is caused by the humans work­ing in the clean­rooms. When select­ing reusable gar­ments for use in con­trolled envi­ron­ments, it is impor­tant to under­stand how they will per­form over their intend­ed life­cy­cle. In addi­tion, for potent prod­uct han­dling, clean­room gar­ments must per­form a dual role: not only to pro­tect the prod­uct from the oper­a­tor, as with asep­tic process­es; but also to pro­tect the oper­a­tor from the haz­ardous chem­i­cals. We felt it was nec­es­sary to pro­vide these pro­fes­sion­als with data on which to base a more informed choice.”
DuPont con­duct­ed the study to map the prop­er­ties of reusable gar­ments typ­i­cal­ly used in clean­rooms when exposed to repeat­ed laun­der­ing and gam­ma radi­a­tion, in order to learn how the per­for­mance of those gar­ments changes with each cycle. The sci­en­tif­ic study focused on fab­ric per­for­mance and exam­ined gar­ment prop­er­ties such as poly­mer struc­ture, per­me­ation, tear strength and Bac­te­r­i­al Fil­tra­tion Effi­cien­cy (BFE) to deter­mine how they are neg­a­tive­ly impact­ed by clean­ing and ster­il­iza­tion regimes over time. The tests, which were under­tak­en by third par­ty lab­o­ra­to­ries, revealed sig­nif­i­cant impacts on crit­i­cal aspects includ­ing pro­tec­tion of the process and the wear­er, dura­bil­i­ty and comfort.
Among the key find­ings were:

• Changes in poly­mer struc­ture: while gam­ma radi­a­tion is effec­tive for ster­il­iza­tion it can also impact poly­mers that make up reusable gar­ments. Changes to the poly­mer matrix will ulti­mate­ly affect the prop­er­ties of the fibres that make up the gar­ments, and the gar­ments themselves.
• Breatha­bil­i­ty and bar­ri­er: bar­ri­er decreas­es while air per­me­abil­i­ty increas­es, which means the gar­ment is pro­vid­ing less pro­tec­tion over time.
• Par­ti­cle shed­ding: as expo­sure to gam­ma radi­a­tion and laun­der­ing increas­es, so does the amount and vari­abil­i­ty of par­ti­cle generation.
• Tear strength: increased gam­ma radi­a­tion and laun­der­ing expo­sure reduces tear strength.
• Bac­te­r­i­al Fil­tra­tion Effi­cien­cy: with a BFE high­er than 98%, sin­gle-use tex­tile Tyvek Iso­Clean has the abil­i­ty to bet­ter fil­ter out bac­te­ria com­pared to reusable clean­room tex­tile, which has a BFE below 70%.

These changes are not always vis­i­ble to the naked eye, so visu­al gar­ment inspec­tion alone may not be suf­fi­cient to under­stand gar­ment per­for­mance. Based on these find­ings, the study offers the fol­low­ing recommendations:

• Con­sid­er per­for­mance data over the entire gar­ment life cycle.
• Enact test­ing pro­to­cols to mon­i­tor the per­for­mance of gar­ments as they age, based on the risk assess­ments and needs of each indi­vid­ual cleanroom.
• Estab­lish cri­te­ria for tak­ing gar­ments out of ser­vice when they no longer meet func­tion­al­i­ty requirements.

In con­clu­sion, Jean-François Teneul says: “Based on the results of our sci­en­tif­ic study — and in the con­text of the draft ver­sion of the revised GMP Annex 1, which includes more Qual­i­ty Risk Man­age­ment (QRM) prin­ci­ples – the focus will have to be not only on the behav­iour and gown­ing pro­ce­dure of the per­son­nel, but also on the per­for­mance of the clean­room cloth­ing sys­tem and the spe­cif­ic risk assess­ment of clean­room gar­ments. The study data will allow the respon­si­ble per­son to make a prop­er assess­ment of the con­t­a­m­i­na­tion risks and costs involved in their appli­ca­tions and to decide whether reusable clean­room gar­ments or sin­gle-use clean­room gar­ments are the right choice.”
The whitepa­per ‘To Reuse or Not to Reuse: A Life Cycle Assess­ment of Reusable Gar­ment Prop­er­ties’ con­tains full details of the method­ol­o­gy and results from the reusable gar­ment study. It is avail­able as a free down­load here: www.tyvek.co.uk/invisible