User Safety Focus


Staying Safe When Weighing Hazardous or Sensitive Materials


METTLER TOLEDO


Many substances processed in today’s working labs or production environments must be kept pure. Many of these substances also pose a risk to user safety, particularly in microbiological and pharmaceutical settings.


The right containments for sensitive and hazardous materials that pose a threat to human health yet require a highly clean environment are safety cabinets and specialised isolators. These enclosures provide a higher degree of protection than standard fume hoods or weighing cabinets, where turbulent airfl ow is a major drawback for weighing scenarios where aseptic or particle-free conditions are required.


Unlike fume hoods or weighing cabinets, safety cabinets and specialised isolators ensure that all air from the lab environment entering the weighing workspace is guided via unidirectional airfl ow through a high- effi ciency particulate air or HEPA-grade purifi cation system to remove contaminants in a practical manner.


The unidirectional system also provides a high degree of protection against exposure to vapours, aerosols or particles for the operator. However, it may be diffi cult to avoid exposure risk completely, particularly in the case of accidental minor or major spills. To further limit exposure risk, operators must adopt safe weighing principles including appropriate operational protocols (e.g. training, SOPs, hygiene management).


Mandatory Personal Protective Equipment (PPE)


Even though the operating principles of safety cabinets and isolators are sound, PPE is always mandatory. This is due to potential toxicity or to the carcinogenic, mutagenic, reprotoxic (CMR) or teratogenic properties of many substances in use in the modern lab.


These PPE items, detailed in Table 1, provide an added level of protection in the event of unforeseen environmental circumstances or equipment malfunction. They should be part of your lab’s SOPs and followed consistently for every weighing or service task.


Table 1. Personal Protective Equipment (PPE) to ensure maximum operator safety. Item


Details, Use Safety Glasses Nitrile Gloves Fine Dust Mask


200 mL Eye Wash Bottle with Integrated Eye Bowl


Protects eyes; can be worn over corrective glasses; must be certifi ed according to EN166 and EN170.


Chemical Protects eyes; can be worn over corrective glasses; must be certifi ed according to EN166 and EN170. protection; protection against cross-contamination; must be certifi ed according to EN374; disposable.


Protects lungs and mucous membranes in the nose and mouth; standard FFP3 to avoid breathing vapours, mist or particulate matter; disposable.


Provides extra precaution in case of unforeseen exposure to chemicals or biological agents; disposable.


Technical Principles of Safety Cabinets and Isolators


Safe Weighing in Specialised Enclosures


Uniform approaches towards substance-handling will make it easier to comply with SOPs on a consistent basis. This helps to ensure your safety, the safety of those using the enclosure after you, and the purity of the product you are handling.


In general, safe laboratory principles are the rule. This includes: • Not eating or drinking in rooms where potentially weighing hazardous materials are present. • Using mandatory PPE for every weighing. • Adopting appropriate containment technology.


Figure 1. Cross-section and functional principle of a safety cabinet for cytotoxics with 3 fi lter levels. ©Berner International GmbH


After establishing the need for PPE and appropriate weighing protocols, we are ready to review the technical principles and benefi ts of a modern safety cabinet. These technical principles can be illustrated by the crosssectional example shown in Figure 1.


The high level of personnel and product protection provided by the safety cabinet is achieved by HEPA fi ltration, the interaction of downfl ow and infl ow at the access opening, and the guidance of the air system itself. All factors combine to determine overall safety-cabinet performance.


INTERNATIONAL LABMATE - FEBRUARY 2020


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