Chemical Sensitizers

Videlock Laboratory · lab-specific standard operating procedure

This is a laboratory-written SOP, not a UCLA EH&S template. It is pending review with EH&S (laboratorysafety@ehs.ucla.edu) before being filed in the Chemical Hygiene Plan. The signed copy of record, with the PI approval and training signatures, is in the lab safety manual.

This SOP covers chemicals in this laboratory classified as respiratory sensitizers (H334) or skin sensitizers (H317). UCLA EH&S does not publish a banded SOP for sensitization, so this document supplements the banded SOPs that cover these materials’ other hazards. Use of any material listed below is subject to pre-approval by the PI.

Materials covered

Hazard description

A sensitizer causes an immune response rather than direct chemical injury. The first exposures may produce no symptoms at all (induction). Once a person is sensitized, subsequent exposures — even to amounts far below any occupational exposure limit — can trigger a reaction. Respiratory sensitization can present as occupational asthma, and it is generally permanent.

There is no exposure level that is reliably safe for an already-sensitized individual. The control strategy is therefore to prevent sensitization from ever occurring, not to keep exposures under a limit.

Dry powders are the highest-risk form: ammonium persulfate, G 418, DNase and FITC-dextran all generate an inhalable aerosol when weighed, and static-charged powder migrates well beyond the balance.

Personal protective equipment

Lab coat Gloves Eye protection
Traditional white lab coat, buttoned, with sleeves down. Nitrile gloves, changed immediately after handling and before touching shared surfaces. Double-glove when weighing powders. ANSI Z87.1-compliant safety glasses; goggles when handling glutaraldehyde or any solution that can splash.

Engineering controls, equipment and work practices

   
Weighing powders Weigh all sensitizing powders inside a fume hood, a ducted balance enclosure or a powder-weighing safety station. A biosafety cabinet is NOT a substitute — it protects the sample, and recirculating models return the aerosol to the room.
Buying out of the problem Wherever the vendor offers it, buy pre-weighed capsules, pre-made solutions or tablet formulations instead of bulk powder. For ammonium persulfate, making a single 10% stock and refrigerating it removes almost all routine powder handling.
Solutions Once in solution these materials are handled on the open bench with the PPE above, provided no aerosol is generated. Vortexing, sonicating or pipetting forcefully re-introduces the aerosol route — do those in the hood.
Gloves Change gloves immediately after handling, and always before touching a shared surface (freezer handle, keyboard, pipettor). Sensitizer transferred to a shared object is the commonest route by which an unrelated lab member becomes exposed.

Labeling and storage

Store in the original closed container in a labelled secondary container. Segregate ammonium persulfate from all organics and reducing agents — it is also a strong oxidizer. Label the storage location so that anyone reaching for a neighbouring container knows a sensitizer is present.

Housekeeping

Spills. Powder spill: do NOT dry-sweep or use compressed air — both re-aerosolise the material. Cover the spill with a damp paper towel from the edges inward, collect into a sealable bag, and wipe the area twice with damp towels. Liquid spill: absorb, then wipe with detergent and water. Bag all cleanup debris as solid hazardous waste. Notify the PI. For a spill larger than can be handled with the lab spill kit, evacuate the room and call 9-1-1 from a campus phone or (310) 825-1491 from a cell phone.

Decontamination. Wipe contaminated surfaces with detergent and water unless specified otherwise above. Dispose of contaminated towels as solid hazardous waste.

Waste

Solid residues, contaminated towels and empty powder containers go into solid hazardous waste — not the regular trash. Aqueous solutions go into a labelled aqueous waste container; do not drain-dispose. Request pickup through the UCLA Waste Accumulation Area program.

Refer to the UCLA Chemical Hygiene Plan for general waste accumulation requirements.

First aid and emergencies

   
Skin contact Remove contaminated gloves and clothing. Wash the area with soap and running water for 15 minutes. Report any rash, hives or itching to the PI — an apparently minor skin reaction is the warning sign that sensitization has occurred.
Inhalation Move the person to fresh air. Any wheeze, chest tightness, cough or shortness of breath after working with these materials is a medical emergency in a potentially sensitized person: call 9-1-1 and notify EH&S at (310) 825-9797.
Eye contact Flush at an eyewash for 15 minutes, holding the eyelids open. Seek medical attention.
Reporting Report every symptomatic exposure to the PI and to UCLA Occupational Health. A documented first reaction is what protects the person from a worse second one.

Emergency: 9-1-1 from a campus phone, or (310) 825-1491 from a cell phone · UCLA EH&S: (310) 825-9797

Training

Everyone who works with these materials reads this SOP and signs the training record held in the lab safety manual.

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