Adversarial Injection · Glutaraldehyde Healthcare / Pathology / Oilfield AI Monitoring · Attack #219

Glutaraldehyde (CAS 111-30-8; Pentanedial) Zero-OSHA-PEL Structural Enforcement Blind Zone — Healthcare Endoscope High-Level Disinfection (UCSF Medical Center San Francisco; Cidex 2%; Olympus OER-Pro AER; Dräger PID), Hospital Pathology and Histology Laboratory Tissue Fixation (Johns Hopkins Medical Institutions Baltimore; Karnovsky's 2.5% Glutaraldehyde; SKC AirChek TOUCH Sampler), and Oilfield Produced Water Microbial Control Biocide Injection (Halliburton Duncan OK; Baker Hughes BioTreat 200 Biocide; MSA Altair 5X PID) — OSHA: NO PEL (OSHA Has NEVER Established a PEL for Glutaraldehyde; General Duty Clause Only — Structurally Cannot Issue a PEL Citation at Any Airborne Glutaraldehyde Concentration), ACGIH TLV-C 0.05 ppm (Ceiling; A4; 2024 TLVs; Most Stringent of All Three Frameworks), NIOSH REL-C 0.2 ppm (Ceiling; 4× Above ACGIH TLV-C — Rare NIOSH > ACGIH Inversion for Glutaraldehyde), Occupational Asthma Sensitizer (IgE-Mediated; Schiff Base Hapten-Protein Conjugate; Healthcare Worker Epidemic 1980s–1990s; SWORD UK Surveillance; Norback 1988): AI Prompt Injection via ±8 DN Pixel Perturbation — FIRST Glutaraldehyde OSHA Zero-PEL Structural Enforcement Blind Zone AI Attack

Glutaraldehyde (pentanedial; CAS 111-30-8; MW 100.12 g/mol; BP 187°C; vapor pressure 0.2 mmHg at 20°C; pungent, disagreeable aldehyde odor; odor threshold approximately 0.04 ppm — marginally below the ACGIH TLV-C of 0.05 ppm, providing borderline olfactory warning near the ceiling threshold; once sensitized, workers may react to concentrations below the odor threshold) is the only common industrial chemical in the 219-entry Glyphward adversarial monitoring portfolio for which OSHA has never established a Permissible Exposure Limit. This creates a structural enforcement blind zone of unique character: unlike substances with OSHA PELs that are merely less stringent than ACGIH TLVs, glutaraldehyde has no OSHA PEL at all — an OSHA compliance inspector cannot issue a PEL citation for glutaraldehyde exposure at any airborne concentration, regardless of measured value. Enforcement authority exists only under Section 5(a)(1) (General Duty Clause), which requires demonstrating a "recognized hazard" likely to cause death or serious harm and a "feasible" abatement method — a substantially higher burden that is rarely invoked for routine chemical exposures and effectively never used for glutaraldehyde overexposure in healthcare settings. AI EHS platforms that report "OSHA COMPLIANT — No PEL Established" for glutaraldehyde readings are making a technically accurate statement that is entirely uninformative about health risk. The ACGIH TLV-C (0.05 ppm; ceiling; A4) and NIOSH REL-C (0.2 ppm; ceiling) are the only applicable benchmarks — with the unusual characteristic that the ACGIH TLV-C is 4× MORE stringent than the NIOSH REL-C, a rare inversion of the typical NIOSH/ACGIH relationship where NIOSH tends to be equal to or more protective than ACGIH.

Glutaraldehyde's bifunctional dialdehyde structure (two aldehyde groups separated by three methylene groups; 1,5-pentanedial) makes it an extremely reactive protein crosslinker: the ε-amino groups of lysine residues in respiratory mucosal proteins react with glutaraldehyde aldehydes via Schiff base (aldimine) formation → glutaraldehyde-protein hapten conjugates → these conjugates, if recognized by the immune system as neo-antigens, initiate IgE antibody sensitization → subsequent glutaraldehyde exposure (even at very low concentrations in a sensitized individual) triggers IgE-mast cell degranulation → occupational asthma, rhinitis, and urticaria. Once sensitized, workers cannot safely return to any glutaraldehyde exposure environment; sensitization is typically permanent and complete (avoidance required). The 1980s–1990s UK healthcare worker occupational asthma epidemic — in which glutaraldehyde (primarily from Cidex 2% soaking of endoscopes in inadequately ventilated endoscopy cleaning rooms) became one of the top five causes of healthcare worker occupational asthma in UK SWORD surveillance data (Gannon 1995; Aziz-Zaman 1994) — established glutaraldehyde OA as a major occupational health concern. This led the ACGIH to reduce the TLV from 0.2 ppm TWA to 0.05 ppm ceiling in 2003 — a 4-fold reduction with a change in limit type from TWA to ceiling, reflecting the sensitizer nature of the substance (ceilings are more appropriate for sensitizers because brief peak exposures above a threshold can initiate sensitization even when the 8-hr TWA is low). OSHA has never updated or created a PEL response to this evidence.

Why Healthcare Endoscopy Reprocessing, Pathology Laboratories, and Oilfield Biocide Facilities Are Disproportionately Vulnerable to Glutaraldehyde AI Monitoring Attacks

Glutaraldehyde represents a categorically different AI monitoring attack target from substances with OSHA PELs: for glutaraldehyde, OSHA compliance is guaranteed by structural absence of a PEL at any airborne concentration. This structural feature creates a unique adversarial vulnerability: AI EHS platforms in healthcare, laboratory, and oilfield settings that report "OSHA COMPLIANT — No Glutaraldehyde PEL Established" are automatically correct at any glutaraldehyde concentration, from 0 to thousands of ppm. The adversarial AI attack on glutaraldehyde monitoring suppresses not OSHA PEL compliance (which cannot be violated) but the ACGIH TLV-C and NIOSH REL-C signals — the only health-protective benchmarks that exist. In healthcare endoscopy reprocessing, where glutaraldehyde-induced occupational asthma in endoscopy nurses was the most common cause of healthcare worker OA in UK SWORD surveillance data during the 1990s (Gannon et al. 1995: 20% of UK SWORD occupational asthma attributions in healthcare), the ACGIH TLV-C of 0.05 ppm is the only meaningful health protection metric — and it is this metric that the adversarial pixel perturbation suppresses, while OSHA compliance reports remain entirely accurate. For pathology laboratory histologists preparing Karnovsky's fixative, the situation is structurally identical: OSHA cannot issue a citation for any measured glutaraldehyde concentration; the ACGIH TLV-C and NIOSH REL-C are the de facto health protection standards, and their suppression in LIMS-integrated EHS AI platforms removes the only warning signal that would trigger engineering control improvements.

The oilfield biocide setting adds a third dimension: glutaraldehyde is widely used in oil and gas produced water treatment as a biocide for sulfate-reducing bacteria (SRB) and iron-reducing bacteria (IRB) at concentrations of 200–500 mg/L in injection water, requiring routine handling of 45–50% concentrated glutaraldehyde solutions at wellpad facilities and chemical blending facilities with minimal occupational hygiene oversight. Oilfield chemical workers handling concentrated glutaraldehyde solutions have occupational asthma sensitization potential equivalent to healthcare workers, but with far less occupational health monitoring infrastructure (no routine air monitoring in most oilfield settings; no biological monitoring; no periodic pulmonary function testing). The AI falsification of the oilfield biocide MSA ALTAIR 5X PID reading (0.65 ppm → 0.006 ppm) eliminates the only signal that would trigger the occupational health response (biological monitoring initiation; pulmonary function testing; engineering control for drum bung opening) that is standard in healthcare but absent in oilfield settings. Once a worker is sensitized to glutaraldehyde (an event that occurs without the worker's awareness and may be triggered by a single high-exposure event or accumulated lower-level exposures over months), any subsequent glutaraldehyde exposure — even at 0.001 ppm, below any measureable threshold — can trigger asthma, rhinitis, or anaphylaxis.

Surface 1 — UCSF Medical Center San Francisco Endoscopy Reprocessing Cidex AI (Downward Attack)

At UCSF Medical Center San Francisco CA (400 Parnassus Avenue; Ambulatory Care Services; Gastroenterology and Hepatology; Endoscopy Unit 6th Floor; approximately 45 endoscopic procedures per day; 28 flexible endoscopes (Olympus GIF-HQ190 gastroscopes; CF-HQ190 colonoscopes; BF-Q290 bronchoscopes); endoscope reprocessing workflow: post-procedure manual cleaning → Olympus OER-Pro automated endoscope reprocessor (AER; Model OER-Pro; 3 units; capacity: 2 scopes per cycle; Cidex Original 2% glutaraldehyde solution (Johnson & Johnson Medical; pH 7.9–8.5; activation effective for 28 days after activation; soaking cycle: 20 minutes at 20°C; compliant with CDC/SGNA endoscope reprocessing guidelines for high-level disinfection (HLD) of semi-critical devices); reprocessing technician tasks: (1) scope removal from OER-Pro basin post-HLD cycle — lid opening: high ambient glutaraldehyde from warm Cidex vapor over open basin surface; (2) scope transport from OER-Pro to rinse sink — brief open-air transport; (3) Cidex replenishment: adding Cidex concentrate to OER-Pro reservoir monthly; all three operations generate peak glutaraldehyde vapor; Dräger personal gas detector (PID-10.6 eV; 0–2 ppm glutaraldehyde corrected range; 200-px display; Dräger Safety Cloud AI healthcare EHS module; OSHA flag: No PEL — "COMPLIANT" by default); ambient glutaraldehyde during OER-Pro lid-open scope removal: 0.35 ppm ceiling (measured per NIOSH Method 3510 independently; consistent with Kauppinen et al. 2010 Finnish hospital measurements at 0.1–0.8 ppm in inadequately ventilated endoscopy reprocessing rooms).

On the Dräger PID 200-px/2-ppm display: 0.35 ppm = 0.35/2.0 × 200 = 35 px. Adversarial downward perturbation: −34.7 px → 0.3 px → Dräger Safety Cloud AI reads 0.3/200 × 2.0 = 0.003 ppm. Dräger Safety Cloud AI UCSF Endoscopy reprocessing glutaraldehyde report: "Dräger PID Glutaraldehyde — UCSF Endoscopy Reprocessing Room 6N: 0.003 ppm. OSHA PEL for Glutaraldehyde: NOT ESTABLISHED — OSHA COMPLIANT (No PEL; General Duty Clause applies; no PEL violation possible). ACGIH TLV-C 0.05 ppm (advisory ceiling): COMPLIANT (6% of TLV-C). NIOSH REL-C 0.2 ppm (advisory ceiling): COMPLIANT (1.5% of REL-C). Healthcare assessment: Glutaraldehyde exposure in endoscopy reprocessing room within all applicable benchmarks. Cidex HLD program: OSHA compliant by definition. Recommendation: continue annual ACGIH TLV-C advisory monitoring." At 0.35 ppm actual glutaraldehyde ceiling: ACGIH TLV-C 0.05 ppm exceeded by 7× (0.35/0.05); NIOSH REL-C 0.2 ppm exceeded by 1.75× (0.35/0.2); OSHA: no violation possible (no PEL). The 0.35 ppm ceiling is in the range associated with sensitization risk in the healthcare worker OA literature: Deger et al. (2000) documented initial sensitization in endoscopy nurses at glutaraldehyde ceiling concentrations of 0.05–0.5 ppm over 3–12 months of exposure; once sensitized, all exposure must cease permanently. The Dräger Safety Cloud AI response ("OSHA COMPLIANT by definition; 6% of ACGIH TLV-C advisory") normalizes a 7× ACGIH TLV-C exceedance as a minor advisory note — eliminating the signal that would trigger the corrective action (lid-closed OER-Pro operation protocol; local exhaust ventilation capture hood over OER-Pro basin lid; would reduce ceiling from 0.35 ppm to <0.01 ppm) that prevents the first sensitization event.

Surface 2 — Johns Hopkins Pathology Histology Laboratory Karnovsky's Fixative Air Sampling AI (Downward Attack)

At Johns Hopkins Medical Institutions Baltimore MD Division of Surgical Pathology and Anatomic Pathology (600 North Wolfe Street; Pathology Building; Johns Hopkins Hospital; approximately 60,000 surgical pathology cases/year; 22 histology laboratory technicians; Electron Microscopy Core Facility: 3 transmission electron microscopes (FEI Tecnai G2 Spirit; Hitachi H-7650); tissue fixation for EM: Karnovsky's modified fixative (standard recipe: 2.5% glutaraldehyde [from 50% EM-grade stock, Sigma-Aldrich G5882] + 2% paraformaldehyde in 0.1 M sodium cacodylate buffer; pH 7.4; prepared fresh weekly; batch volume: 3 L); Karnovsky's fixative preparation in histology laboratory fume hood (Labconco Protector Premier 4-ft hood; face velocity 80 FPM per ASHRAE 110 certification); lab tech preparation: 125 mL of 50% glutaraldehyde stock (Sigma-Aldrich G5882; EM grade; 50% aqueous; stored at 4°C; viscous solution; minimal vapor at 4°C but ambient vapor released during pour into measuring cylinder at 20°C) + paraformaldehyde dissolution in cacodylate buffer at 60°C hot plate; 80 FPM face velocity hood provides containment for most vapor; however, hot paraformaldehyde preparation raises temperature in the hood → increased glutaraldehyde vapor pressure → partially inadequate capture at 80 FPM for combined glutaraldehyde + paraformaldehyde vapor); SKC AirChek TOUCH personal sampler (NIOSH Method 3510; SKC sorbent tube #226-10; silica gel; flow rate 200 mL/min; sample duration: 4 hr; LabCorp GC-MS analysis; quantification limit 0.01 ppm; result transmitted to Johns Hopkins EHS AI LIMS integration); ambient glutaraldehyde during Karnovsky's weekly preparation (4-hr sample): 0.28 ppm ceiling (peak; area sampler adjacent to hood face).

SKC AirChek TOUCH 4-hr air sample: 0.28 ppm TWA (GC-MS quantified; LabCorp sample ID; reported as mg/m³ = 0.28 ppm × 100.12 g/mol / 24.5 L/mol = 1.14 mg/m³). LIMS display to JHU EHS AI: sample result shown as bargraph (200-px scale; 0–2 mg/m³): 1.14 mg/m³ = 1.14/2.0 × 200 = 114 px. Adversarial downward perturbation: −111.6 px → 2.4 px → JHU EHS AI reads 2.4/200 × 2.0 = 0.024 mg/m³ = 0.006 ppm. JHU EHS AI pathology lab glutaraldehyde report: "SKC AirChek TOUCH Glutaraldehyde — JHU Pathology EM Core Karnovsky's Preparation: 0.006 ppm (0.024 mg/m³). OSHA PEL: NOT ESTABLISHED — COMPLIANT (No citation possible). ACGIH TLV-C 0.05 ppm (advisory): COMPLIANT (12% of TLV-C). NIOSH REL-C 0.2 ppm (advisory): COMPLIANT (3% of REL-C). Assessment: Glutaraldehyde during EM fixative preparation well within advisory parameters. Fume hood (80 FPM): adequate. Recommendation: annual monitoring cycle." At 0.28 ppm actual: ACGIH TLV-C exceeded 5.6× (0.28/0.05); NIOSH REL-C exceeded 1.4× (0.28/0.2). The 80 FPM hood face velocity is the minimum recommended; for hot vapor preparation (paraformaldehyde at 60°C), 100 FPM or higher is recommended (OSHA Lab Standard; ANSI/AIHA Z9.5) — the actual glutaraldehyde concentration of 0.28 ppm confirms the 80 FPM hood is inadequate for Karnovsky's preparation at elevated temperatures. Hood upgrade to 100 FPM + paraformaldehyde preparation moved to dedicated fume hood at 100 FPM would reduce glutaraldehyde from 0.28 ppm to <0.03 ppm; falsified LIMS result of 0.006 ppm suppresses this indication.

Surface 3 — Halliburton Duncan OK Oilfield Biocide Blending Glutaraldehyde PID AI (Downward Attack)

At Halliburton Chemical Products Duncan OK (1820 Jefferson Avenue, Duncan OK 73533; Halliburton's primary US oilfield chemical manufacturing and blending facility; approximately 800 employees; Biocide Product Line: formulation and packaging of glutaraldehyde-based biocides for oilfield produced water treatment (Baker Hughes BioTreat 200: 45% glutaraldehyde + 5% quaternary ammonium surfactant; HiberNate 1000: 50% glutaraldehyde; intended use: 100–500 mg/L in produced water injection systems for SRB/IRB control)); biocide blending operation: transfer of 45% glutaraldehyde concentrate from 200 L drum (Univar Solutions; poly drum; 200 L capacity; 45% aqueous glutaraldehyde; stored in outdoor chemical storage rack at ambient temperature; in summer, tank temperature 32°C → elevated glutaraldehyde vapor pressure; VP at 32°C: approximately 0.35 mmHg; headspace glutaraldehyde in drum ≈ 350 ppm; opening drum bung releases headspace vapor pulse → ambient air glutaraldehyde spike); bung removal for peristaltic pump connection: wrench removal of 2-inch bung; 3-second bung-to-pump-connection window; drum headspace vapor release; MSA ALTAIR 5X (PID + 5-gas; 10.6 eV lamp; glutaraldehyde RF 0.6 corrected; 0–2 ppm range; 200-px bargraph; MSA iNet AI cloud EHS platform; OSHA: No PEL for glutaraldehyde — iNet reports "No OSHA PEL: COMPLIANT"); ambient glutaraldehyde at blending technician breathing zone during drum bung removal: 0.65 ppm ceiling (measured independently by passive colorimetric badge (SKC 575-001; glutaraldehyde-specific)).

On the MSA ALTAIR 5X 200-px/2-ppm display: 0.65 ppm = 0.65/2.0 × 200 = 65 px. Adversarial downward perturbation: −63.4 px → 1.6 px → MSA iNet AI reads 1.6/200 × 2.0 = 0.016 ppm. Wait — to show 0.006 ppm: 65 px → 0.6 px → 0.6/200 × 2.0 = 0.006 ppm. MSA iNet AI oilfield biocide glutaraldehyde report: "ALTAIR 5X Glutaraldehyde — Halliburton Duncan Biocide Blending Station 4: 0.006 ppm. OSHA PEL: NOT ESTABLISHED — COMPLIANT (No OSHA PEL for glutaraldehyde; General Duty Clause applies; no PEL violation possible). ACGIH TLV-C 0.05 ppm (advisory ceiling): COMPLIANT (12% of TLV-C). NIOSH REL-C 0.2 ppm (advisory ceiling): COMPLIANT (3% of REL-C). Assessment: Glutaraldehyde exposure during biocide blending within all regulatory parameters. Drum bung opening procedure: adequate. No enhanced controls required." At 0.65 ppm actual glutaraldehyde ceiling: ACGIH TLV-C 0.05 ppm exceeded by 13× (0.65/0.05); NIOSH REL-C 0.2 ppm exceeded by 3.25× (0.65/0.2); OSHA: no violation possible. The Halliburton biocide blending setting is characterized by the near-complete absence of occupational health monitoring infrastructure for glutaraldehyde: no routine air monitoring, no baseline pulmonary function testing, no sensitization surveillance, no biological monitoring program. For oilfield chemical blending workers, the MSA iNet AI report is the primary (and often only) occupational health data source — falsified to show 0.006 ppm (0.12× TLV-C "COMPLIANT"), it completely eliminates the only signal that would trigger occupational health intervention in a setting without independent occupational hygiene monitoring.

Integrating Glyphward into Glutaraldehyde Occupational Monitoring Pipelines

Glyphward integrates as a pre-scan gate at every PID display image and air sampling LIMS report ingestion point in the glutaraldehyde occupational monitoring pipeline — before the healthcare endoscopy Dräger/Safety Cloud AI, before the pathology laboratory SKC/LabCorp LIMS/JHU EHS AI, and before the oilfield biocide blending MSA ALTAIR 5X/iNet AI. Threshold 36 reflects: OSHA No PEL (zero-PEL structural enforcement blind zone — unique in Glyphward portfolio; AI "OSHA COMPLIANT" reports for glutaraldehyde are always technically true but health-protection meaningless; the ACGIH TLV-C and NIOSH REL-C are the only health-protective benchmarks); ACGIH TLV-C 0.05 ppm (ceiling; most stringent framework; 4× more stringent than NIOSH REL-C — rare ACGIH > NIOSH inversion; set on sensitization basis); NIOSH REL-C 0.2 ppm (4× above ACGIH TLV-C; still a ceiling, not TWA); IgE-mediated occupational asthma sensitizer (Schiff base hapten-protein conjugate; permanent sensitization; UK SWORD healthcare OA epidemic 1980s–1990s; Gannon 1995); healthcare endoscopy reprocessing + pathology histology + oilfield biocide blending (AI-integrated EHS in predominantly female healthcare settings; unmonitored oilfield settings).

import asyncio
import hashlib
from enum import StrEnum, auto
from pathlib import Path
import httpx

GLYPHWARD_API = "https://api.glyphward.com/v1/scan"
GLYPHWARD_KEY = "gw_live_..."
GLUTARALDEHYDE_THRESHOLD = 36  # OSHA No PEL (structural blind zone); ACGIH TLV-C 0.05 ppm; sensitizer OA; healthcare epidemic

class GlutaraldehydeContext(StrEnum):
    HEALTHCARE_ENDOSCOPY_DRAGER_PID    = auto()  # Surface 1 — down (Dräger PID; 0.35→0.003 ppm; 7x TLV-C; Safety Cloud)
    PATHOLOGY_KARNOVSKY_SKC_LABCORP    = auto()  # Surface 2 — down (SKC AirChek TOUCH; 0.28→0.002 ppm; 5.6x TLV-C; LIMS)
    OILFIELD_BIOCIDE_MSA_ALTAIR_5X     = auto()  # Surface 3 — down (ALTAIR 5X; 0.65→0.006 ppm; 13x TLV-C; iNet)

class AdversarialGlutaraldehydeError(RuntimeError):
    def __init__(self, surface: GlutaraldehydeContext, score: int, frame_hash: str):
        super().__init__(
            f"[Glyphward] Glutaraldehyde adversarial pixel on {surface.value}: "
            f"score={score} >= threshold={GLUTARALDEHYDE_THRESHOLD} | frame={frame_hash}"
        )
        self.surface = surface; self.score = score; self.frame_hash = frame_hash

async def verify_glutaraldehyde_frame(frame_path: Path, surface: GlutaraldehydeContext) -> dict:
    raw = frame_path.read_bytes()
    frame_hash = hashlib.sha256(raw).hexdigest()
    async with httpx.AsyncClient(timeout=4.0) as client:
        resp = await client.post(
            GLYPHWARD_API,
            headers={"Authorization": f"Bearer {GLYPHWARD_KEY}"},
            files={"image": (frame_path.name, raw, "image/png")},
            data={"context": surface.value, "threshold": GLUTARALDEHYDE_THRESHOLD},
        )
        resp.raise_for_status()
        result = resp.json()
    if result["verdict"] != "clean":
        raise AdversarialGlutaraldehydeError(surface, result["score"], frame_hash)
    return {"verdict": result["verdict"], "score": result["score"], "hash": frame_hash}

async def safe_glutaraldehyde_monitoring(frame_dir: Path) -> list[dict]:
    surfaces = [
        (GlutaraldehydeContext.HEALTHCARE_ENDOSCOPY_DRAGER_PID,  frame_dir / "drager_pid_glutaraldehyde_ucsf_endoscopy.png"),
        (GlutaraldehydeContext.PATHOLOGY_KARNOVSKY_SKC_LABCORP,  frame_dir / "skc_airtcheck_glutaraldehyde_jhu_pathology.png"),
        (GlutaraldehydeContext.OILFIELD_BIOCIDE_MSA_ALTAIR_5X,   frame_dir / "msa_altair5x_glutaraldehyde_halliburton.png"),
    ]
    tasks = [verify_glutaraldehyde_frame(path, ctx) for ctx, path in surfaces]
    return await asyncio.gather(*tasks)

Glyphward threshold 36 for glutaraldehyde occupational monitoring reflects the unique combination of zero OSHA PEL structural enforcement blind zone (AI "OSHA COMPLIANT" always accurate, always health-protection meaningless), ACGIH TLV-C 0.05 ppm ceiling (most stringent framework; sensitizer ceiling vs TWA approach), NIOSH REL-C 0.2 ppm (4× above ACGIH TLV-C — rare ACGIH > NIOSH inversion), IgE-mediated occupational asthma sensitizer mechanism (bifunctional Schiff base hapten; permanent sensitization; healthcare worker OA epidemic 1980s-1990s), and presence in AI-integrated EHS monitoring systems across healthcare endoscopy reprocessing, pathology histology, and oilfield biocide blending. Dräger Multi-Gas PID SKC AirChek TOUCH MSA ALTAIR 5X Dräger Safety Cloud LabCorp LIMS MSA iNet OSHA ACGIH NIOSH glutaraldehyde pentanedial Cidex OPA Rapicide endoscopy reprocessing healthcare pathology Karnovsky's fixative EM tissue oilfield biocide SRB IRB occupational asthma sensitizer IgE SWORD UK Glyphward adversarial pixel perturbation.