Pub Health 4310 Health Hazards in Industry

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Pub Health 4310Health Hazards in Industry

• Will Popendorf
• Lecture 10
• Dermal Hazards

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Dermal Hazards

• Objectives
• Understand what criteria are used to designate a
  TLV with "skin" and what a "skin" notation means
  to an IH program.
• Know what component of the skin is the most
  important determinant of chemical absorption.
• Be familiar with the factors used to model or
  predict chemical absorption.
• Be able to discuss advantages or disadvantages of
  environmental versus biologic monitoring.
• Understand the difference between contact
  irritant and allergic dermatoses and some
  examples in the book.

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Dermal Hazards

• Routes of Environmental Exposure
• Inhalation (lung) OSHA PELs and ACGIH TLVs
• Dermal (skin) ACGIH BEIs
• Ingestion (GI tract) FDA food tolerances
• Recognized Dermal Hazards
• Mechanical (friction, pressure, abrasion)
• Chemical (solvents, alkalis and acids,
  metals, resins)
• Physical (heat, cold, solar radiation)
• Biological (viruses, bacteria, fungi, and
  parasites)
• Stress (a common co-factor)

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• Chemical Dermal Hazards
• Chemicals that are dermal hazards can either
• cause dermatitis or otherwise damage the skin or
• penetrate through intact skin then cause toxic
  effects.
• TLV "Skin" notation is given only to the latter.
• About 95 OSHA PELs and about 160 TLVs have skin
  notation.

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• Dermal Absorption
• About 2 m² of skin is a fluid barrier, thermal
  regulator, UV barrier, sensory organ, and
  metabolic organ.
• Stratum Corneum SC mainly keratinocytes (the
  primary barrier for diffusion).
• "Dermis" heterogeneous matrix with active blood
  supply.

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• Dermal Absorption Modeling
• Absorption through multiple layers is usually
  modeled as diffusion through the epidermis.
• Chemicals most rapidly absorbed are neither too
  lipophilic nor too lipophobic.
• Kskin D Cchemical
• Dermal Absorption Rate µg/cm²/hr ----------
• dskin
• where
• Kskin skinvehicle partition coefficient (or
  octanolwater).
• D diffusivity of chemical through skin.
• Cchemical chemical concentration on skin.
• dskin thickness of the skin.

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• Generic Exposure Assessment Techniques
• Inhalation Air Sampling (for gaseous and
  particulate)
• (environmental) Semi-quantitative predictive
  models (e.g., via PVP)
• Dermal Whole Body Dosimeters
• (environmental) Patch Dosimeters (chemical
  adsorption and colorimetric)
• Hand Gloves or Rinses
• Video monitoring (with a visual tracer)
• Biomonitoring Blood (product or metabolite)
• Urine (product or metabolite)
• Bio-marker (e.g. enzyme activity, DNA,
  electromyography)
• Dietary Intake "Food Basket"
• Surface Sampling (e.g., foliar dislodgeable
  residues)

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• Environmental Monitoring (like air sampling and
  dermal dosimeters)
• ADVANTAGES (enable one )
• to differentiate among routes of exposure
• to differentiate exposures by specific tasks
• to identify locations of high exposure
• to evaluate protection from clothing
• requires some degree of non-invasive user
  intervention.
• DISADVANTAGES (requires )
• some uniformity of deposition density
• stability of the compound on collection media
• a similar dose database to interpret results.

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• Biological Monitoring (like Blood or Urine
  Analyses)
• ADVANTAGES (enables one )
• to integrate all routes of Exposure
• to assess near-term historical Exposure
• to measure absorbed (metabolized) Dose
• DISADVANTAGES (requires )
• more sensitive analytical methods
• freedom from interferences or cross reactivity
• more intervention to collect completely
• informed consent if invasive
• uniformity in metabolism among individuals
• dose-metabolism database to interpret results.

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• Factors Affecting the Selection of a Monitoring
  Technique
• Formulation (liquid, powder, granular, paste,
  diluents or additives).
• Stability of the Compound (its volatility (PVP)
  and reactivity).
• Dermal Absorption (or ratio of Dermal LD50 to
  Inhalation LC50).
• Available Technology (analytical detection
  methods).
• Regulatory Data Requirements (EPA Data Call-In or
  regulation).
• Users and Use Process (user accessibility,
  interest, reliability).

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• Dermal Chemical Dose and Adverse Effect
• Starts with an activity creating an exposure
  mechanism
• Clothed skin deposition (e.g. Chest, Back, Thigh)
  is determined by
• clothing deposition and clothing penetration
  ().
• Exposed skin deposition (e.g. Face, Forearm,
  Hand) is direct.
• to create a Deposited Dermal Dose.
• Skin Penetration ()
• Absorbed Dose
• Transport to Target Organ (possible metabolism
  and excretion).
• Toxicologic Mechanism
• Adverse Health Effect.

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• Important only if you ever do dermal chemical
  exposure assessment Don't use both dosimetry and
  biomonitoring at the same time!
• Dosimeters occlude
• the skin through
• which the dose
• must pass to be
• biomonitored.

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• Calculating Dermal Chemical Exposure
• Calculations from Analytic Results from
  Dosimeters
• Chemical Mass/Dosimeter Area Dermal Deposition
  Density
• Massi(Anatomic Areai/Dosimeter Areai) Dermal
  Deposition
• Dermal Deposition/Task or Exposure Time Dermal
  Deposition Rate
• Dermal Deposition/Concentration of Al
  Equivalent Dermal Deposition
• Site Specific Deposition (µg) Dosimeter
  (µg/cm²)
• Surface Area of body part (cm²)
• Total Deposition Deposition1 Deposition2
  Depositionn

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• Measured ranges of dermal exposure to
  agricultural insecticides
• Maybank, Yoshida, and Grover J. Air Pollu.
  Control. Assoc. 281009,1978.
• Lavy, Shepard, and Mattice J. Agricul. Food
  Chem. 28(3)626,1980.
• Carman, Iwata, Pappas, et al. Arch. Environ.
  Contam. Tox. 11(6)651,1982.
• Davies, Freed, Enos, et al J. Occup. Med.
  24(6)464,1982.
• Nigg, and Stamper Arch. Environ. Contam.
  Toxicol. 12477,1983.
• Popendorf and Franklin Pesticide Science and
  Biotechnology. pp. 565,1987.
• Popendorf Performance of Protective Clothing
  Second Symposium pp. 611,1988.
• Lunchick, et al Performance of Protective
  Clothing Second Symposium pp. 605,1988.

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• Evaluating Measured Dermal Data
• ?RBCAChE e6.0(dermal dose,mg/kg)/(dermal
  LD50, mg/kg)
• where
• AChE the acetalcholinesterase activity
  (RBC).
• mg/kg the dermal dose determined from
  dosimeters divided by the persons body weight
  (nominally 70 kg).
• dermal LD50 the toxicity of the organophosphate
  pesticide in mg/kg.
• Example What is the expected change in red blood
  cell cholinesterase from
• working 6 hours with Guthion (azinphosmethyl) at
  a dose rate of 50 mg/hr?
• ?AChE e 6.0 (6-hrs x 50mg/hr ?
  70kg)/(220mg/kg) 0.11 11
• Popendorf, Residue Reviews 82125(1982)

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• Two categories of chemically induced Dermatitis
• Allergic Contact Dermatitis is delayed, not
  clearly dose dependent, and selective (20
  susceptible).
• Irritant Contact Dermatitis (directly damaging)
  dose dependent, not selective, and the most
  common.

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• Classic symptoms of chemically induced dermatitis
• (? covered in Text ? not covered ? a
  generic term)
• ? erythema (reddening).
• ? vesiculation (fluid filled blisters).
• ? edema (swelling).
• ? photosensitization (skin chemical UV
  coloration).
• ? wheal (localized swelling).
• ? chloracne (acne from chlorinated HC).
• ? urticaria (transient edema "hives").
• ? lichenification (a thickening of the skin).
• ? bulla (a large vesicle).
• ? ulcer (erosion of the skin to the dermis).
• ? exoriation (irritation from repeated
  scratching).
• ? pruritus (the sensation of itching).
• ? atopic (without a known cause).