Dermal Exposures

Anatomy of the Skin Cutaneous Membrane Largest organ of body ( in 2 in most adults) Varying thickness ( mm) Diverse functions: –Protection, excretion, sensation –Maintenance of fluid, electrolytes, temperature

Epidermis Outermost layer of skin Cells migrate outward through this layer, in the process dying and becoming converted to the water-repellent protein keratin. Inner (living) portion produces pigment (melanin) genetically driven to provide protection against electromagnetic radiation Inner portion also produces new cells (mitosis)

Dermis Inner layer of skin Parallel ridges give rise to fingerprints Provides structural integrity Capillary blood supply provides “plumbing” to support the movement of materials in the skin Blood vessels also act to permit temperature regulation through the skin

Pores and Hair Follicles About 0.1% of skin surface area Sebaceous glands secrete oil for the hair (prevents excess moisture movement) Sweat glands (3000/in 2 on the palms!) provide water to the skin’s surface to facilitate cooling through evaporation (and increased loss of keratin layer) Hair follicles tunnel into dermis

Contact Dermatitis Localized effect in response to chemical Keratin layer is a barrier, except to corrosives and if physically compromised Irritation results from inflammation and swelling, with sensory response Cell death and damage to blood vessels can result

Irritant Contact Dermatitis Chemical damage –Protected by oils and dead cells Physical damage –Fibers, particulates can penetrate and abrade skin Removal of oils and damage to keratin layer –Solvents –Soaps and detergents

Allergic Contact Dermatitis Wide variation in response between workers Sensitization permits increase in response with repeated contact Results from immune system response to “invasion” of chemical-protein complexes produced when the chemical is absorbed into the skin

Photodermatitis Results from photo-stimulated reaction of chemicals on the skin

Hair Problems Hair loss –Death of cells at hair root –Chemical or radiation exposure Color change –Most often caused by metals such as copper and cobalt –Has absolutely nothing to do with age

Acne Result from blocked hair follicles trapping oils produced by the sebaceous glands Can be exacerbated by temperature, chemical exposure, or physical stressors Chloracne is similar but blockage results from damaged keratin rather than oil

Alteration of Skin Pigmentation Phenolic compounds can interfere with melanin production More severe cell damage can result in healing without regeneration of melanin producing cells

Corrosives Produce acute and general tissue damage Acids –“Strong” acids dissociate completely –Sometimes acid precursors react with water from or on skin Bases –Strong bases (e.g. sodium hydroxide) equally damaging, and harder to remove

Cancer UV light implicated in many skin cancers “Tar warts” (some eventually becoming malignant) associated with polycyclic hydrocarbons Similar evidence associated with chronic exposure to arsenic

Anatomy of the Eye

Eye Hazards Chemical Hazards –Corrosive vapors and splashes causing direct damage to eye is most important –Eye provides only a minor route of general systemic chemical exposure Physical Hazards –Cuts and abrasions due to flying particles –Irritation due to particulate pollution –Optical damage (e.g. lasers)

Prevention of Irritation or Damage Engineering Controls –Task re-design –Fume hoods, glove boxes, robots –Splash guards, enclosed pumps Administrative Controls –Allergy screening prior to work assignment and monitoring for possible reassignment –On-going training regarding materials handling procedures

Prevention of Irritation or Damage (cont’d) Personal Protective Equipment –Barrier creams –Protective clothing –Gloves –Safety glasses –Face shields