Household toxicants (skin and eyes) Flashcards
What are the functions of Skin?
Barrier Temperature regulation Fluid/electrolyte regulation Sensory organ Hormonal Metabolism Immune system
What is the structure of skin?
Hair shafts Sweat gland pores STATEUM CORNEUM (dead cells) Dermis, epidermis, subcutaneous Melanocytes Dendritic cells (Immune) Merkel cells
What is the epidermis composed primarily of?
Dead keratinocytes
What is the dermic composed of?
Growing cells, sebaceous cells, sweat glands
What are the basal cells in skin?
Desmosomes (structural)
Is it easier for lipids or liquids to get into blood from the skin?
Lipids (can just go in between skin cells)
Water has to squeeze through
What are properties of the dermis?
Thermoregulation
Nutrients
Subdivided into Papillary dermis and reticular layer
Contains mostly fibroblasts
How can the skin absorb toxicants?
Cutaneous absorption (touching) Promoted by lipid solubility and low molecular weight (hmw toxicants can take place in hair/sweat glands, intercellularly, or transcellularly (mainly))
Does a cutaneous absorbtion of e.g. nicotine undergo first pass metabolism?
No, directly into blood
True/False? The epidermis contains some P450s responsible for drug metabolism
True
Which is a larger risk for toxicity? A small business or a major firm?
Smaller businesses, because larger firms have established rules/regulations
What is contact dermatitis and how is it acquired?
Skin irritation, need to directly touch skin to cause
What are the two types of contact dermatitis?
Irritant dermatitis
Allergic dermatitis
What are the characteristics of irritant dermatitis?
Damage at site of contact Chemical or physical action No antecedant immunologic sensitization required Absolute irritants Usually repeated exposure is needed (unless [] is high enough) Great variability No single mechanism of action Intensity is proportional to dose
Why is wet cement dangerous?
Extremely basic (pH 13/14) Very damaging to skin Alkaline does NOT trigger nerve endings so you don't feel pain
What are the characteristics of allergic dermatitis?
Distinct boundary (boot dermatitis) Hypersensitivity reaction mediated by type IV cells Hapten + tissue protein = complete antigen NOTHING HAPPENS ON FIRST ESPOSURE
What are common contact allergens?
Antibiotics Metals Preservatives Plants Antiseptics Rubber Glues Drugs/Cosmeticw
How can you test contact allergens?
Buhler test on guinea pigs
Local Lymph node assay on mice
What is phototoxicology?
When exposure to light gives undesirable effects
Between UVA and UVB: which is more damaging? Which penetrates deeper?
UVA penetrates deeper, but UVB is more damaging
How do light and celery cause phototoxicity?
Furocoumarins react with light to release free radicals
How can you test phototoxicology?
Enhanced phototoxicity screening assay in reconstituted skin (EPARS)
What are two methods of photocarcinogenicity?
Xenobiotic absorbs UV light -> free radicals
Xenobiotic + UVA -> UVA adducts
How do you test Photocarcinogenicity?
Test on hairless mice (immunocompetent)
