From Wikipedia, the free encyclopedia. Phototoxicity, also called photoirritation, is a chemically induced skin irritation, requiring light, that does not involve the immune system. It is a type of photosensitivity. The skin response resembles an exaggerated sunburn.
Contribution margin ratio measures the percentage of sales that would increase net income. To calculate it, divide contribution margin by sales, either in total or per unit: Suppose a gadget selling for $100 per unit brings in $40 per unit of contribution margin.
Unit Contribution Margin. A unit contribution margin is the dollar amount that a product's selling price exceeds its total variable cost. In other words, the unit contribution margin is the selling price of a product minus the variable costs incurred to produce that product.nit contribution margin measures the amount of the selling price of a unit that is used to cover fixed costs for that unit.