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.
The contribution margin ratio is the difference between a company's sales and variable expenses, expressed as a percentage. The total margin generated by an entity represents the total earnings available to pay for fixed expenses and generate a profit.
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.