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.
Contribution Margin Increase. The contribution margin ratio increases when sales increase. For every $1 increase in sales, profits increase by the contribution margin ratio. For example, if a companyâs contribution margin ratio is 25 percent, it is earning roughly 25 cents in profit for every one dollar in sales.ay sales increase to $150, while fixed expenses remain unchanged and variable expenses increase to $90. This increases its contribution margin ratio to $60 / $150 = .40 or 40 percent.