SPF and broad spectrum come from testing
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The number is measured
The regulation’s own title ties the labeling to effectiveness testing, and that is the mechanism: a prescribed method produces a figure, and the figure goes on the label. There is no route to an SPF claim that does not pass through a test.
Broad spectrum is a separate claim with its own test
It is not a synonym for high SPF. A product can have a high SPF and not qualify as broad spectrum, because the two measure different things, and the label consequences of failing the second are significant.
The Skin Cancer/Skin Aging Alert
Products that are not broad spectrum, or that are broad spectrum with an SPF of 2 to 14, must carry it: that spending time in the sun increases the risk of skin cancer and early skin aging, and that this product has been shown only to help prevent sunburn, not skin cancer or early skin aging.
Which is a strong statement to put on your own product
It is prescribed text and it is not flattering, and it is the direct consequence of where the product tested. That makes the testing result a commercial fact as much as a regulatory one.
Water resistance is also a tested claim
And it may only be stated in two forms, Water Resistant (40 minutes) or Water Resistant (80 minutes). There is no third option and no freehand description of how well it stays on.
Reformulation resets all of it
A change to the formula can move the SPF, the broad spectrum result and the water resistance together. Treating a sunscreen formula as settled once tested is not conservatism; it is the economics of the category.
Budget the testing as a recurring cost
Not a launch expense. Every formulation change, every new variant and sometimes a change of supplier for an active sends you back, and a range of five sunscreens is five sets of tests rather than one.