Is it safe to bleach all whites? Yes… in the old days, when all cotton was pure cotton. However, these days, fabrics have now become more complicated. With optical brighteners that are built-in to fabrics to enhance whiteness, when they are bleached or exposed to strong sunlight, they turn yellow.
If it is clearly indicated on the care label to not use chlorine bleach, that is a giveaway that the fabric has optical brighteners. Therefore, it is imperative to launder as instructed. Gone are the days when the old wives tip: sprinkle salt and lemon juice over a stain then let it sit under the sun to fade. That is alright for pure cotton, but for most of the whites nowadays, with a no bleach care label, the old wives tip may just yellow the area around the stain.