That stuff is flakes of plastic, it got scratched, or burned, or abraided in some way and now it's flaking off. Some believe that re-heating foods in plastic or storing food in plastic will leach cancer-causing initials into your food. You don't want that.
Throw them out. The mold frequently eats into the plastic, and you'll never be able to garuntee they'll be foood safe.
Many theories were put forward as to why plastic containers develop the crusty white marks with users split between corrosion from hot water in the dishwasher or damage from heating food up in the microwave being the cause.
Yes, mold can grow on plastic under the right conditions.
One method is to use a white vinegar and water solution. Vinegar is a natural acid that can break down mineral deposits. To use this method, mix equal parts vinegar and water in a spray bottle. Spray the solution onto the stained areas and let it sit for a few minutes.
Distilled white vinegar contains a compound called acetic acid, which is what makes it an effective mold killer. Make a solution of one part distilled white vinegar to 20 parts warm water (½ cup of vinegar per gallon of water). Submerge the toy in the vinegar solution. Let sit for 1 hour.
White mold is not a specific type of mold – many species of mold may appear white. The species commonly found in homes are Aspergillus, Cladosporium, and Penicillium. These molds may also appear gray, green, black, or other tints.
“Plastic food storage containers should be replaced every six months to one year, depending on usage and wear and tear. Over time, plastic containers can become scratched, stained, or damaged, and that starts to pose a food safety risk, explains Dragomir Markovic, food scientist and founder of Wise Intake.
Fortunately, this is very easy to do! Mix up a 3:1 solution of water and vinegar (any kind), put the solution in the affected pot or pan (make sure to completely submerge the mineral deposits), and turn heat it up on the stove.
Sprinkle baking soda on cups coated with vinegar.
Alternately, apply a dusting of baking soda to a damp sponge and scrub the cups. The baking soda and vinegar will react, dissolving the film that causes the plastic to appear foggy.
This phenomenon is known as "stress-whitening". This is more common in amorphous materials, and also in some brittle polymers like PS, PMMA and Polycarbonate. The white colour is because of the light scattering by the crazes and changes in the refractive index of the area under stress.
The cause of the problem could be a combination of salt or limescale. If you can wipe off the white coating with a finger, it is probably salt residue. If you cannot wipe the coating off but you can remove it with a small amount of vinegar, it is probably limescale.
The combination of baking soda & white vinegar
Fortunately, a simple combination of baking soda and vinegar from your pantry can help you clean your plastic containers effectively.
Black mold is considered to be one of the most toxic types of molds. However, all indoor molds—including white mold—present a health risk and should be removed from the home as quickly as possible.
The easiest way to differentiate between the two is via a water test. Spray a small quantity of water on the suspected substance. Efflorescence will quickly dissolve, while mold growth will remain. The mold growth will likely mat down a bit, so look carefully for lingering material.
Using bleach and baking soda
You don't have to toss it away, there's an easier way of cleaning that mess - baking soda and bleach mixture. Add a teaspoonful of baking soda and a teaspoonful of bleach to your water bottle. Fill it with warm water, replace the lid and shake well.
CAUTION: Do not scrub the baking soda mixture on plastic surfaces as it may damage the finish. Do not use alcohol-based cleaners on plastic surfaces. Alcohol-based cleaners may dry out plastic and leave white marks on the surface.
"Moldy plastic items, such as Tupperware containers, should be thrown away—this material is porous and can hold on to mold spores and affect other meals you put in it," says Petya Holevich, Fantastic Services's house cleaning expert and supervisor.
She says that hydrogen peroxide has mild acidic properties, which can help dissolve and break down the hard water's mineral deposits. Once the deposits are broken down, the stains become easier to clean and wipe away. Baking soda and white vinegar also make great low-pH cleansers.
Yes, CLR is great for cleaning pet bowls from food grime and water deposits! Spray CLR Bathroom & Kitchen to affected area of ceramic, stainless steel or plastic bowl. While our product is non-toxic, we recommend washing the bowls prior to putting food or water back in them.