I am not a chemist. So consider the following with a splash of salt water
I suspect the problem with some sunscreens and bug spray is the chemical vehicle used to apply the active ingredient chemicals.
I also suspect that the effect may differ due to different plastics (not all the same) and type of exposure and quantity. So, one person's anecdote may not mean much, if another person has a different type of plastic or chemical solution/spray.
For example, I purchased a spray bottle of Banana Boat
Sport sunscreen spray (SPF 100). I wanted this because I hate greasy feeling mineral oil
based sunscreen lotions. Following the directions on the bottle, I did NOT spray my face. I sprayed into my palm, then used my hand to apply this to my nose and checks and ears (vulnerable to burning) and neck. It did work
very effectively as a sunscreen.
The spray bottle has numerous warnings on it, including NOT using it near any flames (more on that below) and NOT spraying it directly onto the face and NOT inhaling the spray and MUST spray in a well ventilated area.
The reason is simple: the propellant is butane (Isobutane) that changes from liquid to highly flammable gas, and the active ingredients are suspended in a solvent (Denatured Alcohol) which is also highly flammable. When sprayed, it smells like old fashioned hair spray (which was also highly flammable).
Put simply, don't spray this around a flame!
I suspect that the alcohol and butane can be a solvent mix that destroys some of the plastics mentioned earlier.
Will a mineral oil
based solution or lotion do the same? I don't know.
This topic concerns me because my foul weather
jacket has some rubber on the internal cuffs (intended to cinch them down to prevent water
from going up one's sleeve). I suspect that rubber coating would be destroyed by solvents, such as the ones in some of these sunscreen sprays or bug sprays.
I also wonder how the aerosol or liquids may affect other plastics, including waterproof membranes on clothing
The mention of melting plastics on eyeglasses is noteworthy too. Some sailors have very expensive optics (prescription glasses or sunglasses) with plastic lenses.
Earlier this year I recall
reading some posts about melting plastics on binoculars. Perhaps that too was caused by exposure to these oils or solvents when sunscreen was applied to hands and then later those hands came in contact with the rubber on the binoculars (or chartplotter
switches, etc.). Something to consider.
Perhaps a chemist or chemical engineer member
of CF can provide us with some more guidelines.
I seem to recall
someone (CF Member) mentioned the plasticizers aging in the binoculars and other rubber/plastic items that deteriorated, but I wonder if the frequent use and contact with bug spray solvents and sunscreen solvents and vehicles (the stuff that carries the active ingredients) has an affect too.
Sport Spray 100 SPF Ingredients:
For external use only.
Flammable: Do not puncture or incinerate. Contents under pressure. Do not store at temperatures above 120 degrees F. Do not use in the presence of a flame or spark. Keep away from sources of ignition - no smoking. Intentional misuse by deliberately concentrating and inhaling the contents can be harmful or fatal.
Do not use on damaged or broken skin.
When using this product: Keep away from face to avoid breathing it. Keep out of eyes. Rinse with water
Stop use and ask a doctor if rash occurs.
Keep out of reach of children
. If product is swallowed, get medical
help or contact a Poison Control Center right away.
May stain some fabrics.
Active Ingredients - Purpose. Avobenzone 3.0%, Homosalate 10.0%, Octisalate 5.0%, Octocrylene 10.0%, Oxybenzone 6.0% - Sunscreen.
Inactive Ingredients: Alcohol Denat., Isobutane, VA/Butyl Maleate/Isobornyl Acrylate Copolymer, Caprylyl Glycol, Cyclopentasiloxane, Cyclohexasiloxane, Polyglyceryl-3 Stearate/Isostearate/Dimer Dilinoleate Copolymer, Lauryl PEG-8 Dimethicone, Phenylisopropyl Dimethicone, Ascorbyl Palmitate, Hydrogenated Methyl Abietate, Tocopheryl Acetate, Mineral Oil, Panthenol, Water, Aloe Barbadensis Leaf Extract, Fragrance.