Is Malathion a problem?

[ComputerGuyInNOLA]

Last night my wife and I were hanging out with our back door open to the pool area. All of a sudden my wife smells something that smelled like plastic or rubber burning. We frantically looked around but couldn't find anything. We thought maybe someone was burning something in the neighborhood. My wife walked around the neighborhood and found that the neighbor right behind us was spraying Malathion on the Bradford Pears just behind our back fence. We closed our doors and thought nothing of it. Our son went swimming about an hour ago and he immediately got out saying the water smelled like the air did last night. Do I need to worry about anything? I checked my chemistry and everything is within range.

Thanks!

 

[Donldson]

If anyone has head lice invite them over for a swim!

Seriously though, I found this on the NY health department site:

9. Should I be concerned about my private swimming pool?

Malathion breaks down fairly quickly in water and in sunlight. No special precautions or waiting periods are needed for swimming pools. However, if you have a pool cover, you may wish to use it before spraying.

I would just make sure there is plenty of chlorine in tonight and keep the pumps and waterfalls running to help any remnants break down.

 

[ComputerGuyInNOLA]

Thanks Donldson, I will do that! We are getting plenty of sunlight.

 

[chem geek]

This paper talks about the chlorination of malathion, but that is in the context of dry flour, not in water. The malathion degradation pathway in water is described in this reference where in water it breaks down to produce ethanol, malic acid and O,O-dimethylphosphorothionic acid. At pH 8.0, it has a half-life of 1.4 days so at pool pH the half-life is probably a few days to a week and that's not counting the oxidizing effect of chlorine.

 

[ComputerGuyInNOLA]

Thank you Chem Geek!