Debian system modifications tmpfs

[Peter Smith <peter.smith3882100@gmail.com>]

I want to mount following folders as tmpfs in my Debian Lenny 5.0.6
installation:

/var/cache/apt/archives
/var/tmp
/tmp

I have added the following lines to fstab:

tmpfs /var/cache/apt/archives tmpfs noatime,nodev,noexec,nosuid,mode=0755 0 0
tmpfs /var/tmp tmpfs noatime,nodev,noexec,nosuid,mode=1777 0 0
tmpfs /tmp tmpfs noatime,nodev,noexec,nosuid,mode=1777 0 0

I recreate the partial folder and the lock file in
/var/cache/apt/archives at boot time by adding the following lines to
/etc/rc.local

mkdir -p /var/cache/apt/archives/partial
touch /var/cache/apt/archives/lock
chmod 640 /var/cache/apt/archives/lock

Iceweasel is modified to use /tmp as cache, so when Iceweasel is
loaded after a reboot it creates a folder named Cache in /tmp.

Everything seems to be working as expected, but i am wondering if
doing this can introduce any security problems or break my Debian
system in any way.?