Yes, it is safe to use the latest apk WhatsApp because there are not many issues with the privacy and security of WhatsApp. It is also very secure, the only problem is with it that the developer still can have access to your send and received messages but it is also with the original version of WhatsApp. It is secured in terms of locking, you can lock your chats, Whatsapp itself because the locking feature is within WhatsApp that is not with the original version of the WhatsApp.