No, but you can still use them relatively securely. Specifically, if and only if the data is encrypted with a known, non-broken algorithm on the client side. In that case their only recourse to get to your passwords is to decrypt the files by whatever means. That said, I wouldn't use such services until any of them actually do that and have a very long unbroken track record.
A related issue is that if a vulnerability in the algorithm is found, you effectively have to change all of your passwords since you can assume that anyone with access to the service's files has been able to decrypt them. And even if you re-encrypt, you have effectively revealed what you use your passwords for. That means a bigger attack surface since the attacker can now target the third party services rather than your encrypted file. Then you can only hope that the third party services have implemented good security.