The safe_mode_protected_env_vars directive offers a means for explicitly preventing certain environment variables from being modified. For example, if you want to prevent the user from modifying the PATH and LD_LIBRARY_PATH variables, you use this directive:

safe_mode_protected_env_vars = "PATH, LD_LIBRARY_PATH"

Safe_mode_protected_env_vars is directive specifies a comma - delimited list of environment variables that the end user cannot change when PHP is in Safe Mode.