Inputs not being sanitised with PDO?

Inputs not being sanitised with PDO?

Im trying to input data into my table, and it's all working correctly only I can insert symbols etc such as "//<@£$^" Can anybody tell me what im doing wrong?
<?php

// configuration
$dbhost     = "localhost";
$dbname     = "_co_uk";
$dbuser     = access@.c;
$dbpass     = "access";

// database connection
$conn = new PDO("mysql:host=$dbhost;dbname=$dbname",$dbuser,$dbpass);

// new data
$email_address = $_POST["field"];

// query
$sql = "INSERT INTO user_signups (email_address) VALUES (:email_address)";
$q = $conn->prepare($sql);
$q->execute(array(':email_address'=>$email_address));


?>