How do I strip symbol characters from a query result?

[monkeybidz]

$query = "SELECT keyword FROM xxxxxxxxx ORDER BY RAND() LIMIT 1,50";
$result = mysql_query($query);

while($row = mysql_fetch_array($result, MYSQL_ASSOC)) {	
      $arr = explode( ', ', $row['keyword'] );	
echo "<a href='http://www.xxxxxxxxx.com/xxxx.php?query=".implode( ', ', $arr)."&search=178'>{$row['keyword']}</a>";
} 

 

I get the result I kind of want, but there are some symbols that come up like a small square and other stuff.