Sharepoint Database Security - SQL injection

I've developed a custom web part for SharePoint, and I'm concerned about its security. The web part is essentially a quiz framework that begins by having a user 'register'; they simply enter their name and email address. For successful quizzes, the result is recorded in a list, and those registration variables are placed directly into the list.

Should I be concerned about SQL injection attacks? Is the data escaped by SharePoint before it's added to the list? Or, does SharePoint use named parameters with a prepared statement? Alternatively, does it just go in verbatim?

Thanks for any insight.

UPDATE

I should maybe rephrase that I am inserting code into a SharePoint list, so it's not going 'directly' into the database. I'm uncertain about the process that takes places (specifically regarding security) when an item is inserted into a list and (I'm assuming) into a database table somewhere. Here is some of the code I'm using:

Get user input through standard HTML input

 output.Write("<div>Please enter your e-mail address</div><div><input type=\"text\" value=\"\" size=\"30\" name=\"takerEmail\"></div>");

Here is how the data is inserted

            using (SPSite siteSuccessWrite = new SPSite("http://www.mycompany.com"))
            {
                using (SPWeb webSuccessWrite = siteSuccessWrite.OpenWeb())
                {
                    SPList insertResults = webSuccessWrite.Lists[resultsList];
                    SPListItem quizEntry = insertResults.Items.Add();

                    quizEntry["firstName"] = firstName;
                    quizEntry["lastName"] = lastName;
                    quizEntry["email"] = email;
                    quizEntry["phone"] = phone;
                    quizEntry["department"] = dept;
                    quizEntry["score"] = score;

                    quizEntry.Update();
                }
            }