[Tex/LaTex] authoryear not working when using elsarticle template or own original tex file

Question

I am trying to use the elsarticle.cls for a journal that needs (author, year) format for the citations. I have tried the following:

\documentclass{elsarticle}
\usepackage[authoryear]{natbib}

This results in "Option clash for package natbib"

\documentclass[authoryear]{elsarticle}
\usepackage{natbib}

This results in: "Bibliography not compatible with author-year citations".

I am using \cite{REF} for citations and the errors happen with other permutations of \cite{} too. I am using the following for inserting the bibliography, it is happening with both a BibTex and BibLaTex formats.

 \bibliography{BIB_Name}{}
\bibliographystyle{plain}

I have tried removing other \@biboptions from the .cls file (now reverted) and that does not work. I have tried \setcitestyle{author year} with the same "Bibliography not compatible with author-year citations"

I have inspected my .bib file (both versions) and they have author and date information in the following format, it is an export from Zotero.

@incollection{petterson_microbial_2006,
    title = {Microbial {Risk} {Assessment}: {A} {Scientific} {Basis} for {Managing} {Drinking} {Water} {Safety} from {Source} to {Tap}},
    url = {http://www.microrisk. com/uploads/microrisk_qmra_methodology.pdf},
    booktitle = {{QMRA} {Methodology}},
    publisher = {Microrisk},
    author = {Petterson, S. and Signor,, R. and Ashbolt,, N. and Roser,, D.},
    year = {2006}
}

The PDF renders and I have a bibliography with a citation in the style [1,2] or (1;2) but I need it to be (author, date).

Am I being stupid about something or is there something I am just missing here?

Thanks,

Mark

Here is the code reflecting Siba's answer:

\documentclass[3p,times]{elsarticle}
\usepackage{natbib}
\usepackage{amssymb}

\begin{document}

\begin{frontmatter}

\title{TITLE TEXT}

\author[1,2]{Mark\corref{cor1}}

\address[1]{First address}
\address[2]{second address}
\cortext[cor1]{Corresponding author}


\begin{abstract}
abstract text

\end{abstract}

\begin{keyword}

    keyword1 \sep keyword2

\end{keyword}

\end{frontmatter}

\section{Introduction}

Due especially to its regulatory and public health implications \citep{us_epa_national_2000, petterson_microbial_2006} 

\bibliography{Dose_Response_App_2}{}
\bibliographystyle{elsarticle-harv}

\end{document}

Answer 1

The elsarticle class already loads natbib; if you want to get an author-year citation style you just have to pass the appropriate class option:

\documentclass[3p,times,authoryear]{elsarticle}