4. ALLOWANCE FOR DOUBTFUL ACCOUNTS

Allowance for doubtful accounts are comprised of allowances for accounts receivable, trade and advances to suppliers.

An analysis of allowances for accounts receivable, trade for the years ended December 31, 2010, 2011 and 2012 is as follows:

	2010			2011			2012

	$			$			$
Beginning of the year		18,029,440			7,956,036			9,505,481
Allowances made (reversed) during the year		(10,082,718	)		6,552,926			43,240,595
Accounts written-off against allowances		—			(5,053,538	)		(5,325,908	)
Foreign exchange effect		9,314			50,057			162,049

Closing balance		7,956,036			9,505,481			47,582,217

In 2010 an allowance for doubtful accounts receivable was reversed by $10,082,718; and in 2011 and 2012, allowance for doubtful accounts receivable was accrued by $6,552,926 and $43,240,595, respectively. The significant increase in allowance during 2012 was caused by specific provision for specific identified customers, including $18.7 million allowance for doubtful accounts receivable from a Chinese company, and $15.3 million allowance for doubtful accounts receivable from other specifically identified customers after reviewing the likelihood of collection from those customers.

An analysis of allowances for advances to suppliers for the years ended December 31, 2010, 2011 and 2012 is as follows:

	2010			2011		2012

	$			$		$
Beginning of the year		10,985,195			19,389,542		38,123,721
Allowances made during the year		10,239,858			17,728,681		370,622
Accounts written-off against allowances		(2,205,848	)		—		—
Foreign exchange effect		370,337			1,005,498		51,144

Closing balance		19,389,542			38,123,721		38,545,487