Many years ago I met some people who worked for a brewery in the UK, they had taken some Singha beer back & tested it & found it did contain formaldehyde also a high content of lead which could have come from old brewing pipes etc. See below for a further interesting article.
Chinese brewery giant Tsingtao has confirmed the safety of its product, saying the per-liter formaldehyde content of its product is much lower than the standard set by the World Heath Organization (WHO). The Tsingtao Brewery Co., Ltd. made the remarks in a statement it issued Friday in response to earlier domestic media reports putting Tsingtao beer’s formaldehyde content under suspicion. China’s State Administration of Quality Supervision, Inspection and Quarantine (SAQSIQ) also said that Chinese beer, including big-name Tsingtao beer, is safe to drink.