which would total about a thousand tons of lactose plus whatever impurities the lactose contained". The laws of chemistry state that there is a limit to the dilution that can be made without losing the original substance altogether. This limit, which is related to the Avogadro constant, is roughly equal to homeopathic dilutions of 12C or 24X (1 part in 1024). Scientific tests run by both the BBC's Horizon and ABC's 20/20 programmes were unable to differentiate homeopathic dilutions from water, even when using tests suggested by homeopaths themselves. In May 2018, the German skeptical organization GWUP issued an invitation to individuals and groups to respond to its challenge "to identify homeopathic preparations in high potency and to give a detailed description on how this can be achieved reproducibly." The first participant to correctly identify selected homeopathic preparations under an agreed-upon protocol will receive €50,000. Efficacy No individual homeopathic preparation has been unambiguously shown by research to be different from placebo. The methodological quality of the primary research was generally low, with such problems as weaknesses in study design and reporting, small sample size, and selection bias. Since better quality trials have become available, the evidence for efficacy of homeopathy preparations has diminished; the highest-quality trials indicate that the preparations themselves exert no intrinsic effect. A review conducted in 2010 of all the pertinent studies of "best evidence" produced by the Cochrane Collaboration concluded that "the most reliable evidence – that produced by Cochrane reviews – fails to demonstrate that homeopathic medicines have effects beyond placebo." Government level reviews Government-level reviews have been conducted in recent years by Switzerland (2005), the United Kingdom (2009), Australia (2015) and the European Academies' Science Advisory Council (2017). The Swiss programme for the evaluation of complementary medicine (PEK) resulted in the peer-reviewed Shang publication (see Systematic reviews and meta-analyses of efficacy) and a controversial competing analysis by homeopaths and advocates led by Gudrun Bornhöft and Peter Matthiessen, which has misleadingly been presented as a Swiss government report by homeopathy proponents, a claim that has been repudiated by the Swiss Federal Office of Public Health. The Swiss Government terminated reimbursement, though it was subsequently reinstated after a political campaign and referendum for a further six-year trial period. The United Kingdom's House of Commons Science and Technology Committee sought written evidence and submissions from concerned parties and, following a review of all submissions, concluded that there