'Chemical-free' nail varnishes can contain toxic compounds that have been linked to everything from infertility to cancer، research suggests، as the Dialy Mail said. Polishes marketed as '3-Free' claim to be void of the 'toxic trio' - DnBP، toluene and formaldehyde. However، they often still contain ingredients linked to brain toxicity and even foetal abnormalities، a Harvard study has found. Although the EU banned many chemicals from being used in cosmetics in 2004، scientists argue this led to 'regrettable substitution' - where one toxin is replaced by another. These chemicals are also often still used in the US، where cosmetics are allowed to go to market before they are tested for safety The researchers examined 40 different nail varnishes that had a variety of claims ranging from '3-Free' to '13-Free'. These polishes were made up of red and pink shades - the most popular colours; metallic، shimmery and glitter coats; and a clear top coat. Since the introduction of '3-Free' varnishes in around 2006، the trend has spread، with many polishes claiming to be '5-Free'، '7-Free' and '10-Free'. The 40 varnishes were manufactured by 12 brands in total، which were not named in the study. For each of the polishes analysed، the scientists، led by doctoral student Anna Young، noted the online descriptions of their ingredients and labels. And the results show not all 'toxic free' nail polishes are void of chemicals. For instance، the hormone-disruptor TPHP was found at levels above 100ppm in three of the 'Free' brands. Hormone-disrupting chemicals have been linked to conditions such as infertility، endometriosis، polycystic ovary syndrome and even certain cancers، like breast.