Consumers need to be aware that products boasting impeccable environmental credentials aren’t always as green as they seem, according to an investigation by the global consumer watchdog.

Baby wipes that claim to be 0% plastic or dairy-free milk that declares itself as “sustainably sourced” are just some of the products that may be breaking the law by greenwashing, a review by the International Consumer Protection Enforcement Network found.

Amid a boom in consumer interest in products that don’t pollute, the annual ICPEN sweep of websites focused on the environment for the first time this year. It aims to help protect consumers from paying more for goods that claim to be green, but in fact aren’t. As much as 40% of the sustainability claims made online could well be misleading.

Three types of misleading claims were identified, including vague “eco” statements. One milk substitute was said to be sustainably sourced with no further explanation or evidence. Another high street fashion retailer promoted clothes as ‘recycled cotton’ without listing the amount of recycled cotton used.

Companies also created their own-brand eco-labels that weren’t linked to an accredited organization. Others hid or omitted key information, such as a product’s pollution levels in order to appear more environmentally friendly.

In another example, a pack of baby wipes claimed to be 0% plastic without explaining if that meant the product or the packet.

“Too many websites appear to be pushing misleading claims onto consumers, which means that companies offering products with a genuine environmental benefit are not getting the customers they deserve,” said Andrea Coscelli, chief executive of the U.K. Competition and Markets Authority, which co-led the sweep with The Netherlands Authority for Consumers and Markets.