What if your water bottle was making you fat? What if it could be giving you cancer or increasing the chances of your child being born with deformed genitals?
Welcome to the disquieting world of endocrine disrupters, chemicals that mess with the normal functioning of your hormone system. They can be found in flame retardants, cosmetics, pesticides, plastics and a host of daily personal care products.
While toxicology has thought the dosage makes the poison, scientists are finding more evidence that the dosages - once considered safe - of chemicals used in daily products may harm our health and alter the genetic destiny of future generations.
'What hormones do, particularly as the fetus is developing, is they turn genes on and off,' says John Peterson Myers, the founder, chief executive and chief scientist at Environmental Health Sciences in Virginia. 'The timing of turning genes on and off is absolutely crucial ... it makes sure your brain gets wired correctly ... and makes sure you turn out to be the right sex.
'Turns out, they behave the same way [as natural hormones]. Low doses turn genes on and off, high doses are poisonous,' said Myers, who was invited by Greenpeace Hong Kong to give a lecture at Hong Kong Baptist University last week.
With this new information, scientists like Myers are postulating that environmental contaminants may be adding to worldwide epidemics of obesity, infertility, type 2 diabetes and cancer. They may even cause the behavioural disorders like autism by altering the way our genes are expressed as we age.