Page 14 - BBC Knowledge - October 2017 IN

Questions
& Answers
W H AT ’ S I N
...Hand Cream

There are two ways that hand creams act to moisturise your skin. Occlusive agents form a barrier
that traps water, while humectants attract more water to your skin. The problem is that the humectants
are water soluble, while the occlusive agents dissolve in oil. So, to get them to mix in an easy-to-use
formulation, the creams also need an emulsification system. ML

80% Water Fats and oils 7%

Gives the cream volume and Coconut oil, petroleum jelly
dissolves some ingredients. or lanolin (a waxy substance
secreted by woolly animals such
as sheep) might be used as
Glycerine 3% occlusive agents that form a barrier
to block escaping water.
Is a typical humectant used
to draw water in from
the atmosphere. 2.5% Emusifier
Glyceryl stearate and
stearic acid help to stabilise
5% Thickeners the oil/water mixture.

PEG or polyacrylic acid (which may preservatives
appear as carbomer on the label) 2.5%
are long polymer molecules that and fragrance
increase the viscosity of the cream, These improve the product’s shelf life
making it easier to apply. and make it smell nice.

DO ALL FISH AND
SHELLFISH CONTAIN
MERCURY?

Mercury levels in the oceans have tripled
since the Industrial Revolution, thanks to
mining and the burning of fossil fuels.
All sea creatures absorb some of this heavy
metal directly, and, once it’s in the body,
there’s no way of getting rid of it. The amount
of mercury in fish varies between species.
Long-lived predators like tuna and swordfish
tend to contain the most, because they also
absorb mercury from their prey and they’ve
had a long time to accumulate it. The lowest
levels are found in short-lived species lower
down the food chain, such as oysters PHOTOS: ESA/HUBBLE/NASA, GETTY X3 ILLUSTRATIONS: RAJA LOCKEY
and shrimp. HS

14
OCTOBER 2017