Glossary

BFR - Brominated Flame Retardants

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A chemical compound - A substance consisting of two or more chemical elements that are chemically combined in fixed proportions.

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A chemical element - A substance that cannot be divided or changed into different substances by ordinary chemical methods.

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Concentration - A very common concept used in chemistry and related fields. It is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture but most frequently is used in relation to solutions, where it refers to the amount of solute dissolved in a solvent.

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Deca-BDE - Decabromodiphenyl Ether

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HBCD - Hexabromocyclododecane

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Parts per notation - A measure of concentration that is used where low levels of concentration are significant. This is often used to denote the relative abundance of trace elements in the Earth's crust, trace elements in forensics or other analyses, or levels of pollutants in the environment.

Parts per notationAbbreviationsExamples
Parts per hundred Denotes one particle of a given substance for every 99 other particles.
This is the common percent ('%') = 1 part in 102
Very rarely 'pph'
Parts per thousand Denotes one particle of a given substance for every 999 other particles.
Denoted by '‰' [per mil symbol] = 1 part in 103
Occasionally 'ppt'
This is roughly equivalent to one drop of ink in a cup of water, or one second per 17 minutes.
'Parts per thousand' is often used to record the salinity of seawater.
Parts per million Denotes one particle of a given substance for every 999.999 other particles.
1 part in 106
‘ppm’
This is roughly equivalent to one drop of ink in a 40 gallon drum of water, or one second per 280 hours.
Parts per billion Denotes one particle of a given substance for every 999.999.999 other particles.
1 part in 109
‘ppb’
This is roughly equivalent to one drop of ink in a canal lock full of water, or one second per 32 years.
Parts per trillion Denotes one particle of a given substance for every 999,999,999,999 other particles.
1 part in 1012
'ppt'
ppt can be confusing as it is sometimes used for parts per thousand - if you want to use "part per" notation in this case it is safer to use ppth abbreviation (but rarely used) or "pro mille" ‰ sign)
This is roughly equivalent to one drop of ink in an Olympic-sized swimming pool, or one second every 320 centuries.
To put "parts per trillion" into perspective, one part per trillion can be considered equal to:
One inch in 1.6 million miles
One second in 32,000 years
One cent in $10 billion
One square foot of the state of Indiana.
Parts per quadrillion Denotes one particle of a given substance for every 999,999,999,999,999 other particles.
1 part in 1015
'ppq'
ppq is more a theoretical construct then a useful thing, chances are you will never see it in use
This is roughly equivalent to a drop of ink in a medium-sized lake, or one second every 32,000 millennia.
There are no known analytical techniques that can measure with this degree of accuracy; nevertheless, it is still used in some mathematical models of toxicology and epidemiology.

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PCB - Printed circuit boards

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RA - Risk Assessment

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RoHS - Restriction of certain Hazardous Substances Directive

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TBBPA- Tetrabromobisphenol-A

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VECAP - Voluntary Emissions Control Action Programme

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