In which year did the SPI introduce the recycling symbol?

Lecturer: Today, we’re going to look at recycling programmes. The confusion over what we can and cannot recycle continues to confound consumers.  Let’s look at plastics first, as they are especially troublesome, since different types of plastic require different processing to be reformulated and re-used as raw material. Some municipalities accept all types of plastic for recycling, while others only accept jugs, containers and bottles with certain numbers stamped on their bottoms.
  The symbol code we’re familiar with—a single digit ranging from 1
to 7 and surrounded by a triangle of arrows—was designed by The Society                  Q31
of the Plastics Industry, or SPI, in 1988 to allow consumers and recyclers
to differentiate types of plastics while providing a uniform coding system
for manufacturers. The numbers, which many countries now require to be
moulded or imprinted on all—or at least most—containers that can accept
the half-inch minimum-size symbol, identify the type of plastic. The symbols         Q32
also help recyclers do their jobs more effectively.
  The easiest and most common plastics to recycle are made of polyethylene
terephthalate, or PETE, and are assigned the number 1. Examples include
soda and water bottles, medicine containers, and many other common consumer
product containers. Once it has been processed by a recycling facility, PETE
can become fibre-fill for winter coats, sleeping bags and life jackets. It can also
be used to make bean bags, rope, car bumpers, tennis ball felt, combs, cassette        Q33
tapes, sails for boats, fumiture and, of course, other plastic bottles.
   Number 2 is reserved for high-density polyethylene plastics. These
include heavier containers that hold laundry detergents and bleaches as well
as milk, shampoo and motor oil. Plastic labelled with the number 2 is often
recycled into toys, piping, plastic lumber and rope. Like plastic designated           Q34
number 1, it is widely accepted at recycling centres.
  Plastics that are less commonly recycled include polyvinyl chloride,
commonly used in plastic pipes, shower curtains, medical tubing, vinyl              Q35
dashboards, and even some baby bottle nipples. These get the number 3. Like
number 4, which include wrapping films, grocery and sandwich bags, and            Q37
other containers made of low-density polyethylene, and 5, which are poly-propylene
containers used in Tupperware, among other products, few municipal                        Q36
recycling centres will accept it due to its very low rate of recyclability.
  Another useful plastic to recycle is number 6, which is used in polystyrene,
or Styrofoam, items such as coffee cups, disposable cutlery, meat trays,               Q39
packing "peanuts" and insulation. It is widely accepted because it can be reprocessed     Q38/40
into many items, including cassette tapes and rigid foam insulation.
Last, but far from least, the hardest plastics to recycle are items crafted from various combinations of the aforementioned plastics or from unique plastic formulations not commonly used. Usually imprinted with a number 7 or nothing at all, these plastics are the most difficult to recycle and, as such, are seldom collected or recycled. More ambitious consumers should feel free to return such items to the product manufacturers to avoid contributing to the local waste stream, and instead put the burden on the makers to recycle or dispose of the items properly.