Booster seats

Parents are pretty vigilant about car restraints for their children. In fact the law requires that child restraints be used for children up to the age of one year. After that the legislation is less prescriptive, stating only that an ‘appropriate’ restraint should be used. So it’s up to parents to determine just what is appropriate.

Many parents believe that children who have outgrown their baby seat somewhere around age four, can graduate to a booster seat restrained only by an adult sash seatbelt. All booster seats available in Australia are fitted for use with an adult sash and carry directions about suitable weight range.

The parents of three-year-old Isabelle Broadhead knew she was no longer safe in her baby seat and graduated their daughter to such a booster seat. The label stated it was safe for 14-26kg. They believed that the Australian Standards were the toughest in the world and that this was what was safe for her.

Tragically, Isabelle died in a low impact car accident in 2006 as a result of stomach injuries caused by her adult sash seatbelt. Isabelle was 20.5kg and 105 cm tall.

In 2006 Monash University Accident Research Centre (MUARC) completed a research project into the use of child restraints in children aged 4–11 years – the years where children are most likely to be restrained in a booster seat. The aim of the study was to determine whether children in this age group were appropriately restrained while travelling in the family car.

The study used guidelines from the National Highway Traffic Safety Administration (NHTSA) which recommends that height rather than age or weight should be the indicator of what type of child restraint should be employed.

Children are considered to be appropriately restrained in a booster seat if they are between 100 and 140 cm tall. Children over 140 cm can be appropriately restrained in an adult seat belt – a height usually achieved by age ten or eleven.

Almost all of the 700 parents in the survey reported that they always restrained their children in a vehicle. But only 24% of children aged 4–11 years travelled in a booster seat, while 76% used a seat belt alone. 

Of the booster seat group, 93% were considered to be appropriately restrained in accordance with the NHTSA guidelines. However, in the group that used only adult seatbelts, only 25% were considered to be safely restrained. In other words, 75% of these children were too short to be properly restrained by an adult seatbelt alone.

So why did Isabelle die if she was correctly restrained according to all the current guidelines for her weight and height? Her parents believe that it is because our booster seat designs are not stringent enough. Isabelle’s fatal injuries were caused by the adult seat belt cutting across her lower torso.

They argue that the only way to prevent major injury is to use a crotch strap/clip in combination with and an H-harness on booster seats. An H-harness is attached to an anchor bolt or anchor fitting, with the lap belt of the car threaded through the harness. Standards Australia allows for these harnesses to be used without a crotch strap, but it is far safer with the strap fitted.

If a child is small enough to fit into a child restraint that utilises a five point harness (like a 0-4 seat) then use that. An 'H' harness is not as safe as a five point harness child restraint for small children under 5's. All child restraints are attached to an anchor bolt or fitting, which fits securely into an anchorage point.

However, your vehicle may not have anchorage points. In which case you should visit a restraint fitting operator who can install anchorage points and advise you of the most appropriate restraint for your child and vehicle and how to install it.

Second-hand child restraints sometimes appear available for sale, or passed around families and among friends, but should be approached with extreme caution. These may be unsafe and may not comply, or no longer comply, with Australian Safety Standards. Under no circumstances should a restraint be used that is showing signs of UV discoloration, fraying and general wear and tear, or has been in an accident.

Recommendations for Older children

(for children weighing from around 18kg, from about 5 years, until they fit correctly into an adult seat belt at around 145cm tall)

A booster seat can improve the seat belt fit when your child is too big for a forward facing child seat and too small for an adult belt.

• As a general guide, buy a rigid booster seat with a back, side wings and a sash guide to keep the seat belt in place.
• Use an adult lap/sash seat belt or a child harness in conjunction with a centre rear lap belt. When using a harness, remember to tightly adjust the lap belt first, and then the harness, just removing the slack. The lap belt should always be much tighter than the shoulder harness. A booster with crotch clip can help keep the lap belt in place.
• Research findings suggest that children should continue to use a booster seat until good adult seat belt fit can be achieved (about 145cm tall).

Indicators of good adult belt fit include:

• seat belt fits low across the hip bones and not over the soft part of the abdomen
• shoulder or sash strap passes across the outer part of the shoulder, not across neck

When using an adult belt, either alone or in conjunction with a booster seat, do not allow your child to place the sash portion of the belt under their arms or behind their back.

Never use a booster seat with a lap only belt alone

• Invest in your child’s safety – don’t buy a cheap foam booster seat
• Between age 4 and about age 10 children are not safe in an adult seat belt alone.
• Booster seat design is critical. Injuries are prevented where seats are fitted with not only a harness but a crotch strap
• The middle rear seat is the safest seat in the car for children. Child restraints including booster seats must not be fitted in the front seat of a car fitted with a passenger airbag.
• Education is critical. Just because other parents appear to think its okay to use an adult seatbelt doesn’t mean it’s so
• Don’t become complacent – just because they’ve started school, they’re not big enough to leave the booster behind

STATISTICS

• Between 2001 and 2006, 86 children up to age 14 were admitted with seatbelt injuries in Victoria alone.
• Between 1999 and 2006, 52 patients under the age of eight presented to the Royal Children’s Hospital with car crash injuries sustained. 75% of them were wearing an adult seatbelt and had a torso injury.

Sources

Kid Safe NSW  
Monash University Accident Research Unit
Memory of Isabelle Broadhead website   

This article was first published in Australian Family Magazine, May 2007. Updated July 2009.