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The Lies of Unleaded Petrol The Unleaded Petrol THE COMPOSITION OF PETROL ast issue we discussed how there was little evidence to support the claim that the octane-raising substances in unleaded petrol are safer than the lead compound used. In fact, there was little or no evidence to support the claim that lead in petrol has any effect on the levels of lead in the blood. Unleaded technology means something else is added to the petrol to maintain its octane number. What has not been made very clear is that since about 1970 the lead content in leaded petrol has been M 4 reduced. Policy has meant that, over time, lower and lower maximum lead levels have Highly toxic ape y There are three main groups of substances the oi] companies use instead of lead. chemicals are 1. Aromatics—organic compounds based on the benzene ring, a 6-carbon ring with 3 repla cing the lead delocalised double bonds, e.g., benzene, toluene, xylene, etc. 2. Olefines—organic compounds which have double bonds. After combustion, one in our fuel yet critical by-product is 1,3-butadiene. y 3. Oxygenates—organic compounds containing oxygen molecules such as methane, ethane or MTBE (methyl-tertiary-buty] ether). §o vernment The US Environmental Protection Agency has targeted five toxic air pollutants—ben- authorities zene and 1,3-butadiene are the top two on the list. They are both highly carcinogenic sub- stances. 1,3-butadiene has only just come to international attention." G Therefore, there is one very important question to ask. What is the present composition con tinue to of leaded, regular unleaded, and cediieel aietbed fuel? J S In Australia, oil companies do not have to release the exact formulas for making up the underestima te the petrol mixtures. In Britain it is the same as in Australia: the oil companies i rovide C Cc almost no information about the chemical content of lead. In the US, oil companies have serious risks to to release the petrol formulae to the US EPA. I managed to find an Sgeuiank study, 0 done by Dr Michael Dawson and Mr Noel Child of the University of Technology, public health. Sydney, which analysed the composition of many petrol samples from all over Australia.* They also compiled a table of petrol compositions from many other countries (see Tables 1,2 and 3). These figures came from the “International Gasoline Survey, 1994", a report published annually by Associated Octel Company. Using the figures for Australia as an example, in regular unleaded petrol, the total aro- matic content was 27.7%, and benzene level at 2.0% (Table 2). But, for leaded petrol, the total aromatic content was 29.2%, and the benzene level at 2.1% (Table 3). Wow! This means the total aromatic content and the benzene levels are very similar—actually, mar- ginally higher in leaded petrol. If you look at all the other countries in the tables, the per- centage content of benzene and total aromatics in leaded and regular unleaded petrol is also very similar. Standard unleaded petrol has a lower octane number of around 91, whereas leaded petrol has an octane number of 96 or higher. The lead compound added is just enough to By Catherine Simons, B.Sc. increase the octane number from around 91 to over 96. Premium unleaded has an octane a number of 96, so it has much higher levels of aromatics—as well as benzene—than other NEXUS Magazine fuels. For premium unleaded petrol in Australia, the total aromatic content was 36.4%, PO Box 30 with benzene level of 3.3% (Table 1). Mapleton, Qld 4560, Australia This analysis of Australian petrol was conducted before 1st January 1995. At this time, Phone: +61 (074) 42 9280 maximum lead levels were at 0.3 grams per litre. After 1st January 1995, the maximum Fax: +61 (074) 42 9381 lead levels were reduced to 0.2 g/litre, which means that more of these alternative addi- tives—the aromatics, including benzene, and/or olefines—have been used. So, leaded petrol today could have even more alternative additives than regular unleaded petrol. By Catherine Simons, B.Sc. NEXUS Magazine PO Box 30 Mapleton, Qld 4560, Australia Phone: +61 (074) 42 9280 Fax: +61 (074) 42 9381 JUNE - JULY 1995 NEXUS ¢ 25 THE COMPOSITION OF PETROL