The Environmental And Public Health Consequences Of Lead In Petrol



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The Environmental And Public Health Consequences Of Lead In Petrol

Introduction
The continued use of lead in petrol in Australia presents a serious environmental and human health problem.1 Airborne lead, a by-product of the combustion of petrol containing tetraethyl and tetramethyl lead is a highly toxic pollutant, affecting plants, animals and humans, having particularly adverse consequences for the development of human embryos, foetus, newborn and young children.2
In considering these issues, this essay reviews the rationale for the recent public policy changes concerning lead in petrol and examines the constitutional, political, economic and social influences and constraints that surround them.
Lead In The Environment
Lead is now one of the most widely dispersed of environmental pollutants.3 Despite environmental background lead levels generally being extremely low, people living in Australian communities are exposed to lead sources virtually constantly.4
Although the sources of lead contamination are diverse, and include smelting and refining of lead, scrap metal recovery, waste oil combustion, battery manufacture, plumbing, lead flashing, soldered food cans, lead acid batteries, pesticides, fertilisers, and in particular, paint produced prior to 1971, lead from automobile exhausts is the most pervasive.5
The transport and distribution of lead from major emission sources are mainly through air. Airborne lead derived from petrol combustion constitutes approximately 90% of the overall lead emitted in Australian urban areas.6 Although most lead discharged into the air precipitates out near its source, approximately 20% is widely dispersed.7 In fact, studies have demonstrated that lead levels in Greenland correlate with the use of alkyl-leaded petrol in the USA, Eurasia and Canada.8 As the level of airborne lead is primarily a consequence of public consumption of leaded petrol, while point source control is not irrelevant, is not the main issue.

Lead In Petrol


Tetraethyl lead and tetramethyl lead are added to petrol to increase the octane level of the fuel and to prevent ‘knocking’ by limiting the predetonation of the combustion gases in modern high compression automobile engines. Lead is also an effective valve lubricant, reducing the wear on valve seats in some pre-1986 cars.
Tetraethyl lead was first introduced as a gasoline additive in the USA in 1923.9 The dangers associated with leaded petrol were apparent as early as 1924, when New York banned its manufacture, sale and use, though this was reversed when the first President of Ethyl Corporation convinced the US Surgeon General that the economic and military benefits of tetraethyl lead ‘far outweighed the unsubstantiated health risks.’10 In contradiction to the now more widely accepted ‘Precautionary Principle’11, the burden of proof was placed on those concerned about the effects of lead in petrol. Production resumed in 1926, and subsequently, between 1946 and 1978 the amount of lead used per vehicle mile in the USA rose by 80% as more powerful and higher compression engines were introduced.12
Lead In Petrol In Australia
Unleaded petrol was released for sale in Australia in 1985, and since 1986, in accordance with Australian Design Rule 37, as administered under the Federal Motor Vehicles Standard Act, all new petrol fuelled cars have been required to run on unleaded petrol.13
Even though, as Table 1 shows, the use of unleaded petrol increased steadily from 1985 onwards, and lead emissions from petrol have declined in Australia since then, lead from petrol still constitutes the largest urban lead source.14
Table 1 Consumption Of Petrol In Australia (millions of litres)


year

leaded super

unleaded petrol

premium unleaded

total consumption

1985

15,238

274

Unavailable

15,512

1986

15,090

912

Included in unleaded petrol

16,012

1987

14,318

1897

Included in unleaded petrol

16,215

1988

13,830

2869

75

16,774

1989

13,098

4046

95

17,239

1990

11,930

5120

98

17,148

1991

10,860

5920

102

16882

1992

10,234

6703

133

17070

Adapted from: NHMRC, 1993 Reducing Lead Exposure in Australia, 33.

Vehicle lead emissions are indirectly regulated by the existence of statutory limits on petrol lead content. Each State and Territory has its own requirements for permissible concentrations in lead petrol15, which vary significantly between the States.16

Table 2 Regulation of Lead in Petrol By State


existing legislation

1993 maximum lead levels17

1994 maximum lead levels18

NSW metropolitan areas

0.4 grams/litre

0.3 grams/litre

NSW country areas

0.84 grams/litre

0.3 grams/litre

Queensland metro. areas

0.4 grams/litre

0.3

Queensland country areas

0.84 grams/litre

0.3

Northern Territory

0.84 grams/litre

0.4

South Australia

0.65 grams/litre

0.45 (average over 1994)

Western Australia

0.65 grams/litre

0.4

Tasmania

0.4 grams/litre

0.3

Australian Capital Territory

0.4 grams/litre

0.3

Victoria

0.3 grams/litre

0.25

Adapted from: NHMRC, 1993 Reducing Lead Exposure in Australia, 32,

and Australian Institute of Petroleum, Media Release: Reduction in Lead, 30 December 1993, 2.

Prior to 1 January 1994, Australia permitted the highest level of lead in petrol amongst the OECD countries.19 Anachronistically, ‘unleaded’ petrol contains lead, though the amount is limited by statute by each State, typically, as in Victoria20 and NSW21, to a maximum of 0.013 g/l. While leaded petrol accounted for 55% of petrol sales at the beginning of 199322, in March 1994 monthly unleaded petrol sales exceed leaded sales for the first time in Australia’s history.23
The Environmental Effects Of Lead

The Effect of Lead on Soils

Airborne lead accumulates in soils and may persist in the upper layers of the soil surface for up to 20,000 years, continuing to migrate into the micro-organism and grazing food chains until equilibrium is achieved.24

The Effect of Lead on Terrestrial Plants And Micro-organisms

Terrestrial plants absorb lead from the soil and through their leaves, retaining the lead in their roots. Airborne lead can also clog plant stoma, hindering photosynthesis inducing stunted growth or death of the plant, and may even effect plant population genetics at levels of that experienced commonly at roadsides. Airborne lead can also have a significant impact on many of the detritus micro-organisms that are an essential part of the decomposition food chain.25

The Effect of Lead on Animals

Lead adversely affects the central nervous systems of animals and inhibits their ability to synthesise erythrocytes.26 Blood lead levels of ≥40 µg/dl can produce observable clinical symptoms in domestic animals27, whilst grazing animals are directly affected by the consumption of forage and feed contaminated by airborne lead and indirectly by the uptake of lead through plants.28

Human Health Effects Of Lead


Airborne lead can effect humans directly by inhalation, or indirectly through the ingestion of contaminated soil, dust, or plants.29 While the intake of lead in dust for rural children, away from major lead sources such as smelters, has been estimated as approximately 100 times the intake of lead from the air, it is probable that some 90% of the lead in dust originated in the air.30 Tables 3, 4 and 5 provide data to show how the levels of airborne lead affect those for the soil and dust in ‘major urban’, ‘other urban’ and ‘rural areas’ respectively. These tables also detail the consequences of implementing different lead abatement strategies.
Lead can damage organs including the brain, the kidneys, and male and female reproductive systems.31 There is growing evidence that these adverse health effects occur at lower levels of lead exposure than previously considered to cause concern32, and that intellectual impairment can be induced in young children with blood lead levels previously considered as safe.33
The National Health and Medical Research Council (NHMRC) revised its Guidelines for Lead in Australians in 1993, from a blood lead level of 30 µg/dl to the new goal of < 10 µg/dl, declaring a ‘particular urgency in reaching this level in children aged one to four years because of the adverse effects of lead exposure on intellectual development’.34
According to current available data, as shown in Table 6 (overleaf), lowering the level of concern to 10 µg/dl would classify between 26% and 53% of children aged 0-4 years in Australia as having unacceptably high blood levels, while a level of concern of 15 µg/dl would classify between 7% and 22% of children as having unacceptably high blood lead.35
Table 7 below provides an indication of how the exposure rates for children aged 0-4 years shown in Table 6 might change under condition of differing petrol lead levels and rates of ‘switching’ from leaded to unleaded fuels.
Table 7 estimated percentage of australian children a aged 0-4 years with blood lead levels > 10 µg/dl in 1993, 1996 and 1998


Lead content in leaded petrol (gram/litre)

Annual switch rate to ULP

1993

1996

1998

0.3 in 1997

5%

44.58

32.75

17.49

0.3 in 1995; 0.15 in 1997

5%

44.58

22.57

9.64

0.15 in 1995

5%

44.58

11.30

9.64

0.15 in 1995; 0.026 in 1997

5%

44.58

11.30

7.44

0.026 in 1995

5%

44.58

7.44

7.44

0.3 in 1995; 0.15 in 1997

10%

44.58

13.17

8.05

0.3 in 1997

10%

44.58

18.14

10.96

0.15 in 1995

7.5%

44.58

9.69

8.05

0.15 in 1995

10%

44.58

8.52

8.05

Adapted from: NHMRC, 1993 Reducing Lead Exposure in Australia, 143.
a This table is based on the sum of four major exposure groups: Major urban; Other Urban; Rural; and Renovations. Calculations are based on the assumptions that 8% of houses are undergoing renovation, that 65% of houses have lead paint, that food intake = 15 µg lead/day, and that the average lead content of water used by those groups is 10 µg/litre.
Given the recent changes to petrol lead levels, and the transition of leaded petrol from 97 to 96 RON effective from 1 January 199436, Table 7 represents a realistic forecast of the proportions of children likely to remain above the current ‘level of concern’.
Why this is so, and some of the reasons why affirmative regulative action on lead in petrol has been a relatively recent phenomenon are found in the legal, political, economic and social factors that have informed public policy on lead in petrol.
The Leaden Wheels Of Government
Despite Australia having been a leader in the science related to the health effects of lead, work on the health effects of lead has not been matched by action in reducing lead in the environment.37
The legislative framework for the regulation of lead in petrol is complex, involving a mixture of Commonwealth and State laws and regulations. Our discussion begins with a consideration of the Commonwealth’s power to enact binding legislation concerning the environment.

Constitutional issues Relevant To The Lead In Petrol Debate

The Commonwealth Constitution confers no express legislative power on the Commonwealth with respect to ‘the environment’ or ‘the protection of the environment’38, as the Commonwealth has only those powers which the States ceded to it on Federation, or which has been subsequently acquired by referendum.39
There are however, several heads of power that can be relied upon to ground Commonwealth legislation concerning the environment. These are trade and commerce40, taxation41, bounties on the production or export of goods42, foreign corporations and trading or financial corporations formed within the limits of the Commonwealth43, external affairs44, customs45, excise46, the granting financial assistance to any State47, and the territories.48 Of these heads of power, those most relevant to the regulation of lead in petrol are the grants of power relating to trade and commerce, taxation, corporations, excise, and the facility afforded by the external affairs power in the event of the recognition of customary international law relating to lead pollution.
As, subject to certain limitations, inconsistent State laws shall be invalid to the extent of their inconsistency with Commonwealth laws49, these heads of power have, especially in recent times, afforded the Commonwealth great scope.
The fact that there is no specific Commonwealth power over the environment does not prevent the Commonwealth from legislating ‘with respect to’ one of the granted heads of power, whatever the practical effect of that legislation may be.50 As each grant of power is interpreted liberally, carrying with it the implication that all powers necessary to carry the granted power into effect are also granted, a wide incidental power exists with respect to granted subject matters.51
As the Murphyores judgement affirmed, an activity which constitutes the subject of a power may, under that power, though subject to any express limitations in the Constitution, be prohibited or allowed in accordance with any conditions or criteria.52 Similarly, the subsequent Tasmanian Dams case declares ‘now well settled’ the principle that a law upon a subject matter of Commonwealth power does note cease to be valid ‘because it can be characterised as a law upon a topic outside power’.53

Commonwealth Use Of Trade And Commerce And Corporations Powers

Given the Commonwealth’s inability to legislate directly on ‘the environment’, the history of Commonwealth regulation of petrol is interesting. As wholesaling, transporting and retailing of petrol in Australia is carried out exclusively by corporations, and is of a nature that would be characterised as interstate trade54 that could be subject to the control of trading activities55, the Commonwealth has clear authority to use its trade and commerce and corporations power. Which is indeed what it has done.
Commonwealth legislative intervention in petroleum retailing first occurred in 1940, when petrol rationing was introduced as a wartime defence measure. The Commonwealth subsequently assumed monopoly control of the petroleum retail market by introducing a pool arrangement under the National Security (Petroleum Products Distribution) Regulations in 1942. The National Security (Rationing) Regulations 1950 saw rationing cease, with the Commonwealth vacating the field in favour of the States.56 Commonwealth intervention in petrol retailing was invigorated by a 1973 Royal Commission on Petroleum and the subsequent Prices Justification Act 1973 and Trade Practices Act 1974. These were followed by the Petroleum Retail Marketing Franchise Act 1980, and the Petroleum Retail Marketing Sites Act 1980.
Through a complex interaction between the above Acts, a mechanism called ‘rack pricing’ operates to limit wholesale price fluctuation.57 This has allowed the Commonwealth to use economic incentives to encourage the use of unleaded petrol through its use of the excise power.

The Use of Excise As An Economic Incentive To Reduce Lead In Petrol

The head of power of greatest relevance to Commonwealth regulation of lead in petrol is the taxation power58 read in conjunction with the excise power.59 The power to impose and collect excise afforded by s51(ii) is exclusively vested in the Commonwealth to the exclusion of the States by s90 of the Constitution.60 Excise is characterised as a tax on the production or manufacture of goods down to the point of receipt by a consumer.61 Excise on crude oil and petroleum products is imposed by the Commonwealth under the Excise Tariff Act 1921.
The 1993/4 Budget announced a staged increase in fuel excise inducing a 5¢/l differential between unleaded and leaded fuel62, as part of a 10¢/l real increase in leaded petrol excise.63 This was rejected in the Senate and was negotiated to take the form of a price differential of 2¢/l between the excise on unleaded versus leaded petrol, with a 1¢/l differential having come into effect in February 1994, and the second 1¢/l differential due to take effect on 1 August 1994.64
As a result of the mechanisms employed under other heads of power described above, and the market forces retailers are generally subject to, CEPA notes that the excise differential levied on the wholesale petrol price has been reflected consistently in retail prices.65

The Commonwealth External Affairs Power And Future Developments

No international treaty or convention currently exists specifically concerning airborne lead pollution. Very recent developments suggest, however, that international sentiment in this area is growing.66 The USA and Japan having abolished lead in petrol entirely, and others such as New Zealand planning to abolish it by 1996.67
Following the 1993 publication of the OECD Lead Risk Reduction Monograph, strong support has gathered for immediate development of an OECD Council Act on lead.68 If increasing international activity results in an international instrument, or as under Article 38(1) of the ICJ Statute, international custom relating to lead abatement is applied as ‘evidence of a general practice accepted as law’, lead abatement measures, particularly those relating to transboundary pollution as per the Trail Smelter arbitration69, may well assume the character of customary international law.



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