SOME ASPECTS OF LEAD POLLUTION IN ISRAEL
HENRY A. FONER
Geological Survey of Israel, 30 Malkhei Yisrael St., Jerusalem 95501, Israel.
The lead content of petrol used in Israel has been steadily decreasing over the past few years from 0.42 g/litre to 0.15 g/litre. Unleaded petrol has also been introduced. Blood lead levels measured in Israel suggest that some children may be above the 10 ug/dl threshold now considered to be hazardous. The lead contents of soils, food crops, water, and air in Israel are generally low compared those in other developed countries, but measurements indicate that lead is still being added to surface soils. Further work in areas with heavy traffic shows that the reduced Pb level in petrol has so far not resulted in lower soil lead contents.
KEYWORDS: Israel, Lead pollution, soil, water, air, plants
The effects of lead pollution on health have been extensively discussed in recent years (Royal Commission, 1983, EPA 1986a, b, c, d). As far as is known Israel has no acute problem of lead poisoning, as in the U.S.A. for example. However, the recent lowering of the amount of blood Pb considered acceptable in children (CDC, 1991) together with the current move to introduce lead-free petrol and the gradual adoption of European Community standards for motor vehicles, makes this an opportune time to review Pb pollution in Israel.
Sources of lead pollution in Israel may be divided into two major categories: (1) Industrial and domestic and (2) vehicle derived.
Industrial lead exposures in Israel and their effect on blood lead levels (PbB) and health have been the subject of a number of studies notably by Richter et al. (Richter et al., 1980, 1986). These studies showed elevated PbB levels in workers employed in secondary lead smelters, accumulator and plastics factories and increased PbB (and ZPP) at other sites. A major epidemic of lead poisoning involving a number of Arab villages was discovered in 1982 and traced to contaminated flour ground in village mills (Hershko et al., 1984).
Based on the experience of other countries, the vast majority of lead introduced into the environment in Israel comes from the use of leaded petrol. The lead is added to the fuel as an organic compound to improve performance and increase engine life. The number of petrol burning vehicles (mostly private cars) in Israel is increasing rapidly and so is the amount of petrol used shown in Figure 1 (CBS, 1989, 1992.)
Figure 1. Annual petrol consumption and petrol Pb emissions in Israel 1970-1991
Until quite recently all grades of petrol available contained 0.42 g/litre of Pb (IS-90, 1984). This was reduced to 0.30 g/litre in January 1988 and again to an average of 0.15 g/litre in 1990 (0.20 g/litre in 96 octane and 0.10 g/litre in 91 octane fuel). During the past year, unleaded fuel ( In 1987, 1,133,000 tonnes of leaded petrol were consumed in Israel, excluding Judea Samaria and Gaza, (Figure 1). With a specific gravity of 0.75 (IS-90, 1984) this means that some 634 tonnes of Pb were contained in the fuel. As about 75% of the Pb in the fuel is exhausted from the vehicle (Chamberlain, 1983) approximately 475 tonnes per annum of Pb were introduced directly into the atmosphere from this source and dispersed into the air, soil, water and vegetation. This Pb can enter the human body either directly by inhalation or indirectly by ingestion.
This paper surveys the known data on Pb pollution in Israel with special emphasis on the distribution of Pb in air, soil, water and edible crops. It also points out some changes which have occurred since 1988 when the reduction of the amount of Pb in petrol started.
BLOOD LEAD LEVELS
Blood lead levels (PbB) reflect current exposure to Pb. Infants and children absorb Pb more readily than adults and are also much more vulnerable to it. Acceptable PbB levels have dropped considerably over the years. Whereas 20 years
ago PbB’s of 80 ug/dl were considered acceptable, these have dropped to 35 ug/dl for adults and 25 ug/dl for children. The latest recommended no-effect threshold for children for children is as low as 10 ug/dl (CDC, 1991).
PbB levels measured in Israel were usually considered to be low and were not regarded with concern e.g. traffic policemen in central Jerusalem have PbB’s of about 12 ug/dl (Richter et al., 1980). Exceptions can usually be traced to a specific cause, such as work in accumulator factories or smelters
(Richter et al., 1980, 1985, 1986; Berant, 1984). Blood Pb levels in Israel and their possible health effects have been discussed very recently by Richter (1992). In this context, it should be noted that sub-groups with PbB >10 ug/dl include children in the Krayot, near Haifa and the children of lead workers (Richter, et al., 1985, 1986). In view of the lower no-effect thresholds now being introduced, these levels give rise to some concern.
Measurements were made of the lead content of about 700 samples of soil ( taken mainly from roadside sites) during the years 1980-1984. All samples were taken in autumn before the winter rains. Attempts were made to repeatedly sample the same sites, but this was fraught with difficulties as many of the sites were built on during the years. In general, two types of sample were taken: the top 1 cm of soil (T) and a representative soil sample comprising the top 10 cm (S). The samples were analysed for Pb and a series of other elements as well as for clay and organic matter.
TABLE 1 Soil sampling variability for Pb, V and Ni. Concentration of elements in S and T layers, ug/g Depth 0-10 cm (S) | Depth 0-1 cm (T) Pb V Ni | Pb V Ni 52.5 57.5 50.0 95.0 45.0 40.0 80.0 55.0 45.0 135.0 47.5 55.0 55.0 55.0 45.0 115.0 45.0 37.5 65.0 55.0 47.5 140.0 40.0 40.0 85.0 55.0 47.5 105.0 42.5 47.5 50.0 57.5 50.0 70.0 52.5 45.0 37.5 50.0 45.0 57.5 57.5 47.5 45.0 50.0 40.0 70.0 50.0 40.0 40.0 57.5 40.0 67.5 50.0 40.0 50.0 60.0 40.0 65.0 52.5 40.0 65.0 50.0 35.0 75.0 40.0 35.0 Mean 57 55 44 90 48 43 CV (%) 27 6 3 32 12 13 Ratio of T/S.:- Pb = 1.60; V = 0.86; Ni = 0.96
Lead distribution in soils is particularly uneven and this can lead to difficulties in interpretation. Table 1 shows the lead, vanadium and nickel contents of T and S type samples taken at 50 m intervals at a site parallel to the main road from Lod to Ben Gurion Airport. The variability of the Pb results is much greater than those of V and Ni and Pb is enriched in the upper (T) layer compared to the other two elements. These results imply a continuing input of Pb into the soil in contrast to V and Ni.
TABLE 3 National and urban soil Pb concentrations (all values in ug/g) City No. of Mean Median Geometric Range Samples Mean max min Tel Aviv 60 177 55 62 1394 0 Haifa 95 139 28 46 1581 4 Ashdod 135 9 6 6 100 0 Be'ersheva 29 76 28 26 530 3 Jerusalem 78 145 66 71 1075 6 National 609 95 20 24 2500 0 Notes: (1) Haifa: Samples are not distributed log normally. (2) Ashdod: Most samples taken outside town centre.
TABLE 4 Maximum soil lead concentrations found in some Israel cities City Pb Remarks ug/g Jerusalem 1075 Town centre Tel Aviv 1394 Town centre Haifa 1581 Opposite railway station Be'ersheva 530 Town centre Akko 620 Town centre Ashdod 100 Town centre Naharyya 115 Town centre Petah Tiqwa 839 On main Tel Aviv road Bene Beraq 54 In railway station yard Hebron 150 Opposite glass factory Ramla 151 Near town centre
TABLE 2 Analyses of some constituents of soils sampled from the same cultivated sites over a number of years Site Year Pb CaO Ni V Organic Clay ug/g % ug/g ug/g % % 1 JERUSALEM. Flower bed near Old City: 1981 303 * * * * * 1982 310 24.0 30 24 2.1 23 1983 412 22.6 31 36 2.3 23 1984 182 24.0 33 20 2.3 * 2 JERUSALEM. Ramat Eshkol central reservation flower bed. 1982 595 17.1 25 23 5.4 * 1983 342 13.5 40 40 2.8 32 1984 191 9.1 43 36 2.0 * 3 HAIFA. Traffic island. CENTRE: 1982 595 22.9 30 23 3.2 24 1983 516 25.2 29 28 3.0 24 1984 368 27.0 28 20 3.3 * Traffic island. NORTH: 1982 663 22.0 30 24 4.3 26 1983 458 23.7 30 27 3.7 24 1984 406 25.2 30 22 3.0 * Traffic island. SOUTH 1982 373 21.3 27 21 4.1 24 1983 328 24.0 26 22 3.4 13 1984 391 25.1 23 16 2.7 * Traffic island. EAST 1982 369 19.9 35 30 3.6 28 1983 406 23.7 30 34 3.4 26 1984 384 23.2 36 31 3.4 * Traffic island. WEST 1982 388 23.0 25 19 4.6 * 1983 388 25.8 27 29 4.1 26 1984 288 26.7 25 19 2.6 * 4 KFAR HA'YAROK JUNCTION. Strawberry field: 1982 20 0.5 7 12
Table 2 shows the results obtained over the years at a number of intensely cultivated sites.The data appear to show soil Pb was sometimes decreasing over the years in these samples. This is probably due to chance as comparison of Pb determinations at 25 sites during the years 1983 and 1984 generally showed a slight increase over the period. Site no. 4 is particularly interesting as it is situated at one of the busiest road junctions in Israel. The sampling site is 7 m from the verge, some 20 m from a traffic light. The traffic density is about 60,000 cars/day (CBS, 1986) and the Pb concentration remained constant at about 20 ug/g over a three year period. This is quite typical. The Pb content of Israel soils is strongly correlated with the amount of organic matter present. As the amount of organic matter in most Israel soils is very low, Pb does not accumulate. Table 3 shows the ranges of urban and national soil Pb concentrations and Table 4 shows some maxima.
Soil Pb levels in Israel are usually very low compared to those in other heavily motorised countries (Ward, 1989) but are similar to those found in California (Page and Ganje, 1970) which has a similar climate.
Seventeen sites near busy roads were re-sampled in the autumn of 1991 – i.e. after the reduction in petrol lead contents. Eleven sites were found to have unchanged Pb contents. Three had slightly higher and thee slightly lower Pb levels. This is in contrast to the findings in other countries where dramatic decreases were found in similar circumstances (Byrd et al., 1983).
Ingestion of Pb in the food is an important source of PbB as much more Pb is absorbed via the digestive system that through the lungs (Royal Commission, 1983). Unsuccessful attempts were made to find contaminated edible crops in areas close to heavy motor traffic. Table 5 shows the results obtained. The highest Pb content found was 0.7 ug/g in unwashed lettuce close to a very busy road. The usual legal limit for Pb in foodstuffs is 1 ug/g, fresh weight (Codex, 1985).
TABLE 5 Lead content of crops calculated to fresh weight Crop Pb Content (ug/g) Maximum Minimum Lettuce (unwashed) 0.7 0.14 Lettuce (washed) 0.4 0.07 Cabbage 0.15 0.08 Carrots 0.3 0.08 Radish 0.15 0.03 Strawberry (unwashed) 0.15 0.07 Strawberry (washed) 0.15 0.07 Orange 0.25 - Grapefruit 0.25 - Groundnuts 0.15 -
Drinking water in Israel is derived in about equal proportions from Lake Kinneret (the Sea of Galilee) and from underground sources. The Kinneret watershed is not heavily populated and underground sources are generally covered by (alkaline) calcareous rocks. The maximum concentration of lead found in the Kinneret waters between 1978 and 1983 was 6 ug/litre (Sandler et al., 1988). The lead content of wells and ground waters is generally AIR
The concentrations of heavy metals in the air in Israel have recently been discussed (Foner and Ganor, 1992). Values obtained by the present author and from the literature are summed up in Table 6.
Lead in air concentrations in some cities in Israel
City Pb concn. (ug/m3) n Remarks Max. Mean Median
1 Jerusalem - 0.21 - 74 Winter 1979 2 Jerusalem 1.2 0.5 ? - - 1977 3 Tel Aviv 2.50 1.11 8 Winter 1984 4 Tel Aviv 7.70 0.50 - - Before 1979 5 Be'ersheva 0.31 - 0.12 40 Summer 1977, 6 Arad 0.08 0.06 0.06 11 Summer 1987 Notes: (1) Results from single sampling station near the city centre. Refs: (Malenky et al., 1983). (2) Ranges: City centre 1.2-0.5, suburbs 0.1-0.5. Refs: (Richter et al., 1980). (3) Single sampling station near the city centre. Refs: Foner and Ganor, 1986; Ganor and Foner, 1989; Foner, 1990. (4) Mean of geometric means from sampling stations dispersed over the city. Refs: Donagi et al., 1979. (5) Location not specified. Refs: Kushelevsky et al., 1983. (6) from 2 samplers, centrally located. Refs: Foner and Ganor, 1992.
Comparison of air Pb concentrations in Israel with those in the literature show that they are within the normal range found in Europe (WHO, 1987). Concentrations in Tel Aviv in 1984 were below the Israel standard of 5 ug/m3 over 24 hours (Air regs, 1992). The order of air Pb concentrations is Tel Aviv > Be’er Sheva > Jerusalem > Arad which is what would be expected from the type of traffic, climates and populations in these towns.
Environmental Pb concentrations in soil, plants, water and air in Israel are generally low. Blood Pb levels measured in the past were considered to be low, but in the light of recent trends, this should be reconsidered. Further information is needed, especially in the case of children. So far there is no evidence of a long term build-up of Pb in soils but the recent reduction in the Pb content of petrol and the corresponding decrease in atmospheric Pb emissions has not caused the expected decrease in the lead content of soils.
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