Nuclear Instruments and Methods in Physics Research B 189 (2002) 168–173 www.elsevier.com/locate/nimb
PIXE measurement of human hairs from a small-scale mining site of the Philippines S. Murao a
a,*
, E. Daisa b, K. Sera c, V.B. Maglambayan d, S. Futatsugawa
e
Geological Survey of Japan, National Institute of Advanced Industrial Science and Technology, Tsukuba Central 7, 1-1-1 Higashi, Tsukuba 305-8567, Japan b Mines and Geosciences Bureau – CAR, Baguio City 2600, Philippines c Iwate Medical University, Tomegamori, Takizawa 020-0173, Japan d NIGS, University of the Philippines, Diliman, Quezon City 1101, Philippines e Japan Radioisotope Association, Tomegamori, Takizawa, 020-0173, Japan
Abstract In gold-producing regions of the Philippines, so-called pocket miners are mining and smelting the ore by gold amalgamation. The amalgamation process and smelting of amalgam are usually done inside houses especially in the kitchen. It is of concern that people become exposed to vapor mercury by inhalation with this practice. The Mines and Geosciences Bureau of the Philippines – Cordillera Administrative Region (CAR) communicates to pocket miners the hazards of mercury to the body as well as the damage that mercury causes to the environment. Knowing the toxicity of mercury, miners came to request that their head hairs be analyzed. Consequently, a standard-free method of quantitative analysis for untreated bio-samples was applied to the hairs to estimate their degree of exposure to mercury. The analytical result indicated the anomalous accumulation of mercury especially for women who stay longer and often smelt the amalgam inside the house. Ó 2002 Published by Elsevier Science B.V. PACS: 82.80.Ej Keywords: Gold; Mercury; Hair; PIXE; Pocket miner; Philippines; Small-scale mining
1. Introduction Small-scale mining 1 of gold is an important activity for livelihood in local communities of mineralized areas in the Philippines [1], and the gold miners are usually called pocket miners. They are * Corresponding author. Tel.: +81-298-61-3577/54-3632; fax: +81-298-55-1783/54-3633. E-mail address:
[email protected] (S. Murao). 1 For general information on small-scale mining, see [5,6].
groups of persons who mine shallow orebodies with very little capital and simple equipment (Fig. 1). Many pocket miners are recovering gold using mercury and/or cyanide although some indigenous communities do not use such chemicals. Pocket miners situate themselves on mountain slopes of gold-rich areas and generally upstream of water bodies because they need surface water for milling process. Pocket miners in Luzon Island recover free gold from the ground ore coming directly from the tunnels they have driven.
0168-583X/02/$ - see front matter Ó 2002 Published by Elsevier Science B.V. PII: S 0 1 6 8 - 5 8 3 X ( 0 1 ) 0 1 0 3 3 - 3
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Fig. 1. Typical view of small-scale mining in the Philippines.
2. Mining technique More often than not, gold is separated from the ore mainly through gold amalgamation. Ore is first resized using hammers or mallets, then fed to a ball mill. Ground ore is then made to pass through a sluice box using flowing water. Sluice boxes are lined with jute sack or woolen blanket in order to collect very fine gold particles that have become liberated after the preliminary grinding. Free gold that is trapped in the jute sack or woolen blanket is washed in a large basin of water and collected. Other mill tailings contain some impurities alongside the free gold itself. The pocket miners collect the free gold by panning it using either a circular or rectangular GI sheet pan. Middling size particles (heterogeneous in grain size but nearly 50% is 6.3–63 lm) are then manually reground to collect free gold that has not been removed by the previous processes, using a stone grinder called ‘‘ga-id’’. The reground middling is panned to remove its impurities. Collected free gold particles are placed in an amalgamation vessel where mercury is added and regrinding continues until no more gold is left in the middling. After amalgam-
Fig. 2. Squeezed gold amalgam on a miner’s palm.
ation, the pocket miner scoops the amalgam and manually squeezes it on his palm so as to remove any excess mercury (Fig. 2).
3. Smelting and the problem After the free gold is recovered by the amalgamation, the gold amalgam is smelted. Smelting
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Table 1 Present status of miners and family members in study area ID
Gender
Age
Position
Diagnosis
Situation
46824
M
49
Pocket miner.
Unusual forgetfulness.
46818
F
54
Female pocket miner.
Diagnosed with kidney, heart and respiratory troubles. Lower back pains.
46825
M
43
Pocket miner.
46834
M
24
46821
F
26
Pocket miner before. Now another livelihood. Housewife.
Complaint on breathing difficulty, ringing ear trouble and easily gets tired. Complaint on blurring eyesight, difficulty in breathing.
Daily smelted about 100 g or more gold amalgam inside the house during the gold boom of study area. Lately for the past three years he transferred his smelting area beside his ball mill, away from his house. Does sorting, processes her own produce. Smelting is done in a small shaded annex of the house. Smelting room is adjacent to his house. Now outside the mining area.
46823
M
36
Pocket miner since 1990.
Often feels ‘‘flu’’.
46822
F
36
Mother of four kids.
Insomnia, ulcer, anemic to the extent that she tried using sleeping pills.
46836
M
36
Father of five children. Pocket miner/smelter/ gold buyer.
Prone to coughing troubles and blurring eyesight.
46820
F
56
Complaints on chest pains, dizziness.
47104
M
52
Mother, pocket miner. Father, pocket miner.
47105
F
42
Mother of seven children.
40% white hair, Enlarge thyroid (goiter) diagnosed since early 1980s. Heart troubles (palpitation). Difficulty in swallowing and talking for long period. Easily gets mad. Lower back pains. Diagnosed diabetic situation three years ago. Kidney trouble. Had blood-tainted urine in November 1999.
Dysmenorrhea, headache, dizziness.
Lower back pains. Headache. Dizziness. Blood pressure normal. Often feels ‘‘flu’’. Constant blocked throat and/or productive coughing.
Does sorting of muck wastes from her husband’s mining. She smelts her own gold. Does amalgamation, milling and smelting. Smelts an average of 15–30 g gold once a month at their smelting area at the back of the house. Does sorting of muck wastes, milling, amalgamation. Smelts her gold aside from assisting her husband. Smelting area is an enclosed shed at the back of his house which also serves as ball mill area (one wall side is open). He smelts product at an average of once a month. He purifies gold twice a month. Smelting area is a shaded extension of the house.
He is a smoker. During the 1970s and 1980s when a mining company is still a boom where he was a miner, he had been smelting 100 g amalgam gold, more or less daily, at the basement of their house. It was noted that the said basement is about 1.5 m high from house wooden flooring, and is enclosed. To date he smelts an average of 15–30 g gold amalgam once a month at the kitchen adjacent/in front of the main house. Assisted her husband in all mining and milling activities during the 1990s.
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Table 1 (continued) ID
Gender
Age
Position
Diagnosis
47107
F
19
Head pains.
46819
F
16
47106 46835
B F
11 27
Female college student. Parents are both pocket miners. Grade schooler. Mother of five children. Pocket miner/panner.
Situation
On early age, diagnosed of kidney trouble, urinary tract infection and heart enlargement. Healthy looking. Feels pain in her lower right abdomen.
is done at a convenient place within or very close to the pocket miner’s house. Some smelting is done inside the kitchens, under the slightly elevated houses or in outdoor kitchens adjoining the main house. Smelting is sometimes done inside ball mill sheds located close to the pocket miners’ residence. Smelting involves burning a small amount of charcoal. The amount of charcoal is adjusted to the volume of amalgam to be smelted. A manually driven air blower is used to hasten the burning of the charcoal. When the charcoal has produced embers, an earthen cupel is placed in its center. When the cupel is hot enough, the amalgam is placed with a mixture of borax and continuously fanned until the borax melts and free gold separates out. Continuous fanning maintains the melting temperature of gold. Thus, while the Hg in the amalgam is burning, the person operating the blower cannot leave the smelting area. Mercury intoxication could occur when the miner or their family inhale the mercury fumes during smelting or when liquid mercury comes in contact with human skin. The houses of pocket miners are very close to each other and so fumes can reach more than one household. The family would also be affected by mercury because of the smelting in the kitchen. Being concerned with this situation, and being requested by some miners, the authors conducted a preliminary analysis of human hairs from a mining site in Luzon Island. In order to get quick results, a standard-free method of
Parents are always smelting their product inside the kitchen.
Assists her husband in all his mining activity. Assists her husband in processing mine tailings in their leach pad (cyanidation process). They smelt an average of 10–30 g gold amalgam twice a month. Smelting area is a shaded extension at the back of the house.
Iwate Medical University [2] was used for the measurement.
4. Sampling and analysis Scalp hairs were donated to the second author from some miners and their families in a mining site of northern Luzon Island. The second author explained about the analytical method and also about the data handling after the analysis. Letters of consent allowing the authors to anonymously publish the analytical results were prepared and signed by the miners. Their present status is shown in Table 1. PIXE analysis was performed at Nishina Memorial Cyclotron Center established by Japan Radioisotope Association. A small size cyclotron provides a 2.9-MeV-proton beam on a target after passing through a beam collimator of graphite. Hair samples were wiped well with acetone and a few hairs were stuck on to a holder and directly irradiated with proton beams [2]. X-rays of energy higher than that of KKa are detected by a Si(Li) detector (0.0254-mm-thick Be window; 6 mm in active diameter) with a 300-lm-thick Mylar absorber. Another Si(Li) (0.008 mm Be; 4 mm in active diameter) is used for the measurement of lower-energy X-rays (
