- Email: [email protected]
Elevated trace element output in urine following acute volcanic gas exposure
Journal of Volcanology and Geothermal Research 134 (2004) 139 – 148 www.elsevier.com/locate/jvolgeores
Short communication
Elevated trace element output in urine following acute volcanic gas exposure Michael Durand a, Chris Florkowski b, Peter George b, Trevor Walmsley b, Phil Weinstein c,*, Jim Cole a a
Natural Hazards Research Centre, University of Canterbury, Private Bag 4800, Christchurch, New Zealand b Department of Clinical Biochemistry, Canterbury Health Laboratories, Christchurch, New Zealand c Wellington School of Medicine and Health Sciences, University of Otago, New Zealand Received 3 February 2003; accepted 22 January 2004
Abstract Biological monitoring of exposure to gases and respirable particles is common in industry, when urine or blood samples are analysed for elevated levels of various trace elements, but this is almost unheard of in volcanology. In this work, 10 volunteers undertook 20 min of acute gas exposure downwind of fumaroles on White Island, New Zealand. Pre- and post-exposure urine samples were analysed for aluminium, arsenic, rubidium and mercury—elements which are known to be present in volcanic gases—in order to test if any may be used as markers for gas exposure. Statistically significant ( p < 0.025) post-exposure increases in aluminium and rubidium excretion were seen, indicating respiratory absorption during gas exposure. No significant changes were observed in the analyses of arsenic and mercury. We suggest that aluminium and possibly rubidium may be useful markers of exposure to other more hazardous gases, to which volcanologists are exposed when working without respirators near fumaroles, lava flows, or other sources of volcanic gas. D 2004 Elsevier B.V. All rights reserved. Keywords: Volcanic gases; Aluminium; Rubidium; Gas exposure; Biological monitoring; White Island
1. Introduction The unexpected eruption of Galeras volcano in Colombia in 1993, which tragically killed six volcanologists and four tourists, attracted world media attention and highlighted the dangers accepted by those visiting the craters and flanks of active volca-
* Corresponding author. Present address: School of Population Health, University of Western Australia, Perth, Australia. E-mail address: [email protected] (P. Weinstein). 0377-0273/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jvolgeores.2004.01.007
noes (Baxter and Gresham, 1997; Williams, 2002). The main cause of death or injury to those at close range during a volcanic eruption is often bombardment by flying or falling pyroclasts, as was the case at Galeras (Baxter and Gresham, 1997), at Guagua Pichincha in Ecuador, just 2 months after Galeras (Fink, 1995), and on Mt. Etna in Italy in 1979 (Chester et al., 1985) when nine tourists lost their lives. These hazards are extremely serious and in the worst cases threaten a high probability of death for those involved, but they only occur when people are within a few kilometres (and usually a few hundred
140
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
metres) of an exploding vent when an unforeseen eruption occurs. During the potentially long periods between eruptions, when volcanologists and tourists visit active volcanoes and at times descend into the craters, there exists the less dramatic but still potentially serious hazard of toxic gases and aerosols. ‘‘The smell of sulphur is strong, but not unpleasant to a sinner,’’ wrote Mark Twain (1872) after his first visit to Kilauea, Hawai‘i. His description could be accurate for many other volcanoes worldwide which are active but not presently erupting, allowing people, especially volcanologists, to ‘safely’ access craters, fumaroles, lava lakes and other volcanic features where gases are constantly emitted and can present a respiratory hazard. Traditionally, sulphur dioxide (SO2), sulphuric acid (H2SO4), hydrogen sulphide (H2S), hydrogen chloride (HCl), hydrogen fluoride (HF) and carbon dioxide (CO2) have been recognised as the most harmful gases and aerosols emitted by volcanoes (Tho´rarinsson, 1979, 1981; Baxter et al., 1982, 1990; Blong, 1984; Durand and Grattan, 1999, 2001; Allen et al., 2000; Delmelle et al., 2002). Acid gases and aerosols irritate the eyes, nose and throat, and very high or repeated exposures may cause the development of reactive airways dysfunctional syndrome (RADS) or occupational asthma (Bardana, 1999; Malo and Chan-Yeung, 2001). Many other gases and aerosols are present in volcanic plumes, however, including arsenic (As), mercury (Hg), aluminium (Al), rubidium (Rb), lead (Pb), magnesium (Mg) and copper (Cu) (LeCloarec et al., 1992; Andres et al., 1993; Nriagu and Becker, 2003). As, Al and Hg are known to be toxic when inhaled as a fume, or as an aerosol comprising elements in mobile form (Jeffery et al., 1996; Grund et al., 2002; Riihima¨ki et al., 2000; Halbach, 2001), but exposure to these elements and their effect on the body has not been well documented in volcanic environments. Occupational exposure to inhaled Al, As and Hg can elevate urine outputs of these elements (Apostoli et al., 1999; Yokel and McNamara, 2001; Abdennour et al., 2002); indeed, in industrial settings, urine analysis is a standard tool for biological monitoring (Harrison and Sepai, 2000). This paper reports findings from a pilot study investigating changes in urine chemistry of 10 volunteers who were acutely exposed
to volcanic gas at White Island, New Zealand. The purpose of the study was to test the hypothesis:
That exposure to Al, Rb, As and Hg in volcanic gases can be detected by changes in urine chemistry (i.e. that these elements may be used as markers for exposure)
These elements could be useful biological markers of gas exposure because: (a) they are abundant in volcanic gases; (b) there is relatively little in the urine of unexposed healthy humans; and (c) they are not highly reactive in the body, in contrast to SO2, HCl, HF and other more harmful volcanic emissions.
2. Study site and methods White Island lies in the Bay of Plenty, 48 km offshore at the northern end of the Taupo Volcanic Zone, New Zealand (Fig. 1). It is an andesitic composite volcano whose activity, over recorded history (1826 –present), has been characterised by quiet fumarolic and solfataric emissions, punctuated by often extended spells (months –years) of weak – moderate eruptive activity (Cole and Nairn, 1975; Rose et al., 1986; Houghton and Nairn, 1989). At the time of the current study (February 2002), activity was typical of that normally observed between eruptions, with moderate fumarolic degassing in the central subcrater and moderate – strong fumarolic and main-vent degassing in the western subcrater. Average gas emissions from the volcano are typical of other passively degassing andesitic volcanoes, at f 430 t day 1 SO2 and f 1550 t day 1 CO2 (Wardell et al., 2001). The flux of metals from the volcano includes f 6000 kg day 1 Al, f 600 kg day 1 Rb, f 14 kg day 1 As and f 0.6 kg day 1 Hg (Christenson, unpublished data). The metal flux was derived using element to SO2 ratios from chemical traps near the main active vents in the western subcrater, and SO2 fluxes which were determined by correlation spectrometry (Christenson, unpublished data). Ratios of elements to SO2 in the main vent emissions were found to be Al 1.6 10 2, As 4.4 10 5, Rb 1.7 10 3 and Hg 1.7 10 6. We believe these gas ratios are representative of fumarole emissions in the central subcrater, since the main vent
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
141
Fig. 1. Sketch map of White Island and its geographical setting. Fumaroles where subjects were exposed are marked A, B and C, within the area of fumarolic degassing from the hydrothermal system.
and this accessible fumarolic area are fed by the same hydrothermal system (Hedenquist et al., 1993). These fumaroles in the central subcrater were the principle source of gas exposure in this experiment (Fig. 2). Two active fumarolic areas (A and B) lie on the north-eastern side, and one on the southern side (C). All three are on the very lower slopes of the crater walls. Volunteer subjects comprised seven males and three females of average age 27 (range 24– 38), none of whom were taking prescribed medication, nor were they smokers nor asthmatics. Subjects were on the volcano for 2 h and each spent 20 min close ( < 10 m) downwind from fumarole A, B or C, carrying masks around their necks but only using them if deemed necessary. We aimed to simulate working conditions for volcanologists not using masks, which are extreme in comparison to those encountered by tourists. Average exposure to SO2 during this period was monitored with diffusion tubes worn on clothing (Gastec Dositubes 5D). The SO2 data were subsequently used to estimate exposures to HF, HCl, Al, Rb, As and Hg.
These tubes are usually deployed to monitor exposure over 1 h or more, but were found to be accurate to f 75% over 30-min exposure during an earlier reconnaissance trip to White Island.
Fig. 2. Fumarole B at the base of the northern all in the central subcrater, with two subjects in the foreground exposed to gas in the snaking plume (Photo: G. Leonard).
142
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
Urine collection followed a standard protocol by collecting all urine generated during two timed periods. The ‘pre-exposure’ urine sample period was of 3.5 h duration on the day prior to exposure. The ‘postexposure’ sample period lasted 4.75 h and began on arrival at the volcano, included the period of gas exposure itself, and ended f 2 h following departure. The ‘post-exposure’ urine sample therefore contained any elements excreted into urine during or f 2 h following the period on the volcano and near the fumaroles. All analytes were measured in an ISO9002 accredited pathology laboratory using standard methods with known coefficients of variation (CV): Al and inorganic As were analysed on a Varian AA40 Graphite Furnace Atomic Absorption Spectrometer (CV = 5% and 16%, respectively); Rb was measured on a Varian AA100 Flame Atomic Absorption Spectrometer (CV = 7%); Hg was analysed by cold vapour generation using a Perkin Elmer Flow Injection analysis system attached to a Perkin Elmer A100 FAAS (CV = 20%); creatinine was measured using the Jaffe reaction on an Aeroset Biochemistry Analyser (CV = 0.5%). The hypothesis that excretion of each element into urine increased following exposure was tested with the Wilcoxon signed-rank test for matched pairs, a non-parametric test for dependant variables (Moore and McCabe, 2003). Outliers were defined by meeting both of the following standard criteria: (a) by lying three standard deviations above the group mean; and
(b) by lying within the 75th percentile by at least 1.5 the interquartile range (IQR). Outliers identified by both these definitions were removed from the Wilcoxon test.
3. Results Subjects experienced symptoms typical of irritant gas exposure whilst close to the fumaroles—stinging and watering eyes, with occasional and short lived ( < 3 s) difficulty breathing, choking sensations and coughing. Most subjects described the experience as generally unpleasant, but none felt compelled to use the masks provided, nor did they experience any respiratory difficulties following departure from the volcano. Some suffered mild soreness of exposed skin and a red flush similar to sunburn, probably caused by acid accumulation on the skin; this disappeared by the next day. The diffusion tubes worn by each subject recorded average personal exposures of f 6 – 75 ppm SO2 during the 20-min period close to the fumaroles (Table 1). The NIOSH short-term (10 min) exposure limit of 5 ppm (NIOSH, 2003) was exceeded by at least a factor of 2 in nine of the subjects; in the case of subject 4, limits were exceeded by f 30 times. Ratios of gases and trace elements to SO2 in the plume (Rose et al., 1986; Wardell et al., 2001; Christenson, personal communication) allow the calculation of approximate exposures to HCl, HF, Al, Rb As and Hg, shown in
Table 1 Time-averaged SO2 exposure in each subject measured by diffusion tubes, with HCl, HF, Al, Rb, As and Hg exposures inferred from known ratios to SO2 in plume gasesa Subject 1 2 3 4 5 6 7 8 9 10
SO2 (ppm)
HCl (ppm)
HF (ppm)
Al (Ag m
15 12 6 75 21 36 15 24 24 15
5.2 4.2 2.1 25.9 7.3 12.5 5.2 8.3 8.3 5.2
1.6 1.3 0.6 7.8 2.2 3.8 1.6 2.5 2.5 1.6
281 224 112 1405 393 674 281 449 449 281
3
)
Rb (Ag m 93 74 37 463 130 222 93 148 148 93
Exposures above NIOSH occupational health limits shown are in bold. a From Rose et al. (1986), Wardell et al. (2001) and Christenson, personal communication.
3
)
As (Ag m 2.0 1.6 0.8 10.1 2.8 4.9 2.0 3.2 3.2 2.0
3
)
Hg (Ag m 0.2 0.2 0.1 1.0 0.3 0.5 0.2 0.3 0.3 0.2
3
)
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
Table 1. NIOSH occupational exposure limits were exceeded in nine subjects for HCl and As, but in only one case for HF and none for Al and Hg (limits have not been set for Rb exposure). The main exposure route in these conditions is inhalation of gases and aerosols,
143
although absorption by skin/eye contact and by ingestion (mucus clearance) is also possible. Results of the urine analyses for Al, Rb, As and Hg are shown in Fig. 3, panels a –h. Outputs of each element are shown as micromoles (Amol) or nano-
Fig. 3. Al, Rb, As and Hg outputs in urine. Outputs are shown as paired values (pre- and post-exposure) in each subject (1 – 10) as the excretion rate (Amol or nmol h 1) and the ratio of each element to creatinine (Amol or nmol mol 1 creatinine).
144
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
moles (nmol) per hour, correcting for the longer postexposure urine collection period. Elements are also shown as their concentration in urine relative to creatinine (Amol mol 1 or nmol mol 1), a metabolic by-product which, in people with normal renal function, is excreted into urine at a relatively constant rate. Analyte/creatinine ratios therefore control against the effect of hydration upon elemental concentrations in urine. Results show a positive response in mean urinary outputs of Al and Rb following exposure, which was not matched by mean positive changes in Hg or As. A post-exposure increase in the Al output rate was seen in 9 of the 10 subjects, and ranged from 6 to 58 nmol h 1 (factors of 1.5 – 16, respectively). The mean change in the Al output rate was 19 nmol h 1, which was statistically significant at p < 0.025. Al increased relative to creatinine in seven subjects by a factor of 1.6– 64. The mean change of 900 nmol mol 1 creatinine was not statistically significant because of an outlier in creatinine data, subject 9, whose creatinine output per hour increased by a factor of 8 between the two samples. With this outlier removed, the group’s mean change in Al was 1700 nmol mol 1, which was significant at p < 0.005. A post-exposure increase in Rb outputs was observed in the excretion rate (7 subjects) and the concentration relative to creatinine (6 subjects). The mean increase in Rb Amol h 1 was significant at p < 0.025, but the change in Rb Amol mol 1 again was not significant because of the outlier in creatinine output, subject 9. With this data point removed, the group’s mean positive change in Rb was 417 Amol mol 1, which was significant at p < 0.001. In contrast to the Rb and Al results, changes in Hg and As output rates and urine concentrations showed no positive trends. In fact, in most subjects the rate of Hg and As output, and the concentration relative to creatinine, were lowest during the post-exposure period.
4. Discussion In this experiment we attempted to simulate conditions for volcanologists working near active fumaroles or vents, with a view to investigating trace elements in urine as markers for volcanic gas expo-
sure. The only previous investigation of this kind was that by Baxter et al. (1990), who analysed urine samples for Hg, As, fluoride and carbon monoxide following gas exposure near fumaroles on Vulcano, Italy. Concentrations of H2S 60 –150 ppm, HCl>10 ppm and HF 3 –15 ppm were detected close to active fumaroles where scientists were working. These concentrations exceeded 10 min occupational exposure limits (NIOSH, 2003) by 2– 15 times and, with the exception of H2S, were comparable with those our team experienced on White Island. Scientists worked near the active fumaroles for f 4 h, wearing respirators about half the time. The analyses found no elevated levels, but the exposure to the elements tested was not known except for fluoride (as HF). Despite a lack of evidence from past research on volcanoes, it is likely that exposure routes exist for trace elements in volcanic gas. In industrial settings, analysis of body fluids is a standard tool for the biological monitoring of occupational exposure to harmful compounds, and studies almost always reveal enhanced levels of contaminant elements in blood, serum, plasma or urine (Sjo¨gren et al., 1985, 1988; Kono et al., 1987; Elinder et al., 1991; Ljunggren et al., 1991; George et al., 1993; Søyseth et al., 1994; Pierre et al., 1995, 2002; Lund et al., 1997; Riihima¨ki et al., 2000; Gulson et al., 2002). These studies also demonstrate or advocate negative health outcomes as a result of occupational exposure. Significantly, recommended occupational exposure limits need not be exceeded in order to observe enhanced concentrations of a given element in any of these fluids. In the present research, exposures to SO2, HCl and As were recorded and inferred to be above the shortterm limits set for occupational exposures (NIOSH, 2003). Inferred Al and Hg concentrations were below recommended exposure limits, but were similar to those found in industrial settings where enhanced urinary outputs of elements has been found (e.g. Pierre et al., 1995; Abdennour et al., 2002). In this work, however, the 20-min period of acute exposure near the fumaroles was considerably shorter than found in most industrial exposure settings. Both the rate (Amol h 1) and concentration (Amol mol 1 creatinine) of Al in urine increased in subjects 1, 2, 4, 5, 6, 7, 8 and 10 following the exposure to volcanic gas. Statistical hypothesis testing showed the group’s post-exposure shift in Al excretion was
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
significant at p < 0.005 (Amol) and p < 0.001 (Amol mol 1). Although the influence of an unknown and confounding Al source cannot be ruled out, the fact that Al was elevated in 8 of 10 subjects suggests a common source for this change, rather than unlikely confounding sources which might act upon individuals (e.g. mobile Al in food, drinks, toothpaste or deodorants). Urine accounts for f 95% of excreted Al (Yokel and McNamara, 2001), which has a halflife of 5– 9 h (Pierre et al., 1995). Our urine sample period of 4.75 h was therefore sufficient to collect up to half of any Al absorbed by the pulmonary tract during exposure, and subsequently excreted in the urine. The rate and dynamics of Al excretion into urine has, however, been shown to relate to the molecular form of Al during exposure (Pierre et al., 1995), about which we have no data from White Island. A delay between absorption and excretion would mean any late or secondary peak in Al excretion was not collected by our samples. Under these circumstances, the net increases in Al we observe here could merely indicate a still more significant change in Al excretion resulting from gas exposure. The rate and concentration of Rb excreted into urine increased following exposure in subjects 1, 3, 4, 5, 6 and 8. The statistically significant changes in the group’s rate and concentration of urinary Rb excretion ( p < 0.001 and p < 0.025, respectively) also suggests a common source of the extra Rb, rather than the doubtful influence of independently active confounding sources. Considering both elements together, positive postexposure shifts in Al and Rb excretion rate and element/creatinine ratios were seen in subjects 1, 5 and 8. Subjects 4 and 6 showed similar positive changes in all variables, but these were relatively small in at least one variable. There was not, therefore, a clear correlation between Al and Rb excretion, even though positive changes were seen in most subjects and the group’s positive shifts were statistically significant in all variables. Subjects 2, 3 and 7 possessed at least one negative variable in Al or Rb. Reasons for these discrepancies may be related to a number of factors including differing levels of exposure (these three subjects were among the least exposed according to the diffusion tube data) or perhaps personal differences in renal function. In the group as a whole,
145
however, exposures recorded by the diffusion tubes did not correlate with the observed changes in urinary outputs. A clear correlation should not be expected, however, since respiratory absorption of gases and particles varies considerably between individuals. In addition, it is possible the tube readings were not an accurate indication of true respiratory exposure. Further uncertainties exist because it was necessary to estimate metal outputs from the fumaroles by using data from other vents. The As and Hg data show marked differences to those for Al and Rb. Exposure to As, which we expect was above occupational health limits for most subjects, did not result in an observable change in urinary outputs. Concentrations in urine were below detectable limits in subjects 5, 7, 8 and 10, before and following exposure, and any observed changes in the volume excreted and the ratio to creatinine, showed no trend. Changes in Hg excretion were minimal in most cases, and only in subject 1 was there a marked increase in the Hg excretion rate following exposure. A corresponding fall in the Hg/creatinine ratio, however, shows that more Hg was present in the postexposure urine because of the greater rate of urine excretion in this sample. Half-lives of As and Hg are much higher than Al and are in the order of days, which may account for the clear difference in excretion of these elements (Grund et al., 2002; Halbach, 2001). Arsenic excretion occurs mainly through urine, but less than 60% of Hg is excreted in this way, the remainder being lost through faeces and exhaled vapour. Therefore, a lack of excretion into the sampled urine, as well as insufficient exposure and/or absorption, are likely reasons for the observed results. Our experiment suffered from a number of uncertainties concerning exposure assessment, adequacy of the urine sampling periods, and possible confounding sources of mobile Al, Rb, As and Hg. This was, however, a pilot study which was necessarily constrained by what is possible and practical when using human subjects on an active volcano. In this sense, the experiment was a hypothesis-forming exercise, the results from which should be used in a detailed follow-up investigation of urine, blood, plasma and serum markers for volcanic gas exposure. More subjects should be used, and their fluids monitored with bracketed samples over several days before and fol-
146
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
lowing exposure. Exposure itself should also be better quantified in future work. Levels of all the elements tested were well within normal reference limits for individuals with normal renal function who are not occupationally exposed (Cornelis et al., 1975; White and Sabbioni, 1998; Apostoli et al., 1999). It is likely that the health hazards of exposure to these elements in volcanic gases are negligible. This deserves further research, however, respirable exposure to zinc, for example, can cause fume fever, but oral doses of zinc are relatively harmless. Little is known about the toxicity of respired Rb fumes. The results suggest that Al and possibly Rb may be useful markers for volcanic gas exposure. This should certainly be investigated further in future work. In industry, markers in urine or other fluids are used extensively for biological monitoring, but this is not the case in volcanology, where scientists can be exposed to very high concentrations of many toxic gases simultaneously. This experiment concerned a single, short-term exposure to volcanic gas which could be considered as a minimum exposure for volcanologists working without respirators near fumaroles. During eruptions of mafic lavas which may allow relatively close access to active vents and lava flows, the total exposure to gases and aerosols may be orders of magnitude higher. It should be emphasised that volcanologists should always wear respirators when exposed to gases near fumaroles and downwind from active vents. However, for volcanologists who might be repeatedly exposed to acid gases and, in some cases, do not always wear respirators, biological monitoring using exposure markers might provide a means to assess dangerous exposure. The best elements for such work, and thresholds for action, could only be identified after further research.
5. Conclusion In this pilot study, volunteers were acutely exposed to volcanic gas downwind of fumaroles on White Island, New Zealand. The work tested the hypothesis that Al, Rb, As and Hg in urine can be used as biological markers for volcanic gas exposure. All these elements are present in volcanic gases, and with the exception of Rb, have been used for
biological monitoring of occupational exposure in industry. Results show that the excretion rate (Amol h 1) and concentration (Amol mol 1 creatinine) of Al and Rb in urine were elevated in urine following exposure to gas. The group’s positive shift in each element was statistically significant by both variables, suggesting a common cause. We expect that biological variation or changes resulting from intake of mobile elements through food, drinks, or cosmetic products, would act on an individual basis and not produce the observed results. Post-exposure changes in As and Hg were inconclusive. The results therefore suggest that Al and possibly Rb could be used as biological markers for exposure to other, more harmful volcanic gases and aerosols including SO2, H2SO4, H2S, HCl and HF. This should be followed up in future work, since it has implications for volcanologists who risk the development of RADS or occupational asthma, if they are exposed to high concentrations of gases and do not habitually use respirators.
Acknowledgements We thank Jenny and Peter Tait of PeeJay Charters and David Reeve at Whakatane Hospital for logistical support. Bruce Christenson (GNS) is thanked for unpublished emissions data. We are grateful to students from the Universities of Canterbury, Waikato and Auckland for volunteering their fluids. MD was supported by a Fellowship from the University of Canterbury, which also funded the analyses and research logistics. Ethical approval for the work was given by Canterbury Ethics Committee, and participants gave informed consent after the implications of the work were explained. The paper benefited greatly from reviews by Peter Baxter and two anonymous reviewers.
References Abdennour, C., Khelili, K., Boulakoud, M.S., Nezzal, A., Boubsil, S., Slimani, S., 2002. Urinary markers of workers chronically exposed to mercury vapor. Environ. Res. 89 (3), 245 – 249. Allen, A.G., Baxter, P.J., Ottley, C.J., 2000. Gas and particle emissions from Soufriere Hills volcano, Montserrat, West Indies:
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148 characterisation and health hazard assessment. Bull. Volcanol. 62, 8 – 19. Andres, R.J., Kyle, P.R., Chuan, R.L., 1993. Sulphur dioxide and elemental emissions from Mount Etna, Italy, during July, 1987. Geol. Rundsch. 82, 687 – 695. Apostoli, P., Bartoli, D., Alessio, L., Buchet, J.P., 1999. Biological monitoring of occupational exposure to inorganic arsenic. Occup. Environ. Med. 56 (12), 825 – 832. Bardana, E.J., 1999. Reactive airways dysfunction syndrome (RADS): guidelines for diagnosis and treatment and insight into likely prognosis. Ann. Allergy, Asthma, & Immun. 83, 583 – 586. Baxter, P.J., Gresham, A., 1997. Deaths and injuries in the eruption of Galeras Volcano, Colombia, 14 January 1993. J. Volcanol. Geotherm. Res. 77, 325 – 338. Baxter, P.J., Stoiber, R.E., Williams, S.N., 1982. Volcanic gases and health: Masaya volcano, Nicaragua. Lancet, 150 – 151 (July 17, 1982). Baxter, P.J., Tedesco, D., Miele, G., Boubron, J.C., Cliff, K., 1990. Health Hazards from volcanic gases. Lancet, 176 (July 21, 1990). Blong, R.G.C., 1984. Volcanic Hazards: A Source Book on the Effects of Eruptions. Academic Press, Australia. Chester, D.K., Duncan, A.M., Guest, J.E., Kilburn, C.R.J., 1985. Mt. Etna: The Anatomy of a Volcano. Chapman & Hall, London. 389 pp. Cole, J.W., Nairn, I.A., 1975. Catalogue of the active volcanoes of the world including solfatara fields—Part 22: New Zealand. International Association of the Chemistry of the Earth’s Interior, 156 pp. Cornelis, R., Speecke, A., Hoste, J., 1975. Neutron activation analysis for bulk and trace elements in urine. Anal. Chim. Acta 78, 317 – 327. Delmelle, P., Stix, J., Baxter, P., Garcia-Alvarez, J., Barquero, J., 2002. Atmospheric dispersion, environmental effects and potential health hazard associated with the low-altitude gas plume of Masaya volcano, Nicaragua. Bull. Volcanol. 64, 423 – 434. Durand, M., Grattan, J., 1999. Extensive respiratory health effects of volcanogenic dry fog in 1783 inferred from European documentary sources. Envron. Geochem. Health 21, 371 – 376. Durand, M., Grattan, J., 2001. Effects of volcanic air pollution on health. Lancet 357, 164. Elinder, C.G., Ahrengart, L., Lidums, V., Petterson, E., Sjo¨gren, B., 1991. Evidence of aluminium accumulation in aluminium welders. Br. J. Ind. Med. 48, 735 – 738. Fink, J., 1995. Exploding volcanic myths. Nature 373, 660 – 661. George, P.M., Walmsley, T.A., Currie, D., Wells, J.E., 1993. Lead exposure during recreational use of small-bore rifle ranges. N.Z. Med. J. 106, 422 – 424. Grund, S.C., Hanusch, K., Wolf, H.U., 2002. Arsenic and arsenic compounds: toxicology. Ullman’s Encyclopedia of Industrial Chemistry. Wiley, doi:10.1002/14356007.a03 _ 113 (http:// www.mrw.interscience.wiley.com/veic). Gulson, B.L., Palmer, J.M., Bryce, A., 2002. Changes in blood lead of recreational shooter. Sci. Total Environ. 293, 143 – 150. Halbach, S., 2001. Mercury, mercury alloys, and mercury com-
147
pounds: toxicology and environmental health. Ullman’s Encyclopedia of Industrial Chemistry. Wiley, DOI: 10.1002/143560007. a16_269 (http://www.mrw.interscience.wiley.com/veic). Harrison, J., Sepai, O., 2000. Should control measures be based on air measurements or biological/biological effect monitoring? Occup. Med. (Lond.) 50 (1), 61 – 63. Hedenquist, J.W., Simmons, S.F., Giggenbach, W.F., Eldridge, C.S., 1993. White Island, New Zealand, volcanic – hydrothermal system represents a geochemical environment of high-sulfidation Cu and Au ore deposition. Geology 21, 731 – 734. Houghton, B.F., Nairn, I.A. (Eds.), 1989. The 1976 – 82 eruption sequence at White Island volcano (Whakaari), Bay of Plenty, New Zealand. N. Z. Geol. Surv. Bull. 103, 138 pp. Jeffery, E.H., Abreo, K., Burgess, E., Cannata, J., Greger, J.L., 1996. Systemic aluminium toxicity: effects on the bone, haematopoietic tissue, and kidney. J. Toxicol. Environ. Health 48, 649 – 665. Kono, K., Yoshida, Y., Yamagata, H., Watanabe, M., Shibuya, Y., Doi, K., 1987. Urinary fluoride monitoring of industrial hydrofluoric acid exposure. Environ. Res. 42, 415 – 420. LeCloarec, M.F., Allard, P., Ardouin, B., Giggenbach, W.F., Sheppard, D.S., 1992. Radioactive isotopes and trace elements in gaseous emissions from White Island, New Zealand. Earth Planet. Sci. Lett. 108, 19 – 28. Ljunggren, K.G., Lidums, V., Sjo¨gren, B., 1991. Blood and urine concentrations of aluminium among workers exposed to aluminium flake powders. Br. J. Ind. Med. 48, 106 – 109. Lund, K., Ekstrand, J., Boe, J., Søstrand, P., Kongurand, J., 1997. Exposure to hydrogen fluoride: An experimental in human and concentrations of fluoride in plasma, symptoms and lung function. Occup. Environ. Med. 54, 32 – 37. Malo, J.L., Chan-Yeung, M., 2001. Occupational asthma. J. Allergy Clin. Immunol. 108, 317 – 328. Moore, D.S., McCabe, G.P., 2003. Introduction to the Practice of Statistics, Fourth edition. Freeman, New York, 828 pp. NIOSH, G.P., 2003. Online NIOSH Pocket Guide to Chemical Hazards National Institute of Occupational Safety and Health. http://www.cdc.gov/niosh/. Nriagu, J., Becker, C., 2003. Volcanic emissions of mercury to the atmosphere: global and regional inventories. Sci. Total. Environ. 304, 3 – 12. Pierre, F., Baruthio, F., Diebold, F., Biette, P., 1995. Effect of different exposure compounds on urinary kinetics of aluminium and fluoride in industrially exposed workers. Occup. Environ. Med. 52, 396 – 403. Pierre, F., Vallayer, C., Baruthio, F., Peltier, A., Pale, S., Rouyer, J., Goutet, P., Aubrege, B., Lecossois, C., Guillemin, C., Elcabache, J.-M., Verelle, B., Fabries, J.-F., 2002. Specific relationship between blood lead and air lead in the crystal industry. Int. Arch. Occup. Environ. Health 75, 217 – 223. Riihima¨ki, V., Ha¨nninen, H., Akila, R., Kovala, T., Kuosma, E., Paakkulainen, H., Valkonen, S., Engstro¨m, B., 2000. Body burden of aluminium in relation to central nervous system function among inert-gas welders. Scand. J. Work, Environ. & Health 26, 118 – 130. Rose, W.I., Chuan, R.L., Giggenbach, W.F., Kyle, P.R., Symonds, R.B., 1986. Rates of sulphur dioxide and particle emissions
148
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
from White Island volcano, New Zealand, and an estimate of the total flux of major gaseous species. Bull. Volcanol. 48, 181 – 188. Sjo¨gren, B., Lidums, V., Ha¨kansson, M., Hedstro¨m, L., 1985. Exposure and urinary secretion of aluminium during welding. Scand. J. Work, Environ. & Health 11, 39 – 43. Sjo¨gren, B., Elinder, C.G., Lidums, V., Chang, G., 1988. Uptake and urinary excretion of aluminium among welders. Int. Arch. Occup. Environ. Health 60, 77 – 79. Søyseth, V., Kongerud, J., Ekstrand, J., Boe, J., 1994. Relation between fluoride and bronchial responsiveness in aluminium potroom workers with work-related asthma-like symptoms. Thorax 49, 984 – 989. Tho´rarinsson, S., 1979. On the damage caused by volcanic eruptions with special reference to tephra and gases. In: Sheets, P.D., Grayson, D.K. (Eds.), Volcanic Activity and Human Ecology. Academic Press, New York, pp. 125 – 159.
Tho´rarinsson, S., 1981. Greetings from Iceland: ash-falls and volcanic aerosols in Scandinavia. Geogr. Ann. 63A, 109 – 118. Twain, M., 1872. Letters from Hawai‘i. Reprinted. In: Grove Day, A. (Ed.), Mark Twain’s Letters from Hawai‘i. University of Hawai‘i Press, Honolulu, HI, p. 1975. Wardell, L., Kyle, P., Dunbar, N., Christenson, B., 2001. White Island Volcano, New Zealand; carbon dioxide and sulfur dioxide emission rates and melt inclusion studies. Chem. Geol. 177, 187 – 200. White, M.A., Sabbioni, E., 1998. Trace element reference values in tissues from inhabitants of the European Union. X. A study of 13 elements in blood and urine of a United Kingdom population. Sci. Total Environ. 216, 253 – 270. Williams, S., 2002. Surviving Galeras Little Brown and Co., London, 270 pp. Yokel, R.A., McNamara, P.J., 2001. Aluminium toxicokinetics: An updated minireview. Pharmacol. Toxicol. 88, 159 – 167.
Short communication
Elevated trace element output in urine following acute volcanic gas exposure Michael Durand a, Chris Florkowski b, Peter George b, Trevor Walmsley b, Phil Weinstein c,*, Jim Cole a a
Natural Hazards Research Centre, University of Canterbury, Private Bag 4800, Christchurch, New Zealand b Department of Clinical Biochemistry, Canterbury Health Laboratories, Christchurch, New Zealand c Wellington School of Medicine and Health Sciences, University of Otago, New Zealand Received 3 February 2003; accepted 22 January 2004
Abstract Biological monitoring of exposure to gases and respirable particles is common in industry, when urine or blood samples are analysed for elevated levels of various trace elements, but this is almost unheard of in volcanology. In this work, 10 volunteers undertook 20 min of acute gas exposure downwind of fumaroles on White Island, New Zealand. Pre- and post-exposure urine samples were analysed for aluminium, arsenic, rubidium and mercury—elements which are known to be present in volcanic gases—in order to test if any may be used as markers for gas exposure. Statistically significant ( p < 0.025) post-exposure increases in aluminium and rubidium excretion were seen, indicating respiratory absorption during gas exposure. No significant changes were observed in the analyses of arsenic and mercury. We suggest that aluminium and possibly rubidium may be useful markers of exposure to other more hazardous gases, to which volcanologists are exposed when working without respirators near fumaroles, lava flows, or other sources of volcanic gas. D 2004 Elsevier B.V. All rights reserved. Keywords: Volcanic gases; Aluminium; Rubidium; Gas exposure; Biological monitoring; White Island
1. Introduction The unexpected eruption of Galeras volcano in Colombia in 1993, which tragically killed six volcanologists and four tourists, attracted world media attention and highlighted the dangers accepted by those visiting the craters and flanks of active volca-
* Corresponding author. Present address: School of Population Health, University of Western Australia, Perth, Australia. E-mail address: [email protected] (P. Weinstein). 0377-0273/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jvolgeores.2004.01.007
noes (Baxter and Gresham, 1997; Williams, 2002). The main cause of death or injury to those at close range during a volcanic eruption is often bombardment by flying or falling pyroclasts, as was the case at Galeras (Baxter and Gresham, 1997), at Guagua Pichincha in Ecuador, just 2 months after Galeras (Fink, 1995), and on Mt. Etna in Italy in 1979 (Chester et al., 1985) when nine tourists lost their lives. These hazards are extremely serious and in the worst cases threaten a high probability of death for those involved, but they only occur when people are within a few kilometres (and usually a few hundred
140
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
metres) of an exploding vent when an unforeseen eruption occurs. During the potentially long periods between eruptions, when volcanologists and tourists visit active volcanoes and at times descend into the craters, there exists the less dramatic but still potentially serious hazard of toxic gases and aerosols. ‘‘The smell of sulphur is strong, but not unpleasant to a sinner,’’ wrote Mark Twain (1872) after his first visit to Kilauea, Hawai‘i. His description could be accurate for many other volcanoes worldwide which are active but not presently erupting, allowing people, especially volcanologists, to ‘safely’ access craters, fumaroles, lava lakes and other volcanic features where gases are constantly emitted and can present a respiratory hazard. Traditionally, sulphur dioxide (SO2), sulphuric acid (H2SO4), hydrogen sulphide (H2S), hydrogen chloride (HCl), hydrogen fluoride (HF) and carbon dioxide (CO2) have been recognised as the most harmful gases and aerosols emitted by volcanoes (Tho´rarinsson, 1979, 1981; Baxter et al., 1982, 1990; Blong, 1984; Durand and Grattan, 1999, 2001; Allen et al., 2000; Delmelle et al., 2002). Acid gases and aerosols irritate the eyes, nose and throat, and very high or repeated exposures may cause the development of reactive airways dysfunctional syndrome (RADS) or occupational asthma (Bardana, 1999; Malo and Chan-Yeung, 2001). Many other gases and aerosols are present in volcanic plumes, however, including arsenic (As), mercury (Hg), aluminium (Al), rubidium (Rb), lead (Pb), magnesium (Mg) and copper (Cu) (LeCloarec et al., 1992; Andres et al., 1993; Nriagu and Becker, 2003). As, Al and Hg are known to be toxic when inhaled as a fume, or as an aerosol comprising elements in mobile form (Jeffery et al., 1996; Grund et al., 2002; Riihima¨ki et al., 2000; Halbach, 2001), but exposure to these elements and their effect on the body has not been well documented in volcanic environments. Occupational exposure to inhaled Al, As and Hg can elevate urine outputs of these elements (Apostoli et al., 1999; Yokel and McNamara, 2001; Abdennour et al., 2002); indeed, in industrial settings, urine analysis is a standard tool for biological monitoring (Harrison and Sepai, 2000). This paper reports findings from a pilot study investigating changes in urine chemistry of 10 volunteers who were acutely exposed
to volcanic gas at White Island, New Zealand. The purpose of the study was to test the hypothesis:
That exposure to Al, Rb, As and Hg in volcanic gases can be detected by changes in urine chemistry (i.e. that these elements may be used as markers for exposure)
These elements could be useful biological markers of gas exposure because: (a) they are abundant in volcanic gases; (b) there is relatively little in the urine of unexposed healthy humans; and (c) they are not highly reactive in the body, in contrast to SO2, HCl, HF and other more harmful volcanic emissions.
2. Study site and methods White Island lies in the Bay of Plenty, 48 km offshore at the northern end of the Taupo Volcanic Zone, New Zealand (Fig. 1). It is an andesitic composite volcano whose activity, over recorded history (1826 –present), has been characterised by quiet fumarolic and solfataric emissions, punctuated by often extended spells (months –years) of weak – moderate eruptive activity (Cole and Nairn, 1975; Rose et al., 1986; Houghton and Nairn, 1989). At the time of the current study (February 2002), activity was typical of that normally observed between eruptions, with moderate fumarolic degassing in the central subcrater and moderate – strong fumarolic and main-vent degassing in the western subcrater. Average gas emissions from the volcano are typical of other passively degassing andesitic volcanoes, at f 430 t day 1 SO2 and f 1550 t day 1 CO2 (Wardell et al., 2001). The flux of metals from the volcano includes f 6000 kg day 1 Al, f 600 kg day 1 Rb, f 14 kg day 1 As and f 0.6 kg day 1 Hg (Christenson, unpublished data). The metal flux was derived using element to SO2 ratios from chemical traps near the main active vents in the western subcrater, and SO2 fluxes which were determined by correlation spectrometry (Christenson, unpublished data). Ratios of elements to SO2 in the main vent emissions were found to be Al 1.6 10 2, As 4.4 10 5, Rb 1.7 10 3 and Hg 1.7 10 6. We believe these gas ratios are representative of fumarole emissions in the central subcrater, since the main vent
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
141
Fig. 1. Sketch map of White Island and its geographical setting. Fumaroles where subjects were exposed are marked A, B and C, within the area of fumarolic degassing from the hydrothermal system.
and this accessible fumarolic area are fed by the same hydrothermal system (Hedenquist et al., 1993). These fumaroles in the central subcrater were the principle source of gas exposure in this experiment (Fig. 2). Two active fumarolic areas (A and B) lie on the north-eastern side, and one on the southern side (C). All three are on the very lower slopes of the crater walls. Volunteer subjects comprised seven males and three females of average age 27 (range 24– 38), none of whom were taking prescribed medication, nor were they smokers nor asthmatics. Subjects were on the volcano for 2 h and each spent 20 min close ( < 10 m) downwind from fumarole A, B or C, carrying masks around their necks but only using them if deemed necessary. We aimed to simulate working conditions for volcanologists not using masks, which are extreme in comparison to those encountered by tourists. Average exposure to SO2 during this period was monitored with diffusion tubes worn on clothing (Gastec Dositubes 5D). The SO2 data were subsequently used to estimate exposures to HF, HCl, Al, Rb, As and Hg.
These tubes are usually deployed to monitor exposure over 1 h or more, but were found to be accurate to f 75% over 30-min exposure during an earlier reconnaissance trip to White Island.
Fig. 2. Fumarole B at the base of the northern all in the central subcrater, with two subjects in the foreground exposed to gas in the snaking plume (Photo: G. Leonard).
142
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
Urine collection followed a standard protocol by collecting all urine generated during two timed periods. The ‘pre-exposure’ urine sample period was of 3.5 h duration on the day prior to exposure. The ‘postexposure’ sample period lasted 4.75 h and began on arrival at the volcano, included the period of gas exposure itself, and ended f 2 h following departure. The ‘post-exposure’ urine sample therefore contained any elements excreted into urine during or f 2 h following the period on the volcano and near the fumaroles. All analytes were measured in an ISO9002 accredited pathology laboratory using standard methods with known coefficients of variation (CV): Al and inorganic As were analysed on a Varian AA40 Graphite Furnace Atomic Absorption Spectrometer (CV = 5% and 16%, respectively); Rb was measured on a Varian AA100 Flame Atomic Absorption Spectrometer (CV = 7%); Hg was analysed by cold vapour generation using a Perkin Elmer Flow Injection analysis system attached to a Perkin Elmer A100 FAAS (CV = 20%); creatinine was measured using the Jaffe reaction on an Aeroset Biochemistry Analyser (CV = 0.5%). The hypothesis that excretion of each element into urine increased following exposure was tested with the Wilcoxon signed-rank test for matched pairs, a non-parametric test for dependant variables (Moore and McCabe, 2003). Outliers were defined by meeting both of the following standard criteria: (a) by lying three standard deviations above the group mean; and
(b) by lying within the 75th percentile by at least 1.5 the interquartile range (IQR). Outliers identified by both these definitions were removed from the Wilcoxon test.
3. Results Subjects experienced symptoms typical of irritant gas exposure whilst close to the fumaroles—stinging and watering eyes, with occasional and short lived ( < 3 s) difficulty breathing, choking sensations and coughing. Most subjects described the experience as generally unpleasant, but none felt compelled to use the masks provided, nor did they experience any respiratory difficulties following departure from the volcano. Some suffered mild soreness of exposed skin and a red flush similar to sunburn, probably caused by acid accumulation on the skin; this disappeared by the next day. The diffusion tubes worn by each subject recorded average personal exposures of f 6 – 75 ppm SO2 during the 20-min period close to the fumaroles (Table 1). The NIOSH short-term (10 min) exposure limit of 5 ppm (NIOSH, 2003) was exceeded by at least a factor of 2 in nine of the subjects; in the case of subject 4, limits were exceeded by f 30 times. Ratios of gases and trace elements to SO2 in the plume (Rose et al., 1986; Wardell et al., 2001; Christenson, personal communication) allow the calculation of approximate exposures to HCl, HF, Al, Rb As and Hg, shown in
Table 1 Time-averaged SO2 exposure in each subject measured by diffusion tubes, with HCl, HF, Al, Rb, As and Hg exposures inferred from known ratios to SO2 in plume gasesa Subject 1 2 3 4 5 6 7 8 9 10
SO2 (ppm)
HCl (ppm)
HF (ppm)
Al (Ag m
15 12 6 75 21 36 15 24 24 15
5.2 4.2 2.1 25.9 7.3 12.5 5.2 8.3 8.3 5.2
1.6 1.3 0.6 7.8 2.2 3.8 1.6 2.5 2.5 1.6
281 224 112 1405 393 674 281 449 449 281
3
)
Rb (Ag m 93 74 37 463 130 222 93 148 148 93
Exposures above NIOSH occupational health limits shown are in bold. a From Rose et al. (1986), Wardell et al. (2001) and Christenson, personal communication.
3
)
As (Ag m 2.0 1.6 0.8 10.1 2.8 4.9 2.0 3.2 3.2 2.0
3
)
Hg (Ag m 0.2 0.2 0.1 1.0 0.3 0.5 0.2 0.3 0.3 0.2
3
)
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
Table 1. NIOSH occupational exposure limits were exceeded in nine subjects for HCl and As, but in only one case for HF and none for Al and Hg (limits have not been set for Rb exposure). The main exposure route in these conditions is inhalation of gases and aerosols,
143
although absorption by skin/eye contact and by ingestion (mucus clearance) is also possible. Results of the urine analyses for Al, Rb, As and Hg are shown in Fig. 3, panels a –h. Outputs of each element are shown as micromoles (Amol) or nano-
Fig. 3. Al, Rb, As and Hg outputs in urine. Outputs are shown as paired values (pre- and post-exposure) in each subject (1 – 10) as the excretion rate (Amol or nmol h 1) and the ratio of each element to creatinine (Amol or nmol mol 1 creatinine).
144
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
moles (nmol) per hour, correcting for the longer postexposure urine collection period. Elements are also shown as their concentration in urine relative to creatinine (Amol mol 1 or nmol mol 1), a metabolic by-product which, in people with normal renal function, is excreted into urine at a relatively constant rate. Analyte/creatinine ratios therefore control against the effect of hydration upon elemental concentrations in urine. Results show a positive response in mean urinary outputs of Al and Rb following exposure, which was not matched by mean positive changes in Hg or As. A post-exposure increase in the Al output rate was seen in 9 of the 10 subjects, and ranged from 6 to 58 nmol h 1 (factors of 1.5 – 16, respectively). The mean change in the Al output rate was 19 nmol h 1, which was statistically significant at p < 0.025. Al increased relative to creatinine in seven subjects by a factor of 1.6– 64. The mean change of 900 nmol mol 1 creatinine was not statistically significant because of an outlier in creatinine data, subject 9, whose creatinine output per hour increased by a factor of 8 between the two samples. With this outlier removed, the group’s mean change in Al was 1700 nmol mol 1, which was significant at p < 0.005. A post-exposure increase in Rb outputs was observed in the excretion rate (7 subjects) and the concentration relative to creatinine (6 subjects). The mean increase in Rb Amol h 1 was significant at p < 0.025, but the change in Rb Amol mol 1 again was not significant because of the outlier in creatinine output, subject 9. With this data point removed, the group’s mean positive change in Rb was 417 Amol mol 1, which was significant at p < 0.001. In contrast to the Rb and Al results, changes in Hg and As output rates and urine concentrations showed no positive trends. In fact, in most subjects the rate of Hg and As output, and the concentration relative to creatinine, were lowest during the post-exposure period.
4. Discussion In this experiment we attempted to simulate conditions for volcanologists working near active fumaroles or vents, with a view to investigating trace elements in urine as markers for volcanic gas expo-
sure. The only previous investigation of this kind was that by Baxter et al. (1990), who analysed urine samples for Hg, As, fluoride and carbon monoxide following gas exposure near fumaroles on Vulcano, Italy. Concentrations of H2S 60 –150 ppm, HCl>10 ppm and HF 3 –15 ppm were detected close to active fumaroles where scientists were working. These concentrations exceeded 10 min occupational exposure limits (NIOSH, 2003) by 2– 15 times and, with the exception of H2S, were comparable with those our team experienced on White Island. Scientists worked near the active fumaroles for f 4 h, wearing respirators about half the time. The analyses found no elevated levels, but the exposure to the elements tested was not known except for fluoride (as HF). Despite a lack of evidence from past research on volcanoes, it is likely that exposure routes exist for trace elements in volcanic gas. In industrial settings, analysis of body fluids is a standard tool for the biological monitoring of occupational exposure to harmful compounds, and studies almost always reveal enhanced levels of contaminant elements in blood, serum, plasma or urine (Sjo¨gren et al., 1985, 1988; Kono et al., 1987; Elinder et al., 1991; Ljunggren et al., 1991; George et al., 1993; Søyseth et al., 1994; Pierre et al., 1995, 2002; Lund et al., 1997; Riihima¨ki et al., 2000; Gulson et al., 2002). These studies also demonstrate or advocate negative health outcomes as a result of occupational exposure. Significantly, recommended occupational exposure limits need not be exceeded in order to observe enhanced concentrations of a given element in any of these fluids. In the present research, exposures to SO2, HCl and As were recorded and inferred to be above the shortterm limits set for occupational exposures (NIOSH, 2003). Inferred Al and Hg concentrations were below recommended exposure limits, but were similar to those found in industrial settings where enhanced urinary outputs of elements has been found (e.g. Pierre et al., 1995; Abdennour et al., 2002). In this work, however, the 20-min period of acute exposure near the fumaroles was considerably shorter than found in most industrial exposure settings. Both the rate (Amol h 1) and concentration (Amol mol 1 creatinine) of Al in urine increased in subjects 1, 2, 4, 5, 6, 7, 8 and 10 following the exposure to volcanic gas. Statistical hypothesis testing showed the group’s post-exposure shift in Al excretion was
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
significant at p < 0.005 (Amol) and p < 0.001 (Amol mol 1). Although the influence of an unknown and confounding Al source cannot be ruled out, the fact that Al was elevated in 8 of 10 subjects suggests a common source for this change, rather than unlikely confounding sources which might act upon individuals (e.g. mobile Al in food, drinks, toothpaste or deodorants). Urine accounts for f 95% of excreted Al (Yokel and McNamara, 2001), which has a halflife of 5– 9 h (Pierre et al., 1995). Our urine sample period of 4.75 h was therefore sufficient to collect up to half of any Al absorbed by the pulmonary tract during exposure, and subsequently excreted in the urine. The rate and dynamics of Al excretion into urine has, however, been shown to relate to the molecular form of Al during exposure (Pierre et al., 1995), about which we have no data from White Island. A delay between absorption and excretion would mean any late or secondary peak in Al excretion was not collected by our samples. Under these circumstances, the net increases in Al we observe here could merely indicate a still more significant change in Al excretion resulting from gas exposure. The rate and concentration of Rb excreted into urine increased following exposure in subjects 1, 3, 4, 5, 6 and 8. The statistically significant changes in the group’s rate and concentration of urinary Rb excretion ( p < 0.001 and p < 0.025, respectively) also suggests a common source of the extra Rb, rather than the doubtful influence of independently active confounding sources. Considering both elements together, positive postexposure shifts in Al and Rb excretion rate and element/creatinine ratios were seen in subjects 1, 5 and 8. Subjects 4 and 6 showed similar positive changes in all variables, but these were relatively small in at least one variable. There was not, therefore, a clear correlation between Al and Rb excretion, even though positive changes were seen in most subjects and the group’s positive shifts were statistically significant in all variables. Subjects 2, 3 and 7 possessed at least one negative variable in Al or Rb. Reasons for these discrepancies may be related to a number of factors including differing levels of exposure (these three subjects were among the least exposed according to the diffusion tube data) or perhaps personal differences in renal function. In the group as a whole,
145
however, exposures recorded by the diffusion tubes did not correlate with the observed changes in urinary outputs. A clear correlation should not be expected, however, since respiratory absorption of gases and particles varies considerably between individuals. In addition, it is possible the tube readings were not an accurate indication of true respiratory exposure. Further uncertainties exist because it was necessary to estimate metal outputs from the fumaroles by using data from other vents. The As and Hg data show marked differences to those for Al and Rb. Exposure to As, which we expect was above occupational health limits for most subjects, did not result in an observable change in urinary outputs. Concentrations in urine were below detectable limits in subjects 5, 7, 8 and 10, before and following exposure, and any observed changes in the volume excreted and the ratio to creatinine, showed no trend. Changes in Hg excretion were minimal in most cases, and only in subject 1 was there a marked increase in the Hg excretion rate following exposure. A corresponding fall in the Hg/creatinine ratio, however, shows that more Hg was present in the postexposure urine because of the greater rate of urine excretion in this sample. Half-lives of As and Hg are much higher than Al and are in the order of days, which may account for the clear difference in excretion of these elements (Grund et al., 2002; Halbach, 2001). Arsenic excretion occurs mainly through urine, but less than 60% of Hg is excreted in this way, the remainder being lost through faeces and exhaled vapour. Therefore, a lack of excretion into the sampled urine, as well as insufficient exposure and/or absorption, are likely reasons for the observed results. Our experiment suffered from a number of uncertainties concerning exposure assessment, adequacy of the urine sampling periods, and possible confounding sources of mobile Al, Rb, As and Hg. This was, however, a pilot study which was necessarily constrained by what is possible and practical when using human subjects on an active volcano. In this sense, the experiment was a hypothesis-forming exercise, the results from which should be used in a detailed follow-up investigation of urine, blood, plasma and serum markers for volcanic gas exposure. More subjects should be used, and their fluids monitored with bracketed samples over several days before and fol-
146
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
lowing exposure. Exposure itself should also be better quantified in future work. Levels of all the elements tested were well within normal reference limits for individuals with normal renal function who are not occupationally exposed (Cornelis et al., 1975; White and Sabbioni, 1998; Apostoli et al., 1999). It is likely that the health hazards of exposure to these elements in volcanic gases are negligible. This deserves further research, however, respirable exposure to zinc, for example, can cause fume fever, but oral doses of zinc are relatively harmless. Little is known about the toxicity of respired Rb fumes. The results suggest that Al and possibly Rb may be useful markers for volcanic gas exposure. This should certainly be investigated further in future work. In industry, markers in urine or other fluids are used extensively for biological monitoring, but this is not the case in volcanology, where scientists can be exposed to very high concentrations of many toxic gases simultaneously. This experiment concerned a single, short-term exposure to volcanic gas which could be considered as a minimum exposure for volcanologists working without respirators near fumaroles. During eruptions of mafic lavas which may allow relatively close access to active vents and lava flows, the total exposure to gases and aerosols may be orders of magnitude higher. It should be emphasised that volcanologists should always wear respirators when exposed to gases near fumaroles and downwind from active vents. However, for volcanologists who might be repeatedly exposed to acid gases and, in some cases, do not always wear respirators, biological monitoring using exposure markers might provide a means to assess dangerous exposure. The best elements for such work, and thresholds for action, could only be identified after further research.
5. Conclusion In this pilot study, volunteers were acutely exposed to volcanic gas downwind of fumaroles on White Island, New Zealand. The work tested the hypothesis that Al, Rb, As and Hg in urine can be used as biological markers for volcanic gas exposure. All these elements are present in volcanic gases, and with the exception of Rb, have been used for
biological monitoring of occupational exposure in industry. Results show that the excretion rate (Amol h 1) and concentration (Amol mol 1 creatinine) of Al and Rb in urine were elevated in urine following exposure to gas. The group’s positive shift in each element was statistically significant by both variables, suggesting a common cause. We expect that biological variation or changes resulting from intake of mobile elements through food, drinks, or cosmetic products, would act on an individual basis and not produce the observed results. Post-exposure changes in As and Hg were inconclusive. The results therefore suggest that Al and possibly Rb could be used as biological markers for exposure to other, more harmful volcanic gases and aerosols including SO2, H2SO4, H2S, HCl and HF. This should be followed up in future work, since it has implications for volcanologists who risk the development of RADS or occupational asthma, if they are exposed to high concentrations of gases and do not habitually use respirators.
Acknowledgements We thank Jenny and Peter Tait of PeeJay Charters and David Reeve at Whakatane Hospital for logistical support. Bruce Christenson (GNS) is thanked for unpublished emissions data. We are grateful to students from the Universities of Canterbury, Waikato and Auckland for volunteering their fluids. MD was supported by a Fellowship from the University of Canterbury, which also funded the analyses and research logistics. Ethical approval for the work was given by Canterbury Ethics Committee, and participants gave informed consent after the implications of the work were explained. The paper benefited greatly from reviews by Peter Baxter and two anonymous reviewers.
References Abdennour, C., Khelili, K., Boulakoud, M.S., Nezzal, A., Boubsil, S., Slimani, S., 2002. Urinary markers of workers chronically exposed to mercury vapor. Environ. Res. 89 (3), 245 – 249. Allen, A.G., Baxter, P.J., Ottley, C.J., 2000. Gas and particle emissions from Soufriere Hills volcano, Montserrat, West Indies:
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148 characterisation and health hazard assessment. Bull. Volcanol. 62, 8 – 19. Andres, R.J., Kyle, P.R., Chuan, R.L., 1993. Sulphur dioxide and elemental emissions from Mount Etna, Italy, during July, 1987. Geol. Rundsch. 82, 687 – 695. Apostoli, P., Bartoli, D., Alessio, L., Buchet, J.P., 1999. Biological monitoring of occupational exposure to inorganic arsenic. Occup. Environ. Med. 56 (12), 825 – 832. Bardana, E.J., 1999. Reactive airways dysfunction syndrome (RADS): guidelines for diagnosis and treatment and insight into likely prognosis. Ann. Allergy, Asthma, & Immun. 83, 583 – 586. Baxter, P.J., Gresham, A., 1997. Deaths and injuries in the eruption of Galeras Volcano, Colombia, 14 January 1993. J. Volcanol. Geotherm. Res. 77, 325 – 338. Baxter, P.J., Stoiber, R.E., Williams, S.N., 1982. Volcanic gases and health: Masaya volcano, Nicaragua. Lancet, 150 – 151 (July 17, 1982). Baxter, P.J., Tedesco, D., Miele, G., Boubron, J.C., Cliff, K., 1990. Health Hazards from volcanic gases. Lancet, 176 (July 21, 1990). Blong, R.G.C., 1984. Volcanic Hazards: A Source Book on the Effects of Eruptions. Academic Press, Australia. Chester, D.K., Duncan, A.M., Guest, J.E., Kilburn, C.R.J., 1985. Mt. Etna: The Anatomy of a Volcano. Chapman & Hall, London. 389 pp. Cole, J.W., Nairn, I.A., 1975. Catalogue of the active volcanoes of the world including solfatara fields—Part 22: New Zealand. International Association of the Chemistry of the Earth’s Interior, 156 pp. Cornelis, R., Speecke, A., Hoste, J., 1975. Neutron activation analysis for bulk and trace elements in urine. Anal. Chim. Acta 78, 317 – 327. Delmelle, P., Stix, J., Baxter, P., Garcia-Alvarez, J., Barquero, J., 2002. Atmospheric dispersion, environmental effects and potential health hazard associated with the low-altitude gas plume of Masaya volcano, Nicaragua. Bull. Volcanol. 64, 423 – 434. Durand, M., Grattan, J., 1999. Extensive respiratory health effects of volcanogenic dry fog in 1783 inferred from European documentary sources. Envron. Geochem. Health 21, 371 – 376. Durand, M., Grattan, J., 2001. Effects of volcanic air pollution on health. Lancet 357, 164. Elinder, C.G., Ahrengart, L., Lidums, V., Petterson, E., Sjo¨gren, B., 1991. Evidence of aluminium accumulation in aluminium welders. Br. J. Ind. Med. 48, 735 – 738. Fink, J., 1995. Exploding volcanic myths. Nature 373, 660 – 661. George, P.M., Walmsley, T.A., Currie, D., Wells, J.E., 1993. Lead exposure during recreational use of small-bore rifle ranges. N.Z. Med. J. 106, 422 – 424. Grund, S.C., Hanusch, K., Wolf, H.U., 2002. Arsenic and arsenic compounds: toxicology. Ullman’s Encyclopedia of Industrial Chemistry. Wiley, doi:10.1002/14356007.a03 _ 113 (http:// www.mrw.interscience.wiley.com/veic). Gulson, B.L., Palmer, J.M., Bryce, A., 2002. Changes in blood lead of recreational shooter. Sci. Total Environ. 293, 143 – 150. Halbach, S., 2001. Mercury, mercury alloys, and mercury com-
147
pounds: toxicology and environmental health. Ullman’s Encyclopedia of Industrial Chemistry. Wiley, DOI: 10.1002/143560007. a16_269 (http://www.mrw.interscience.wiley.com/veic). Harrison, J., Sepai, O., 2000. Should control measures be based on air measurements or biological/biological effect monitoring? Occup. Med. (Lond.) 50 (1), 61 – 63. Hedenquist, J.W., Simmons, S.F., Giggenbach, W.F., Eldridge, C.S., 1993. White Island, New Zealand, volcanic – hydrothermal system represents a geochemical environment of high-sulfidation Cu and Au ore deposition. Geology 21, 731 – 734. Houghton, B.F., Nairn, I.A. (Eds.), 1989. The 1976 – 82 eruption sequence at White Island volcano (Whakaari), Bay of Plenty, New Zealand. N. Z. Geol. Surv. Bull. 103, 138 pp. Jeffery, E.H., Abreo, K., Burgess, E., Cannata, J., Greger, J.L., 1996. Systemic aluminium toxicity: effects on the bone, haematopoietic tissue, and kidney. J. Toxicol. Environ. Health 48, 649 – 665. Kono, K., Yoshida, Y., Yamagata, H., Watanabe, M., Shibuya, Y., Doi, K., 1987. Urinary fluoride monitoring of industrial hydrofluoric acid exposure. Environ. Res. 42, 415 – 420. LeCloarec, M.F., Allard, P., Ardouin, B., Giggenbach, W.F., Sheppard, D.S., 1992. Radioactive isotopes and trace elements in gaseous emissions from White Island, New Zealand. Earth Planet. Sci. Lett. 108, 19 – 28. Ljunggren, K.G., Lidums, V., Sjo¨gren, B., 1991. Blood and urine concentrations of aluminium among workers exposed to aluminium flake powders. Br. J. Ind. Med. 48, 106 – 109. Lund, K., Ekstrand, J., Boe, J., Søstrand, P., Kongurand, J., 1997. Exposure to hydrogen fluoride: An experimental in human and concentrations of fluoride in plasma, symptoms and lung function. Occup. Environ. Med. 54, 32 – 37. Malo, J.L., Chan-Yeung, M., 2001. Occupational asthma. J. Allergy Clin. Immunol. 108, 317 – 328. Moore, D.S., McCabe, G.P., 2003. Introduction to the Practice of Statistics, Fourth edition. Freeman, New York, 828 pp. NIOSH, G.P., 2003. Online NIOSH Pocket Guide to Chemical Hazards National Institute of Occupational Safety and Health. http://www.cdc.gov/niosh/. Nriagu, J., Becker, C., 2003. Volcanic emissions of mercury to the atmosphere: global and regional inventories. Sci. Total. Environ. 304, 3 – 12. Pierre, F., Baruthio, F., Diebold, F., Biette, P., 1995. Effect of different exposure compounds on urinary kinetics of aluminium and fluoride in industrially exposed workers. Occup. Environ. Med. 52, 396 – 403. Pierre, F., Vallayer, C., Baruthio, F., Peltier, A., Pale, S., Rouyer, J., Goutet, P., Aubrege, B., Lecossois, C., Guillemin, C., Elcabache, J.-M., Verelle, B., Fabries, J.-F., 2002. Specific relationship between blood lead and air lead in the crystal industry. Int. Arch. Occup. Environ. Health 75, 217 – 223. Riihima¨ki, V., Ha¨nninen, H., Akila, R., Kovala, T., Kuosma, E., Paakkulainen, H., Valkonen, S., Engstro¨m, B., 2000. Body burden of aluminium in relation to central nervous system function among inert-gas welders. Scand. J. Work, Environ. & Health 26, 118 – 130. Rose, W.I., Chuan, R.L., Giggenbach, W.F., Kyle, P.R., Symonds, R.B., 1986. Rates of sulphur dioxide and particle emissions
148
M. Durand et al. / Journal of Volcanology and Geothermal Research 134 (2004) 139–148
from White Island volcano, New Zealand, and an estimate of the total flux of major gaseous species. Bull. Volcanol. 48, 181 – 188. Sjo¨gren, B., Lidums, V., Ha¨kansson, M., Hedstro¨m, L., 1985. Exposure and urinary secretion of aluminium during welding. Scand. J. Work, Environ. & Health 11, 39 – 43. Sjo¨gren, B., Elinder, C.G., Lidums, V., Chang, G., 1988. Uptake and urinary excretion of aluminium among welders. Int. Arch. Occup. Environ. Health 60, 77 – 79. Søyseth, V., Kongerud, J., Ekstrand, J., Boe, J., 1994. Relation between fluoride and bronchial responsiveness in aluminium potroom workers with work-related asthma-like symptoms. Thorax 49, 984 – 989. Tho´rarinsson, S., 1979. On the damage caused by volcanic eruptions with special reference to tephra and gases. In: Sheets, P.D., Grayson, D.K. (Eds.), Volcanic Activity and Human Ecology. Academic Press, New York, pp. 125 – 159.
Tho´rarinsson, S., 1981. Greetings from Iceland: ash-falls and volcanic aerosols in Scandinavia. Geogr. Ann. 63A, 109 – 118. Twain, M., 1872. Letters from Hawai‘i. Reprinted. In: Grove Day, A. (Ed.), Mark Twain’s Letters from Hawai‘i. University of Hawai‘i Press, Honolulu, HI, p. 1975. Wardell, L., Kyle, P., Dunbar, N., Christenson, B., 2001. White Island Volcano, New Zealand; carbon dioxide and sulfur dioxide emission rates and melt inclusion studies. Chem. Geol. 177, 187 – 200. White, M.A., Sabbioni, E., 1998. Trace element reference values in tissues from inhabitants of the European Union. X. A study of 13 elements in blood and urine of a United Kingdom population. Sci. Total Environ. 216, 253 – 270. Williams, S., 2002. Surviving Galeras Little Brown and Co., London, 270 pp. Yokel, R.A., McNamara, P.J., 2001. Aluminium toxicokinetics: An updated minireview. Pharmacol. Toxicol. 88, 159 – 167.