Ann. occup. Hyg., Vol. 48, No. 3, pp. 209-217, 2004
© 2004 British Occupational Hygiene Society
Published by Oxford University Press
Dermal Exposure to Electroplating Fluids and Metalworking Fluids in the UK
Health and Safety Laboratory, Health and Safety Executive, Broad Lane, Sheffield S3 7HQ, UK
Received 1 October 2003; in final form 7 January 2004
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONSAMPLING METHODSANALYTICAL METHODSRESULTS AND DISCUSSIONCONCLUDING REMARKSREFERENCES |
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This paper describes workplace dermal exposure measurements that were carried out by the Health and Safety Laboratory as part of the EU RISKOFDERM project. Exposure to metalworking fluids (MWFs) was measured at three sites on 25 subjects who were ‘mechanically treating solid objects’ as they loaded and supervised milling and boring machines and lathes. Thirty-one samples were obtained, of which 18 were exposures to neat mineral oils and 13 to water–oil mixes. All subjects wore Tyvek® whole-body oversuits that were analysed in their entirety to extract the MWF. The geometric mean surface loading rate of the 31 oversuits was 62 µg/cm2/h (GSD = 4.6) and of the seven pairs of sampling gloves (worn inside protective gloves) was 2900 µg/cm2/h (GSD = 1.67). Exposure to electroplating fluids was measured at three sites on 27 subjects who were dipping objects into tanks of either chromic acid, nickel sulphate, copper sulphate, copper cyanide or zinc hydroxide. All subjects wore Tyvek® whole-body oversuits that were surface scanned over their areas using a portable X-ray fluorescence spectrometer to detect all the metal atoms simultaneously. Contamination was assessed using the method of Dirichlet tessellation. The geometric mean surface loading rate of the 26 oversuits was 37 µg/cm2/h (GSD = 3.5) and of the 25 pairs of sampling gloves (worn inside protective gloves) was 190 µg/cm2/h (GSD = 2.75). Almost all of the electroplating samples were below the limit of quantification. More than one species of metal atoms was found on some of the samples afterwards, indicating cross-contamination from other baths during the sampling period.
Keywords: dermal exposure; Dirichlet tessellation; electroplating; metalworking fluids; PXRF; X-ray fluorescence
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONSAMPLING METHODSANALYTICAL METHODSRESULTS AND DISCUSSIONCONCLUDING REMARKSREFERENCES |
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This paper describes two sets of workplace dermal exposure measurements that were carried out by the Health and Safety Laboratory (HSL) as part of the EU RISKOFDERM project (RISKOFDERM, 1999). The project was an opportunity to study dermal exposure in a generic manner, i.e. to measure in terms of a product or formulation, rather than to particular hazardous substance as an ingredient of concern in that product. This generic approach allows exposure to be inferred for a range of hazardous substances that might be encountered during similar tasks but using different products. Examples of these are metalworking fluids (MWFs) that contain components that present different hazards and electroplating where different hazardous liquids are used in the same way.
The approach adopted by the RISKOFDERM project was to group work scenarios into six types, named dermal exposure operations (DEO) units (van Hemmen et al., 2003). These were selected so as to reflect mixtures of the three different mechanisms through which dermal exposure can take place, as described by Schneider et al. (1999) in the conceptual dermal exposure model. The DEO units were chosen to facilitate modelling of the exposure. Properties desirable for the data in the DEO units are described in Marquart et al. (2003) and in Rajan-Sithamparanadarajah et al. (2004), but, in brief, there was a need to ensure that dermal exposure was only sampled for those work activities that contributed to the scenarios within the DEO and to eliminate other work activities that could contribute significant dermal exposure.
Data were gathered in the RISKOFDERM project for potential dermal exposure (PDE) of the body and both actual dermal exposure (ADE) and PDE of the hands, depending on circumstances. ADE and PDE are defined in Rajan-Sithamparanadarajah et al. (2004), but, briefly, PDE is exposure of the outer clothing and exposed skin, while ADE is exposure of the skin, be it exposed or covered.
Machining using metalworking fluids
Dermal exposure to MWFs can cause irritation and contact dermatitis to machine operators. Dermatitis can arise from biocides that are often added, sometimes in excess, to combat the bacteria that colonize the machines’ sumps. It can also arise from emulsifiers, odorants, metal fines and from the oil itself (Health & Safety Executive, 2002b). Bacteria (and their endotoxins) can cause or exacerbate respiratory allergic reactions when aerosolized (Simpson et al., 2003). At the time that this study was carried out, MWFs had an occupational exposure standard (OES) of 5 mg/m3 (Health & Safety Executive, 2002a). This was later withdrawn and replaced with guidance values of 3 mg/m3 for neat oil MWFs and 1 mg/m3 for water–oil mix MWFs (Health & Safety Executive, 2002b).
Three sites were visited that carried out machining of either hydraulic components, commercial vehicle engines or car components, using a variety of milling, drilling, boring, grinding and lathe machinery. Most of these were manually operated, but some were computer numerically controlled (CNC) machines. The tasks observed were mainly changing the workpiece, changing the machine tool and tuning the machine, which are classed as the DEO ‘handling of contaminated objects’ in the RISKOFDERM project. Sampling times ranged from 18 to 90 min, and sampling was terminated if a significant change of job took place. Of the five MWFs used in the machines, two were neat mineral oils and three were water–oil mixes. The material safety data sheets all referred to the OES and three of them also recommended use of impervious gloves, a message repeated on the labels of the containers. However, only one subject out of the 25 observed actually wore gloves. The rest would not wear them because they could be caught in the machines. Subjects wore cotton/polyester coats but no other protective clothing.
Electroplating
The electroplating industry utilizes many toxic, corrosive and irritant chemicals at high concentrations in dipping baths. We visited three electroplating works that used a variety of dipping baths containing a range of metals in solution: chromic acid, nickel chloride, nickel sulphate, copper sulphate, copper cyanide and zinc hydroxide. Apart from the corrosive nature of the acid and alkaline solutions and the toxicity of the cyanide, these metals also have specific hazards to the skin. Chromic acid contains Cr(VI), which is a carcinogen. It causes ulcers of particular character and longevity and inhalation causes perforations of the nasal septum. Nickel and Cr(VI) can cause skin sensitization. Dermal exposure was most likely to occur during loading items into and unloading items out of the baths. Items were strung on wires from metal poles that straddled the baths. The poles were raised and lowered manually, which sometimes involved leaning across the bath. This was classed as the DEO ‘immersing of objects’ in the RISKOFDERM project. Sampling times ranged from 15 to 60 min, with one exceptionally short sampling time of 4 min. Subjects wore glasses or goggles, elbow-length nitrile gloves and safety boots. At one site (Factory L) they wore ankle-length rubber aprons that covered their chests and wrapped around the sides of their legs. The chromic acid baths incorporated extra controls to reflect the nature of the hazard: either an antifoaming layer to prevent evaporation or local exhaust ventilation.
A summary of the factories visited and the number of samples and questionnaires gathered at each factory is given in Table 1.
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SAMPLING METHODS |
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TOPABSTRACTINTRODUCTIONSAMPLING METHODSANALYTICAL METHODSRESULTS AND DISCUSSIONCONCLUDING REMARKSREFERENCES |
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Thin, lightweight, Tyvek® oversuits (Pro-Tech Classic) were issued to the subjects to wear over the top of any protective clothing that they normally used, to measure PDE. At one site the oversuits would not fit over the aprons, so the aprons were worn on top. The suits were removed after the sampling period, put onto coat-hangers and bagged immediately into ‘dry cleaning bags’. Subjects were issued with white cotton gloves (Radiospares part no. 562-952), which they wore underneath their protective gloves whilst dipping or machining to measure ADE. The gloves were all placed individually into Ziploc sealable bags after the sampling period. Oversuits and gloves exposed to MWF were kept in an ice-box on site and transferred to a cold room on receipt at the laboratory.
In order to express all measurements of analytes in terms of product, samples of MWF were taken from each machine’s sump. Samples of electroplating baths were not taken: the companies’ own quality control analyses for that day were used.
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ANALYTICAL METHODS |
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TOPABSTRACTINTRODUCTIONSAMPLING METHODSANALYTICAL METHODSRESULTS AND DISCUSSIONCONCLUDING REMARKSREFERENCES |
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A summary of the analytical methods and their detection limits is given in Table 2. The detection limits are given in milligrams per segment analysed [except for portable X-ray fluorescence spectrometry (PXRF)] and are independent of the surface area of the segment, be it a section of oversuit or an entire oversuit in one piece. The PXRF detection limits described later did depend on segment size and are reported in Table 2 as combined readings for the entire glove or XL size oversuit. The proportions of analyte in the various bulk formulations and the recovery efficiencies from the sampling media are given in Table 3.
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Machining using MWFs
Neat mineral oil and water–oil mix MWFs required different, incompatible analytical methods. One subject operated two machines at once, one using each type. This sample could not be analysed and is not reported in Table 1.
Mineral oils
The oversuits were sealed in their entirety in 2 l jars with 1 l of pure hexane. They were left overnight to dissolve the oil and then mixed in the jar for 1 h on a motorized roller. A sample of the hexane was removed and run through a liquid chromatograph (HPLC) column to detect long-chain oils (C10H22) that were present. No oil was detected in the blank oversuit material, so the LOQ was taken as the lowest calibration point, which was equivalent to 550 mg oil over an entire oversuit. No glove samplers were used.
Water–oil mixes
All of these contained boron, which was used as a marker element. The oversuits were cut into seven sections: head, left leg, right leg, left mid-section, right mid-section, left upper body and arm and right upper body and arm. These were placed in separate plastic beakers with 1 l of pure water (0.5 l for the head section), stirred for 1 h to dissolve out the boron and assayed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). Recovery efficiency was checked in triplicate at three concentrations by spiking known volumes of fluid directly onto sections of clean oversuit material, drying them overnight and analysing as above. Oversuit sections were measured carefully and the surface areas calculated for each of the five available sizes: M, L, XL, XXL and XXXL. Individual sampling gloves were assayed as above with 250 ml of pure water. Clean gloves and sections of clean oversuits were analysed and found to release no measurable boron into solution.
Electroplating
The range of metals used by this industry made the PXRF a particularly suitable instrument to analyse splashes on the samplers because it could measure all the metals simultaneously and directly. Wet chemistry methods, such as acid digestion, can lead to underestimates of exposure because metal oxides that can form on the sampling media after splashing with the electrolyte are impossible to redissolve.
The PXRF (Spectrace 9000) was used at 104 locations on each oversuit as described elsewhere in this issue (Roff et al., 2004). Six new oversuits were measured in their entirety to act as blanks and to calculate LOD and LOQ. Tesselating surface areas were used to weight the results after the method of Wheeler and Warren (2002), which were then summed to represent the entire oversuit of 
30 000 cm2 (Table 4). Results were only retained for the reported dipping elements chromium (Cr), nickel (Ni), copper (Cu) and zinc (Zn). The PXRF readings (µg/cm2) were calibrated against known surface loadings made by pipetting known volumes of certified standard solutions of chromium or nickel nitrate evenly over pieces of material. The readings were 31% of the surface loadings for chromium and 66% for nickel. This analytical detection efficiency is shown as the ‘recovery efficiency’ in Table 3. The results were converted into equivalent amounts of dipping bath solution. No calibrations were made for copper and zinc because all PXRF results were <LOD.
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Gloves
Each glove was laid flat on a Perspex sheet and sandwiched between pieces of Mylar film. An aluminium strip was inserted along each finger of the glove to shield the other side of the glove from the
-radiation emissions. Each side was measured at six places: the middle of each finger and the centre of the palm (or back). The measurements were weighted by surface area, as determined from blank gloves. The fingertips were the areas likely to be most heavily exposed, but these were avoided because they would not have been representative of the sides or the lower ends of the fingers. |
RESULTS AND DISCUSSION |
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TOPABSTRACTINTRODUCTIONSAMPLING METHODSANALYTICAL METHODSRESULTS AND DISCUSSIONCONCLUDING REMARKSREFERENCES |
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Results were all corrected for analytical recovery efficiency. OECD guidelines (OECD, 1997) state that correction must be made outside the 80–120% region, but does not forbid it inside. A summary of the results is given in Table 4 for all scenarios. All results are shown as surface loading rates in terms of the formulation used in order to allow comparison of different sampling times and different analytes. This makes the assumption that loading occurred in a linear fashion over the sampling time.
The results are presented for whole-body oversuits measured as one piece except for the water–oil mix MWFs, which are the sums of six segments. Those oversuits are counted in Table 4 as ‘<LOD’ only if all six segments are <LOD. They are counted as ‘<LOQ’ if none of the six segments were 
LOQ but at least one was LOD.
Results in all cases were better described by log-normal than by normal statistics, so Table 4 also shows geometric means and geometric SD values.
Machining using MWFs
The individual results for whole oversuits are shown in Fig. 1a. Three results were <LOD and two results were <LOQ. Different segments of water–oil mix oversuits gave different frequencies of occurrence of ‘<LOD’ (Table 5). Water–oil mixes gave lower contamination rates than mineral oil at Factory P but higher at Factory G. Analysis of variance showed that there was no overall significant effect of fluid or factory.
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A breakdown of geometric mean surface loading rates by body location for water–oil mixes is shown in Fig. 1b. The highest deposition rates were on the left leg and middle of the body. The head, arms and upper body comprised 43% of the surface area, but only 12% of the fluid (by mass) deposited on them. This is consistent with the observation that bare hands were frequently soaked and were wiped on the legs.
From the little data available for gloved hands (seven results from one subject) the deposition rates were 20 times that of the body, but that is to compare ADE of the hands inside protective gloves with PDE of the outside layer of the body clothing. Part of this difference may be accounted for by the higher absorbency of the sampling gloves relative to the oversuit samplers, but this is a surprisingly high ratio given that the sampling gloves were worn beneath protective gloves. It indicates either that the protective gloves were themselves saturated or that they were removed from time to time, which would have allowed the sampling gloves to become wet. Approximately 0.5–1.4 ml of fluid was retained on the sampling glove pairs, so they were wet but not fully saturated. There was no correlation with the (potential) body exposure (Pearson).
Electroplating
The results for electroplating are shown in Table 4 and Fig. 2 for oversuits and undergloves. The relevant analyte (Cr, Ni, Cu or Zn) is marked above each sample in Fig. 2, and the results in Table 4 are calculated in terms of splashed solution from these analytes. However, there were several anomalies that are not shown in Fig. 2. Higher loadings of different metal analytes were found on the undergloves and clothing than of the metal used in the bath of the observed job. The different analytes on undergloves could have been caused by momentary removal of the protective glove to pick up stray objects or touch another bath. Transfer from the insides of used protective gloves could also explain this. For oversuits, the subject may well have brushed or leaned against more than one type of bath within the sampling time. Transfer could have occurred from the inside surface of the aprons (where worn) or the outside of their workwear.
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A substantial number of results for immersion were <LOD for the target analyte element (17 out of 27 oversuits, 20 out of 27 undergloves). Minor contamination was evident on many oversuits, but this was insufficient to raise the average level above the LOD. The LOD for undergloves was higher than for oversuits because of the smaller number of PXRF readings taken, so this could account for the higher frequency of underglove not detected. One sample duration was not recorded, so there are only 26 results in Table 4. The geometric mean contamination rate was four times higher on the sampling undergloves than on the oversuits. Momentary outer glove removal could account for these levels either through touching objects with the hands or touching contaminated outer glove surfaces through inadequate donning and doffing procedures. Ingress was unlikely around the cuff during normal use because of the length of the gauntlets, but penetration through cuts in the glove material is a possibility. There were only four results where both body and hands exceeded the LOQ values. Their correlation, although very good (r = 0.98) is unreliable. Figure 3 shows the data.
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Typical patterns of exposure are shown for oversuits in Fig. 4. Figure 4a shows a subject who wore a long apron for some of the time, which covered the chest and upper legs but not the shoulders. There was contamination on the shoulders but not on the chest. However, the (covered) upper legs were well contaminated, as confirmed by the inset photograph of the leg area of the oversuit (arrowed), confirming the need for the apron. Conversely, Fig. 4b shows a subject who did not wear an apron at all. There was higher exposure to the chest area, but this time not to the legs. This could have been due to a different height of bath or an effective guard or a more careful worker, although no differences in work practices were observed.
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CONCLUDING REMARKS |
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TOPABSTRACTINTRODUCTIONSAMPLING METHODSANALYTICAL METHODSRESULTS AND DISCUSSIONCONCLUDING REMARKSREFERENCES |
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Sampling methodology
In retrospect, we should have adopted a handwashing method for MWFs when gloves were refused, but no methodology was available on site at the time. Gloves were accepted during a pilot visit, so the problem was not foreseen. Any dermal exposure measurements using surrogate skin sampling media such as patches, oversuits or gloves raises the question of sampling efficiency and retention relative to the skin. The different media used by partners in the RISKOFDERM project may (or may not) have measured in a similar fashion to each other, but none of the samplers necessarily resembled the skin.
Machining using MWFs
The hands were the areas most contaminated with MWFs. Where operators refused to wear sampling gloves it was observed that their hands were frequently soaked with fluid. Failure to use impermeable protective gloves in accordance with the safety data sheets of the fluids is a cause for concern. For the one subject that did wear gloves, the sampling gloves underneath were highly contaminated (up to 1.4 ml fluid per pair) considering that they were worn underneath the protective gloves. The location of this within the glove cannot be specified and it could have been solely at the cuff entry to the glove rather than at the fingers and palms. This is an inherent drawback of underglove sampling. To be able to quantify the risks to health from dermal exposure further work is required to develop methods that provide a more reliable measure of actual exposure to liquids such as MWFs in circumstances where surrogate skin or glove sampling is inappropriate. Handwash and wipe methods or quantitative use of fluorescent tracers are alternative methods of assessing actual hand exposure.
Electroplating
The 104 sampling points of the Dirichlet tesselation method (Wheeler and Warren, 2002) offer better representation of the body surface than the 11 points of the OECD patch method. One of the benefits of PXRF is the range of substances detected simultaneously, demonstrated here by the detection of anomalous metals present on the oversuits compared with the reported main task carried out by the subject. One of the drawbacks of PXRF is its relative lack of sensitivity. This was most apparent in the dipping measurements, which produced many results <LOD for both oversuits and undergloves. Although the results for many of the oversuits are classed as <LOD or <LOQ, discernible patterns of exposure were apparent, similar to Fig. 4. The influence of LOD is discussed in more detail elsewhere in this issue (Roff et al., 2004). The presence of detectable quantities of other metals implies that there was contamination around the workplace and that the workers were being re-contaminated by their own dirty protective clothing. This shows that exposure can take place not just from the immersion activity, but also from incidental contact. All the pathways for dermal exposure must be taken into account in any risk assessment. The RISKOFDERM project (Marquart et al., 2003; van Hemmen et al., 2003) aims to build on previous work such as that of DREAM (van Wendel-de-Joode et al., 2003).
Acknowledgements—The authors gratefully acknowledge the cooperation of the management and workforce at the participating workplaces and the assistance of the following HSL analytical staff: Matthew Coldwell, Christopher Keen, Stephen Bradley, Beth Rawson, Penelope Simpson, Lisa Griffiths and Paul Roberts. This study was performed within the European project RISKOFDERM with financial support from EU and the UK Health & Safety Executive, which is gratefully acknowledged.
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FOOTNOTES |
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* Author to whom correspondence should be addressed. Tel: +44-114-289-2498; e-mail: martin.roff{at}hsl.gov.uk
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REFERENCES |
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TOPABSTRACTINTRODUCTIONSAMPLING METHODSANALYTICAL METHODSRESULTS AND DISCUSSIONCONCLUDING REMARKSREFERENCES |
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Health & Safety Executive. (2002a) Occupational exposure limits 2002, EH40/2002. London: HMSO.
Health & Safety Executive. (2002b) Working safely with metalworking fluids—good practice manual. Sudbury: HSE Books.
Marquart H, Brouwer DH, Gijsbers JHJ, Links IHM, Warren N, van Hemmen JJ. (2003) Determinants of dermal exposure relevant for exposure modelling in regulatory risk assessment. Ann Occup Hyg; 47: 599–608.
OECD. (1997) Environmental health and safety publications series on testing and assessment no. 9: Guidance document for the conduct of studies of occupational exposure to pesticides during agricultural application, OEDE/GD(97)148y. Paris: OECD.
Rajan-Sithamparanadarajah R, Roff M, Delgado P, et al. (2004) Patterns of dermal exposure to hazardous substances in European Union workplaces. Ann Occup Hyg; 48: 285–297.
RISKOFDERM. (1999) Contract number QLK4-CT-1999-01107, 5th Framework Programme of the European Union. Luxemburg: European Commission.
Roff M, Bagon DA, Chambers H, Dilworth EM, Warren N. (2004) Dermal exposure to dry powder spray paints using PXRF and the method of Dirichlet tesselations. Ann Occup Hyg; 48: 257–265.
Schneider T, Vermeulen R, Brouwer DH, Cherrie JW, Kromhout H, Fogh CL. (1999) Conceptual model for assessment of dermal exposure. Occup Environ Med; 56: 765–73.
Simpson A, Stear M, Groves J, et al. (2003) Occupational exposure to metalworking fluid mist and sump fluid contaminants. Ann Occup Hyg; 47: 17–30.
Wheeler J, Warren N. (2002) A Dirichlet tesselation-based sampling scheme for measuring whole-body exposure. Ann Occup Hyg; 46: 209–17.
van Hemmen JJ, Auffarth J, Evans PG, Rajan-Sithamparanadarajah R, Marquart H, Oppl R. (2003) RISKOFDERM: risk assessment of occupational dermal exposure to chemicals. An introduction to a series of papers on the development of the toolkit. Ann Occup Hyg; 47: 595–8.
van Wendel-de-Joode B, Brouwer DH, Vermeulen R, van Hemmen JJ, Heederik D, Kromhout H. (2003) DREAM: a method for semi-quantitative dermal exposure assessment. Ann Occup Hyg; 47: 71–87.
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