Inhalational and dermal exposures during spray application of biocides

Inhalation and dermal exposure to biocidal products during foam and spray applications

OBJECTIVES

Foaming and spraying are common application techniques for biocidal products. In the past, inhalation and dermal exposure during spraying have been investigated extensively. Currently, however, no exposure data are available for foaming, hindering a reliable risk assessment for foam applications of biocidal products. The focus of this project was the quantification of inhalation and potential dermal exposure to non-volatile active substances during the foam application of biocidal products in occupational settings. In some settings, exposure during spray application was measured for comparative purposes.

METHODS

The inhalation and dermal exposure of operators were investigated during the application of benzalkonium chlorides and pyrethroids by foaming and spraying, considering both small- and large-scale application devices. Inhalation exposure was measured by personal air sampling; potential dermal exposure was measured using coveralls and gloves.

RESULTS

Potential dermal exposure was substantially higher than inhalation exposure. Changing from spraying to foaming reduced inhalation exposure to airborne non-volatile active substances, but had no relevant effect on potential dermal exposure. However, for potential dermal exposure, considerable differences were observed between the application device categories.

CONCLUSIONS

To our knowledge, this study presents the first comparative exposure data for the foam and spray application of biocidal products in occupational settings with detailed contextual information. The results indicate a reduction of inhalation exposure with foam application compared to spray application. However, special attention is necessary for dermal exposure, which is not reduced by this intervention.

Design and Construction of a Low-Cost Test Bench for Testing Agricultural Spray Nozzles

Droplet size distribution is probably the most important feature of a spray as it affects all aspects of a phytosanitary treatment, i.e., biological, environmental, and safety aspects. This study describes a low-cost laboratory test bench able to analyze agricultural spray nozzles under realistic conditions. The design of the equipment was mainly based on the ISO 5682-1 standard. It has a couple of 3 m long rails, along which the nozzle under test moves while spraying, controlled by a closed-loop position and speed controller. The drops were captured with three Petri dishes containing silicone oil, photographed by means of a digital single-lens reflex (DSLR) camera, and then analyzed with the ImageJ software in order to measure the usual spray parameters: the volumetric diameters, the Sauter mean diameter, and the number mean diameter. Spray trials and tuning of the system parameters were managed by means of a purposely designed user interface running on a Windows 10 PC. Some tests were carried out by using an Albuz ATR80 orange hollow cone nozzle at the working pressures of 0.3, 0.5, 1.0, and 1.5 MPa. The results about spray quality agree with the factory information, and the whole system, even if some aspects still need improvements, has proven reliable.

Biocidal spray product exposure: Measured gas, particle, and surface concentrations compared with spray model simulations

The purpose of the study was to compare measured air and surface concentrations after application of biocidal spray products with concentrations simulated with the ConsExpo Web spray simulation tool. Three different biocidal spray products were applied in a 20 m³ climate test chamber with well-controlled environmental conditions (22 ± 1 °C, 50 ± 2% relative humidity, and air exchange rate of 0.5 h^-1). The products included an insect spray in a pressurized spray can, another insect spray product, and a disinfectant, the latter two applied separately with the same pumped spray device. The measurements included released particles, airborne organic compounds in both gas and particle phase, and surface concentrations of organic compounds on the wall and floor in front of the spraying position and on the most remote wall. Spraying time was a few seconds and the air concentrations were measured by sampling on adsorbent tubes at 9-13 times points during 4 hr after spraying. The full chamber experiment was repeated 2-3 times for each product. Due to sedimentation the concentrations of the particles in air decayed faster than explained by the air exchange rate. In spite of that, the non-volatile benzalkonium chlorides in the disinfectant could be measured in the air more than 30 min after spraying. ConsExpo Web simulated concentrations that were about half of the measured concentrations of the active substances when as many as possible of the default simulation parameters were replaced by the experimental values. ConsExpo Web was unable to simulate the observed faster decay of the airborne concentrations of the active substances, which might be due to underestimation of the gravitational particle deposition rates. There was a relatively good agreement between measured surface concentrations on the floor and calculated values based on the dislodgeable amount given in the selected ConsExpo Web scenarios. It is suggested to always supplement simulation tool results with practical measurements when assessing the exposure to a spray product.

Inhalation exposure during spray application and subsequent sanding of a wood sealant containing zinc oxide nanoparticles

Nano-enabled construction products have entered into commerce. There are concerns about the safety of manufactured nanomaterials, and exposure assessments are needed for a more complete understanding of risk. This study assessed potential inhalation exposure to ZnO nanoparticles during spray application and power sanding of a commercially available wood sealant and evaluated the effectiveness of local exhaust ventilation in reducing exposure. A tradesperson performed the spraying and sanding inside an environmentally-controlled chamber. Dust control methods during sanding were compared. Filter-based sampling, electron microscopy, and real-time particle counters provided measures of exposure. Airborne nanoparticles above background levels were detected by particle counters for all exposure scenarios. Nanoparticle number concentrations and particle size distributions were similar for sanding of treated versus untreated wood. Very few unbound nanoparticles were detected in aerosol samples via electron microscopy, rather nano-sized ZnO was contained within, or on the surface of larger airborne particles. Whether the presence of nanoscale ZnO in these aerosols affects toxicity merits further investigation. Mass-based exposure measurements were below the NIOSH Recommended Exposure Limit for Zn, although there are no established exposure limits for nanoscale ZnO. Local exhaust ventilation was effective, reducing airborne nanoparticle number concentrations by up to 92% and reducing personal exposure to total dust by at least 80% in terms of mass. Given the discrepancies between the particle count data and electron microscopy observations, the chemical identity of the airborne nanoparticles detected by the particle counters remains uncertain. Prior studies attributed the main source of nanoparticle emissions during sanding to copper nanoparticles generated from electric sander motors. Potentially contrary results are presented suggesting the sander motor may not have been the primary source of nanoparticle emissions in this study. Further research is needed to understand potential risks faced by construction workers exposed to mixed aerosols containing manufactured nanomaterials. Until these risks are better understood, this study demonstrates that engineering controls can reduce exposure to manufactured nanomaterials; doing so may be prudent for protecting worker health.

Human exposure to conventional and nanoparticle--containing sprays-a critical review

The release of pesticides from conventional spray products has been investigated in depth, and suitable analytical techniques detecting the mass of the released substances are available. In contrast, nanoparticle-containing sprays are less studied, although they are perceived as critical for consumers because inhalation exposure can occur to potentially toxic nanoparticles. A few recent studies presented analytical concepts for exposure experiments and generated data for exposure assessment. This study attempts to review and compare the current approaches to characterize nanosprays and to identify challenges for future research. Furthermore, experimental setups used for exposure assessment from conventional sprays are reviewed and compared to setups used for nanoparticle-containing sprays. National and international norms dealing with nanoparticle characterization, spray characterization and exposure are inspected with regard to their usefulness for standardizing exposure assessment. Different approaches in the field of exposure modeling are reviewed and compared. The conclusion is that due to largely varying experimental setups to date exposure values for nanosprays are difficult to compare. All studies are only conducted with a limited set of sprays, and no systematic evaluation of the study conditions is available. A suitable set of experimental setups as well as minimum reporting requirements should be agreed upon to enable the systematic evaluation of consumer sprays in the future. Indispensable features of such experimental setups are developed in this review.

Measurement of operator exposure to chlorpyrifos

BACKGROUND

To date, no research has been conducted to establish exposure levels for occupational pesticide operators under typical use scenarios in China. Through surrogate skin techniques (the whole-body method), the authors monitored dermal and inhalation exposure of pesticide applicators in China. In addition, the exposure of pesticide mixers was analysed.

RESULTS

The total dermal exposure of inexperienced and experienced applicators was respectively 4037 and 536 mg kg(-1) of active ingredient (AI) handled for application to maize that was <80 cm in height. The exposure level was highest on hands; the closer to the hands, the lower arms and the upper legs, the higher the exposure. The unit exposure of mixers differed according to the formulation; exposure to emulsifiable concentrate (EC) and oil-in-water emulsion (EW) was greater than exposure to wettable powder (WP) or wettable dispersible granules (WG). The unit exposure of mixers via inhalation was significantly greater than that of applicators when chlorpyrifos (48% EC) was used (P < 0.0001).

CONCLUSIONS

The main objectives of this study were to provide an indication of the realistic exposure risk of mixers and applicators, and to contribute useful information for risk mitigation and management and epidemiological studies in China.

Exposure and health risk assessment of applicators to DDT during indoor residual spraying in malaria vector control program

We assessed exposure of applicators, health risk of DDT to the applicators and evaluated the applicability of existing pesticide exposure models for indoor residual spraying (IRS). Patch sampling for dermal and personal air sampler for inhalation exposure were used in monitoring 57 applicators on the exposure assessment to DDT. The exposure of the applicators was also estimated using three exposure models. The mean actual dermal exposure was 449 mg total DDT per applicator per one house treatment. The applicators were exposed to DDT much beyond the estimated AOEL (acceptable operator exposure level) of DDT. The exposure estimated with ConsExpo 5.0 b01 model is situated between the median and the 75th percentile of the experimental data. On the other hand, spraying model 1 and spraying model 10 overestimate the exposure. Thus, these three models cannot be directly used for the particular circumstances of IRS as a tool for risk assessment. In general, use of DDT in IRS as a control method for malaria mosquitoes holds a high health risk for the applicators. Strict implementation of spraying procedures stated in the IRS manual of World Health Organization (WHO) is necessary to reduce the exposure level and health risk of applicators to DDT.

Advanced Reach Tool (ART): development of the mechanistic model

This paper describes the development of the mechanistic model within a collaborative project, referred to as the Advanced REACH Tool (ART) project, to develop a tool to model inhalation exposure for workers sharing similar operational conditions across different industries and locations in Europe. The ART mechanistic model is based on a conceptual framework that adopts a source receptor approach, which describes the transport of a contaminant from the source to the receptor and defines seven independent principal modifying factors: substance emission potential, activity emission potential, localized controls, segregation, personal enclosure, surface contamination, and dispersion. ART currently differentiates between three different exposure types: vapours, mists, and dust (fumes, fibres, and gases are presently excluded). Various sources were used to assign numerical values to the multipliers to each modifying factor. The evidence used to underpin this assessment procedure was based on chemical and physical laws. In addition, empirical data obtained from literature were used. Where this was not possible, expert elicitation was applied for the assessment procedure. Multipliers for all modifying factors were peer reviewed by leading experts from industry, research institutes, and public authorities across the globe. In addition, several workshops with experts were organized to discuss the proposed exposure multipliers. The mechanistic model is a central part of the ART tool and with advancing knowledge on exposure, determinants will require updates and refinements on a continuous basis, such as the effect of worker behaviour on personal exposure, 'best practice' values that describe the maximum achievable effectiveness of control measures, the intrinsic emission potential of various solid objects (e.g. metal, glass, plastics, etc.), and extending the applicability domain to certain types of exposures (e.g. gas, fume, and fibre exposure).

Determination of operator exposure levels to insecticide during bait applications in olive trees: study of coverall performance and duration of application

In this study the operator exposure levels during bait applications of an insecticide in olive groves were determined using a whole body dosimetry method for dermal exposure. The study design allowed the roles of application task duration and coverall type to be evaluated as factors influencing operator exposure. Twenty applications were carried out with knapsack sprayers in the Tanagra region of Viotia, Greece, ten of which were for a 1h and ten for a 3h duration. An in-house GC-NPD analytical method was developed and validated for the determination of malathion, the active substance (a.s.) of the insecticide formulation used in field trials. The mean recovery of field-fortified samples was 84% (%RSD=3.0). Field trial results generally indicated lower operator exposure levels than indicated by the most relevant operator exposure predictive model. Residues of malathion on internal dosimeters were compared to those measured on the respective outer coveralls (potential dermal exposure) to evaluate the protective factor of each one of the two coverall types used. Both coverall types provided satisfactory levels of protection and can be considered as suitable protection for the conditions of the application scenario studied. Furthermore, the results indicated that there is not a strong correlation between exposure levels and duration of application.

Consumer exposure to biocides--identification of relevant sources and evaluation of possible health effects

BACKGROUND

Products containing biocides are used for a variety of purposes in the home environment. To assess potential health risks, data on products containing biocides were gathered by means of a market survey, exposures were estimated using a worst case scenario approach (screening), the hazard of the active components were evaluated, and a preliminary risk assessment was conducted.

METHODS

Information on biocide-containing products was collected by on-site research, by an internet inquiry as well as research into databases and lists of active substances. Twenty active substances were selected for detailed investigation. The products containing these substances were subsequently classified by range of application; typical concentrations were derived. Potential exposures were then estimated using a worst case scenario approach according to the European Commission's Technical Guidance Document on Risk Assessment. Relevant combinations of scenarios and active substances were identified. The toxicological data for these substances were compiled in substance dossiers. For estimating risks, the margins of exposure (MOEs) were determined.

RESULTS

Numerous consumer products were found to contain biocides. However, it appeared that only a limited number of biocidal active substances or groups of biocidal active substances were being used. The lowest MOEs for dermal exposure or exposure by inhalation were obtained for the following scenarios and biocides: indoor pest control using sprays, stickers or evaporators (chlorpyrifos, dichlorvos) and spraying of disinfectants as well as cleaning of surfaces with concentrates (hydrogen peroxide, formaldehyde, glutardialdehyde). The risk from aggregate exposure to individual biocides via different exposure scenarios was higher than the highest single exposure on average by a factor of three. From the 20 biocides assessed 10 had skin-sensitizing properties. The biocides isothiazolinone (mixture of 5-chloro-2-methyl-2H-isothiazolin-3-one and 2-methyl-2H-isothiazolin-3-one, CMI/MI), glutardialdehyde, formaldehyde and chloroacetamide may be present in household products in concentrations which have induced sensitization in experimental studies.

CONCLUSIONS

Exposure to biocides from household products may contribute to induction of sensitization in the population. The use of biocides in consumer products should be carefully evaluated. Detailed risk assessments will become available within the framework of the EU Biocides Directive.

Dermal exposure of pesticide applicators as a measure of coverall performance under field conditions

In this study, the field performance of two coverall designs used by pesticide applicators was determined. Two coverall types were selected based on data from previously conducted comfort testing under field conditions in southern Europe. Dermal exposure was measured during 22 applications conducted with 11 operators using similar hand-held spray guns in greenhouse pepper crops in the Ierapetra region of Crete, Greece. One of the coverall designs studied was made from a cotton/polyester material treated with a water-repellent Resist Spills(R) finish, which was compared in the field study to a coverall of similar design, but using a woven, untreated cotton material. An in-house analytical method was developed and validated for determining residues of the active substance (a.s.) malathion on the dosimeters. The derived levels of dermal exposure were used as a measure of the protection provided by the two types of coveralls. In addition, by comparing the total amount of the a.s. recovered from outer and inner dosimeters (potential dermal exposure = 238.8 mg kg(-1) a.s. for the cotton coverall and 160.44 mg kg(-1) a.s. for the Resist Spills coverall), a value could be determined for the degree of coverall penetration. The mean penetration (milligrams per kilogram a.s.) of the outer coveralls, calculated as a percentage of the total contamination, was 0.4% for the water-repellent coverall and 2.3% for the cotton coverall. The mean recovery from the laboratory and field-fortified samples was >91 and 74%, respectively and used as the main criterion for quality control of the analytical data. Under the field trial conditions evaluated, both the coverall designs gave better protection than the default values used in the most relevant predictive exposure model. Therefore, they could be considered as appropriate tools of personal protection when both comfort and field performance is taken into account under the specific application scenario.

Derivation of single layer clothing penetration factors from the pesticide handlers exposure database

Quantitative characterization of the penetration of chemical residues through various types and configurations of clothing is an important underpinning of mitigation strategies to reduce dermal exposure to occupational cohorts. The objective of the evaluation presented herein is the development of pesticide clothing penetration (or conversely protection) factors for single layer clothing (i.e., long-sleeved shirt, long pants; gloves are not included) based on dermal exposure monitoring data (passive dosimetry) included in the Environmental Protection Agency's Pesticide Handlers Exposure Database (PHED). The analysis of penetration per replicate was conducted by comparison of the inside and outside (total deposition), expressed as mug/cm(2), for each replicate pair of dermal dosimeters. Clothing penetration was investigated as a function of job classification, dosimetry sampling method, body part, application method, and type of formulation. Grand mean single layer clothing penetration values for patch (n=2029) and whole-body (n=100) dosimeter samples from PHED were 12.12 (SE=0.33; SD=15.02) and 8.21 (SE=1.01; SD=10.14) percent, respectively. Linear regression was used to evaluate clothing penetration as a function of outer dosimeter loading. The regression analysis supports the hypothesis that single layer clothing penetration increases with decreasing outer dosimeter loading.

Dermal absorption of solvents as a major source of exposure among shipyard spray painters

OBJECTIVE

The purpose of this study was to evaluate the relevance of inhalational and dermal exposure to solvents in shipyard spray painters. Special emphasis was placed on the spatial distribution of dermal exposure and absorption across different regions of the body.

METHODS

Fifteen male spray painters were recruited for this study. The subjects were monitored during a 3-day work period using a repeated-measures study design. Air and dermal exposure of solvents were collected each day. Urine was collected before and after the work shift.

RESULTS

Air samples showed that the workers were primarily exposed to ethylbenzene and xylene. The concentrations of ethylbenzene and xylene outside the workers' masks were 59.2 +/- 10.4 (mean +/- standard error [SE]) ppm and 29.4 +/- 4.70 ppm, whereas those inside the masks were 7.91 +/- 17.4 ppm and 3.83 +/- 8.22 ppm, respectively. The average mass of ethylbenzene and xylene across the different body regions inside the block units of assembled ships were 305.1 +/- 63.9 mg and 165.6 +/- 34.1 mg. The quantity was, on average, 5.8 and 5.1 times higher than those collected outside the blocks. In both measurements, the highest exposure mass was found on the upper legs, and the lowest exposure mass was found on the back. Principal component analysis (PCA) was used to transform the variables of dermal exposure for all investigated body regions into only one principal component. Multiple regression analyses revealed a significant relationship between dermal exposure to xylene (PCA dermal xyl) and urinary methylhippuric acid (MHA) levels, adjusting for air xylene exposure (R2=0.491, P<0.05).

CONCLUSIONS

:The present study indicated that dermal exposure to xylene significantly increased the urinary levels of MHA, suggesting that dermal exposure to solvents was an important route among spray painters.

Field protection effectiveness of chemical protective suits and gloves evaluated by biomonitoring

OBJECTIVES

To determine the effectiveness of protective suits and gloves by biomonitoring.

METHODS

Fifteen male spray painters at a ship coating factory were studied for two weeks. Workers wore no protective clothing during the first week and wore protective suits and gloves during the second week. Sampling was conducted on four consecutive working days each week. Ethyl benzene and xylene in the air were collected by using 3M 3500 organic vapour monitors. Urine was collected before and after each work shift.

RESULTS

Urinary mandelic acid (MA) and methyl hippuric acid (MHA) levels were divided by the personal exposure concentrations of ethyl benzene and xylene, respectively. Mean (SE) corrected MA and MHA concentrations in the first week were 1.07 (0.18) and 2.66 (0.68) (mg/g creatinine)/(mg/m3), and concentrations in the second week were 0.50 (0.12) and 1.76 (0.35) (mg/g creatinine)/(mg/m3) in the second week, respectively. Both MA and MHA concentrations in the second week (when spray painters wore protective suits and gloves) were lower than in the first week, respectively (p<0.001, p = 0.011). Mean decrease in MA and MHA biomarkers were 69% and 49%, respectively.

CONCLUSION

This study successfully evaluated the effectiveness of chemical protective suits and gloves by using biomarkers as urinary MA and MHA. This method is feasible for determining the performance of workers wearing personal protective equipment. Moreover, the experimental results suggest that dermal exposure may be the major contributor to total body burden of solvents in spray painters without protective suits and gloves.

Evaluation of dermal absorption and protective effectiveness of respirators for xylene in spray painters

OBJECTIVES

To determine the contribution of dermal absorption on the total exposure dose and the performance of respirators in the field for xylene in spray painters.

METHODS

Eighteen male spray painters worked at shipyard were recruited for this study. The subjects were monitored during a 3-day-work period using a repeated-measures study design. Personal exposure to xylene outside and inside mask were collected using two 3 M model 3500 organic vapor monitors, respectively. Urine was collected before and after the work shift and urinary methyl hippuric acid (MHA) was determined. Total 98 of air and urine samples were obtained, respectively.

RESULTS

Air sampling results showed that workers were primarily exposed to xylene and ethyl benzene. Xylene and ethyl benzene concentrations outside the mask were 52.6+/-63.7 (mean+/-SD) and 33.2+/-32.4 ppm, and concentrations inside the mask were 2.09+/-2.74 and 1.79+/-2.16 ppm, respectively. The median workplace protection factors of respirators for xylene and ethyl benzene were 25.0 and 17.4, respectively. On average, workers could reduce xylene inhalation by 96% and ethyl benzene inhalation by 94% for wearing respirators. A significant correlation (R(2)=0.935; P<0.001) was found between the WPFs for xylene and ethyl benzene. Total urinary MHA concentration was 240.2+/-42.3 (mean+/-SE) mg/g creatinine, whereas urinary MHA via skin absorption was estimated to be 202.1+/-40.1 mg/g creatinine. The contribution of dermal absorption to the total exposure dose of xylene was 64+/-4.3%.

CONCLUSION

The present study showed that inhalation of solvent vapors in workers decreased as a result of wearing respirators and dermal exposure became the main contributor to the total body burden of solvents. Because workers had different attitude and behavior to wear respirators, the measured workplace protection factors varied. It is therefore equally important to prevent from being exposed to solvents through skin for shipyard spray painters.