Personal protective equipment for registration purposes of pesticides

Regulatory authorities in North America, Europe and Australia use different approaches for the estimation of exposure reduction effectiveness of personal protective equipment (PPE) in registration processes of agrochemical pesticides. TNO has investigated current views and facts for the use of default values and set up a discussion paper which can be used as a starting point to achieve an internationally harmonised set of PPE protection factors for regulatory use. For inhalation exposure Loading it is proposed to use the assigned protection factors (APF) as deduced by BSI (British Standard Institution) and ANSI (American National Standards Institution). Since these values are somewhat variance and since in agricultural settings efficient control and proper training and education with respect to inhalation protection devices is generally absent, it is good to err on the safe side and to use the Lowest of both values, if available. For dermal exposure Loading differentiations are made for operators and re-entry workers and further for hand and body protection. Next to this the restrictions and framework for the use of the proposed defaults are very relevant. Oral exposure loading is only considered in special cases where dermal exposure may be relatively high and the hand-mouth shunt may lead to appreciable oral exposure loading. The presented defaults for PPE have been discussed with experts of regulatory authorities and industry, but a formal discussion still has to take place. This needs to be done on EU level between Member States. The current proposal is based on state-of-the-art knowledge and policy considerations, but further research is needed to better underpin the proposed values and/or to adapt them.

Accuracy of a semiquantitative method for Dermal Exposure Assessment (DREAM)

BACKGROUND

The authors recently developed a Dermal Exposure Assessment Method (DREAM), an observational semiquantitative method to assess dermal exposures by systematically evaluating exposure determinants using pre-assigned default values.

AIM

To explore the accuracy of the DREAM method by comparing its estimates with quantitative dermal exposure measurements in several occupational settings.

METHODS

Occupational hygienists observed workers performing a certain task, whose exposure to chemical agents on skin or clothing was measured quantitatively simultaneously, and filled in the DREAM questionnaire. DREAM estimates were compared with measurement data by estimating Spearman correlation coefficients for each task and for individual observations. In addition, mixed linear regression models were used to study the effect of DREAM estimates on the variability in measured exposures between tasks, between workers, and from day to day.

RESULTS

For skin exposures, spearman correlation coefficients for individual observations ranged from 0.19 to 0.82. DREAM estimates for exposure levels on hands and forearms showed a fixed effect between and within surveys, explaining mainly between-task variance. In general, exposure levels on clothing layer were only predicted in a meaningful way by detailed DREAM estimates, which comprised detailed information on the concentration of the agent in the formulation to which exposure occurred.

CONCLUSIONS

The authors expect that the DREAM method can be successfully applied for semiquantitative dermal exposure assessment in epidemiological and occupational hygiene surveys of groups of workers with considerable contrast in dermal exposure levels (variability between groups >1.0). For surveys with less contrasting exposure levels, quantitative dermal exposure measurements are preferable.

Patterns of Dermal Exposure to Hazardous Substances in European Union Workplaces

Workplace dermal exposure assessment is a complex task that aims to understand the dynamic interaction between the skin and the hazardous substances present in the surrounding environment. A European project known as RISKOFDERM gathered dermal exposure data in 85 workplaces (industrial and other types) in five countries in Europe. In order to optimize data collection and to develop a representative picture of dermal exposure, scenarios (tasks made up of a series of activities) were grouped together into dermal exposure operation units (DEOs). The allocation of scenarios to relevant DEOs was achieved on the basis of similarities of exposure routes, tasks and professional judgement. Sampling and quantification procedures were based on the approaches recommended by the OECD protocol. The laboratories involved in the analysis of the samples participated in quality assurance programmes. This exercise resulted in 419 body measurements and 437 measurements on hands expressed in terms of formulation (product) in use. Exposures for a given scenario varied by several orders of magnitude. The extent and patterns of exposure were found to be dependent on various exposure determinants, including inter- and intra-scenario variations. Hands were found to be the most contaminated parts of the body. Exposure patterns for liquid and solid contaminants were different. On the basis of the analysis of the data presented here, the averaged results (median and 95th percentile) for a given DEO unit should not be used as a representative measure of dermal exposure for all scenarios within that DEO without taking the exposure determinants into account. However, the data could be used to develop an exposure matrix (indicative exposure distributions) for different types of scenario and workplace, using determinants of exposure and a Bayesian approach to integrating expert opinion.

Classification of dermal exposure modifiers and assignment of values for a risk assessment toolkit

This paper describes how default dermal exposure values can be adjusted with modifier values for specific work situations. The work presented here is supplementary to a toolkit developed for the EU RISKOFDERM project. This toolkit is intended for the assessment and management of dermal risks in small and medium sized enterprises. Potential dermal exposure (on the outer envelope of the body) is estimated with an algorithm whereby modifier values are applied multiplicatively to dermal default exposure values. These exposure modifiers with their assigned factors are intended to increase or decrease the potential (default) dermal exposure accordingly. Default estimates are modified to obtain two modified defaults: potential exposure rate to the hands and to the body. Quantitative exposure data is at present inadequate and insufficient to derive meaningful information that can be used for the selection of independent modifiers and the assignment of appropriate values. Instead, available information from the literature was considered and, in combination with expert judgement, 15 potential dermal modifiers were selected. Modifiers were classified and grouped into non-overlapping groups in order to avoid double scoring. Values were assigned to modifiers in three different exposure routes, i.e. direct contact, surface contact and deposition. Depending on the significance of a modifier, the values assigned to modifiers were weighted in equal steps on a log-scale. The values assigned to modifiers as presented in this paper are open to validation and revision once new data become available.

Determinants of dermal exposure relevant for exposure modelling in regulatory risk assessment

Risk assessment of chemicals requires assessment of the exposure levels of workers. In the absence of adequate specific measured data, models are often used to estimate exposure levels. For dermal exposure only a few models exist, which are not validated externally. In the scope of a large European research programme, an analysis of potential dermal exposure determinants was made based on the available studies and models and on the expert judgement of the authors of this publication. Only a few potential determinants appear to have been studied in depth. Several studies have included clusters of determinants into vaguely defined parameters, such as 'task' or 'cleaning and maintenance of clothing'. Other studies include several highly correlated parameters, such as 'amount of product handled', 'duration of task' and 'area treated', and separation of these parameters to study their individual influence is not possible. However, based on the available information, a number of determinants could clearly be defined as proven or highly plausible determinants of dermal exposure in one or more exposure situation. This information was combined with expert judgement on the scientific plausibility of the influence of parameters that have not been extensively studied and on the possibilities to gather relevant information during a risk assessment process. The result of this effort is a list of determinants relevant for dermal exposure models in the scope of regulatory risk assessment. The determinants have been divided into the major categories 'substance and product characteristics', 'task done by the worker', 'process technique and equipment', 'exposure control measures', 'worker characteristics and habits' and 'area and situation'. To account for the complex nature of the dermal exposure processes, a further subdivision was made into the three major processes 'direct contact', 'surface contact' and 'deposition'.

Deriving Default Dermal Exposure Values for Use in a Risk Assessment Toolkit for Small and Medium-sized Enterprises

This paper describes the derivation of default task-based dermal exposure values for use in a risk assessment toolkit for small and medium-sized enterprises (SMEs). A set of separately determined dermal exposure modifiers have been applied to published studies of dermal exposure to obtain 'normalized' dermal exposure data sets. These data sets are grouped according to task and then further subdivided by making a distinction between processes involving solid and liquid products. For each of the resulting 12 groups, two default exposure rates are required: potential exposure rate to the hands and potential exposure rate to the body. Default values for risk assessment are then derived by taking a weighted average of the 75th percentiles of these normalized exposure distributions. In addition, a measure of peak surface concentration is required to take into account the risk of local skin effects. The higher of the (modified) hand and body exposure rates after applying the relevant penetration factors for clothing and gloves is used. Usually this will be the hand exposure rate. These default values serve as robust initial exposure estimates in a risk assessment toolkit for SMEs.

A Toolkit for Dermal Risk Assessment: Toxicological Approach for Hazard Characterization

The toxicological background for hazard assessment using a simple to use toolkit for assessment and management of health risks from occupational dermal exposure is presented. Hazard assessment is intended to answer the following questions: (i) is the substance under consideration capable of damaging the skin; (ii) is the substance under consideration capable of leading to systemic health effects after having penetrated the skin; (iii) to what extent may the substance become systemically available; (iv) is the hazard influenced by the concentration? Local effects (like irritation or corrosion) and systemic effects (like drowsiness or liver damage) are treated separately, taking into account their possible interrelations. Hazard assessment is performed on the basis of easily available risk phrases, which give a short characterization of the inherent toxicity of a pure chemical or preparation. The information provided by risk phrases and possibly additional data is transformed into a one-dimensional ranking system of intrinsic toxicity (IT) scores. IT scores are expressed in broad categories like low, moderate, high or extreme. This ranking provides plausible information on the relevance of potential skin contact to health effects.

A Toolkit for Dermal Risk Assessment and Management: An Overview

The European Research project RISKOFDERM (QLK4-CT-1999-01107) has two major goals. One is the development of a conceptual model for dermal risk assessment for regulatory purposes, such as the registration of new chemicals. The other goal is to develop a simple-to-use toolkit for assessment and management of health risks from occupational dermal exposure. This toolkit was constructed by analysing the major determinants of dermal hazard and dermal exposure. The results were combined in the form of a decision-tree that leads the user of the toolkit through a number of questions on the hazardous properties of the chemical in use, and on the exposure situation. The toolkit translates the information given by the user into broad data categories of hazard and exposure that lead to a rough estimate of health risk from dermal exposure. This is done separately for local skin effects and skin allergy on the one hand, and systemic effects after skin penetration on the other hand. After going through the decision-tree, the user is advised to act to control the risk, and to read general information on dermal exposure and a statement describing the uncertainty of the risk estimate produced by the toolkit. The final version of the toolkit will be available for use on portable or stationary computers and runs the decision algorithms in the background so that the non-expert user only will see the judgements, the recommendations and the general information. The toolkit will be evaluated before release by experts on the various elements included in the toolkit and by field experts in its practical use. The toolkit is an attempt to adapt elements of exact science to a situation where the necessary input data are of limited quality and are only estimates. The toolkit does not claim to give precise answers based on imprecise information. The purpose is to enable the user to estimate the order of magnitude of hazard, exposure and risk, and to encourage the user to deal with the issues of dermal hazard, exposure and control.

Proposal for an approach with default values for the protection offered by PPE, under European new or existing substance regulations

Introduction of personal protective equipment (PPE) in the process of quantitative exposure and risk assessment should be addressed carefully. PPE which have been designed and manufactured according to CE-criteria and have proved to pass relevant test criteria, can be classified as "proper functioning". However, test criteria for PPE are not equal to levels of protection which can be achieved in the workplace, because actual workplace exposure scenarios, fit, maintenance and storage may differ substantially from the test conditions. The proper use of PPE is related to issues which form a part of a PPE-programme. Such a programme should be implemented in a company to ensure selection of proper PPE and information, training and instruction of employees how to wear PPE properly. Assigned protection factors (APFs) for different designs of respiratory protective devices (RPD) have been introduced to quantify effectiveness of RPD in the workplace. Similar APFs are proposed for dermal protection (gloves and clothing). In general biological monitoring studies show lower reduction of internal exposure than estimated by reduction of external exposure. Therefore, conservative estimates of protection by PPE, i.e. the lowest APFs, are proposed for risk assessment purposes if "proper use of proper functioning" PPE as part of a PPE-programme cannot be demonstrated.

EUROPOEM, a predictive occupational exposure database for registration purposes of pesticides

For registration of agricultural pesticides, the risks for humans, animals, and the environment must be determined. The risk assessment is based on an appraisal of the levels of exposure and the hazards of the active substance(s) in the plant protection product, that is, the agricultural pesticide. Funded by the European Commission (AIR3 CT93-1370), the EUROPOEM database has been developed by a group of experts, representing governments, industry, and academia. The currently available exposure database reflects exposure to operators (mixer/loaders and applicators). The EUROPOEM approach is based on a harmonized protocol for conduct of field studies of operator exposure (presently published as an Organization for Economic Cooperation and Development [OECD] Guidance Document) and a tiered approach to exposure and risk assessment. The database is constructed from exposure data obtained in representative field studies. These field studies are considered according to criteria reflecting the quality of documentation, study design, adequate methodology, number of replicates, and QA/QC elements, for use of the inhalation and dermal exposure data. The resulting exposure data were combined according to comparable use scenarios. From the resulting databases typical surrogate potential exposure values have been obtained, which are determined by their use for either acute or chronic health effects, and the size of the database. For large databases (over 50-100 data points), from many different field studies (10 or more), the 75th percentile is taken if the exposure is considered leading to chronic effects. For smaller databases, a more conservative 90th percentile is taken as surrogate value, or none at all for very small databases (15-20 or less data points from 3 or less different field studies). The choice for the 75th percentile is based on the assumed or observed lognormal distribution of the exposure data, as being the most relevant typical value for long-term effects, since the 75th percentile of log-normal distributions is nominally very similar to a calculated arithmetic mean (AM). The AM, as such however, is irrelevant for log-normal distributions.

Assessment of dermal exposure during airless spray painting using a quantitative visualisation technique

The range of dermal exposure to non-volatile compounds during spray painting was studied in a semi-experimental study involving three enterprises and 12 painters. A fluorescent tracer was added to the paint and deposition of the tracer on clothing and uncovered parts of the skin was assessed using video imaging and processing techniques. A container (volume 36 m(3)) was sprayed with a colourless laquer (varnish) containing 66.7 mg/l fluorescent whitening agent. All painters sprayed the outside of the container. Nine painters repeated the painting a second time and five also sprayed the inside of the container. The painters wore white Tyvek coveralls, but no gloves. Duration of spraying the outside ranged from 4 to 21 min with a mean of 10 min and the amount of paint sprayed ranged from 3.0 to 12.8 l (mean 6.6 l). The mass of tracer deposited on the coverall ranged from 2.2 to 471 microg (90th percentile 256 microg), whereas, mass deposited on skin (i.e. the hands, wrists, and face) ranged from 0.01 to 52 microg tracer (90th percentile 20 microg). The quantity of tracer on the coverall was three times higher after spraying the inside of the container compared to spraying the outside, whereas the quantity on the skin was similar in both cases. On average 10% of the surface area of the coverall and skin was exposed during spraying the outside. Exposures, expressed in units of mass per area exposed were slightly higher for skin compared to coverall. In this study, deposited mass of tracer was correlated with an alternative exposure metric, i.e. surface area exposed multiplied by the duration of exposure, which has been proposed as a surrogate for uptake. Using a quantitative fluorescent tracer technique, it could be demonstrated that body parts which showed the lowest mass of tracer had the highest exposure as mass per surface area. Compared to other techniques which only determine mass, the ability to identify and quantify the actual surface area exposed is a clear advantage of the quantitative fluorescent tracer technique.

Biocides Steering Group on human exposure assessment: a preliminary report

In a project granted by DG XI of the European Commission, it is attempted to collate experimental and theoretical data on human (workers and consumers) exposure assessment to biocidal products, and to outline the methodology for sampling and measurement. On the basis of the available evidence, approaches are presented for the exposure assessment to be used for estimation of risks in authorization procedures under the recently accepted Directive 98/8/EC. Gaps in knowledge are indicated, making it possible to study the issues involved in a comprehensive and cost-effective way. Some recommendations are given on how to best do this. The current project has been detailed in a final report.

Proposal for the assessment of quantitative dermal exposure limits in occupational environments: Part 1. Development of a concept to derive a quantitative dermal occupational exposure limit

Dermal uptake of chemicals at the workplace may contribute considerably to the total internal exposure and so needs to be regulated. At present only qualitative warning signs--the "skin notations"--are available as instruments. An attempt was made to develop a quantitative dermal occupational exposure limit (DOEL) complementary to respiratory occupational exposure limits (OELs). The DOEL refers to the total dose deposited on the skin during a working shift. Based on available data and experience a theoretical procedure for the assessment of a DOEL was developed. A DOEL was derived for cyclophosphamide and 4,4-methylene dianiline (MDA) according to this procedure. The DOEL for MDA was tested for applicability in an actual occupational exposure scenario. An integrated approach is recommended for situations in which both dermal and respiratory exposures contribute considerably to the internal exposure of the worker. The starting point should be an internal health based occupational exposure limit--that is, the maximum dose to be absorbed without leading to adverse systemic effects. The proposed assessment of an external DOEL is then either based on absorption rate or absorption percentage. The estimation of skin penetration seems to be of crucial importance in this concept. If for a specific substance a maximal absorption rate can be estimated a maximal skin surface area to be exposed can be assessed which may then serve the purpose of a DOEL. As long as the actual skin surface exposed is smaller than this maximal skin surface area the internal OEL will not be exceeded, and therefore, no systemic health problems would be expected, independent of the dermal dose/unit area. If not, the DOEL may be interpreted as the product of dermal dose/unit area (mg/cm2) and exposed skin surface area (cm2). The proposed concept for a DOEL is relevant and can be made applicable for health surveillance in the occupational situation where dermal exposure contributes notably to the systemic exposure. Further research should show whether this concept is more generally applicable.

Proposal for the assessment to quantitative dermal exposure limits in occupational environments: Part 2. Feasibility study for application in an exposure scenario for MDA by two different dermal exposure sampling methods

OBJECTIVE

To evaluate two different techniques for assessing dermal exposure to 4,4'-methylene dianiline (MDA) in a field study. The results were used to test the applicability of a recently proposed quantitative dermal occupational exposure limit (DOEL) for MDA in a workplace scenario.

METHODS

For two consecutive weeks six workers were monitored for exposure to MDA in a factory that made glass fibre reinforced resin pipes. Dermal exposure of the hands and forearms was assessed during week 1 by a surrogate skin technique (cotton monitoring gloves) and during week 2 by a removal technique (hand wash). As well as the dermal exposure sampling, biological monitoring, measurement of MDA excretion in urine over 24 hours, occurred during week 2. Surface contamination of the workplace and equipment was monitored qualitatively by colorimetric wipe samples.

RESULTS AND CONCLUSIONS

Geometric means of daily exposure ranged from 81-1762 micrograms MDA for glove monitoring and from 84-1783 micrograms MDA for hand washes. No significant differences, except for one worker, were found between exposure of the hands in weeks 1 and 2. Significant differences between the mean daily exposure of the hands (for both weeks and sampling methods) were found for all workers. The results of the colorimetric wipe samples indicated a general contamination of the workplace and equipment. Excretion of MDA in 24 hour urine samples ranged from 8 to 249 micrograms MDA, whereas cumulative MDA excretion over a week ranged from 82 to 717 micrograms MDA. Cumulative hand wash and MDA excretion results over a week showed a high correlation (R2 = 0.94). The highest actual daily dermal exposure found seemed to be about 4 mg (hand wash worker A on day 4), about 25% of the external DOEL. Testing of compliance by means of a biological limit value (BLV) led to similar results for the same worker. It is concluded that both dermal exposure monitoring methods were applicable and showed a compatible performance in the present exposure scenario, where the exposure relevant to dermal absorption is considered mainly restricted to hands. The concept for a DOEL seemed to be relevant and applicable for compliance testing and health surveillance in the situation under investigation.

Exposure to methyl bromide during greenhouse fumigation on Crete, Greece

In agricultural areas where greenhouses and dwellings are intermixed, the general population as well as the professional applicators may be exposed to pesticides. In a field study on Crete, exposure to methyl bromide during soil fumigation was assessed. Exposure of applicators (both contractors and farmers) were measured with personal air sampling equipment. Environmental monitoring inside and outside greenhouses combined with meteo data formed the basis for calculating the exposure of the general population with a computer aided dispersion model. Exposure of contractors exceeded the TLV value. The safe limit for the general population living close to a fumigated greenhouse is also exceeded.

Exposure and risk estimation for pesticides in high-volume spraying

During twenty applications with a spray pistol of methomyl to chrysanthemums, inhalation exposure as well as potential and actual dermal exposure were monitored using the 'whole-body'-method. On the basis of the exposure data, in terms of exposure to the liquid formulation and the spray liquid, the possible health risk for methomyl and thirteen other pesticides, frequently used in ornamentals, was indicatively assessed. From the No-Observed-Adverse-Effect-Level (NOAEL) in animal experiments an Indicative Limit Value (ILV) was derived. The ILV is considered indicative for the limit of daily exposure for a worker which probably gives no rise to adverse health effects. This value is a rough approximation since the database for a proper assessment of such a value is generally incomplete. Assuming that exposure is independent of the pesticide, using a suitable format, the actual observed exposure can be compared with the ILV. To reduce the dermal exposure levels below the ILV the exposure of especially the hands has to be reduced e.g. by using impermeable gloves.

The influence of skin moisture on the dermal absorption of propoxur in human volunteers: a consideration for biological monitoring practices

A large number of workers in agriculture are exposed daily (through skin contact) to pesticides either directly during mixing and loading or indirectly due to contact. The aim of this study was to investigate the influence of skin moisture on the dermal uptake of the pesticide propoxur. The study was conducted in human volunteers under controlled temperature conditions (30 degrees C) and environmental relative humidities of either 50, 70 or 90%. The study was approved by the Medical Ethics Committee. In this study a linear relationship between the environmental relative humidity and the level of skin moisture was observed. The results indicate that the level of skin moisture influences the absorption of propoxur via the dermal route, dramatically ranging from, on average, 13, 33-63% of the potentially absorbed dose' which is excreted in urine as the primary metabolite 2-isopropoxyphenol (IPP) at relative humidity levels of, on average 50, 70 and 90%, respectively. The 'potentially absorbed dose' is defined as the difference between the applied dose and the dislodged dose after 4 h. It can be concluded that by assessing health risks of workers in agriculture exposed dermally to pesticides and e.g. in testing the efficiency of protective clothing under realistic conditions, the influence of the level of skin moisture on absorption of substances may be considerable and has to be taken into account.

Assessment of dermal exposure to chemicals

The methods for the dermal exposure assessment vary in their complexity and are in some sense complementary to each other. The most easy-to-use methods involve a pseudo-skin-approach, such as gloves and removal by washing. In some cases generic modelling appears to be possible. The experimental methods can indicate and even quantitate the presence of chemicals on the skin. This enables studies on the occurrence of local effects in relation to the exposure. When the interest is on systemic effects, the dermal exposure is only of interest if it represents the amount that is available for penetration through the skin. This may vary largely between compounds due to the large variation in dermal absorption. When this degree of absorption is not known, the alternate method may be biological monitoring, at least when it is based on a detailed pharmacokinetic knowledge of that compound. The most sophisticated method, applied to study occupational exposures, is formed by a combination of monitoring on clothing (pseudo-skin), hand washing (removal) and biological monitoring. In any case, the assessment of dermal exposure should be based on a sampling strategy that takes into account the distribution of the contamination on the body, the variation in time of the exposure, the duration of the exposure as well as the degree of skin protection afforded by clothing.

Estimation of long-term exposure to pesticides

Quantifying the exposure of agricultural workers to pesticides is difficult in the face of the heterogeneity of the pesticides used, the variability in methods of application, and the lack of adequate exposure data. This report describes an attempt to estimate long-term dermal and inhalation exposure of bulb farmers by the development of an exposure index. This proposed exposure index consists of generic levels of exposure specific to the method of application, which were derived from databases as well as from field studies. The index is further determined by farm-related parameters such as acreage and number of pesticide applications ascertained from questionnaire responses. A widely used dithiocarbamate mixture served as a marker compound for exposure to other pesticides. Ranking of 127 bulb farmers according to calculated lifetime dermal exposure correlated only moderately to ranking based on duration of exposure, e.g., years of exposure and farm acreage. This finding indicates that the proposed exposure index could provide a useful estimate of long-term exposure to a mixture of pesticides in epidemiological investigations.

Skin contamination, airborne concentrations, and urinary metabolite excretion of propoxur during harvesting of flowers in greenhouses

In eight greenhouses used for carnation culture, workers engaged in harvesting (n = 16), were monitored for dermal and respiratory exposure and urinary excretion of propoxur. Dermal exposure of hands and forearms was estimated from dislodgable foliar residue, using a transfer factor (a measure of transfer of pesticides from leaves to the skin) and the total number of working hours. Total estimated dermal and respiratory exposure during harvesting ranged from 0.2 to 46 mg and from 3 to 278 micrograms, respectively. To study the relationship between external and internal exposure to propoxur, respiratory and dermal exposure levels were compared with the total amount of 2-isopropoxyphenol (IPP), the major metabolite of propoxur, excreted in urine in 24 hr. The Pearson correlation coefficient between dermal exposure and the total amount of excreted IPP was 0.95. A correlation coefficient of 0.84 was found between respiratory exposure and the amount of IPP excreted. The latter association was probably caused by the covariation of respiratory and dermal exposure levels (r = 0.85). Assuming negligible oral absorption, calculations indicated that dermal exposure could account for > 80% of the amount of excreted IPP. On the basis of the amount of IPP excreted, there was no reason to suspect increased health risks for workers from exposure to propoxur during harvesting.

Risk assessment of dermal exposure of greenhouse workers to pesticides after re-entry

On 18 farms for rose culture in greenhouses in The Netherlands, dermal exposure of hands and forearms to abamectin (avermectin B1), dodemorph (4-cyclododecyl-2,6-dimethylmorpholinium acetate) and bupirimate (5-butyl-2-(ethylamino)-6-methyl-4-pyrimidinyl dimethylsulphate) was measured during crop activities. Dermal exposure during cutting (75 workers) amounted to 13 micrograms/h, 1.8 mg/h, and 2.2 mg/h for abamectin, dodemorph and bupirimate, respectively. Dermal exposure to abamectin and dodemorph during sorting (21 workers) and bundling (30 workers) was comparable with that during cutting. From the dependence of dermal exposure on the amount of dislodgeable foliar residue (DFR) a transfer factor was estimated to be 1,200, 4,550, and 2,400 cm2/h for abamectin, dodemorph and bupirimate, respectively. For sorting and bundling these factors were of the same order of magnitude. The results suggested that work rate was also a determinant of dermal exposure. The within-farm variance of dermal exposure during cutting appeared to account for approximately 30% of the unexplained part of the variation remaining after regression on DFR and application technique. The final unexplained part in the variation of dermal exposure during cutting was amongst others due to the variation between the different farms in which the measurements were performed. A health risk evaluation of the observed levels of dermal exposure after re-entry of greenhouses led to the conclusion that a health hazard may exist, especially after application of high rates of relatively toxic pesticides which easily penetrate the skin.

Pesticides in the cultivation of carnations in greenhouses: Part I--Exposure and concomitant health risk

Respiratory exposure and dermal exposure of the hands and forearms to the pesticides chlorothalonil, thiophanate-methyl, thiram, and zineb during application and during crop activities have been measured on 18 farms for carnation culture in glass-covered greenhouses in the Netherlands. Farms were selected according to a "worst case" strategy with regard to dermal exposure during cutting of flowers. For 94 workers, the geometric mean dermal exposure rate during cutting (measured on long-sleeved cotton glove monitors) was 10.1 mg/hr (active ingredient per unit of actual working time) and during sorting/bundling of these flowers by 35 workers the dermal exposure rate was 7.3 mg/hr. The average concentration in air as measured by personal air sampling during cutting after a pesticide had been dusted was 0.07 mg/m3. For the same area, spraying a pesticide exposed the applicator to a dermal exposure seven times higher than dusting. However, during dusting respiratory exposure was higher. Generally, overall exposure is higher during re-entry activities than during application. From the observed levels of dermal exposure during harvesting (re-entry) and from toxicity data, health risk occurs after application of pesticides that are relatively toxic and show relatively good skin-penetrating properties at relatively high application rates. The respiratory exposure to dusted pesticides after re-entry is about as high as during application of these pesticides and may in some situations also result in health risks. Training and education of greenhouse workers on (personal) hygiene and use of protective gloves are advocated in order to reduce exposure.

Pesticides in the cultivation of carnations in greenhouses: Part II--Relationship between foliar residues and exposures

The relationship between the levels of dermal and respiratory exposure to pesticides and the amount of pesticide on the leaves of the plants has been studied during cutting of carnations in greenhouses. The study was focused on four pesticides and performed in 18 farms in the Netherlands. Dermal exposure measured by using long-sleeved cotton gloves is strongly related to the amount of dislodgeable foliar residue (DFR). A transfer factor from leaves to hands of approximately 4500 cm2/hr (one-sided projected area) has been calculated. Small differences have been noticed between the different pesticides. Dermal exposure of hands and forearms to pesticides during cutting of carnations can be predicted from measurements of DFR. The DFR was mainly determined by the amount of pesticide remaining from previous applications and the last application rate, not by the application technique (spraying or dusting). The concentrations in the breathing zone after dusting of zineb (dustable powder) and chlorothalonil (wettable powder) were significantly correlated with the dislodgeable foliar residue. The concentrations of thiram did not correlate with DFR. Respiratory exposure results from dispersion of foliar dust containing pesticides.

Assessment of dermal and inhalation exposure to zineb/maneb in the cultivation of flower bulbs

In bulb farming the use of pesticides for crop protection and bulb disinfection is extensive. To estimate long-term occupational exposure to pesticides, generic levels of exposure specific to the method of working were needed. In order to derive these values, dermal and inhalation exposure to the fungicide mixture zineb/maneb was assessed for different methods of mixing and loading a wettable powder formulation. Further, dermal exposure was also assessed for two methods of disinfection of bulbs. Observed exposure was expressed in terms of method-specific levels of exposure, which makes it possible to compare exposure resulting from different methods of working, with respect to the amount of pesticide handled, or whether ladling the pesticide with a scoop or dipping the bulbs using baskets resulted in high exposure. Moreover, the relative importance of dermal and inhalation exposure routes was estimated. The results show that during mixing and loading with bare hands dermal exposure is by far the greater contributor (greater than 99%) to the total estimated exposure. Comparing these results and also some preliminary results of the dermal protection provided by working gloves, with tentative health-based limit values of exposure, emphasize the need for a programme on appropriate dermal protection.

Exposure to styrene and health complaints in the Dutch glass-reinforced plastics industry

A study of the health hazards for workers exposed to styrene in the Dutch glass-reinforced plastics industry was undertaken. The open mould techniques of filament winding, spraying and hand laminating were chosen for study because exposure of workers using them was expected to be high. Occupational hygiene surveys were conducted in four plants. In addition to measurements of exposure, data on health complaints were collected. In 12 smaller plants exposure was estimated in walk-through surveys. The results show that although most of the plants had implemented control measures such as ventilation and extraction, the levels of exposure constituted a health risk. Time-weighted average concentrations for workers involved in filament winding ranged from 134 to 716 mg m-3, for those who were spraying from 48 to 602 mg m-3 and for those laminating manually from 18 to 538 mg m-3. The 'no-adverse-effect level' based on effects observed in man is considered to be 105 mg m-3, and the acute subjective health effects experienced by the population studied supported this value. To reduce exposure to below 105 mg m-3, control measures should combine engineering with codes of practice adapted to the particular process or processes employed.

An automated method for the determination of acetyl and pseudo cholinesterase in hemolyzed whole blood

The aim of the present study was to develop a method which allows determination of pseudo (PsChE) and acetyl cholinesterase (AChE) activities in single hemolyzed blood samples of workers exposed to cholinesterase-inhibiting compounds, avoiding the time-consuming and laborious separation of plasma and erythrocytes. Two methods based on Ellman's colorimetric determination of cholinesterase activity were compared, and three different substrates were tested. The best results were obtained with the substrates butyrylthiocholine and acetyl(beta-methyl)thiocholine, both showing a substrate specificity of more than 97% with respect to PsChE and AChE, respectively. The method showed sensitivity to detect low levels of inhibition of AChE and PsChE in blood. The between-day precision was less than 4% for both cholinesterase activities. It was demonstrated with this method that hemolyzed blood can be stored at -20 degrees C at least 18 months without loss of cholinesterase activity. The method has been used for 18 months in a monitoring program for laboratory employees working with various cholinesterase-inhibiting compounds. The average co-efficients of intraindividual variation amounted to 6.8% (range 2.2-9.6%; 90 percentile, 8%) and 6.6% (range 2.9-9.9%; 90 percentile, 7.9%) for PsChE and AChE, respectively. In a group of non-exposed workers the average intraindividual variations were 4.0% (range 1.5-7.7%; 90 percentile, 7.6%) and 3.6% (range 0.6-6.6%; 90 percentile, 5.3%), respectively. Using the value of 4.0%, it appears possible to detect an individual decrease in cholinesterase activity of more than 8% below a baseline based on three determinations. The method can thus be used to detect relatively low levels of cholinesterase inhibition.

Occupational exposure to lead and blood pressure: a study in 105 workers

A group of workers, occupationally exposed to lead and cadmium compounds (n = 53), was compared to a group of workers not exposed to these metals (n = 52). The average values of systolic, diastolic, and mean blood pressure were found to be higher in the exposed group (p less than 0.05). In contrast with the correlation between CdU and blood pressure, the correlation between PbB and systolic and mean blood pressure remained statistically significant after controlling for age and pulse rate (r = 0.22, p less than 0.05). The prevalence of potential hypertension (defined as systolic blood pressure greater than or equal to 160 mm Hg and/or diastolic blood pressure greater than or equal to 95 mm Hg and/or under treatment for hypertension) was higher in the exposed group, but the observed relative risk was not statistically significant: relative risk = 1.91 (95% confidence limits, 0.90-4.05). Furthermore, a significant correlation between PbB and Hgb (r = -0.28, p = 0.004) was observed. Differences in kidney function, as assessed in this study, were not detected.