- Email: [email protected]
Pyrethroids used indoors – Biological monitoring of exposure to pyrethroids following an indoor pest control operation
Int. J. Hyg. Environ. Health 206, 85 ± 92 (2003) ¹ Urban & Fischer Verlag http: // www.urbanfischer.de/journals/intjhyg
International Journal of Hygiene and Environmental Health
Pyrethroids used indoors ± Biological monitoring of exposure to pyrethroids following an indoor pest control operation Gabriele Lenga, b , Ulrich Ranftc, Dorothee Sugiric, Wolfgang Hadnagya, Edith Berger-Prei˚d, Helga Idela a b c d
Institute of Hygiene, Heinrich-Heine-University, D¸sseldorf, Germany Bayer AG, Medical Department, Leverkusen, Germany Medical Institute of Environmental Hygiene, D¸sseldorf, Germany Fraunhofer Institute of Toxicology, Aerosol Research, Drug Research and Clinical Inhalation, Hannover, Germany
Received August 1, 2002 ¥ Revision received October 15, 2002 ¥ Accepted November 2, 2002
Abstract A prospective epidemiological study with respect to pyrethroid exposure was carried out combining clinical examination, indoor monitoring and biological monitoring. The results of the biological monitoring are presented. Biological monitoring was performed in 57 persons before (T1) as well as 1 day (T2), 3 days (T3), 4 ± 6 months (T4), and 10 ± 12 months (T5) following a pest control operation (PCO) with pyrethroid containing products such as cyfluthrin, cypermethrin, deltamethrin or permethrin. Pyrethroids in blood were measured by GC-ECD. The respective metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (DBCA), 3-phenoxybenzoic acid (3-PBA) and fluorophenoxybenzoic acid (FPBA) were measured in urine using GC/MS. For all cases the concentrations of pyrethroids in blood were found to be below the detection limit of 5 mg/l before and after the PCO. With a detection limit of 0.2 mg/l of the investigated metabolites, the percentage of positive samples were 7% for cis-DCCA, 3.5% for trans-DCCA and 5.3% for 3-PBA before PCO. One day after PCO (T2) the percentage of positive samples increased remarkably for cisDCCA (21.5%), trans-DCCA (32.1%) and 3-PBA (25%) showing significantly increased internal doses as compared to pre-existing values. This holds also true for T3, whereas at T4 and T5 the significant increase was no more present. FPBA and DBCA concentrations were below the respective detection limit before PCO and also in most cases after PCO. In 72% of the subjects the route of pyrethroid uptake (measured by determining the DCCA isomeric ratio) was oral/inhalative and in 28% it was dermal. Based on the biological monitoring data it could be shown that appropriately performed pest control operations lead to a significant increase of pyrethroid metabolite concentration in the early phase (1 and 3 days) after pyrethroid application as compared to the pre-exposure values. However, evaluated metabolite concentrations 4 ± 6 months after PCO did not exceed values of published background levels. Key words: Biological monitoring ± pyrethroids ± indoor pest control operations ± prospective study
Corresponding author: PD Dr. Gabriele Leng, Medical Department, Bayer AG, D-51368 Leverkusen. Phone: 49 214 30 65679, Fax: 49 214 30 21307, E-mail: [email protected]
1438-4639/03/206/02-085 $ 15.00/0
86
G. Leng et al.
Introduction Synthetic pyrethroids like cyfluthrin, cypermethrin, deltamethrin and permethrin belong to the most frequently used insecticides. Pyrethroids are used in plant and storage protection, wood preservation, impregnation of wool carpets and textiles, disinfection and pest control. Exposure to pyrethroids does not only concern workers in the chemical industry (production, filling, formulation), farmers, and pest control operators, but also the general population. They may be exposed by food contaminated with pyrethroid residues or by indoor pyrethroids resulting from self-spraying of pyrethroids against mosquitoes, from pyrethroid treated textile floor coverings or by pest control operations. The insecticidal effect of pyrethroids is based on their neurotoxic potential, which is determined by a prolonged opening of the sodium channel (Aldridge, 1990; Narahashi, 1992). In insects and in mammalians (only at nearly lethal dosage) this effect evokes repetitive nerve actions associated with hyperactivity, tremor, ataxia, convulsions and possible paralysis (Aldridge, 1990; Narahashi, 1992). Compared with other insecticides such as organophosphates,
Fig. 1.
Pyrethroids and their corresponding metabolites.
the mammalian toxicity of pyrethroids is low (Matsuo, 1989). In man, a variety of reversible symptoms such as paraesthesia, irritations of the skin and mucosa, headache, dizziness, and nausea are reported following high occupational pyrethroid exposure (He et al., 1988, 1989). In most cases symptoms occur immediately after exposure ± only in a few cases after 30 min up to 8 hours (He et al., 1988). The duration of symptoms varies between 30 minutes and 32 hours depending on the pyrethroid. With regard to health aspects of the general population no clear pyrethroid-related effects are obvious. It is claimed, that there are thousands of pyrethroid intoxications (people with irreversible symptoms) in Germany each year (M¸ller-Mohnssen, 1991, 1995). However, a causal relation between pyrethroid exposure and symptoms is doubtful, since the only diagnostic tool used were questionnaires and pyrethroid exposure, in most cases dated back to many years ago. In a retrospective study it is described that 6 out of 23 persons showed health effects with a possible relation to pyrethroid exposure (Altenkirch et al., 1996).
Pyrethroid exposure and biological monitoring
An objective evaluation of possible human health effects caused by pyrethroids can be obtained using a prospective epidemiological approach including indoor and biological monitoring combined with an assessment of the individual health status. This design was used in the present study investigating persons before and several times after professional indoor pest control operations (PCO) using a pyrethroid-containing product. Human effect monitoring was performed to evaluate the individual health status. As a part of the prospective study the present paper focuses on the biological monitoring data. The main goal was to investigate to which extent an appropriately performed professional pest control operation with a pyrethroid-containing product leads to an increase of the internal pyrethroid dose of the exposed subjects. For detecting an internal pyrethroid dose, the concentrations of pyrethroids in blood can be referred to (K¸hn, 1997). However, pyrethroids are metabolized very fast and can be determined in plasma only a few hours after exposure (Leng et al., 1997b). The metabolites are renally eliminated with a half-life time of about 6 hours (Eadsforth et al., 1988; Woollen et al., 1992). For example, after cyfluthrin exposure 93% of the metabolites are eliminated during the first 24 hours (Leng et al., 1997a). It was of further interest to investigate the route of uptake of pyrethroids after a pest control operation. Toxicokinetic studies showed that the dermal route plays a minor role (Eadsforth et al., 1988) and that the inhalation or oral uptake is the main source of absorption. For pyrethroids it is possible to distinguish between an oral/inhalative and a dermal uptake by determining the isomeric ratio of the metabolite DCCA.
87
Material and methods Study design The present study was carried out from 1996 to 1999 and included five medical examinations (Figure 2) performed at the locality of the pest control operation (PCO). The first examination was performed before PCO (T1), the other four examinations one day (T2), 3 days (T3), 4 to 6 months (T4) and 10 to 12 months (T5) after the PCO. Each examination consisted of a general medical and a neurophysiological examination accompanied by a questionnaire-based interview. In addition, blood and urine was sampled for determination of general clinical and immunological parameters as well as for performing biological monitoring. With respect to indoor monitoring, house dust and airborne particulate matter was sampled before PCO and one day, 4 to 6 months as well as 10 to 12 months after the PCO to be analyzed at the Fraunhofer Institute of Toxicology and Aerosol Research in Hannover, Germany (Berger-Prei˚ et al., 2002). The aim of the study was to recruit 90 persons to be exposed to pyrethroids in the near future by a pest control operation and living close to D¸sseldorf. Therefore professional pest control operators were asked to inform us of planned PCOs using a pyrethroid-containing product to combat insects, e.g. cockcroaches. Most of the pest control operators denied using pyrethroids or refused to participate in the study. Reason for this was the controversial public discussion about pyrethroid induced diseases and several legal actions against pest control operators. For this reason the recruitment of persons was expanded throughout Germany. This was done via news papers, radio campaigns, lectures at pest control operator meetings and personal contacts. Based on these difficulties, recruitment of persons reached a distance of up to 400 km remote from D¸sseldorf. Furthermore, persons with diabetes mellitus, renal deficiency, auto immune diseases, neurological or psychiatric disorders were excluded from the study as well as subjects where alcoholism or drug consumption was assumed. Another exclusion factor was a history of PCO during the last 6 months before the study. Subjects were also excluded when a second PCO with pyrethroids was performed during the study. Finally 61 volunteers (40 men and
Fig. 2. Study design ± time scheme. B biological monitoring (pyrethroids in blood and their metabolites in urine); I indoor monitoring (pyrethroids in house dust and airborne particulate matter); E effect monitoring (medical-, neurophysiological examination, questionnaires, immunological parameters); tbef examination before pyrethroid application T1; t 0 pest control operation (PCO) no examination; t 24 hours 1. examination after PCO T2; t 72 hours 2. examination after PCO T3; t 4 ± 6 months 3. examination after PCO T4; t 10 ± 12 months 4. examination after PCO T5.
88
G. Leng et al.
21 women with a mean age of 37.8 years) participated in the study. The study group consisted of participants exposed at their private home (n 33) and at their working place (e.g. bakery, restaurant) (n 28). The subjects were informed about the aim of the study and they had to give their consent in participating. Indoor PCO (spot-spraying) was done by professional pest control operators because of cockcroach infestation. Forty subjects were exposed to cyfluthrin (Solfac EW 50¾), 9 to permethrin (KO-Konzentrat 0.4%¾), 7 to cypermethrin (Microcip¾) and 5 to deltamethrin (Detmol-delta¾). The duration of action of the products is about 4 hours. During this time the participants were not allowed to be present in the rooms. Thereafter, the rooms were ventilated (windows were opened or the air conditioning was switched on) for 4 hours. Thus, the participants entered the rooms about 8 hours after the PCO.
Biological monitoring Biological monitoring was performed at each of the following 5 investigation days (Figure 2): a few days before the PCO (T1, n 57) as well as 1 day (T2, n 56), 3 days (T3, n 57), 4 ± 6 months (T4, n 56) and 10 ± 12 months (T5, n 31) after the PCO. The pyrethroids cyfluthrin, cypermethrin, deltamethrin and permethrin were determined in blood plasma by GC-ECD with a detection limit of 5 mg/l (K¸hn, 1997). Moreover, the pyrethroid-specific metabolites cis-3-(2,2-dichlorovinyl)2,2-dimethylcyclopropane carboxylic acid (cis-DCCA), trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA), cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropane carboxylic acid (cis-DBCA), 3phenoxybenzoic acid (3-PBA) and fluorophenoxybenzoic acid (FPBA) were determined in the urine of each subject by GC/MS (K¸hn et al., 1996). The metabolite FPBA is specific for cyfluthrin and DBCA for deltamethrin exposure. The metabolite 3-PBA occurs after permethrin, cypermethrin and deltamethrin exposure and cis- as well as trans-DCCA after permethrin, cypermethrin and cyfluthrin exposure (Figure 1). Urine samples (spontaneous as well as 24 hour urine samples) were collected in polyethylene tubes and stored deep frozen ( 21 8C) until analysis. The urine samples were subject to an acid-induced hydrolysis, followed by liquid-liquid extraction and methylation. EI-mass spectra were recorded using a Finnigan ITD 800 ion trap detector equipped with a Perkin Elmer autosystem gas chromatograph with a temperature-programmable split/splitless injector. The methylated derivatives were separated diastereoselectively on an apolar DB 5 ms fused silica capillary column (30 m 0.25 mm i.d., 0.1 mm film). The injection volume was 5 ml with helium as a carrier gas. Electron impact was at 70 eV. Quantification was achieved by internal calibration using 2-PBA as internal standard. The limit of detection of all metabolites was 0.2 mg/l (K¸hn et al, 1996; Leng et al., 1997a, b). In this study the ratio trans-DCCA: cis-DCCA was calculated to investigate whether the major way of uptake was dermal (ratio 1) or inhalative/oral (ratio > 1) after a
PCO (Eadsforth et al., 1988; Woollen et al., 1992, Leng et al., 1997a). Statistical analysis of the biological monitoring data Nonparametric statistical methods were used because the results were not normally distributed and the proportion of data below the detection limit (DL) was high. Univariate distribution was best characterized by percentiles, bivariate and multivariate analyses were performed using the Wilcoxon signed rank test and Friedman test, respectively. Concentrations below DL were considered with 1/2 DL (0.1 mg/l). For all calculations, the SAS software package version 6.12 under Windows NT and Open VMS was used (SAS, 1989). The level of significance was set at p < 0.05. The study protocol was approved by the ethical committee of the Heinrich-Heine-University of D¸sseldorf.
Results In all cases the concentrations of cyfluthrin, cypermethrin, deltamethrin and permethrin in plasma were below the detection limit of 5 mg/l. In Table 1 the median, 75th and 95th percentiles as well as the maximum values of each metabolite for T1 to T5 are presented considering values below and above DL. The median of the tested metabolites was 0.1 mg/l before PCO (T1) and at each time after PCO (T2 ± T5). This holds also true for the 75th percentile with the exception of trans-DCCA at T2 (0.2 mg/l) and 3-PBA (T2: 0.15 mg/l; T3: 0.2 mg/l). Regarding the 95th percentiles, values from 0.1 up to 1.8 mg/l were obtained. The highest maximum values were found for cis-DCCA (12.8 mg/l), for trans-DCCA (13.4 mg/l), and for 3-PBA (11.5 mg/l) at T2. Moreover the number of samples with concentrations 0.2 mg/l urine (detection limit) for T1 to T5 is presented in Table 1. Before PCO (T1) the majority of samples revealed metabolite concentrations below the DL of 0.2 mg/l, which was true for all samples regarding DBCA and FPBA. Concentrations above the DL were in the range of 0.2 and 1.5 mg/l. As compared with T1, one day after PCO (T2) the number of cases with detectable concentrations increased from 4 to 12 for cis-DCCA, from 2 to 18 for trans-DCCA and from 3 to 14 for 3-PBA. For FPBA a small increase from 0 to 2 was observed, whereas cis-DBCA remained undetectable. With respect to cis-DCCA, trans-DCCA and 3PBA the number of cases with concentrations above DL decreased during the time course from T3 to T5. This holds also true for FPBA, but with a much lower number of cases above DL. For cis-DBCA concen-
Pyrethroid exposure and biological monitoring
89
Table 1. Pyrethroid metabolite concentrations (mg/l urine) as well as number of samples detection limit before and after pest control operation (PCO) applying a pyrethroid containing product. For the calculation, values below the detection limit of 0.2 mg/l were considered to be 1/2 DL (0.1 mg/l). Time of Measurement metabolite concentration (mg/l urine)
T1 n 57 median 75th percentile 95th percentile maximum samples DL
T2 n 56 median 75th percentile 95th percentile maximum samples DL
T3 n 57 median 75th percentile 95th percentile maximum samples DL
T4 n 56 median 75th percentile 95th percentile maximum samples DL
T5 n 31 median 75th percentile 95th percentile maximum samples DL
Cis-DCCA
0.1 0.1 0.5 1.2 4
0.1 0.1 0.2 12.8 12
0.1 0.1 0.2 5.2 9
0.1 0.1 0.6 1.0 7
0.1 0.1 0.1 0.7 1
Trans-DCCA
0.1 0.1 0.1 1.2 2
0.1 0.2 0.5 13.4 18
0.1 0.1 0.4 5.0 13
0.1 0.1 1.5 3.2 6
0.1 0.1 1.3 2.1 4
DBCA
0.1 0.1 0.1 0.1 0
0.1 0.1 0.1 0.1 0
0.1 0.1 0.1 1.4 1
0.1 0.1 0.1 0.4 1
0.1 0.1 0.3 0.5 2
3-PBA
0.1 0.1 0.2 0.8 3
0.1 0.15 0.6 11.5 14
0.1 0.2 0.9 4.0 16
0.1 0.1 1.0 2.4 8
0.1 0.1 1.8 2.4 4
FPBA
0.1 0.1 0.1 0.1 0
0.1 0.1 0.1 0.2 2
0.1 0.1 0.2 0.3 3
0.1 0.1 0.1 0.2 1
0.1 0.1 0.1 0.1 0
DL: detection limit, 0.2 mg/l urine T1: before PCO; T2: 1 day after the PCO; T3: 3 days after the PCO T4: 4 ± 6 months after the PCO; T5: 10 ± 12 months after the PCO
Table 2. Comparison of pyrethroid metabolite concentrations before and after pest control operation (PCO) by means of the Wilcoxon signed rank test and Friedman test. p-values are given. Pyrethroid metabolite
T1 ± T2 ( Wilcoxon signed rank test, n 47)
T1 ± T3 ( Wilcoxon signed rank test, n 47)
T1 ± T4 ( Wilcoxon signed rank test, n 47)
T1 ± T2 ± T3 ± T4 ( Friedman test, n 47)
Cis-DCCA Trans-DCCA DBCA 3-PBA FPBA
0.037 0.002 n.c. 0.026 0.500
0.031 0.001 1.0 0.003 0.250
0.359 0.297 1.0 0.088 1.0
0.057 0.001 0.572 0.006 0.158
n.c.: non calculable T1: before PCO T2: 1 day after the PCO T3: 3 days after the PCO T4: 4 ± 6 months after the PCO T5 was not considered because of the low number of samples
90
G. Leng et al.
trations between 0.2 and 0.6 mg/l were found at T3 (n 1), T4 (n 1) and T5 (n 2). In a few cases higher metabolite concentrations were observed. Two samples obtained from the same person showed the highest concentrations (> 3 mg/l) of cis-DCCA, trans-DCCA and 3-PBA at T2 and T3, respectively. Higher concentrations (> 1 mg/l) were also found for trans-DCCA and 3-PBA for 2 to 3 other samples of different persons at T4 and T5. According to time course comparison as tested by the Friedman test and the Wilcoxon signed rank test significant alterations were found (Table 2). This was due to cis-DCCA, trans-DCCA and 3-PBA at T2 and T3 revealing increased metabolite concentrations in urine as compared to T1. The isomeric trans/cis-DCCA ratio for subjects with DCCA concentrations above DL was calculated to get information about the pyrethroid uptake routes. A ratio of 1 is attributed to a mainly dermal uptake and a ratio > 1 to a mainly inhalative/oral uptake. For five subjects a predominantly dermal and for 13 subjects a predominantly inhalative/oral uptake can be ascribed. The route of uptake remained unchanged for the same persons during the study.
Discussion Assessment of internal body burden reflects exposure and uptake of substances, which can be related to adverse health effects. Exposure to high pyrethroid doses, as seen in cases of acute intoxication leads to detectable pyrethroid concentrations in blood during the first hour after exposure rapidly decreasing within 24 hours (Leng and Lewalter, 1999). In a previous study, pyrethroid plasma levels of 30 pest control operators were all below the detection limit of 5 mg/l between 4 and 12 hours after exposure (Leng et al. 1997b). On the other hand, for most of the pest control operators metabolites in urine were detectable. As shown in the present study, an appropriately performed PCO did not lead to detectable concentrations of pyrethroids in blood of exposed persons (DL < 5 mg/l). By measuring pyrethroids in house dust and airborne particulate matter it could be demonstrated that in all cases pyrethroids were really applied. The pyrethroid metabolites cis-DCCA, transDCCA and 3-PBA were detectable in a low percentage before PCO. After PCO the percentage of detectable concentrations increased remarkably for these metabolites. The cyfluthrin-specific metabolite
FPBA as well as the deltamethrin-specific metabolite cis-DBCA were not detectable before PCO and only in a few cases after PCO. FPBA is considered to be a suitable indicator of a known cyfluthrin exposure (Leng and Lewalter, 1999; Leng et al., 1997a, b). Interestingly, it was found in this study that FPBA seems to be a poor indicator, although 40 persons were exclusively exposed to cyfluthrin. In contrast, even if not attributable to one specific pyrethroid, cis-DCCA, trans-DCCA and 3-PBA are more appropriate for the evaluation of the internal dose. It could be shown, that these metabolites increased significantly one and 3 days after the PCO. In this context it is noteworthy, that 3-PBA is not a metabolite of cyfluthrin. In one case of PCO with cyfluthrin extremely high concentrations of 3-PBA at T2 and T3 in connection with high concentrations of cisDCCA and trans-DCCA were observed. In a few cases higher concentrations of trans-DCCA and 3PBA between 1.5 and 3.0 mg/l were also found at T4 and/or T5 for the first time. The high concentrations of 3-PBA found directly after PCO with cyfluthrin and the high concentrations of metabolites after half a year or later may not result from the PCO and may be attributed to additional exposure by pyrethroids from other sources. With respect to the background levels of pyrethroid metabolites in the general population several studies exist describing the 95th percentiles to be used as reference values. In a collective of 254 persons the 95th percentile for total DCCA was 0.5 mg/l and for 3-PBA 0.6 mg (Butte et al., 1998). Based on a collective of 45 persons the 95th percentiles were 0.6 mg/l for cis-DCCA, 0.9 mg/l for trans-DCCA and < DL for DBCA and FPBA (Hardt et al., 1999). In an urban population of 1,177 persons also including children the 95th percentiles were 0.5 mg/l for cisDCCA, 1.5 for trans-DCCA, 0.3 mg/l for DBCA and 0.3 mg/l for FPBA (Heudorf and Angerer, 2001). With respect to cis-DCCA before PCO the 95th percentile of 0.5 mg/l found in this study is similar to published values. In contrast, the 95th percentiles of trans-DCCA and 3-PBA concentrations are lower than the background levels reported by other authors. The 95th percentile of 0.9 mg/l described by Hardt et al. (1999) was assumed to have been caused by intake of pyrethroid residues from contaminated food. Regarding short periods after PCO (T2 and T3) the concentrations (95th percentile) of cis-DCCA, trans-DCCA and 3-PBA were still in the range of the background level of published values with the exception of 3-PBA at T3. Furthermore, these values were not higher than those found for 145 persons exposed in their homes by permethrin derived from
Pyrethroid exposure and biological monitoring
woolen carpets (Berger-Prei˚ et al., 2002). In contrast, in a former study by us investigating the metabolite concentrations in urine of pest control operators, in 64% of the cases metabolites were found in a concentration range of 0.5 ± 277 mg/l with the median being 35 mg/l (Wieseler, 1998). The existing background exposure of the general population seems to be mainly caused by the uptake of diet (Appel, personal communication; Hardt et al., 1999; Heudorf and Angerer, 2001). Therefore, variation of background levels may be a matter of life style and manner of nutrition. This can in part explain the lower metabolite concentrations before PCO which may be due to above mentioned factors in our study group. With respect to exposure by the PCO, internal doses were increased but did not exceed the general background level. For pyrethroids it is possible to distinguish between a dermal or inhalative/orale uptake by determining the ratio of the cis- and trans-DCCA isomers. A volunteer study with cyfluthrin showed that there is a typical metabolite elimination profile. After inhalation and oral uptake the concentration of trans-DCCA was twice as high as that of the cisisomer (Leng et al., 1997a). Woollen demonstrated that after dermal application of cypermethrin the trans/cis isomeric ratio was 1 and after oral uptake approximately 2 (Woollen et al., 1992; Woollen, 1993). In the present study the oral/inhalative uptake seems to play the major role showing an isomer ratio > 1 for 13 out of 18 subjects. However, for 5 persons a dermal uptake must be taken into consideration. Based on the results of the present study it can be concluded that an appropriately performed pest control operation leads to a significantly increased pyrethroid metabolite concentration in the early phase (1 and 3 days) after pyrethroid application as compared to the pre-exposure values. In general, evaluated metabolite concentrations did not exceed values of published background levels. Acknowledgement. This study was supported by BMBF and IVA (07 INR 30 A/B). The authors thank the consultants of the study Prof. Altenkirch (Berlin, FRG), Prof. Angerer (Erlangen, FRG), Prof. Jˆckel (Essen, FRG) Dr. Leist (Frankfurt, FRG), Dr. Lewalter (Leverkusen, FRG) and Dr. Miksche (Leverkusen, FRG) for the intensive discussion.
91
References Aldridge, W. N.: An assessment of the toxicological properties of pyrethroids and their neurotoxicity. Crit. Rev. Toxicol. 21, 89 ± 104 (1990). Altenkirch, H., Hoppmann, D., Brockmeier, B., Walter, G.: Neurological investigations in 23 cases of pyrethroid intoxication reported to the German Federal Health Office. Neurotoxicology 17, 645 ± 651 (1996). Berger-Prei˚, E., Levsen, K., Leng, G., Idel, H., Sugiri, D., Ranft, U.: Indoor pyrethroid exposure in homes with woollen textile floor coverings. Int. J. Hyg. Environ. Health 205, 459 ± 472 (2002). Butte, W., Walker, G., Heinzow, B.: Referenzwerte der Konzentration von Permethrin-Metaboliten im Urin. Umweltmed. Forsch. Prax. 3, 21 ± 26 (1998). Eadsforth, C. V., Bragt, P. C., van Sittert, N. J.: Human dose-excretion studies with pyrethroid insecticides cypermethrin and alphacypermethrin: relevance for biological monitoring. Xenobiotica 18, 603 ± 614 (1988). Hardt, J., Heudorf, U., Angerer, J.: Zur Frage der Belastung der Allgemeinbevˆlkerung durch Pyrethroide. Umwelt. Forsch. Prax. 4, 51 ± 55 (1999). He, F., Sun, S., Han, K., Wu, Y., Yao, P., Wang, S., Liu, L.: Effects of pyrethroid insecticides on subjects engaged in packaging pyrethroids. Br. J. Industr. Med. 45, 548 ± 551 (1988). He, F., Wang, S., Liu, L., Chen, S., Zhang, Z., Sun, J.: Clinical manifestations of acute pyrethroid poisoning. Arch. Toxicol. 63, 54 ± 58 (1989). Heudorf, U., Angerer, J.: Metabolites of pyrethroid insecticides in urine specimens: current exposure in an urban population in Germany. Environ. Health Persp. 109, 213 ± 217 (2001) K¸hn, K.-H., Leng, G., Bucholski, K. A., Dunemann, L., Idel, H.: Determination of pyrethroid metabolites in human urine by capillary gas chromatography-mass spectrometry, Chromatographia 43, 285 ± 292 (1996) K¸hn, K.-H.: Bestimmung von Pyrethroiden und ihren Metaboliten in Blut und Urin mittels GC/MS und GCECD. Dissertationsarbeit, Shaker Verlag, Aachen, FRG (1997). Leng, G., Leng, A., K¸hn, K.-H., Lewalter, J., Pauluhn, J.: Human dose excretion studies with the pyrethroid insecticide cyfluthrin: urinary metabolite profile following inhalation. Xenobioatica 27, 1272 ± 1283 (1997a). Leng, G., K¸hn, K.-H., Idel, H.: Biological monitoring of pyrethroids in blood and pyrethroid metabolites in urine: applications and limitations. Sci. Total. Environ. 199, 173 ± 181 (1997b). Leng, G., Lewalter, J.: Dosis-Marker kontra Suszeptibili‰tsmarker in der Risiko-Bewertung des PestizidUmganges. Arbeitsmed. Sozialmed. Umweltmed. 34, 24 ± 29 (1999). Matsuo, M.: Toxicological study on pyrethroid insecticides for household use. Aerosol Age 1, 37 (1989).
92
G. Leng et al.
M¸ller-Mohnssen, H.: Insektizide: Wissenschaft ist als Fr¸hwarnsystem ausgeschaltet. Dt. ærzteblatt 88, 1966 ± 1971 (1991). M¸ller-Mohnssen, H., Hahn, K.: ‹ber eine Methode zur Fr¸herkennung neurotoxischer Erkrankungen (am Beispiel einer Pyrethroidexposition). Gesundheitswesen 57, 214 ± 222 (1995) Narahashi, T.: Nerve membrane Na channels as targets of insecticides. Trends. Pharmacol. Sci. 13, 236 ± 241 (1992). SAS/STAT User's Guide, Version 6, 4th ed., vol. 1 and 2, Cary, NC : SAS Institute Inc. (1989).
Wieseler, B., Leng, G., K¸hn, K.-H., Idel, H.: Effects of pyrethroid insecticides on pest control operators. Bull. Environ. Contam. Toxicol. 60, 837 ± 844 (1998). Woollen, B. H., Marsh, J. R., Laird, W. J. D., Lesser, J. E.: The metabolism of cypermethrin in man: differences in urinary metabolite profiles following oral and dermal administration. Xenobiotica 22, 983 ± 991 (1992). Woollen B. H.: Biological monitoring for pesticide absorption. Ann. Occup. Hyg. 37, No. 5, 525 ± 540 (1993).
International Journal of Hygiene and Environmental Health
Pyrethroids used indoors ± Biological monitoring of exposure to pyrethroids following an indoor pest control operation Gabriele Lenga, b , Ulrich Ranftc, Dorothee Sugiric, Wolfgang Hadnagya, Edith Berger-Prei˚d, Helga Idela a b c d
Institute of Hygiene, Heinrich-Heine-University, D¸sseldorf, Germany Bayer AG, Medical Department, Leverkusen, Germany Medical Institute of Environmental Hygiene, D¸sseldorf, Germany Fraunhofer Institute of Toxicology, Aerosol Research, Drug Research and Clinical Inhalation, Hannover, Germany
Received August 1, 2002 ¥ Revision received October 15, 2002 ¥ Accepted November 2, 2002
Abstract A prospective epidemiological study with respect to pyrethroid exposure was carried out combining clinical examination, indoor monitoring and biological monitoring. The results of the biological monitoring are presented. Biological monitoring was performed in 57 persons before (T1) as well as 1 day (T2), 3 days (T3), 4 ± 6 months (T4), and 10 ± 12 months (T5) following a pest control operation (PCO) with pyrethroid containing products such as cyfluthrin, cypermethrin, deltamethrin or permethrin. Pyrethroids in blood were measured by GC-ECD. The respective metabolites cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (DCCA), cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane carboxylic acid (DBCA), 3-phenoxybenzoic acid (3-PBA) and fluorophenoxybenzoic acid (FPBA) were measured in urine using GC/MS. For all cases the concentrations of pyrethroids in blood were found to be below the detection limit of 5 mg/l before and after the PCO. With a detection limit of 0.2 mg/l of the investigated metabolites, the percentage of positive samples were 7% for cis-DCCA, 3.5% for trans-DCCA and 5.3% for 3-PBA before PCO. One day after PCO (T2) the percentage of positive samples increased remarkably for cisDCCA (21.5%), trans-DCCA (32.1%) and 3-PBA (25%) showing significantly increased internal doses as compared to pre-existing values. This holds also true for T3, whereas at T4 and T5 the significant increase was no more present. FPBA and DBCA concentrations were below the respective detection limit before PCO and also in most cases after PCO. In 72% of the subjects the route of pyrethroid uptake (measured by determining the DCCA isomeric ratio) was oral/inhalative and in 28% it was dermal. Based on the biological monitoring data it could be shown that appropriately performed pest control operations lead to a significant increase of pyrethroid metabolite concentration in the early phase (1 and 3 days) after pyrethroid application as compared to the pre-exposure values. However, evaluated metabolite concentrations 4 ± 6 months after PCO did not exceed values of published background levels. Key words: Biological monitoring ± pyrethroids ± indoor pest control operations ± prospective study
Corresponding author: PD Dr. Gabriele Leng, Medical Department, Bayer AG, D-51368 Leverkusen. Phone: 49 214 30 65679, Fax: 49 214 30 21307, E-mail: [email protected]
1438-4639/03/206/02-085 $ 15.00/0
86
G. Leng et al.
Introduction Synthetic pyrethroids like cyfluthrin, cypermethrin, deltamethrin and permethrin belong to the most frequently used insecticides. Pyrethroids are used in plant and storage protection, wood preservation, impregnation of wool carpets and textiles, disinfection and pest control. Exposure to pyrethroids does not only concern workers in the chemical industry (production, filling, formulation), farmers, and pest control operators, but also the general population. They may be exposed by food contaminated with pyrethroid residues or by indoor pyrethroids resulting from self-spraying of pyrethroids against mosquitoes, from pyrethroid treated textile floor coverings or by pest control operations. The insecticidal effect of pyrethroids is based on their neurotoxic potential, which is determined by a prolonged opening of the sodium channel (Aldridge, 1990; Narahashi, 1992). In insects and in mammalians (only at nearly lethal dosage) this effect evokes repetitive nerve actions associated with hyperactivity, tremor, ataxia, convulsions and possible paralysis (Aldridge, 1990; Narahashi, 1992). Compared with other insecticides such as organophosphates,
Fig. 1.
Pyrethroids and their corresponding metabolites.
the mammalian toxicity of pyrethroids is low (Matsuo, 1989). In man, a variety of reversible symptoms such as paraesthesia, irritations of the skin and mucosa, headache, dizziness, and nausea are reported following high occupational pyrethroid exposure (He et al., 1988, 1989). In most cases symptoms occur immediately after exposure ± only in a few cases after 30 min up to 8 hours (He et al., 1988). The duration of symptoms varies between 30 minutes and 32 hours depending on the pyrethroid. With regard to health aspects of the general population no clear pyrethroid-related effects are obvious. It is claimed, that there are thousands of pyrethroid intoxications (people with irreversible symptoms) in Germany each year (M¸ller-Mohnssen, 1991, 1995). However, a causal relation between pyrethroid exposure and symptoms is doubtful, since the only diagnostic tool used were questionnaires and pyrethroid exposure, in most cases dated back to many years ago. In a retrospective study it is described that 6 out of 23 persons showed health effects with a possible relation to pyrethroid exposure (Altenkirch et al., 1996).
Pyrethroid exposure and biological monitoring
An objective evaluation of possible human health effects caused by pyrethroids can be obtained using a prospective epidemiological approach including indoor and biological monitoring combined with an assessment of the individual health status. This design was used in the present study investigating persons before and several times after professional indoor pest control operations (PCO) using a pyrethroid-containing product. Human effect monitoring was performed to evaluate the individual health status. As a part of the prospective study the present paper focuses on the biological monitoring data. The main goal was to investigate to which extent an appropriately performed professional pest control operation with a pyrethroid-containing product leads to an increase of the internal pyrethroid dose of the exposed subjects. For detecting an internal pyrethroid dose, the concentrations of pyrethroids in blood can be referred to (K¸hn, 1997). However, pyrethroids are metabolized very fast and can be determined in plasma only a few hours after exposure (Leng et al., 1997b). The metabolites are renally eliminated with a half-life time of about 6 hours (Eadsforth et al., 1988; Woollen et al., 1992). For example, after cyfluthrin exposure 93% of the metabolites are eliminated during the first 24 hours (Leng et al., 1997a). It was of further interest to investigate the route of uptake of pyrethroids after a pest control operation. Toxicokinetic studies showed that the dermal route plays a minor role (Eadsforth et al., 1988) and that the inhalation or oral uptake is the main source of absorption. For pyrethroids it is possible to distinguish between an oral/inhalative and a dermal uptake by determining the isomeric ratio of the metabolite DCCA.
87
Material and methods Study design The present study was carried out from 1996 to 1999 and included five medical examinations (Figure 2) performed at the locality of the pest control operation (PCO). The first examination was performed before PCO (T1), the other four examinations one day (T2), 3 days (T3), 4 to 6 months (T4) and 10 to 12 months (T5) after the PCO. Each examination consisted of a general medical and a neurophysiological examination accompanied by a questionnaire-based interview. In addition, blood and urine was sampled for determination of general clinical and immunological parameters as well as for performing biological monitoring. With respect to indoor monitoring, house dust and airborne particulate matter was sampled before PCO and one day, 4 to 6 months as well as 10 to 12 months after the PCO to be analyzed at the Fraunhofer Institute of Toxicology and Aerosol Research in Hannover, Germany (Berger-Prei˚ et al., 2002). The aim of the study was to recruit 90 persons to be exposed to pyrethroids in the near future by a pest control operation and living close to D¸sseldorf. Therefore professional pest control operators were asked to inform us of planned PCOs using a pyrethroid-containing product to combat insects, e.g. cockcroaches. Most of the pest control operators denied using pyrethroids or refused to participate in the study. Reason for this was the controversial public discussion about pyrethroid induced diseases and several legal actions against pest control operators. For this reason the recruitment of persons was expanded throughout Germany. This was done via news papers, radio campaigns, lectures at pest control operator meetings and personal contacts. Based on these difficulties, recruitment of persons reached a distance of up to 400 km remote from D¸sseldorf. Furthermore, persons with diabetes mellitus, renal deficiency, auto immune diseases, neurological or psychiatric disorders were excluded from the study as well as subjects where alcoholism or drug consumption was assumed. Another exclusion factor was a history of PCO during the last 6 months before the study. Subjects were also excluded when a second PCO with pyrethroids was performed during the study. Finally 61 volunteers (40 men and
Fig. 2. Study design ± time scheme. B biological monitoring (pyrethroids in blood and their metabolites in urine); I indoor monitoring (pyrethroids in house dust and airborne particulate matter); E effect monitoring (medical-, neurophysiological examination, questionnaires, immunological parameters); tbef examination before pyrethroid application T1; t 0 pest control operation (PCO) no examination; t 24 hours 1. examination after PCO T2; t 72 hours 2. examination after PCO T3; t 4 ± 6 months 3. examination after PCO T4; t 10 ± 12 months 4. examination after PCO T5.
88
G. Leng et al.
21 women with a mean age of 37.8 years) participated in the study. The study group consisted of participants exposed at their private home (n 33) and at their working place (e.g. bakery, restaurant) (n 28). The subjects were informed about the aim of the study and they had to give their consent in participating. Indoor PCO (spot-spraying) was done by professional pest control operators because of cockcroach infestation. Forty subjects were exposed to cyfluthrin (Solfac EW 50¾), 9 to permethrin (KO-Konzentrat 0.4%¾), 7 to cypermethrin (Microcip¾) and 5 to deltamethrin (Detmol-delta¾). The duration of action of the products is about 4 hours. During this time the participants were not allowed to be present in the rooms. Thereafter, the rooms were ventilated (windows were opened or the air conditioning was switched on) for 4 hours. Thus, the participants entered the rooms about 8 hours after the PCO.
Biological monitoring Biological monitoring was performed at each of the following 5 investigation days (Figure 2): a few days before the PCO (T1, n 57) as well as 1 day (T2, n 56), 3 days (T3, n 57), 4 ± 6 months (T4, n 56) and 10 ± 12 months (T5, n 31) after the PCO. The pyrethroids cyfluthrin, cypermethrin, deltamethrin and permethrin were determined in blood plasma by GC-ECD with a detection limit of 5 mg/l (K¸hn, 1997). Moreover, the pyrethroid-specific metabolites cis-3-(2,2-dichlorovinyl)2,2-dimethylcyclopropane carboxylic acid (cis-DCCA), trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid (trans-DCCA), cis-3-(2,2-dibromovinyl)2,2-dimethylcyclopropane carboxylic acid (cis-DBCA), 3phenoxybenzoic acid (3-PBA) and fluorophenoxybenzoic acid (FPBA) were determined in the urine of each subject by GC/MS (K¸hn et al., 1996). The metabolite FPBA is specific for cyfluthrin and DBCA for deltamethrin exposure. The metabolite 3-PBA occurs after permethrin, cypermethrin and deltamethrin exposure and cis- as well as trans-DCCA after permethrin, cypermethrin and cyfluthrin exposure (Figure 1). Urine samples (spontaneous as well as 24 hour urine samples) were collected in polyethylene tubes and stored deep frozen ( 21 8C) until analysis. The urine samples were subject to an acid-induced hydrolysis, followed by liquid-liquid extraction and methylation. EI-mass spectra were recorded using a Finnigan ITD 800 ion trap detector equipped with a Perkin Elmer autosystem gas chromatograph with a temperature-programmable split/splitless injector. The methylated derivatives were separated diastereoselectively on an apolar DB 5 ms fused silica capillary column (30 m 0.25 mm i.d., 0.1 mm film). The injection volume was 5 ml with helium as a carrier gas. Electron impact was at 70 eV. Quantification was achieved by internal calibration using 2-PBA as internal standard. The limit of detection of all metabolites was 0.2 mg/l (K¸hn et al, 1996; Leng et al., 1997a, b). In this study the ratio trans-DCCA: cis-DCCA was calculated to investigate whether the major way of uptake was dermal (ratio 1) or inhalative/oral (ratio > 1) after a
PCO (Eadsforth et al., 1988; Woollen et al., 1992, Leng et al., 1997a). Statistical analysis of the biological monitoring data Nonparametric statistical methods were used because the results were not normally distributed and the proportion of data below the detection limit (DL) was high. Univariate distribution was best characterized by percentiles, bivariate and multivariate analyses were performed using the Wilcoxon signed rank test and Friedman test, respectively. Concentrations below DL were considered with 1/2 DL (0.1 mg/l). For all calculations, the SAS software package version 6.12 under Windows NT and Open VMS was used (SAS, 1989). The level of significance was set at p < 0.05. The study protocol was approved by the ethical committee of the Heinrich-Heine-University of D¸sseldorf.
Results In all cases the concentrations of cyfluthrin, cypermethrin, deltamethrin and permethrin in plasma were below the detection limit of 5 mg/l. In Table 1 the median, 75th and 95th percentiles as well as the maximum values of each metabolite for T1 to T5 are presented considering values below and above DL. The median of the tested metabolites was 0.1 mg/l before PCO (T1) and at each time after PCO (T2 ± T5). This holds also true for the 75th percentile with the exception of trans-DCCA at T2 (0.2 mg/l) and 3-PBA (T2: 0.15 mg/l; T3: 0.2 mg/l). Regarding the 95th percentiles, values from 0.1 up to 1.8 mg/l were obtained. The highest maximum values were found for cis-DCCA (12.8 mg/l), for trans-DCCA (13.4 mg/l), and for 3-PBA (11.5 mg/l) at T2. Moreover the number of samples with concentrations 0.2 mg/l urine (detection limit) for T1 to T5 is presented in Table 1. Before PCO (T1) the majority of samples revealed metabolite concentrations below the DL of 0.2 mg/l, which was true for all samples regarding DBCA and FPBA. Concentrations above the DL were in the range of 0.2 and 1.5 mg/l. As compared with T1, one day after PCO (T2) the number of cases with detectable concentrations increased from 4 to 12 for cis-DCCA, from 2 to 18 for trans-DCCA and from 3 to 14 for 3-PBA. For FPBA a small increase from 0 to 2 was observed, whereas cis-DBCA remained undetectable. With respect to cis-DCCA, trans-DCCA and 3PBA the number of cases with concentrations above DL decreased during the time course from T3 to T5. This holds also true for FPBA, but with a much lower number of cases above DL. For cis-DBCA concen-
Pyrethroid exposure and biological monitoring
89
Table 1. Pyrethroid metabolite concentrations (mg/l urine) as well as number of samples detection limit before and after pest control operation (PCO) applying a pyrethroid containing product. For the calculation, values below the detection limit of 0.2 mg/l were considered to be 1/2 DL (0.1 mg/l). Time of Measurement metabolite concentration (mg/l urine)
T1 n 57 median 75th percentile 95th percentile maximum samples DL
T2 n 56 median 75th percentile 95th percentile maximum samples DL
T3 n 57 median 75th percentile 95th percentile maximum samples DL
T4 n 56 median 75th percentile 95th percentile maximum samples DL
T5 n 31 median 75th percentile 95th percentile maximum samples DL
Cis-DCCA
0.1 0.1 0.5 1.2 4
0.1 0.1 0.2 12.8 12
0.1 0.1 0.2 5.2 9
0.1 0.1 0.6 1.0 7
0.1 0.1 0.1 0.7 1
Trans-DCCA
0.1 0.1 0.1 1.2 2
0.1 0.2 0.5 13.4 18
0.1 0.1 0.4 5.0 13
0.1 0.1 1.5 3.2 6
0.1 0.1 1.3 2.1 4
DBCA
0.1 0.1 0.1 0.1 0
0.1 0.1 0.1 0.1 0
0.1 0.1 0.1 1.4 1
0.1 0.1 0.1 0.4 1
0.1 0.1 0.3 0.5 2
3-PBA
0.1 0.1 0.2 0.8 3
0.1 0.15 0.6 11.5 14
0.1 0.2 0.9 4.0 16
0.1 0.1 1.0 2.4 8
0.1 0.1 1.8 2.4 4
FPBA
0.1 0.1 0.1 0.1 0
0.1 0.1 0.1 0.2 2
0.1 0.1 0.2 0.3 3
0.1 0.1 0.1 0.2 1
0.1 0.1 0.1 0.1 0
DL: detection limit, 0.2 mg/l urine T1: before PCO; T2: 1 day after the PCO; T3: 3 days after the PCO T4: 4 ± 6 months after the PCO; T5: 10 ± 12 months after the PCO
Table 2. Comparison of pyrethroid metabolite concentrations before and after pest control operation (PCO) by means of the Wilcoxon signed rank test and Friedman test. p-values are given. Pyrethroid metabolite
T1 ± T2 ( Wilcoxon signed rank test, n 47)
T1 ± T3 ( Wilcoxon signed rank test, n 47)
T1 ± T4 ( Wilcoxon signed rank test, n 47)
T1 ± T2 ± T3 ± T4 ( Friedman test, n 47)
Cis-DCCA Trans-DCCA DBCA 3-PBA FPBA
0.037 0.002 n.c. 0.026 0.500
0.031 0.001 1.0 0.003 0.250
0.359 0.297 1.0 0.088 1.0
0.057 0.001 0.572 0.006 0.158
n.c.: non calculable T1: before PCO T2: 1 day after the PCO T3: 3 days after the PCO T4: 4 ± 6 months after the PCO T5 was not considered because of the low number of samples
90
G. Leng et al.
trations between 0.2 and 0.6 mg/l were found at T3 (n 1), T4 (n 1) and T5 (n 2). In a few cases higher metabolite concentrations were observed. Two samples obtained from the same person showed the highest concentrations (> 3 mg/l) of cis-DCCA, trans-DCCA and 3-PBA at T2 and T3, respectively. Higher concentrations (> 1 mg/l) were also found for trans-DCCA and 3-PBA for 2 to 3 other samples of different persons at T4 and T5. According to time course comparison as tested by the Friedman test and the Wilcoxon signed rank test significant alterations were found (Table 2). This was due to cis-DCCA, trans-DCCA and 3-PBA at T2 and T3 revealing increased metabolite concentrations in urine as compared to T1. The isomeric trans/cis-DCCA ratio for subjects with DCCA concentrations above DL was calculated to get information about the pyrethroid uptake routes. A ratio of 1 is attributed to a mainly dermal uptake and a ratio > 1 to a mainly inhalative/oral uptake. For five subjects a predominantly dermal and for 13 subjects a predominantly inhalative/oral uptake can be ascribed. The route of uptake remained unchanged for the same persons during the study.
Discussion Assessment of internal body burden reflects exposure and uptake of substances, which can be related to adverse health effects. Exposure to high pyrethroid doses, as seen in cases of acute intoxication leads to detectable pyrethroid concentrations in blood during the first hour after exposure rapidly decreasing within 24 hours (Leng and Lewalter, 1999). In a previous study, pyrethroid plasma levels of 30 pest control operators were all below the detection limit of 5 mg/l between 4 and 12 hours after exposure (Leng et al. 1997b). On the other hand, for most of the pest control operators metabolites in urine were detectable. As shown in the present study, an appropriately performed PCO did not lead to detectable concentrations of pyrethroids in blood of exposed persons (DL < 5 mg/l). By measuring pyrethroids in house dust and airborne particulate matter it could be demonstrated that in all cases pyrethroids were really applied. The pyrethroid metabolites cis-DCCA, transDCCA and 3-PBA were detectable in a low percentage before PCO. After PCO the percentage of detectable concentrations increased remarkably for these metabolites. The cyfluthrin-specific metabolite
FPBA as well as the deltamethrin-specific metabolite cis-DBCA were not detectable before PCO and only in a few cases after PCO. FPBA is considered to be a suitable indicator of a known cyfluthrin exposure (Leng and Lewalter, 1999; Leng et al., 1997a, b). Interestingly, it was found in this study that FPBA seems to be a poor indicator, although 40 persons were exclusively exposed to cyfluthrin. In contrast, even if not attributable to one specific pyrethroid, cis-DCCA, trans-DCCA and 3-PBA are more appropriate for the evaluation of the internal dose. It could be shown, that these metabolites increased significantly one and 3 days after the PCO. In this context it is noteworthy, that 3-PBA is not a metabolite of cyfluthrin. In one case of PCO with cyfluthrin extremely high concentrations of 3-PBA at T2 and T3 in connection with high concentrations of cisDCCA and trans-DCCA were observed. In a few cases higher concentrations of trans-DCCA and 3PBA between 1.5 and 3.0 mg/l were also found at T4 and/or T5 for the first time. The high concentrations of 3-PBA found directly after PCO with cyfluthrin and the high concentrations of metabolites after half a year or later may not result from the PCO and may be attributed to additional exposure by pyrethroids from other sources. With respect to the background levels of pyrethroid metabolites in the general population several studies exist describing the 95th percentiles to be used as reference values. In a collective of 254 persons the 95th percentile for total DCCA was 0.5 mg/l and for 3-PBA 0.6 mg (Butte et al., 1998). Based on a collective of 45 persons the 95th percentiles were 0.6 mg/l for cis-DCCA, 0.9 mg/l for trans-DCCA and < DL for DBCA and FPBA (Hardt et al., 1999). In an urban population of 1,177 persons also including children the 95th percentiles were 0.5 mg/l for cisDCCA, 1.5 for trans-DCCA, 0.3 mg/l for DBCA and 0.3 mg/l for FPBA (Heudorf and Angerer, 2001). With respect to cis-DCCA before PCO the 95th percentile of 0.5 mg/l found in this study is similar to published values. In contrast, the 95th percentiles of trans-DCCA and 3-PBA concentrations are lower than the background levels reported by other authors. The 95th percentile of 0.9 mg/l described by Hardt et al. (1999) was assumed to have been caused by intake of pyrethroid residues from contaminated food. Regarding short periods after PCO (T2 and T3) the concentrations (95th percentile) of cis-DCCA, trans-DCCA and 3-PBA were still in the range of the background level of published values with the exception of 3-PBA at T3. Furthermore, these values were not higher than those found for 145 persons exposed in their homes by permethrin derived from
Pyrethroid exposure and biological monitoring
woolen carpets (Berger-Prei˚ et al., 2002). In contrast, in a former study by us investigating the metabolite concentrations in urine of pest control operators, in 64% of the cases metabolites were found in a concentration range of 0.5 ± 277 mg/l with the median being 35 mg/l (Wieseler, 1998). The existing background exposure of the general population seems to be mainly caused by the uptake of diet (Appel, personal communication; Hardt et al., 1999; Heudorf and Angerer, 2001). Therefore, variation of background levels may be a matter of life style and manner of nutrition. This can in part explain the lower metabolite concentrations before PCO which may be due to above mentioned factors in our study group. With respect to exposure by the PCO, internal doses were increased but did not exceed the general background level. For pyrethroids it is possible to distinguish between a dermal or inhalative/orale uptake by determining the ratio of the cis- and trans-DCCA isomers. A volunteer study with cyfluthrin showed that there is a typical metabolite elimination profile. After inhalation and oral uptake the concentration of trans-DCCA was twice as high as that of the cisisomer (Leng et al., 1997a). Woollen demonstrated that after dermal application of cypermethrin the trans/cis isomeric ratio was 1 and after oral uptake approximately 2 (Woollen et al., 1992; Woollen, 1993). In the present study the oral/inhalative uptake seems to play the major role showing an isomer ratio > 1 for 13 out of 18 subjects. However, for 5 persons a dermal uptake must be taken into consideration. Based on the results of the present study it can be concluded that an appropriately performed pest control operation leads to a significantly increased pyrethroid metabolite concentration in the early phase (1 and 3 days) after pyrethroid application as compared to the pre-exposure values. In general, evaluated metabolite concentrations did not exceed values of published background levels. Acknowledgement. This study was supported by BMBF and IVA (07 INR 30 A/B). The authors thank the consultants of the study Prof. Altenkirch (Berlin, FRG), Prof. Angerer (Erlangen, FRG), Prof. Jˆckel (Essen, FRG) Dr. Leist (Frankfurt, FRG), Dr. Lewalter (Leverkusen, FRG) and Dr. Miksche (Leverkusen, FRG) for the intensive discussion.
91
References Aldridge, W. N.: An assessment of the toxicological properties of pyrethroids and their neurotoxicity. Crit. Rev. Toxicol. 21, 89 ± 104 (1990). Altenkirch, H., Hoppmann, D., Brockmeier, B., Walter, G.: Neurological investigations in 23 cases of pyrethroid intoxication reported to the German Federal Health Office. Neurotoxicology 17, 645 ± 651 (1996). Berger-Prei˚, E., Levsen, K., Leng, G., Idel, H., Sugiri, D., Ranft, U.: Indoor pyrethroid exposure in homes with woollen textile floor coverings. Int. J. Hyg. Environ. Health 205, 459 ± 472 (2002). Butte, W., Walker, G., Heinzow, B.: Referenzwerte der Konzentration von Permethrin-Metaboliten im Urin. Umweltmed. Forsch. Prax. 3, 21 ± 26 (1998). Eadsforth, C. V., Bragt, P. C., van Sittert, N. J.: Human dose-excretion studies with pyrethroid insecticides cypermethrin and alphacypermethrin: relevance for biological monitoring. Xenobiotica 18, 603 ± 614 (1988). Hardt, J., Heudorf, U., Angerer, J.: Zur Frage der Belastung der Allgemeinbevˆlkerung durch Pyrethroide. Umwelt. Forsch. Prax. 4, 51 ± 55 (1999). He, F., Sun, S., Han, K., Wu, Y., Yao, P., Wang, S., Liu, L.: Effects of pyrethroid insecticides on subjects engaged in packaging pyrethroids. Br. J. Industr. Med. 45, 548 ± 551 (1988). He, F., Wang, S., Liu, L., Chen, S., Zhang, Z., Sun, J.: Clinical manifestations of acute pyrethroid poisoning. Arch. Toxicol. 63, 54 ± 58 (1989). Heudorf, U., Angerer, J.: Metabolites of pyrethroid insecticides in urine specimens: current exposure in an urban population in Germany. Environ. Health Persp. 109, 213 ± 217 (2001) K¸hn, K.-H., Leng, G., Bucholski, K. A., Dunemann, L., Idel, H.: Determination of pyrethroid metabolites in human urine by capillary gas chromatography-mass spectrometry, Chromatographia 43, 285 ± 292 (1996) K¸hn, K.-H.: Bestimmung von Pyrethroiden und ihren Metaboliten in Blut und Urin mittels GC/MS und GCECD. Dissertationsarbeit, Shaker Verlag, Aachen, FRG (1997). Leng, G., Leng, A., K¸hn, K.-H., Lewalter, J., Pauluhn, J.: Human dose excretion studies with the pyrethroid insecticide cyfluthrin: urinary metabolite profile following inhalation. Xenobioatica 27, 1272 ± 1283 (1997a). Leng, G., K¸hn, K.-H., Idel, H.: Biological monitoring of pyrethroids in blood and pyrethroid metabolites in urine: applications and limitations. Sci. Total. Environ. 199, 173 ± 181 (1997b). Leng, G., Lewalter, J.: Dosis-Marker kontra Suszeptibili‰tsmarker in der Risiko-Bewertung des PestizidUmganges. Arbeitsmed. Sozialmed. Umweltmed. 34, 24 ± 29 (1999). Matsuo, M.: Toxicological study on pyrethroid insecticides for household use. Aerosol Age 1, 37 (1989).
92
G. Leng et al.
M¸ller-Mohnssen, H.: Insektizide: Wissenschaft ist als Fr¸hwarnsystem ausgeschaltet. Dt. ærzteblatt 88, 1966 ± 1971 (1991). M¸ller-Mohnssen, H., Hahn, K.: ‹ber eine Methode zur Fr¸herkennung neurotoxischer Erkrankungen (am Beispiel einer Pyrethroidexposition). Gesundheitswesen 57, 214 ± 222 (1995) Narahashi, T.: Nerve membrane Na channels as targets of insecticides. Trends. Pharmacol. Sci. 13, 236 ± 241 (1992). SAS/STAT User's Guide, Version 6, 4th ed., vol. 1 and 2, Cary, NC : SAS Institute Inc. (1989).
Wieseler, B., Leng, G., K¸hn, K.-H., Idel, H.: Effects of pyrethroid insecticides on pest control operators. Bull. Environ. Contam. Toxicol. 60, 837 ± 844 (1998). Woollen, B. H., Marsh, J. R., Laird, W. J. D., Lesser, J. E.: The metabolism of cypermethrin in man: differences in urinary metabolite profiles following oral and dermal administration. Xenobiotica 22, 983 ± 991 (1992). Woollen B. H.: Biological monitoring for pesticide absorption. Ann. Occup. Hyg. 37, No. 5, 525 ± 540 (1993).