Effects of fenvalerate exposure on semen quality among occupational workers

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1 Contraception 73 (2006) Original research article Effects of fenvalerate exposure on semen quality among occupational workers Tan Lifeng a, T, Wang Shoulin c, Ji Junmin a, Sun Xuezhao a, Li Yannan a, Wang Qianli a, Chen Longsheng b a Center for Disease Control of Changzhou, Jiangsu , People s Republic of China b Changzhou Hygienic Bureau, Jiangsu , People s Republic of China c School of Public Health, Nanjing Medical University, Jiangsu , People s Republic of China Received 31 January 2005; revised 6 June 2005; accepted 22 June 2005 Abstract Purpose: The purpose of the study was to observe the effects of fenvalerate exposure on the semen quality of occupational workers. Materials and Methods: Thirty-two male workers who were exposed to fenvalerate and 46 male administrators in the office in the same pesticide factory were selected as the exposure group and internal control group, respectively, and 22 male administrators in a center for disease control served as the external control group. In order to evaluate the exposure levels, the concentration of fenvalerate, toluene and xylene in the ambient air of the work place in these three groups were monitored simultaneously for 3 consecutive days. Moreover, the amount of fenvalerate in individual sampling and dermal contamination were evaluated in the exposure group and external control group. After the semen was collected according to the standard method, the workers semen qualities were analyzed. Results: Concentration of fenvalerate in the exposure areas was mg/m 3. The fenvalerate concentration in individual samplings in the exposure areas was 0.11 mg/m 3. The dermal contamination for workers in the fenvalerate exposure area was 0.05 mg/m 3. Fenvalerate was not detected in individual samplings collected in external areas. Sperm motion parameters through routine semen analysis in the exposure group were decreased significantly, and the abnormality rate of viscidity and coagulation was increased significantly as compared with the internal and the external control groups ( p b.05 or p b.01). Furthermore, sperm progression and beat cross frequency (BCF) (4.20F1.68 Hz) in the exposure group were also significantly lower than those in the external control group by computer-assisted sperm motility analysis (CASA) ( p b.05). Conclusion: Occupational exposure to fenvalerate could affect the semen quality of the workers, but the conclusion warrants further complete investigation due to various limitations of the study. D 2006 Elsevier Inc. All rights reserved. Keywords: Fenvalerate; Occupational exposure; Semen quality; Sperm morphology; Computer-assisted sperm analysis 1. Introduction China is one of the largest agricultural countries. With increased production and application of pesticide, public health issues related to pesticide have received more and more attention. Fenvalerate, a member of synthetic pyrethroids, type II, is widely used in agricultural and indoor pest control in China due to its high insecticidal activity and low hazard potential to humans. In past decades, the neurotoxic effects induced by fenvalerate have been well studied. T Corresponding author. Tel.: ; fax: address: cztanlifen@163.com (T. Lifeng). However, some recent reports indicate that pyrethroids are linked to endocrine disruption, subsequently leading to reproductive dysfunction. Fenvalerate induced a significant decrease in testis weight, epididymal sperm counts, sperm motility and marker testicular enzymes for testosterone biosynthesis [1]. Also, oral administration of deltamethrine for 65 consecutive days decreased the conception rate in nontreated females (mated with treated male) [2]. Studies in our laboratory also found that fenvalerate could interrupt the steroid biosynthesis in male Sprague Dawley rats [3]. To our knowledge, only a few studies have been conducted on the reproductive effects of fenvalerate on human beings [4]. Therefore, in this study, we selected pesticide plant workers who were exposed to fenvalerate as the target population /$ see front matter D 2006 Elsevier Inc. All rights reserved. doi: /j.contraception

2 T. Lifeng et al. / Contraception 73 (2006) The reproductive toxicity induced by fenvalerate in male workers was evaluated through semen-quality analysis. 2. Materials and methods 2.1. Study population The pesticide factory, which is located in a suburb of a city in southeast China, has been in operation since the 1970s. The factory is divided into two areas: production area and office area. A total of 100 male participants, ages between 21 and 42 years, were selected for the study and donated semen samples. Thirty-two of them were fenvalerate-exposed workers in the pesticide plant, and 46 men from the office area of the same factory served as the internal controls. Twenty-two men who were officers in a center for disease control (CDC) located in the urban district of the same city served as the external control group. The populations were similar with respect to length of service, smoking and drinking habits, which are associated with decreased semen quality. All subjects were asked to complete a face-to-face questionnaire including occupational history and lifestyle. The study was approved by the local ethics committee. Informed written consent was given by each participant. An institutional review board approval was obtained prior to the beginning of this study Investigation on labor hygiene Air sampling analysis In order to evaluate the exposure levels in the three groups, the workshop for fenvalerate manufacturing was selected as the exposure area and the office in the same factory as the internal control area. The office in a CDC was chosen as the external control area. Air samples were collected to detect air concentration of fenvalerate by using CD-1 air sampler (Beijing Detection Instrument Factory, Beijing, China) in these areas for 3 consecutive days. The concentrations of fenvalerate and related solvents, such as toluene and xylene, were measured by vapor phase chromatography (GD-14A, Shimadzu, Japan) Individual sampling and dermal contamination assessment Three participants in the exposure group and external control group, respectively, were selected randomly for individual sampling by taking active personal samplers (Xinyu Analysis Instrument Factory, Jiangsu, China) and for dermal contamination measurements. The individual samples were collected for 3 consecutive days (n = 9). The individual dermal contamination was measured by attaching fibrous filter membranes to 10 body areas. Total dermal contamination ¼ Mean dermal contamination Body area 84:1% Mean dermal contamination ¼Dermal collected quantity =336:4 cm 2 ðcollected areaþ 2.3. Semen analysis Sperm collection and routine semen analysis All semen samples were obtained by masturbation into a sterile wide-mouth and metal-free plastic container after 3 days of recommended sexual abstinence. In addition, every participant completed a form about sperm collection information. After liquefaction at 378C for 30 min and within 1 h of production, routine semen analysis according to the WHO method [5] was performed to assess parameters of sperm quality including liquefaction time, ph value, viscidity, sperm volume, sperm motility, percent motile sperm, sperm density, sperm count per ejaculum by A-cell slide Sperm morphology Semen smears were prepared according to a standardized method. Then, they were stained with 2% Giemsa for 30 min. A single technician assessed sperm morphology using the strict morphology method recommended by WHO [4], in which only sperm with absolutely no defects is classified as normal Assessment of sperm motility by CASA Sperm motility was analyzed using HST computerassisted sperm motility analysis (CASA) system (Hobson Tracking Systems, Sheffield, England) operating with HST-7 V1B software. The following sperm motility parameters were determined: curvilinear velocity (VCL, Am/s), average path velocity (VAP, Am/s), straight line velocity (VSL, Am/s), beat cross frequency (BCF, Hz), straightness (STR, %) and linearity (LIN, %) Quality control Strict quality control measures were enforced throughout the entire study. Each sample was assessed twice in parallel. For instance, sperm concentration was determined twice and the difference (D) between the two results was calculated according to the formula: [D (%)=(max min)/min100%]. If D V15%, use the mean value of two results to express the final value; if D N15%, test the sample a third time and use the median value of three results as the final value. Semen samples with known sperm parameters were used on a regular basis for quality assessment Statistical analysis The data are expressed as meanfsd. The data were analyzed using one-way ANOVA with post hoc analysis. All the statistical analyses were performed with SPSS for Windows (version 10.0). The significance level was set at Results 3.1. Exposure measurement As shown in Table 1, the concentrations of fenvalerate in the ambient air in the exposure areas were markedly higher than those in the internal control and external control areas.

3 94 T. Lifeng et al. / Contraception 73 (2006) Table 1 Concentrations of fenvalerate, toluene and xylene in the ambient air of the work place (mg/m 3 ) Area n Fenvalerate (10 4 ) Toluene Xylene Geometric mean Range Geometric mean Range Geometric mean Range Exposure T, TT Internal control External control T p b.01 compared with external control. TT pb.01 compared with internal control. Table 2 Comparison of semen parameters among the three groups Group n Volume ph a Motility Progression Concentration (10 6 /ml) Sperm count (10 6 ) (ml) a (%) a (grade) a Geometric mean Range Geometric mean Exposure F F F F0.52T T, TT Internal control F F F F0.64T External control F F F F a Values are expressed as meanfsd. T p b.05 compared with external control. Range Table 3 Abnormality rate of semen parameters in each group Group n Liquefying time Volume ph Viscidity Motility Progression Coagulation Concentration Sperm count n % n % n % n % n % n % n % n % n % Exposure T, TT TTT TT, TTT TT, TTT Internal control TTT External control T p b.01 compared with external control. TTT pb.05 compared with external control. Table 4 Abnormality rate of sperm morphology in each group (%) Group n Total abnormality Head abnormality Neck abnormality Tail abnormality Mixed abnormality Exposure Internal control External control Table 5 Comparison of sperm movement ability among the three groups (meanfsd) Group VCL (Am/s) VAP (Am/s) VSL (Am/s) BCF (Hz) LIN (%) STR (%) MOT (%) Exposure 71.23F F F F1.68T 40.33F7.06T, TT 72.43F9.89T, TT 23.75F15.25 Internal control 71.99F F F F F F F12.56 External control 72.31F F F F F F F9.03 MOT indicates motility. T p b.05 compared with external control.

4 T. Lifeng et al. / Contraception 73 (2006) No significant difference was found in related solvents, such as toluene and xylene, in the studied areas. These solvents may also act as reproductive toxicants. To further evaluate exposure quantity, we measured the individual cumulative exposure quantity in one shift. The ranges of fenvalerate concentration in individual samplings in the exposure areas were mg/m 3. The geometric mean was 0.11 mg/m 3. Fenvalerate was not detected in individual samplings collected in the external areas. Because fenvalerate can be absorbed not only through inhalation but also by dermal contact, we measured dermal contamination on the above workers. In the exposure group, the ranges of dermal contamination were mg/m 2, and the geometric mean was 0.05 mg/m Effects of fenvalerate on routine semen parameters Sperm progression and sperm count in the fenvalerateexposed group were significantly lower than those in the internal control and external control group (Table 2). The abnormality rates of viscidity, coagulation and sperm count in the exposure group were increased significantly as compared with the internal and external group (Table 3) Effects of fenvalerate on sperm morphology No significant difference was detected in sperm morphology in the present study (Table 4) Effects of fenvalerate on sperm motility As seen in Table 5, significant decreases in sperm motility parameters of LIN and STR in the exposure group were detected in comparison with those in the internal and external control group. No significant changes were found in the other parameters. 4. Discussion The question of a possible decline in semen quality has been widely studied. With increased awareness, there has been a parallel increased concern at all levels of society that exposure to environmental contaminants, especially environmental endocrine disrupters (EEDs), can have adverse effects on human fertility. Indeed, there is a perception that the prevalence of human infertility is increasing. Several kinds of pesticides, including pyrethroids, have been identified as EEDs. It has been reported that pyrethroids may impair male reproductive function [2]. However, most studies focused on the reproductive and endocrine effects through animal or cell culture experiments. Due to species differences, the results cannot be directly extrapolated to humans. It is essential to study the reproductive effects of pyrethroids on humans. The functional competence of sperm as well as the production of a sufficient number of sperm is an absolute requirement from the male side to ensure fertilization. Forward, progressive and sustained motility is an important function of sperm, and the evaluation of sperm motility should provide useful information for evaluating chemical effects on male fertility [6]. Routine semen analysis and sperm progression in the exposure group were significantly decreased. The abnormality rates of viscidity and coagulation were also markedly increased in the exposure group. As for sperm counts, although there was a significant difference between the exposure group and two control groups, we could not regard it as different under real circumstances. No distinction has been found among groups in the other two related parameters, sperm volume and sperm concentration. The reason may be due to higher standard derivation and the use of geometric means. Additional studies are needed to clarify such phenomenon. Previously, we found that fenvalerate induced sperm DNA damage in exposed workers using both Comet and TUNEL assays [7]. It is well known that DNA damages may result in cell death or induction of mutations. DNA damage due to apoptosis has been found to occur in testis during spermatogenesis, predominately at the spermatogonia and dividing cell level [8,9]. Therefore, sperm DNA damage could be one of the mechanisms for the changes in routine semen parameters. Sperm motility can indirectly reflect its fertilizability. There are correlations between fertility rate and motility parameters such as VSL, ALH, BCF, VCL, LIN and STR in in vitro fertilizing capacity of rat spermatozoa [10]. Moreover, Toth et al. [11] found that some reproductive toxicants could affect the motility of sperm at low-dose exposure, which did not result in changes in other reproductive measures, e.g., sperm morphology. Therefore, the measurement of sperm motility is a more sensitive method to study male reproductive toxicity. In the present study, CASA was used to measure the features of sperm motility. We found that LIN, STR and BCF in the exposure group were significantly decreased compared to those in the internal and external group. The morphology of seminal spermatozoa is the end result of a highly complex process of cellular modifications that occurs during spermatogenesis [12]. Sperm morphology examination is an important parameter to evaluate sperm function. However, no significant difference was detected in the studied population. We might speculate that the exposure level was not high enough to cause such lesion. In conclusion, fenvalerate had an adverse effect on male workers semen quality in the study. DNA damage may have been one of the mechanisms. Due to various limitations of the present study, e.g., the size of samples, the results warrant further investigation. Acknowledgments This project was supported by Jiangsu Science and Technology Office (No. BS ). The authors thank Mr. Wang Xinru for technical assistance.

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