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PubMed1998

Genotoxicity in workers exposed to methyl bromide.

To address the genotoxicity of in vivo methyl bromide (CAS 74-83-9) exposure in humans, we collected blood and oropharyngeal cells as part of a cross-sectional morbidity study of methyl bromide-exposed fumigation workers and their referents. Micronuclei were measured in lymphocytes and oropharyngeal cells, and hypoxanthine-guanine phosphoribosyl transferase gene (hprt) mutations were measured in lymphocytes. A total of 32 workers and 28 referents provided specimens. Among current non-smokers, mean hprt variant frequencies (Vfs) were found to be elevated among workers compared to referents (geometric mean: workers=4.49x10(-6), referents=2.96x10-(6); two-sided p=0.22); this difference was more pronounced among workers with 4 h or more of recent methyl bromide exposure compared to referents (geometric mean: workers=6.56x10(-6), referents=2.96x10(-6); two-sided p=0.06). Mean oropharyngeal cell micronuclei were higher among workers compared to referents (mean: workers=2.00, referents=1.31; two-sided p=0.08); the results were similar when workers with 4 h or more of recent methyl bromide exposure were compared to referents (mean: workers=2.07, referents=1.31; two-sided p=0.13). No consistent differences between workers and referents were observed for frequencies of kinetochore-negative lymphocyte micronuclei, or kinetochore-positive lymphocyte micronuclei. The study was limited by a sample size sufficient only for detecting relatively large differences, absence of a reliable method to measure the intensity of workplace methyl bromide exposures, and relatively infrequent methyl bromide exposure (e.g., the median length of exposure to methyl bromide during the 2 weeks preceding the survey was 4 h). In conclusion, our findings provide some evidence that methyl bromide exposure may be associated with genotoxic effects in lymphocytes and oropharyngeal cells. Further study on the genotoxicity of methyl bromide exposure in humans is warranted.

Adult↗
PubMed2006

Serum dioxin levels in former chlorophenol workers.

Using gas chromatography/mass spectrometry, we measured lipid-adjusted serum levels for all 2,3,7,8-substituted dioxins and furans, and four coplanar polychlorinated biphenyls in 62 workers with chlorophenol exposure and 36 workers without chlorophenol exposures working at the same plant during the same time. We oversampled among workers diagnosed with chloracne. Mean dioxin background levels from 36 nonchlorophenol workers were estimated as 6.0 parts-per-trillion (ppt) for 2,3,7,8 tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD) and 67.5 ppt for 1,2,3,4,6,7,8 heptachlorodibenzo-p-dioxin (Hepta-CDD). We found different dioxin and furan profiles for trichlorophenol and pentachlorophenol (PCP) workers. Among trichlorophenol workers with chloracne, we found 2,3,7,8-TCDD (mean=30.5 ppt) above background levels and among PCP workers with chloracne, we found high levels of Hepta-CDD (mean=312.5 ppt) and other higher chlorinated dioxins and furans. Cumulative exposure estimates for dioxins for both 2,3,7,8-TCDD and the higher chlorinated dioxins created in the early 1980s for our epidemiology studies were highly correlated with serum dioxin levels when age and body mass index were taken into account. While workers previously diagnosed with chloracne had high serum dioxin levels, some workers without diagnosed chloracne also had high levels. Among tradesworkers with plant-wide responsibilities, we observed serum dioxins and PCB levels higher than background indicating workplace exposures. We estimate that the mean level of 2,3,7,8-TCDD present in the serum of workers on the date workplace exposure terminated was 267 ppt (ranging from 8 to 1184 ppt) assuming a 9-year half-life, 582 ppt (ranging from 10 to 2,641 ppt) assuming a 7-year half-life, and 1928 ppt (ranging from 22 to 17,847) when a toxicokinetic model is used. We conclude that our findings are consistent with other studies reporting high serum dioxin levels among chlorophenol workers after occupational exposures.

Aged↗
PubMed2000

Do hornets have zombie workers?

Colonies of the European hornet, Vespa crabro, are typically founded by a single queen mated to a single male. From the resulting colony relatedness pattern we predicted strong worker-queen conflict over male production where both the workers and the queen attempt to produce the colony's males. To test for this conflict, male production was studied in 15 hornet nests using a combination of DNA microsatellite analysis (282 males), worker ovary dissections (500 workers from eight nests) and 50 h of observation (four nests). In contrast to our prediction, the data show that hornet males are queens' sons, that workers never attempt to lay eggs, rarely have activated ovaries, and that there is no direct aggression between the queen and the workers. This contrasts with other data for vespine wasps, which support relatedness predictions. Dolichovespula arenaria has the same kin structure as V. crabro and workers produce males in many colonies. The similarity between these two species makes it difficult to explain why workers do not reproduce in V. crabro. Self-restraint is expected if worker reproduction significantly reduces colony productivity but there is no obvious reason why this should be important to V. crabro but not to D. arenaria. Alternatively, queen control may be important. The absence of expressed queen-worker conflict rules out physical control. Indirect pheromonal control is a possibility and is supported by the occurrence of royal courts and queen pheromone in Vespa but not Dolichovespula. Pheromonal queen control is considered evolutionarily unstable, but could result from a queen-worker arms race over reproductive control in which the queen is ahead. The genetic data also revealed diploid males in one colony, the first example in the vespine wasps, and two colonies with double matrilines, suggesting that occasional usurpation by spring queens occurs.

Alleles↗
PubMedDate not supplied

Respiratory consequences of exposure to wood dust and formaldehyde of workers manufacturing oriented strand board.

A cross-sectional study was performed at a plant in which 99 workers were employed in the manufacture of oriented strand board. This group was compared with 165 unexposed workers from the petroleum industry. Both groups were assessed, using a questionnaire, spirometry, and skin prick tests to common environmental antigens. Environmental studies showed a low dust level of 0.27 mg/m3, consisting of particles of a mass median aerodynamic equivalent diameter of 2.5 microns. There were variable concentrations of formaldehyde, up to 0.27 ppm. A significant difference between the oriented strand board workers and oil field workers was noted for the forced expiratory volume in 1 s/forced vital capacity ratio, without significant differences in either the forced expiratory volume in 1 s or the forced vital capacity. Oriented strand board workers who were current smokers were three times as likely to have a forced expiratory volume in 1 s/forced vital capacity ratio of less than 75% of that found in the currently smoking oil field workers. Significant reductions in forced expiratory volume in 1 s (p = .044) and forced vital capacity (p = .022) in oriented strand board workers were noted across the work shift. The oriented strand board workers complained of self-reported asthma and of lower respiratory tract symptoms significantly more frequently than did oil workers for all of the symptoms examined. The prevalence of atopy was not different in the two groups. Lung function was significantly better in oriented strand board workers who had no symptoms, compared with oriented strand board workers who were symptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Exposure of workers to 2,3,7,8-substituted polychlorinated dibenzo-p-dioxin (PCDD) and dibenzofuran (PCDF) compounds in sawmills previously using chlorophenol-containing antistain agents.

The use of chlorophenol-containing antistain agents (e.g., Ky5, a wood preservative) ceased in Finland at the end of the 1980s, after 5 decades of use. Exposure of workers to the impurities in these agents (i.e., polychlorinated dibenzo-p-dioxins [PCDDs] and dibenzofurans [PCDFs]) was assessed at three sawmills at which personnel used a sodium chlorophenate product as an antistain agent. Given that compounds accumulate in body fat and their half-lives in humans are long, we could determine 2,3,7,8-substituted PCDDs and PCDFs 5-9 y after the last exposure occurred. We used high-resolution gas chromatography/high-resolution mass spectrometry to determine PCDDs/PCDFs in plasma from 39 Ky5-exposed workers and 18 nonexposed workers. The average total plasma concentration of PCDD/PCDF of the Ky5-exposed workers at the three sawmills were 1018, 945, and 1165 pg/g fat, and corresponding concentrations in the nonexposed workers were 743, 1124, and 844 pg/g fat, respectively. We found no significant differences in total levels between Ky5-exposed workers and nonexposed workers. However, concentrations of the 1,2,3,4,6,7,8-HpCDF isomer were significantly higher (p < .01) among the Ky5-exposed workers at all three sawmills (averages of 224, 99, and 148 pg/g fat) than among their respective nonexposed workers (averages of 43, 48, and 44 pg/g fat). These results indicate that workers had handled Ky5. When we expressed concentration levels in international toxic equivalents (I-TEQs), the mean total I-TEQ PCDD/PCDF of Ky5-exposed workers was significantly lower at one of the sawmills (average = 42 pg I-TEQ/g) than at the other two sawmills (averages of 64 and 62 pg I-TEQ/g)(p < .05). Nevertheless, total concentrations at the sawmills studied were within the range of background levels in the general population.

Adult↗
PubMed2001

Occupational lead exposure and amino acid profiles and liver function tests in industrial workers.

The aim of the present study is to determine the effect of blood lead on the plasma levels of amino acids and serum liver enzymes in industrial workers in United Arab Emirates (UAE). This comparison study consisted of 100 industrial workers (exposed) and 100 non-industrial workers (non-exposed), matched for age, sex and nationality selected from Al-Ain, Abu-Dhabi Emirates. Industrial workers had higher proportion (19%) of smokers than non-industrial workers (11%) which was not considered to be statistically significantly different. Industrial workers had significantly higher mean of blood lead level (77.5 +/- 42.8 miccrog x dl(-1)) than non-industrial workers (19.8 +/- 12.3 microg x dl(-1)). The amino acid analysis showed higher values among industrial than non-industrial workers for histidine, isoleucine, leucine, threonine, lysine, valine, methionine and arginine (essential amino acids, (p<0.0001). Ornithine, taurine, glutamic acid, serine, glycine, proline and alanine (non-essential amino acids) showed significantly higher values in industrial when compared with the non-industrial workers (p<0.0001). Plasma liver function test, cardiac enzymes and renal function test were carried out on industrial and non-industrial workers. The results revealed alkaline phosphatase (p=0.012) and lactate dehydrogenase (p=0.029) were significantly higher in industrial than in non-industrial workers. On the basis of this study, it can be concluded that a substantial difference in amino acid profiles, blood lead and LFT between exposed and non-exposed was found. These results might be related to lead exposure and might have affects on the kidneys or liver.

Adult↗
PubMed1991

First-year changes in blood lead and zinc protoporphyrin levels within two groups of occupational lead workers.

Quarterly changes in blood lead (PbB) and zinc protoporphyrin (ZPP) levels experienced by 30 male lead-acid storage battery workers and 24 auto assembly workers during their initial year of occupational lead exposure are described. The greatest absolute and percentage increases above baseline PbB levels occurred during the first 3 months of continuous exposure when battery and assembly workers' average PbB levels increased by 99% and 134%, respectively. Peak average PbB levels were reached during the second quarter of exposure for battery workers (27.3 micrograms/dL) and during the third quarter for assembly workers (34.3 micrograms/dL). Mean ZPP levels increased steadily through the first 3 quarters of exposure for both groups of workers before declining slightly during the final 3 months. Third-quarter average ZPP levels were 46.6 micrograms/dL for battery workers and 59.4 micrograms/dL for assembly workers. In general, for the assembly workers, the slopes of quarterly dose (PbB)-effect (loge ZPP) regressions increased with increasing exposure duration (up to 0.044 by the third quarter of exposure) and were significant (p less than 0.0001). Similar calculations for the battery workers were not statistically significant (p greater than 0.05) and showed no exposure-related trends. Probit-based dose (PbB)-response (ZPP level greater than two standard deviations above the baseline ZPP) analyses of the assembly worker data resulted in a 30.0 micrograms/dL ED50 estimate (PbB concentration at which 50% of a similarly exposed population would be expected to develop an "elevated" ZPP level).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2004

Shift workers' mortality scrutinized.

The objective of this article is to reappraise previous published data on the mortality of male shift workers from Taylor and Pocock (1972). Mortality rate ratios were calculated for shift workers, ex-shift workers, and for shift workers plus ex-shift workers, respectively, compared to day workers using the Mantel-Haenszel method. The overall risk for current and former shift workers was 1.05 (95% Confidence Interval: 0.95-1.16). For ex-shift workers the mortality was increased compared to day workers (1.24, 95% Confidence Interval: 1.03-1.51). In the age specific analyses increased mortality was observed in shift workers compared with day workers in the age group of 45-54 yrs (Relative Risk: 1.47, 95% Confidence Interval: 1.12-1.93). We suggest that shift work is associated with increased mortality risk.

Adult↗
PubMed1994

Measles immunity in a population of healthcare workers.

OBJECTIVES: To evaluate measles seroprevalence among cohorts of new employees and to evaluate vaccine responses of susceptible adult healthcare workers. DESIGN: New employees were screened for measles susceptibility as part of employee evaluations. Anti-IgG measles antibody tests were completed on 2,473 workers. Demographic, measles history, and measles vaccination information was collected using a short questionnaire. Susceptible workers were vaccinated and screened for vaccine responses following vaccination. RESULTS: Ninety-three workers (4%) were seronegative, and 56 (2%) were equivocal. Individuals in the youngest cohort (born after 1956) were significantly more likely to be susceptible than those in the middle cohort (born 1951 to 1956) and those in the oldest cohort (born before 1951) (P < 0.01). The middle cohort included eight (5%) of the 149 seronegative or equivocal workers. Among the members of the youngest cohort, those from the United States were more likely to be susceptible (P < 0.01) than those from outside the United States. Of the 106 vaccinated susceptible workers whose follow-up serologies were determined, 90 (85%) developed positive IgG serologies, six had equivocal results, and 10 were seronegative. Eleven of the 16 non- or hyporesponders were revaccinated and re-evaluated; nine developed low positive IgG antimeasles levels, one exhibited an equivocal response, and one failed to respond. CONCLUSIONS: A small but important proportion of healthcare workers are susceptible to measles. Whenever feasible, measles immunity programs for healthcare workers should include workers born before 1957. Of workers born after 1956, those from outside the United States are more likely to be immune than workers from inside the United States. Using the currently available vaccine, revaccination of initial non- or hyporesponders appears to be effective.

Adolescent↗
PubMed2002

Excessive daytime sleepiness and risk of occupational injuries in non-shift daytime workers.

STUDY OBJECTIVES: Only a few studies have examined the possible association between excessive daytime sleepiness (EDS) and risk of occupational injuries, and most of them were based on self-reports. This study tested this association in daytime workers using injury data taken from organizational archives. DESIGN: A retrospective and prospective study. It covered injury occurrence during two years prior to a sleep disorder assessment/education procedure and injury occurrence in the following year. The workers were given the assessment results and, when applicable, a letter to the treating physician. SETTING: Eight industrial plants. Lectures and discussions on sleep disorders, treatment, and implications to safety and quality of life were conducted with small groups who completed the sleep assessment questionnaire beforehand. The workers completed the sleep assessment questionnaire prior to the lecture/discussion. PARTICIPANTS: 532 non-shift daytime workers. INTERVENTIONS: N/A. MEASURES AND RESULTS: A battery of questionnaires to assess EDS (by the Epworth Sleepiness Scale), suspected sleep disorders, sleep habits, and job and environmental conditions. Of the workers studied 22.6% had EDS. Most of those (96.3%) indicated that they had experienced this propensity for the past two years or more and 56% of them had experienced it for 10 years or more. Logistic regression analysis indicated that during the two-year period prior to the procedure, EDS was associated with an increased risk of sustaining a work injury (OR=2.23, 95% CI 1.30-3.81), even after controlling for possible confounders, including factory category, job and environmental conditions. In the year after the procedure, the injury rate decreased by one-third in the workers with EDS but remained unchanged in the workers without EDS. Consequently, the association between EDS and injury was no longer significant (OR=1.42, 95% CI 0.71-2.85). CONCLUSION: EDS is a prevalent phenomenon in non-shift daytime workers. Workers with EDS had over two-fold higher risk of sustaining an occupational injury. Providing workers with the assessment results and of the implications of EDS for safety may explain the decrease in occupational injuries upon follow-up. This decrease might have occurred either because of workers taking steps to reduce EDS and/or adopting safety behaviors.

Adult↗
PubMed2001

HIV surveillance among female sex workers.

Female sex workers are at high risk for infection with HIV, and their clients may act as a bridging population by spreading HIV to the general population. Comprehensive HIV surveillance among sex workers includes surveillance of HIV infection, of sexually transmitted infections and of risk behavior. Surveillance of HIV infection among sex workers is critical for countries with low-level or concentrated HIV epidemics, and can help in monitoring the response to the HIV epidemic in countries with a generalized epidemic. Sex workers are a vulnerable population, and particular attention needs to be paid to human rights issues including consent, confidentiality and stigma. Collaborations with key players in the local sex work scene--sex workers themselves in the first place--and alliances with salient institutions and groups are key to the success of surveillance among sex workers. Surveillance activities should have a strong link to interventions targeted at sex workers. Surveillance for HIV infection among sex workers can be institution- or community-based. Institutional settings include screening programs for registered sex workers, of sexually transmitted diseases clinics, and re-education camps. Specific sources of bias need to be considered in different settings, and must be measured--through the collection of socio-demographic and behavioral data--to allow a correct interpretation of prevalence data and time trends. Community-based HIV infection surveillance can be conducted in a probability sample of the sex worker population, thereby reducing selection bias. This requires the mapping of sex workers' contact venues, and drawing a random sample from the resulting sampling frame.

Cross-Sectional Studies↗
PubMed1997

Risk indicators of low back pain among workers in Japan. Association of familial and physical factors with low back pain.

STUDY DESIGN: A questionnaire was given to 3,042 Japanese workers at a factory in 1992. It surveyed age, gender, weight, height, job classification, and work environment, as well as the perceived causes, onset age, and characteristics of low back pain. Family history of low back pain among first-degree relatives and perception of physical condition also were assessed. OBJECTIVES: To investigate the risk indicators of low back pain in Japanese workers with various kinds of job classifications in a manufacturing company. SUMMARY OF BACKGROUND DATA: Risk indicators of low back pain in Japanese patients have not been fully investigated in previous studies. METHODS: Prevalence rates and characteristics of low back pain were examined among 3,042 factory workers (2,517 men and 525 woman) with jobs with varying physical demands. In the analysis of risk indicators of low back pain, the odds ratios and 95% confidence intervals were computed. In addition, a multiple logistic analysis was performed to evaluate risk indicators of low back pain. RESULTS: Point and lifetime prevalence of low back pain were correlated with the physical demands of the job. The perceived cause found to be most associated with low back pain were lifting in workers with jobs requiring moderate to heavy work and sports activity in sedentary workers. Family history of low back pain in parents, siblings, and children was a risk indicator of low back pain. The average age of the first attack of low back pain in workers with a family history of it in their parents was significantly younger than that in workers with no family history in a multiple logistic analysis in male workers, the physical work demands, age, and family history of low back pain in their parents were risk indicators; however, obesity was not a risk indicator. Physical and mental conditions of workers also were associated with low back pain. CONCLUSIONS: The physical job demands show a clear association with the point and lifetime prevalence of low back pain, and improvements in work conditions may decrease low back symptoms among workers. It is likely that a family history of low back pain and physical and mental conditions of workers also should be considered in the management of low back pain.

Adult↗
PubMed1995

Prevalence of hepatitis C infection in health care workers affiliated with a liver transplant center.

The risk of hepatitis C to liver transplantation health care workers has not been identified. We compared the occupational risk of hepatitis C in health care workers associated with liver transplantation with risk of health care workers affiliated with the same institutions but not involved in transplantations. Health care workers were recruited from 2 transplant centers. Participation was voluntary; results were confidential. An occupational and health history questionnaire was completed and blood was donated for testing. Health care workers were categorized into 3 groups according to risk for hepatitis C infection: very high, high, and low risk. A total of 241 health care workers were recruited from 2 transplant centers. Fifty-nine percent (142/241) were female; mean age was 38.7 years. Health care workers included: 48.5% (117/241) nurses, 24.9% (60/241) physicians, and 17% (42/241) laboratory personnel. The mean number of years in their occupation was 13.5 years (range < 1 year to 38 years). Twenty-four percent (57/241) were categorized in a very high risk occupation for hepatitis C, 66% (158/241) in a high risk occupation, and 10.8% (26/241) in a low risk occupation. A total of 2.1% (5/241) of health care workers were reactive to hepatitis C by enzyme immunosorbent assay; three of these were positive by polymerase chain reaction testing. Of the 3, none had a history of hepatitis or transfusion. However, 5.3% (3/57) of health care workers involved with liver transplantation were infected, as compared with 0% (0/184) who were not (P = 0.013). We conclude that health care workers associated with liver transplantation may be at a higher risk for hepatitis C when compared with health care workers not associated with transplantation.

Adult↗
PubMed1996

Airway function and respiratory symptoms in sanitation workers.

The prevalence of acute and chronic respiratory symptoms and lung-function changes was studied in a group of 81 municipal sanitation workers. In addition, the prevalence of chronic respiratory symptoms and lung function was studied in 65 control workers. There were significantly higher prevalences of all chronic respiratory symptoms among the sanitation workers than among the control workers. Sanitation workers (smokers and nonsmokers) 40 years of age or older had higher prevalences of all chronic respiratory symptoms than younger workers. In addition, sanitation workers (both smokers and nonsmokers) employed for 10 years or longer had significantly higher prevalences of chronic respiratory symptoms than control workers. There was also a high prevalence of acute symptoms, which developed among the sanitation workers during work shifts. Of these symptoms, prevalences were highest for dryness of the nose and throat, followed by throat and eye irritation. Lung-function testing demonstrated significantly diminished forced vital capacity (FVC) and 1-second forced expiratory volume (FEV1) for the 81 sanitation workers compared with control values. These differences only become significant after 10 or more years of employment in the sanitation industry and were not entirely explained by smoking. These differences were smaller and not statistically significant for maximum flow rates at 50% and the last 25% of the vital capacity. Our data suggest that sanitation worker--particularly those with long periods of work exposure--may develop acute and/or chronic respiratory symptoms accompanied by decreases in lung function (primarily FVC and FEV1).

Adult↗
PubMed1998

Mortality of short-term workers in two international cohorts.

The purpose of this study was to compare the pattern of mortality of blue-collar workers employed less and more than 1 year in the man-made vitreous fiber (MMVF) and the reinforced plastic industries, the latter group being exposed to styrene. We conducted an analysis among 21,784 workers with less than 1 year of employment (short-term workers) and 19,117 workers with 1 or more years of employment (long-term workers) employed in eight European countries. We conducted analyses based on external as well as internal comparisons. In both cohorts, the standardized mortality ratio for all causes among short-term workers was approximately 40% higher, compared with that for longer-term workers. In internal comparisons, the difference was reduced to 9% in the MMVF cohort and 11% in the styrene cohort. Workers with less than 1 month of employment displayed an increased mortality in both cohorts and in most countries. The increased mortality among short-term workers was not concentrated shortly after they quit employment. In both cohorts, short-term workers had a higher mortality from external causes, while little difference was seen in mortality from ischemic heart disease and malignant neoplasms. Although extra-occupational factors may contribute to increase the mortality of short-term workers and, in particular, of those employed for less than 1 month, the difference observed in analyses adjusted for characteristics of employment suggested a relatively small difference in mortality from most causes.

Adult↗
PubMed2003

Participatory mapping of sex trade and enumeration of sex workers using capture-recapture methodology in Diego-Suarez, Madagascar.

BACKGROUND: Capture-recapture methodology has been employed to estimate the size of hidden or difficult-to-reach human populations such as sex workers, homeless persons, and intravenous drug users. This study took place in the context of efforts to improve the quality of curative and preventive services for sexually transmitted infections offered to sex workers in Diego-Suarez, Madagascar in partnership with sex workers. GOAL: The goal of this study was to better understand sex-trading practices, map out sex work sites, and estimate the size of a mobile sex-worker population in Diego-Suarez, Madagascar using methods that can be reproduced in other resource-poor settings. STUDY DESIGN: Forty sex workers were trained to function as field researchers. Key informants in designated neighborhoods were identified and interviewed. Basic maps of sex-trade sites were designed by hand. The number of sex workers in Diego-Suarez was estimated using capture-recapture methodology. An educational brochure was used to "capture" sex workers during a first phase, and "recapture" 2 weeks later. RESULTS: Most sex trade was street based and mobile. Capture-recapture methods estimated a total of 2684 sex workers (95% CI: 2588-2780) in Diego-Suarez, or approximately 12% of the 15- to 49-year-old female population in the city. CONCLUSION: Geographic mapping and capture-recapture proved to be low-cost and relatively easy to use techniques for counting a hard-to-reach population, such as female street-based sex workers. Sex workers can be capable fieldworkers, and their active participation in research concerning sex work should be considered whenever possible. A high proportion of women of reproductive age were found to engage in sex work, indicating that there is an urgent need to scale up sexually transmitted infection and HIV prevention activities targeting sex workers, their sexual partners, and the general population.

Adolescent↗
PubMed2005

Honeybee workers use cues other than egg viability for policing.

Worker policing, wherein social insect workers prevent their sisters from reproducing by eating worker-laid eggs, is recognized as a textbook example of kin selection in action. However, the evolutionary basis of policing was recently challenged in a study that suggested that police-workers remove worker-laid eggs not because rearing workers' sons reduces worker fitness, but merely because worker-laid eggs have low viability. Here, we refute Pirk et al.'s conclusions. First, we confirm earlier work that showed equal viability of eggs laid by queens and workers. Second, a statistical analysis of the data of Pirk et al. reveals that their own data do not support the conclusion that worker-laid eggs are policed merely because of their low viability. Third, we present data that unequivocally show that police-workers cannot discriminate between dead and live eggs. Hence, our study seriously weakens the challenge to the kin-selected basis of policing in honeybees.

Animals↗
PubMed2003

The adaptive significance of inquiline parasite workers.

Social parasites exploit the socially managed resources of their host's society. Inquiline social parasites are dependent on their host throughout their life cycle, and so many of the traits inherited from their free-living ancestor are removed by natural selection. One trait that is commonly lost is the worker caste, the functions of which are adequately fulfilled by host workers. The few inquiline parasites that have retained a worker caste are thought to be at a transitional stage in the evolution of social parasitism, and their worker castes are considered vestigial and non-adaptive. However, this idea has not been tested. Furthermore, whether inquiline workers have an adaptive role outside the usual worker repertoire of foraging, brood care and colony maintenance has not been examined. In this paper, we present data that suggest that workers of the inquiline ant Acromyrmex insinuator play a vital role in ensuring the parasite's fitness. We show that the presence of these parasite workers has a positive effect on the production of parasite sexuals and a negative effect on the production of host sexuals. This suggests that inquiline workers play a vital role in suppressing host queen reproduction, thus promoting the rearing of parasite sexuals. To our knowledge, these are the first experiments on inquiline workers and the first to provide evidence that inquiline workers have an adaptive role.

Animals↗