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PubMed1989

Sex worker, client sex behaviour and condom use in Harare, Zimbabwe.

One-hundred sex workers and 100 clients were interviewed at a bar/disco complex in Harare, Zimbabwe in 1989. Sociodemographic characteristics of sex workers and clients were examined. Almost a third of sex workers and nearly 90% of clients had engaged in commercial sex over 5 or more years. Sex workers reported that they worked an average of 4.6 nights a week, averaged 2.2 clients a night and charged a mean of Z$8.7 per session and Z$19.8 per night. Clients reported that they averaged 7.4 visits a month to a sex worker and paid a mean of Z$6.2 per session and Z$17.2 per night. Over half the sex workers said their last client was drunk and nearly two-thirds said he was a repeat client. Sex workers and clients were asked about the sex behaviours completed in their last paid sex act. Vaginal intercourse was reported by 98% of sex workers and clients alike. Manual stimulation of the sex worker's and client's genitalia was reported by roughly 80% of sex workers and clients. Oral and anal sex were rarely reported. Fifty-four percent of sex workers and 44% of clients reported using a condom in their last paid sex act. Client reports thus suggest that sex worker reports of sex acts and condom use with the last client possess considerable validity. Ethnographic approaches were used to study the social and work environment of sex workers. Ethnographic analysis demonstrated a lack of organisation among sex workers and a need to develop cohesive groups for successful health interventions. The study also highlighted the need to include clients in health interventions, the possible role of alcohol as an impediment to health interventions and the feasibility of using bar/disco security and the bar personnel as health educators.

Adolescent↗
PubMed2006

The evolution of worker caste diversity in social insects.

Morphological diversification of workers is predicted to improve the division of labor within social insect colonies, yet many species have monomorphic workers. Individual-level selection on the reproductive capacities of workers may counter colony-level selection for diversification, and life-history differences between species (timing of caste determination, colony size, genetic variation available) may mediate the strength of this selection. We tested this through phylogenetically independent contrast analyses on a new data set for 35 ant species. Evidence was found that early divergence of queen-worker developmental pathways may facilitate the evolution of worker diversity because queen-worker dimorphism was strongly positively associated with diversity. By contrast, risks for colonies that invest in specialized workers and colony size effects on costs of worker reproduction seem unlikely to strongly affect the evolution of worker diversity because there was no significant association between colony size and diversity when controlling statistically for queen-worker dimorphism. Finally, worker diversity was greater in species with multiple lineages per colony, and it was negatively associated with relatedness in monogynous species. This could be due to high intracolonial genetic variance favoring the expression and evolution of great worker diversity or to diversity evolving more easily when there is selection for repression of worker reproduction (worker policing).

Animals↗
PubMed1998

Human immunodeficiency virus seroprevalence and condom use among female sex workers in Italy.

BACKGROUND AND OBJECTIVES: In two different studies, we evaluated the human immunodeficiency virus (HIV) seroprevalence rate and the condom use in a group of female sex workers working in Italy. STUDY DESIGN: In the first study we collected data on HIV serologic testing of female sex workers; in the second study, we evaluated the use of condoms and high-risk sexual practices by sex workers with their clients and nonpaying partners. RESULTS: Overall, 131 of 802 (16%) were HIV positive: 36 of 558 (6%) professional sex workers and 95 of 244 (39%) sex workers who used intravenous drugs. There was a significant increase of seroprevalence among professional sex workers between 1988 to 1990 and 1991 to 1995 (2% versus 11%, P < or = 0.001), whereas among the sex workers who used intravenous drugs, the increase was not significant (37% versus 40%, P = 0.70). Similarly, the HIV seroprevalence in the Italian professional sex workers is constant in the two periods of time (2% versus 1%). In the second study, 97 of 102 (95%) sex workers reported regular condom use with clients, whereas 63% of sex workers reported they never used them with nonpaying partners. Fourteen sex workers reported having nonpaying partners who used intravenous drugs and 6 reported having nonpaying bisexual partners; 8 of these 20 partners were HIV positive. CONCLUSION: The results of the first study showed a significant increase of seroprevalence among professional sex workers, whereas the high seroprevalence among sex workers who used intravenous drugs was constant. The results of the second study showed that sex workers may be at higher risk for HIV infection through noncommercial sexual intercourses.

Adult↗
PubMed2003

Colony insularity through queen control on worker social motivation in ants.

We investigated the relative contribution of the queen and workers to colony nestmate recognition cues and on colony insularity in the Carpenter ant Camponotus fellah. Workers were either individually isolated, preventing contact with both queen and workers (colonial deprived, CD), kept in queenless groups, allowing only worker-worker interactions (queen deprived, QD) or in queenright (QR) groups. Two weeks post-separation QD and QR workers were amicable towards each other but both rejected their CD nestmates, which suggests that the queen does not measurably influence the colony recognition cues. By contrast, aggression between QD and QR workers from the same original colony was apparent only after six months of separation. This clearly demonstrates the power of the Gestalt and indicates that the queen is not a dominant contributor to the nestmate recognition cues in this species. Aggression between nestmates was correlated with a greater hydrocarbon (HC) profile divergence for CD than for QD and QR workers, supporting the importance of worker-worker interactions in maintaining the colony Gestalt odour. While the queen does not significantly influence nestmate recognition cues, she does influence colony insularity since within 3 days QD (queenless for six months) workers from different colony origins merged to form a single queenless colony. By contrast, the corresponding QR colonies maintained their territoriality and did not merge. The originally divergent cuticular and postpharyngeal gland HC profiles became congruent following the merger. Therefore, while workers supply and blend the recognition signal, the queen affects worker-worker interaction by reducing social motivation and tolerance of alien conspecifics.

Analysis of Variance↗
PubMed2003

Exposure to secondhand smoke at work: a survey of members of the Australian Liquor, Hospitality and Miscellaneous Workers Union.

OBJECTIVE: To measure workers' attitudes towards and experiences of exposure to secondhand smoke (SHS) in the workplace. METHOD: A stratified random sample of members from the Victorian Branch of the Australian Liquor, Hospitality and Miscellaneous Workers Union (LHMU) was interviewed by telephone in September 2001. Of the 1,078 respondents surveyed (77% response rate), hospitality workers comprised 49% of the sample, while the remainder comprised community services, property services and manufacturing workers. RESULTS: Overall, 54% of union members were employed in workplaces that did not completely ban smoking and 34% reported being exposed to SHS during their typical working day. Workplaces with total smoking bans had a high level of compliance with these restrictions, with no workers in these settings indicating exposure to SHS at work. Compared with other workers, hospitality workers reported working in environments that had more permissive smoking policies. Consistent with this, 56% of hospitality workers said they were exposed to SHS during a typical day at work compared with 11% of other workers. Overall, 79% of workers expressed concern about exposure to SHS, including 66% of smokers. Compared with other workers, hospitality workers reported a higher level of concern about exposure to SHS at work. CONCLUSION: These findings provide evidence that many workers, and especially those employed in the hospitality sector, are exposed to SHS during their working day and are concerned about the effects of such exposure on their health. IMPLICATIONS: These findings indicate that workplace smoke-free policies are effective in reducing worker exposure to SHS and demonstrate support for the extension of smoke-free policies to hospitality workplaces.

Adult↗
PubMed1994

Increased albumin excretion in industrial workers due to shift work rather than to prolonged exposure to low concentrations of chlorinated hydrocarbons.

OBJECTIVES: It has been reported that groups of workers in petrochemical industries who have been exposed to low concentrations of chemicals for prolonged periods have an increased urinary albumin excretion compared with unexposed controls. This increase, however, seemed to be unrelated to the extent, duration, and type of exposure. The aim of the present study was to investigate the suggestion that the small increase in albumin excretion might be due to differences in physical workload between the exposed and control groups or to the fact that the exposed workers are shift workers whereas the controls are employed on day duty. METHODS: To elucidate the effect of shift work, again a series of renal and hepatic variables were studied in organochlorine workers but now with two different control groups. One control group comprised shift workers and the other only workers on day duty. The exposed and both control groups had roughly equal physical workloads, although one control group comprised shift workers and the other workers who work only during day time. RESULTS: There were no significant changes in the results of the liver tests between the exposed group and either of the control groups, nor between the two control groups. No significant differences for any renal test were found between the exposed workers and control shift workers, but albumin was significantly lower in the control day workers than in the exposed workers and control shift workers. CONCLUSIONS: The results suggest that the previously reported small increase in albuminuria in industrial workers is due to alterations in circadian rhythms due to the shift work system rather than to prolonged exposure to low concentrations of potentially nephrotoxic chemicals.

Adult↗
PubMed2006

The influence of workplace environment on lung function of flour mill workers in Jalgaon urban center.

The workplace environment affects the health of workers. Unhygienic conditions are observed in the workplace environment of flour mills as fine organic flour dust gets airborne in the indoor environment of the flour mills. The present work was undertaken to study the health problems related to the workplace environment of flour mill workers. The results show that flour mill workers are receiving a heavy dose (average exposure concentration, 624 microg/m3) of flour dust. To determine the impact of flour dust on the lung function of the workers spirometric analysis was conducted. Significant declines in forced vital capacity (FVC), peak expiratory flow rate (PEFR) and forced expiratory volume in one second (FEV1) were observed in the flour mill workers as compared to expected values. This study reveals reduced lung efficiency of flour mill workers due to excessive exposure to fine organic dust prevalent in the workplace environment. The impairment in lung efficiency was increased with duration of exposure in the flour mill workers. The analysis of questionnaires used to generate information on self-reported problems reveals that most of the workers were suffering from asthma and respiratory problems. Furthermore, the data shows that 42% of the flour mill workers were having shortness of breath problems, 34% of workers were having frequent coughing, and 19% workers were having respiratory tract irritation. We recommend the compulsory use of personal protective equipment (nose mask) by flour mill workers during working hours. This would help to protect the workers health from the flour dust prevalent in the workplace environment. A regular periodic examination is necessary to measure the impact of particulate matter on the health of the flour mill workers.

Adult↗
PubMed1997

A study of complaints of fatigue by workers employed in Vietnamese factories with newly imported technology.

The aim was to study the actual situation of subjective fatigue among the Vietnamese workers in factories with newly imported technology. A cross-sectional study concerning working conditions and the fatigue complaints of 389 workers who are employed in 10 Vietnamese factories with newly imported technology, was conducted from August to September 1994. About 60% of the workers were satisfied with their current working conditions. Regarding occupational risks at the workplace, heat, dust and noise were identified as the three most dangerous risks. About 46% of the workers complained about the incompatibility of the machines and equipment they were using, which are too large for Vietnamese workers. One third of all workers felt that the work pace is too rapid. Seventeen percent of the workers considered their working conditions monotonous. Finally, among 150 female workers under 40 years old, 45 workers (30.0%) complained of irregularity of menstruation. Generally these problems were more common among workers in textile factories. The prevalence rate of subjective fatigue complaints was significantly increased after work in all 30 items. The fatigue level were substantially high among workers in textile factories. Female workers in this sector had a high prevalence rate of irregularity of menstruation. There were many problems observed in the Vietnamese factories with newly imported technology. Special consideration is required to improve the working conditions of female workers in the textile industry. Both the Vietnamese government and donor countries have to give special attention to the transfer of worker-friendly technology to Vietnam, in order to achieve sound economic development.

Adult↗
PubMed2001

Effects of blasting fumes on exposure and short-term lung function changes in tunnel construction workers.

OBJECTIVES: This study attempts to determine the effects of exposure to blasting fumes and its influence on the lung function of tunnel workers. METHODS: Two groups of tunnel workers, one using ammonium nitrate fuel oil (ANFO) as the explosive and the other using size-sensitized emulsion (SSE), with 24 workers per group, were compared with a reference group (N=34) with low exposure. Spirometry was used to determine lung function. Personal exposure to total and respirable dust, alpha-quartz, volatile organic compounds, oil mist and vapors, formaldehyde, nitrogen dioxide, and carbon monoxide was measured. RESULTS: The ANFO workers were more exposed to all the agents than the reference group and more exposed than the SSE workers to all the agents except total dust and carbon monoxide. The SSE workers were significantly more exposed to total dust and alpha-quartz than the reference group. High peak exposures to nitrogen dioxide (up to 20 ppm) occurred for the ANFO workers in contrast to the SSE workers, whose exposure did not exceed 2 ppm. The lung function of the ANFO workers significantly decreased by 3% for forced vital capacity, 7% for forced expiratory volume in 1 second, and 8% for forced expiratory flow rate from 25% to 75% of the forced vital capacity over the 11-day period. The changes were reversible. There were no significant changes among the SSE workers and the outdoor workers. The ANFO workers had a significant decrease in FEV1.0 when compared with both the SSE and outdoor workers. CONCLUSIONS: Tunnel workers using ANFO explosive show a temporary reduction in lung function, whereas those using SSE do not. The most likely explanation for the observed changes is peak exposures to nitrogen dioxide.

Adult↗
PubMed1991

Health care workers with AIDS. National surveillance update.

OBJECTIVES: To characterize health care workers with the acquired immunodeficiency syndrome (AIDS) in the United States and to evaluate the role of occupational transmission of the human immunodeficiency virus (HIV). DATA SOURCE: National AIDS surveillance data. METHODS: Health care workers with AIDS are reported to the Centers for Disease Control by state and local health departments. Health care workers who do not report a nonoccupational risk for HIV infection are termed undetermined risk cases and are investigated by health departments using a standard protocol. RESULTS: Through June 30, 1990, there were 5425 cases of AIDS in health care workers reported in the United States. Three of these workers developed AIDS following well-documented occupational exposure to HIV-infected blood. Of the 539 health care workers initially reported without a nonoccupational risk, follow-up investigations were completed for 303. Nonoccupational risk factors were established for 237 (78.2%) of the 303 investigated health care workers; 66 workers (21.8%) remained in the undetermined category. Follow-up information was incomplete for 236 health care workers who also remained in the undetermined category, resulting in 5120 health care workers (94.4%) with AIDS with nonoccupational risks for HIV infection. Overall, health care workers were more likely than non-health care workers with AIDS to have an undetermined risk for HIV infection (5.6% vs 2.8%; P less than .001). While many of the 66 investigated health care workers had jobs involving contact with patients and/or potential contact with blood, none reported percutaneous, mucous membrane, or cutaneous exposures to blood or body fluids known to be infected with HIV. CONCLUSION: Surveillance data suggest that most health care workers with AIDS acquired their HIV infection through a nonoccupational route.

Acquired Immunodeficiency Syndrome↗
PubMed2001

Environmental factors and health problems among workers of the national project in Toshka.

The National Project in Toshka is a recognized agricultural one, as well as a comprehensive developmental project. The present study was carried out to investigate environmental factors and health problems among workers in this National Project. Environmental levels of vibration, noise, heat stress, total suspended particulates and respirable dust were measured in the different activities of the project during May 2000. The health records of Behera Company Incorporation, the project main implementing contractor, in the period 1997-1999 were analyzed. Workers were classified according to the nature of occupational exposure into three groups namely; earth workers, concrete workers, and services and administration workers. Records of occupational accidents of the same group of workers and in the same period were analyzed as well. Results showed that all the measured environmental factors were within the permissible levels of exposure in the different project activities. Workers showed a significant lower rate of total health problems in the last studied year (1999) as compared to the previous two years (1997-1998) (p=0.001). Prevalence rates of musculoskeletal disorders, urinary tract troubles, ear-nose-throat (ENT) problems and chest problems were significantly higher in earth and concrete workers than in services and administration workers (p=0.001, 0.011, 0.036 and 0.044, respectively). Both occupational accident frequency and severity rates were very low in comparison to other major construction projects such as the High Dam. These rates showed decreasing trends throughout the studied years; however, relatively higher rates were observed among earth workers than the other groups. Miscellaneous wounds were the commonest presentation of occupational injuries among the three occupational groups. In conclusion, the current use of modern technology accounted for the low levels of enviro mental exposure factors, as well as the high safety standards. Workers showed a significant degree of acclimatization to work in this region; therefore, inhabitants and workers should be encouraged to engage this new community. The low rates of health problems among workers observed in this study reflected a satisfactory level of medical services. Preplacement and periodic medical examinations of construction workers aught to consider musculoskeletal, urinary tract, ENT and chest conditions among them.

Accidents, Occupational↗
PubMed1996

Body mass index of tannery workers in Kanpur, India.

During two cross sectional surveys in 1988 and 1994 the body mass index among tannery workers in Kanpur, India and its association with exposure to chemicals, dust and awkward ergonomic conditions, socio-economic and health status were studied. Fifty six per cent of the workers had in 1988 a BMI of less than 18.50, the cut-off value for malnutrition. In 1994 the proportion of malnourished workers had decreased to 41 per cent, being statistically significant lower than in 1988. Workers with a high exposure to lifting weights of more than 20 kg had significantly lower BMI than workers without this exposure. No other differences in mean BMI were found between workers without exposure to chemicals, dust and other awkward ergonomic conditions and workers with high or very high exposures, nor did the mean BMI of workers with occupational related conditions such as dermatitis, work related respiratory symptoms and low back pain differ from those without these conditions. There was no association between mean BMI and industrial modifications. In the 1994 survey workers who took sick leave in the year prior to the survey, workers of small/medium sized tanneries and workers without an ESI card had significantly lower BMI than workers without sick leave, workers of large tanneries and workers with an ESI card. Mean BMI of labourers with a monthly income of less than Rs 550 was significantly lower than that of tannery staff not engaged in leather work in this income group. No association was found between mean BMI and smoking, use of alcohol, educational level and income. The nutritional status of labourers in developing countries deserves more attention within the field of occupational health and safety.

Adult↗
PubMed1997

Social and economic impact of neurotoxicity in hazardous waste workers in Lenoir, North Carolina.

A detailed study of workers at a hazardous waste incinerator in Lenoir, North Carolina, revealed significant financial losses resulting from health problems caused by the incinerator. The losses included approximately $3 million for 3 years of medical care for 28 workers employed at the incinerator. Future wage losses for exposed workers were projected to be from $14 million to $15 million. Loss of the incinerator as a viable employment base was a significant blow to the local economy. Third-party payers of medical costs, government and private, were also at risk of financial loss. Workers' compensation benefits ranging from $6500 to $274,000 per person were paid by insurance companies to some workers; however, these benefits did not always cover the medical expenses incurred. As a result of their illnesses, 11 of the 28 workers (39%) had to sell or give up their homes, 8 workers (36%) lost their vehicles, 19 workers (68%) began to receive Social Security Disability payments, and 11 workers (39%) obtained food stamps. One worker not included in these figures died 3 years after he settled with the state workers' compensation program. Five of the 28 interviewed workers continue to work in spite of continuing health problems. The 23 workers who cannot work will have estimated lifetime medical expenses of $25.4 million.

Air Pollutants, Occupational↗
PubMed2001

Improving the quality of workers' compensation health care delivery: the Washington State Occupational Health Services Project.

This article has summarized research and policy activities undertaken in Washington State over the past several years to identify the key problems that result in poor quality and excessive disability among injured workers, and the types of system and delivery changes that could best address these problems in order to improve the quality of occupational health care provided through the workers' compensation system. Our investigations have consistently pointed to the lack of coordination and integration of occupational health services as having major adverse effects on quality and health outcomes for workers' compensation. The Managed Care Pilot Project, a delivery system intervention, focused on making changes in how care is organized and delivered to injured workers. That project demonstrated robust improvements in disability reduction; however, worker satisfaction suffered. Our current quality improvement initiative, developed through the Occupational Health Services Project, synthesizes what was learned from the MCP and other pilot studies to make delivery system improvements. This initiative seeks to develop provider incentives and clinical management processes that will improve outcomes and reduce the burden of disability on injured workers. Fundamental to this approach are simultaneously preserving workers' right to choose their own physician and maintaining flexibility in the provision of individualized care based on clinical need and progress. The OHS project then will be a "real world" test to determine if aligning provider incentives and giving physicians the tools they need to optimize occupational health delivery can demonstrate sustainable reduction in disability and improvements in patient and employer satisfaction. Critical to the success of this initiative will be our ability to: (1) enhance the occupational health care management skills and expertise of physicians who treat injured workers by establishing community-based Centers of Occupational Health and Education; (2) design feasible methods of monitoring patient outcomes and satisfaction with the centers and with the providers working with them in order to assess their effectiveness and value; (3) establish incentives for improved outcomes and worker and employer satisfaction through formal agreements with the centers and providers; and (4) develop quality indicators for the three targeted conditions (low back sprain, carpal tunnel syndrome, and fractures) that serve as the basis for both quality improvement processes and performance-based contracting. What lessons or insights does our experience offer thus far? The primary lesson is the importance of making effective partnerships and collaborations. Our policy and research activities have benefited significantly from the positive relationship the DLI established with the practice community through the Washington State Medical and Chiropractic Associations and from the DLI's close association with the Healthcare Subcommittee of the Workers' Compensation Advisory Committee. This committee is established by state regulation and serves as a forum for dialogue between the committee and the employer and labor communities. Our experience thus underscores the importance of establishing broad-based support for delivery system innovations. Our research activities have also benefited from the close collaboration between DLI program staff and UW health services researchers. The DLI staff brought important program and policy experience, along with an appreciation of the context and environment within which the research, policy, and R&D activities were conducted. The UW research team brought scientific rigor and methodological expertise to the design and implementation of the research and policy activities. In Washington State, the DLI represents a "single payer" for the purposes of workers' compensation. As discussed earlier, Washington State, along with five other states, has a state-fund system that requires all employers that are not self-insured to purchase workers' compensation insurance through the state fund. No matter what one feels about the merits or drawbacks of a single-payer system of health care financing, the fact is that such a system creates important opportunities for policy initiatives and for research and evaluation. Our ability to access population-based data on injured workers and to develop policy initiatives through innovation and pilot testing to assess whether proposed changes are really improvements has been critical. Understanding what works within the constraints and complexities of the system on a small scale is critical in order to bring forth policy and processes that will be of value systemwide. Finally, we note that general medical care faces many of the same quality-related problems and challenges as occupational health care. Medical care for chronic diseases, such as diabetes, is often fragmented and uncoordinated. (ABSTRACT TRUNCATED)

Case Management↗
PubMed2002

Group effects on insecticide toxicity in workers of the Formosan subterranean termite, Coptotermes formosanus Shiraki.

Coptotermes formosanus workers were treated topically with insecticide and subsequently held individually or in groups to examine possible effects on insecticide toxicity. Chlorpyrifos, cypermethrin and chlordane toxicities were 1.4-, 1.5-, and 1.3-fold greater, respectively, among workers held in groups compared with those held individually after insecticide treatment. Experiments were conducted to examine how enhanced toxicity occurred among termites held in groups after topical insecticide treatment. When workers were treated topically with chlordane and immediately placed with untreated workers, significantly greater numbers of untreated workers were killed compared with controls at all ratios examined (insecticide-treated:untreated). These data indicated that workers treated topically with insecticide were capable of somehow transferring a lethal dose of insecticide to untreated workers confined in the vial. Chlordane was recovered from untreated workers which had been confined with chlordane-treated workers; significantly higher quantities of chlordane were recovered from dead workers exposed to chlordane-treated workers compared with surviving workers exposed to chlordane-treated workers. Possible mechanisms of insecticide transfer from insecticide-treated to untreated termites are discussed.

Animals↗
PubMed1995

Chronic and acute respiratory effects among grain mill workers.

Exposure to flour dust may induce chronic respiratory manifestations as well as acute ventilatory effects. We compared the prevalence of respiratory symptoms, ventilatory impairment, and variations in pulmonary function over the workshift in a group of mill workers exposed to wheat flour and in referent workers. One hundred and forty-two men exposed to flour in a mill and 37 referent workers were included in this study. Each subject completed a standardized questionnaire. Pulmonary function tests were performed before and after the workshift. The assessment of environmental exposure to flour showed high concentrations during some jobs with a high percentage of inhalable particles and a low concentration of respirable particles. The exposed workers had a significantly higher prevalence of usual cough and usual phlegm than the referents. The prevalence of asthma, based on the questionnaire, was similar. Before the workshift, the exposed workers had significantly lower mean lung function values for peak flow rate and forced expiratory flow rate at 75% of the vital capacity than the referents. After the workshift, all the lung function values showed a slight decrease, significant for forced vital capacity and forced expiratory volume during 1 s in both groups. Among the exposed workers, the asthmatic subjects had a significantly higher decrease across the shift than the nonasthmatic workers. This result is probably linked to bronchial hyperreactivity. Among nonasthmatic subjects, the decrease was larger in nonexposed workers than in exposed workers. A higher prevalence of respiratory symptoms and lower pulmonary function values were observed among mill workers by comparison with referents. Moreover, the data suggest that asthmatic status and the time of spirometric measurements need to be taken into account in epidemiological studies on exposure to airborne allergens. In addition, the study does not exclude a healthy worker effect with selection of dust-resistant subjects or better identification of asthmatic subjects among the workers exposed to an allergenic substance than among the nonexposed workers.

Adult↗
PubMed2001

Monocyte-macrophage system and polymorphonuclear leukocytes in workers exposed to low levels of metallic mercury.

Our previous research (Soleo L, Vacca A, Vimercati L et al. Occup Environ Med 1997;54:437-442) showed a reduction in tumor necrosis factor-alpha (TNF-alpha) serum levels in workers with prolonged exposure to low doses of inorganic mercury, suggesting an in vivo functional defect of the monocyte-macrophage system. On this basis, here we wondered whether workers exposed to lower doses of metallic mercury displayed possible changes in the monocyte-macrophage system. In this particular cohort of workers, we also sought for the effects of the exposure on the polymorphonuclear leukocytes (PMNL) chemotaxis. The monocyte-macrophage system and the natural killer (NK) cells were examined in 19 exposed workers and in 25 unexposed workers, as the control group (controls). Specifically, the circulating monocyte-macrophage cells and their CD13, CD15 and CD33 subsets, serum cytokines (IL-8, GM-CSF and TNF-alpha) and the NK cells were analyzed. In seven exposed and seven controls randomly chosen workers the PMNL chemotaxis was also assessed. The selected indicator of mercury exposure were the levels of mercury in the urine (U-Hg), that was significantly higher in exposed workers than the controls (9.7 +/- 5.5 microg/l and 2.4 +/- 1.2 microg/l, respectively). None of the exposed workers had shown signs of either acute or chronic inorganic mercury toxicity or any form of hypersensitivity. Several immunological variables tested, monocyte-macrophage cells and their subsets, NK cells and serum cytokines overlapped between the exposed and the control workers. When the workers were considered as a whole (exposed plus controls), no correlation was found between current U-Hg and all immunological parameters. However, when exposed workers were studied separately, an inverse correlation was disclosed between cumulative U-Hg and cells (as percentage) expressing the CD13 (r = -0.599; P = 0.007) and CD15 (r = -0.614; P = 0.005) molecules, and NK cells (r = -0.455; P = 0.05). Moreover, a significant impairment in the PMNL chemotaxis (t = 3.70; P = 0.003) was observed in the exposed workers. The results of our study suggest that the exposure to very low levels of metallic mercury led to subtle impairment of circulating monocyte and NK cells (as percentages) according to the increase in U-Hg levels, as well as of the PMNL chemotactic function in this particular group of workers, even though they remain clinically asymptomatic. Therefore, we suggest that impairment of these parameters provide a sensitive indicator of metallic mercury and other chemical contaminants present in the environment.

Adult↗
PubMed2004

Social parasitism by male-producing reproductive workers in a eusocial insect.

The evolution of extreme cooperation, as found in eusocial insects (those with a worker caste), is potentially undermined by selfish reproduction among group members. In some eusocial Hymenoptera (ants, bees and wasps), workers can produce male offspring from unfertilized eggs. Kin selection theory predicts levels of worker reproduction as a function of the relatedness structure of the workers' natal colony and the colony-level costs of worker reproduction. However, the theory has been only partially successful in explaining levels of worker reproduction. Here we show that workers of a eusocial bumble bee (Bombus terrestris) enter unrelated, conspecific colonies in which they then produce adult male offspring, and that such socially parasitic workers reproduce earlier and are significantly more reproductive and aggressive than resident workers that reproduce within their own colonies. Explaining levels of worker reproduction, and hence the potential of worker selfishness to undermine the evolution of cooperation, will therefore require more than simply a consideration of the kin-selected interests of resident workers. It will also require knowledge of the full set of reproductive options available to workers, including intraspecific social parasitism.

Aggression↗