Reproductive Health Among Nickel Refinery Workers
| Principal investigator(s): | Evert Nieboer
(McMaster University) |
| Co-investigator(s): | Valeri Tchachtchine (Kola Research Laboratory for Occupational Health [Russia]); Eiliv Lund, Jon Oyvind Odland (University of Tromso [Norway]), Yngvar Thomassen (National Instititute of Occupational Health [Oslo, Norway]), Steven Schrader (National Institute for Occupational Safety and Health [USA]), Ted Haines (McMaster University) |
| Sponsoring Institution: | McMaster University and the University of Tromsø, Tromsø, Norway |
Objective
To investigate whether occupational exposure to nickel compounds is causally linked to pregnancy loss, pregnancy complications, birth defects and reduced birth rate and size.
Method
The study was conducted among workers in the nickel refinery complex located at Monchegorsk in the Murmansk region of Russia. A comprehensive exposure assessment using cutting-edge personal monitors involving 350 workers was employed to construct a job exposure matrix for current and past female nickel-refinery workers. Nickel and cobalt concentrations in urine and in the water-soluble subfraction of the inhalable aerosol fraction were used for this. A birth registry was set up for Monchegorsk, including all births (24,534) from March 1973 to December 2001, inclusive. A worker questionnaire database was also constructed using personal and lifestyle information obtained in a questionnaire administered to 717 female nickel workers and 980 controls. A pilot semen quality study of 111 male workers was also completed.
Results and Conclusions
The comprehensive exposure assessments illustrated the benefit of using cutting-edge personal monitors that measure major aerosol fractions and subfractions. Categorical nickel and cobalt exposure levels of background, low and high were assigned to all delivering women in the registry (40% of whom were employees of the nickel company). An examination of perinatal mortality and pregnancy risk factors among the delivering women illustrated the epidemiological value and power of the birth registry. There was no association between genital malformations and maternal exposure: odd ratio of 0.81 (95% CI: 0.52-1.26). Women working in jobs with solvent exposure had a non-significant two-fold risk (p>0.05), but actual solvent levels were not measured. Using the data in the birth registry and in the linked worker questionnaire, the following can now be investigated with minimal effort: other malformations, spontaneous abortion, pregnancy complications, and fetal development. This work is ongoing. And finally, the pilot semen quality study suggested that occupational exposure may reduce selected aspects of sperm quality, but this needs follow-up because of small study sample size.
Details
At the Fifth International Conference on Nickel Biochemistry, Toxicology and Ecologic Issues held in Sudbury, ON, in 1992, one of the researchers of our international team presented a paper expressing concerns about reproductive health issues among Russian female nickel-refinery workers. The raw data presented was based on female workers employed in the nickel electrorefining division of the metal-refinery complex at Monchegorsk in the Kola Peninsula of western Russia (the Murmansk region). A follow-up study of these workers and those involved in preparing the starting electrodes of impure nickel (called anodes) was conducted in 1995-1997. It concluded that a detailed epidemiologic (statistical) study was warranted because the personal exposure assessments conducted indicated high levels of nickel. Further, such a study was deemed feasible because of the availability of a favourable pool of subjects and suitable health and occupational records. With this background, a comprehensive exposure assessment and pregnancy outcome study was launched on January 1, 2001. It was jointly funded by the Nickel Producers Environmental Research Association (NiPERA), Durham NC, USA and the Ontario Workplace Safety and Insurance Board (WSIB).
The Reproductive Health Study had three main components. First, a detailed exposure assessment using state-of-the art personal monitors and biological monitoring was carried out in the nickel- and copper-related refining operations. Based on this, the exposure ratings background, low and high were assigned to all past and current female workers for use in the reproductive-health studies. The cutting-edge equipment employed allowed the measurement of: aerosol fractions of different size, the chemical makeup of aerosol particles, and the amount of the workplace dust which is water-soluble and thus readily taken up by the body. Our results demonstrate the benefits of measuring such aspects of worker exposure. Particle size determines where in the respiratory system aerosols deposit, and their chemical make-up helps us to understand the internal dose received and how they exert their toxic effects. Our work has shown that the personal samplers constructed with new technologies can be used routinely in the workplace, and this should be encouraged.
The second and third components of the research dealt with reproductive health of female workers and the developmental health of their babies before and just after birth. In support of these related studies, a comprehensive birth registry was set up in which extensive information is recorded for all births registered in the city of Monchegorsk during the period March 1, 1973 to December 31, 2001. In 1995, Monchegorsk had a population of 66,200. Its main employer has been the metal-refining complex, with nickel and copper as its main products. The birth registry consists of 24,534 live or still-born births, with 200 pieces of recorded information about the mother and baby. Over 40% of the delivering women were employed in some capacity by the metal-refining factory. A number of studies using the birth registry have focused on more general health issues surrounding the mothers and the babies to illustrate the quality and type of the data in the birth registry, as well as its potential use in further research. Specifically, perinatal mortality (i.e. dead at birth or death during the first 7 days) for all deliveries has been explored, as well as pregnancy risk factors for all delivering women. The first study of a series has been completed in which pregnancy outcomes and the development of babies before and just after birth are investigated in relation to occupational exposure. It is concluded that exposure to water-soluble nickel has no effect on the risk of genital malformations. However, some risk was apparent for jobs involving solvent use. This apparent effect needs further investigation as actual solvent exposures were not measured. Other neonatal outcomes among female nickel workers to be pursued using the birth registry are malformations of the skeleton and muscles, and the occurrence of newborns small for gestational age. Spontaneous abortions and pregnancy complications will also be studied in relation to working in the nickel refinery. For this, the birth registry data has been supplemented by a database of personal information obtained in a questionnaire administered to 717 current female nickel-refinery workers and 990 control subjects. The worker questionnaire is compatible with and electronically linked to the birth registry.
Further, a pilot study of semen quality was conducted among male nickel-refinery workers and suggests that exposure to nickel compounds may impair selected aspects of sperm quality. Exposure was estimated by urinary nickel concentrations. This is a tentative conclusion because too few workers were tested. Additional research is therefore recommended.
The exposure assessment component of the research described has helped to strengthen occupational hygiene practices in Russia. This discipline is not well established there. Similarly, the birth registry is the first in Russia, and has illustrated the usefulness of this tool for monitoring and standardizing medical practices in relation to pregnancy care and identifying trends in related health outcomes. The Russian Federation Ministry of Health has set out occupational health legislation to usher in personal monitoring in the workplace and has accepted, in principal, the benefits of establishing birth registries elsewhere in Russia in support of the health care system. In fact, a birth registry for medical and research use is being set up with the help of the research team for the entire Kola Peninsula. It involves all the hospitals with delivery departments, and with a central office in Murmansk.
Publications
1. Vaktskjold A., Talykova L.V., Chashchin, V.P., Nieboer E., Thomassen Y., Odland J.Ø. (2006). "Genital Malformations in Newborns of Female Nickel-Refinery Workers." Scandinavian Journal of Work Environment and Health 32(1):41-50.
2. Vaktskjold A. (2006). The Quality and Use of Two Health Registries in Russia: The Arkhangelsk Cancer Registry and the Kola Birth Registry. International Journal of Circumpolar Health 65(3):274-276.
3. Nieboer E., Thomassen Y., Chashchin V., Odland J.Ø. (2005). Metals in Perspectives. Occupational Exposure Assessment of Metals. Journal of Environmental Monitoring 7:411-415.
4. Thomassen Y., Nieboer E., Romanova N., Nikanov A., Hetland S., van Spronsen E.P., Odland J.Ø., Chashchin V. (2004), "Multi-Component Assessment of Worker Exposures in a Copper Refinery. Part 1. Environmental Monitoring." Journal of Environmental Monitoring 6:985-991.
5. Vaktskjold A., Talykova L., Chashchin V., Nieboer E., Odland J.¨. (2004), "The Kola Birth Registry and Perinatal Mortality in Monèegorsk, Russia." Acta Obstetricia et Gynecologica Scandinavica 83:58-69.
6. Vaktskjold A., Paulsen E.E., Talykova L., Nieboer E., Odland J.Ø. (2004), "The Prevalence of Selected Pregnancy Outcome Risk Factors in the Life-Style and Medical History of the Delivering Population in North-Western Russia." International Journal of Circumpolar Health 63(1):39-60.
7. Weinbruch S., van Aken P., Ebert M., Thomassen Y., Skogstad A., Chaschin V.P., Nikonov A. (2002), "The Heterogeneous Composition of Working Place Aerosols in a Nickel Refinery: A Transmission and Scanning Electron Microscope Study." Journal of Environmental Monitoring 4:344-350.
8. Koch W., Dunkhorst W., Lödding H., Thomassen Y., Skaugste N.P., Nikanov A., Vincent J. (2002), "Evaluation of the Respicon® as a Personal Inhalable Sampler in Industrial Environments." Journal of Environmental Monitoring 4:657-662.
9. Höflich B.L.W., Wentzel M., Ortner H.M., Weinbruch S., Skogstad A., Hetland S., Thomassen Y., Chaschin V.P., Nieboer E. (2000), "Chemical Composition of Individual Aerosol Particles from Working Areas in a Nickel Refinery." Journal of Environmental Monitoring 2:213-217.
10. Odland J.Ø., Tchachtchine V.P., Bykov V., Fiskebeck P.E., Lund E., Thomassen Y., Nieboer E. (1999). "Critical Evaluation of Medical, Statistical, and Occupational Data Sources in the Kola Peninsula of Russia Pertinent to Reproductive Health Studies." International Archives of Occupational and Environmental Health 72:151-160.
11. Thomassen Y., Nieboer E., Ellingsen D., Hetland S., Norseth T., Odland J.Ø., Romanova N., Chernova S., Tchachtchine V.P. (1999), "Characterisation of Workers’ Exposure in a Russian Nickel Refinery." Journal of Environmental Monitoring 1:15-22.
For more information:
nieboere@mcmaster.ca
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