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arc and resistance welding and tumours of the endocrine glands: a swedish case-control study with focus on extremely low frequency magnetic fields

by:Maghard      2020-02-22
Mechanism of potential effects of extremely low frequency (ELF)
The magnetic field of carcinogenic action has not been determined.
A potential pathway may be the interaction with the endocrine system.
Objective: to analyze the occupational exposure of welding and endocrine gland tumors to the ELF magnetic field.
Method: This case
The control study was based on a cohort of increased prevalence among highly exposed populations.
A total of 174 endocrine gland tumors were found, 1985-94 cases, and data were obtained from 140 cases (80%)of these cases;
A control frequency of 1692 gender and age matches was selected, 1306 (77%)
Got the individual.
A short questionnaire was sent to the case and control center workplace staff administrator.
Exposure Assessment is based on questions about work tasks, exposure to different types of welding, and exposure to solvents.
Results: the risk of all tumors in the endocrine glands of individuals welded at some point during follow-up increased overall.
The reason for the increased risk is arc welding;
There is no clear evidence of an association for resistance welding.
We found increased thyroid risk associated with arc welding and resistance welding.
It was also noted that the risk of anterior lobe tumors used for electrowelding increased inaccurately.
No mixed effects were found in solvent exposure and no signs of biological interaction.
Conclusion: exposure to a high level of ELF magnetic field may explain an increased risk of endocrine gland tumors associated with welding.
Biological mechanism of potential effects of extremely low frequency (ELF)
The magnetic field of carcinogenic action has not been determined.
It is unlikely to be genetically toxic when exposed to the ELF magnetic field.
The association between the ELF magnetic field observed in the epidemiology study and cancer is not so much initiation as due to initiation or progression effects, if these associations reflect causality.
Hormonal factors have been discussed as a link between the exposure of the ELF magnetic field and the development of cancer.
The potential effect of the Pineal magnetic field on the pineal gland, the decrease in melatonin secretion, followed by the effect of estrogen levels, which may affect the development of cancer, such as breast cancer, was suggested.
Experimental evidence of the effect of the 2, 3 ELF magnetic field on melatonin in the human body is weak, but some occupational studies have shown that levels of melatonin in highly exposed workers have decreased.
4-6 most of the occupational studies on ELF magnetic fields and breast cancer do not show a correlation, but some studies have shown that, in particular, it has an effect on premenopausal breast cancer in women aged 7, 8, and 9, breast cancer in men.
11-14 also showed an increase of 14 in the risk of anterior lobe tumors in highly exposed individuals, 15 years of age and in certain occupational groups with a high level of ELF magnetic field.
The cause of endocrine tumors is largely unknown, but brain tumors, for example, are thought to rely on excessive hormones (hypothalamic)stimulation.
Since the hormonal system appears to be the common denominator of breast cancer and endocrine tumors, the potential pathways between the ELF magnetic field and cancer development can be mediated by interaction with the endocrine system.
This interaction, if true, should be very complex.
There are great differences in laboratory research on biological effects of ELF magnetic fields;
It has been suggested that this variability can be used
A linear relationship between exposure and biological response.
The tumor of the endocrine gland is usually very small and has not been found, so-
Called micro-tumor
Hormones are not only believed to contribute to the development of endocrine tumors.
In turn, tumors usually secrete hormones;
Pititary tumors may produce prolactin, which seems to play an important role in the development of breast cancer in women.
In addition, prolactin in male breast cancer (
And brain tumor)
According to the case report, it was suggested to play an important role.
19-21 there is a hormone that can be secreted by a tumor (PTH)
Moreover, individuals with increased thyroid hormone secretion may have a higher risk of developing different types of malignant tumors.
22-24 the purpose of this study was to analyze the risk of endocrine gland tumors in arc and resistance welders using welding as an alternative measure of exposure to the ELF magnetic field.
Arc welding may produce an ELF magnetic field of several hundred Tetra, 25 Tesla, and resistance welding may produce a higher magnetic field density.
26 based on the measurements of 13 welders randomly selected, we found that the mean shift arithmetic average was 1.
The average maximum is 90 Tesla and 142 Tesla.
The advantage of this study is that welding should produce a significant contrast exposed to extremely small magnetic fields and that welding is evaluated at a personal level.
In crowd-based cases, the main welding contact was assessed at the individual level
Control studies included 140 cases of endocrine gland tumors.
Welding is associated with a double increase in the risk of endocrine tumors. A three-
In arc welders, the risk of thyroid tumors and thyroid tumors was found to have increased four times.
For resistance welding, the estimated relative risk is 2.
Six thyroid glands were found.
No conclusive results were obtained for brain tumors.
No confusion with solvent exposure.
The connection between welding and endocrine gland tumors may be mediated by exposure to a high level of magnetic field.
Research Objects and methods of this case
The control study was based on a previously established cohort of highly exposed populations such as increased prevalence of resistant welders.
The queue was established through a link between some central registries.
First, the industrial sector where resistance welding is possible has been identified.
The second step is to identify all the companies and workplaces within these branches.
The third and final step is to identify all persons employed in these companies and workplaces during the 1985-94 study period.
The group consists of 537 692 men and 180 529, both in the past and now exposed to extremely low frequency magnetic fields used in two different groups, focusing on cancer diseases15 and degenerative diseases.
28 previous cohort study and this case-
The control research has been approved by the ethics committee of Karolinska college in the Swedish capital Stockholm Mo.
Cases and control cases of endocrine gland tumors in the cohort, as well as cases diagnosed with leukemia, obtained brain and breast tumors from 1985 through matching with the Swedish Cancer Registry.
Here we report the results of endocrine tumors.
In order to facilitate the collection of data on the case-
Control study we restricted the study population and selected cases and controls from workplaces that met certain criteria: these cases and controls should still be present when collecting data;
During 1985, there were at least 10 employees and at least one welder (
ISCO working code 755)
Employed for a period of time during this period.
The ultimate criterion is at least one cancer case (
All the diagnostics mentioned above)
It should take place in the workplace during 1985.
In January 1, 1998, these standards were met in 673 workplaces.
One control for each cancer case (
All the diagnostics mentioned above)
Selected, the frequency of age and gender matching.
A total of 1692 controls were selected and information about 1306 controls was provided (77%)
Got the individual.
Because we assumed that the exposure distribution throughout the control group reflected the exposure distribution of the Target case study basis, we used all controls in the analysis of endocrine tumors.
During 1985, a total of 174 endocrine tumors were found and data were obtained from 140 cases (80%)of these cases. The non-
Participation accounted for 22% of the original learning scale, mainly due to the refusal of a few large companies to participate.
The withdrawal was caused by companies that did not participate in the study;
The remaining 29% is due to the failure of the individual reports involved within the company.
140 cases of endocrine gland tumors were distributed in the thyroid gland (
These intervals were selected due to uneven distribution.
Calculate all risk estimates using SAS software.
29 we analyzed the potential interactions exposed to welding and solvents by testing whether the joint effect was greater than the sum of the independent effects of each single factor calculated by calculating the synergy index.
30 results we found that the overall increased risk of endocrine gland tumors in subjects welded at some point during follow-upup (table 1).
The reason for the increased risk is arc welding, and there is no support association for resistance welding.
View this table: View the inline View popup Table 1 odds ratio (OR)
In all tumors of the endocrine glands exposed to workers from a high level of ELF magnetic field welded, Sweden is a different subtype of the endocrine glands, and we found an increased thyroid risk associated with arc welding, increased thyroid risk associated with arc welding and resistance welding (table 2).
For the lower brain glands, we only observed an inaccurate but increased risk of electrical welding.
View this table: View the inline View popup Table 2 odds ratio (OR)
For subtypes of endocrine tumors of workers exposed to a high level of ELF magnetic field produced by welding, the analysis of average welding time per week in Sweden 195-94 yielded some results consistent with exposure
Response Association.
This is most evident in all endocrine tumors, especially in welders (table 1)
But also for thyroid tumors (p < 0. 01)
For welding machines and all types of welding (
Not shown in table).
We have not observed any conclusive results about the exposure.
Response mode between resistance welding machines.
Regarding solvent exposure, we observed the association between the once exposed and adrenaline tumors (ORu200a=u200a3. 2, 95% CI 1. 0 to 10. 3).
Interaction Analysis between welding and exposure to solvents does not reveal any biological interactions
That is to say, all the synergies are below 1. 0.
However, the number of cases in the grouping is small and the analytical capacity for the synergy index is limited.
The discussion of the impact between welders is attributed to arc welding, not resistance welding, which is contrary to our expectations.
Resistance welding usually has an ELF magnetic field higher than arc welding.
These welders are affected by a magnetic field of up to 100 amps of current.
26 it is well known that arc welding in the current range of 100-500 amps can also cause a large amount of exposure to the ELF magnetic field.
31 However, the exposure of arc welding to the head and neck may be higher than that of resistance welding, as arc welding machines usually carry (carried)
The cable on the shoulder, 31 should be particularly close to the thyroid gland.
For the thyroid gland, the risk of resistance welders is increased, but for arc welders, this association is stronger.
To some extent, the difference between the two welding methods is explained by the low prevalence of a small number of cases and resistance welding.
When we previously analyzed the relationship between the tumor of the endocrine gland and the exposure to the ELF magnetic field, in this case,
The control study was based on the fact that we found an increased risk of brain tumors in men with the highest exposure group> 0. 53 µT, RR 2. 4 (0. 9 to 6. 2).
15 It was also suggested that women were at increased risk of developing thyroid tumors, but the result was based on a small number of cases. The case-
The control study section supports the hypothesis associated with endocrine gland tumors produced by cohort studies, but there are differences in the location of specific tumors involved.
Different methods of exposure assessment may be an explanation of the difference.
In the cohort analysis, we used the subject\'s occupational code in the Census and associated it with the work contact matrix.
27. Exposure assessment at the individual level applicable in the case --
The impact of error classification on control studies should be small.
For example, we should also, in accordance with the code of practice recorded in the census, capture the person in contact with welding when there is no indication of such contact.
This difference may also be due to inconsistency in the nature of high exposure in the two studies.
The high exposure population in the cohort analysis includes not only welders, but also several other occupations.
In addition to iodine deficiency and ionising radiation associated with thyroid cancer, environmental risk factors for endocrine gland tumors that do not appear to be determined (
Not considered in the current study).
We believe that solvent exposure is the most likely confusion.
The control of the solvent did not change the result to a large extent.
Arc welding is accompanied by exposure to welding smoke (
Nickel and chromium, for example
For example, 34 and mixed UV radiation from these factors cannot be ignored.
One advantage of this study is that exposure is assessed at an individual level and there is no study of the possibility of personal recall bias.
Nevertheless, this study may theoretically be affected by exposure to classification errors, but the possibility of differential bias should be limited. The case-
No control status was disclosed to the representative of the company/workplace.
If the informant is aware of an employee\'s illness, this can create bias and we don\'t see any reason for him/her to exaggerate the welding rather than being exposed to the solvent.
We did not observe any compelling association of solvent exposure, except for an increase in risk estimates for adrenaline tumors. Non-
Participation can lead to selection bias.
The exit was mainly caused by some big companies.
Their refusal was due to a lack of resources to participate.
These companies seem unlikely to have the characteristic of changing effects and results.
The main shortcomings caused
Participation may be a reduction in statistical capacity.
Age-standardized incidence of endocrine tumors considered (ICD-7 code 195)
Sweden increased from less than 2 cases per 100 person years to about 1960 cases per 100 person years, and increased to about 11 in 1990.
The corresponding figure for men is close to 6 per 100 (
Data from the Swedish Cancer Registry).
However, the decline in incidence can be noted over the past five years.
35 advanced diagnosis and wider application of imaging techniques should be the main explanation for this increase, but part of this trend can of course be explained by an increase in the incidence of these tumors.
Conclusion studies have shown that the risk of endocrine gland tumors in workers exposed to arc or resistance welding has tripled.
Welding is evaluated on a personal level and it is known that these processes require an extremely high level of ELF magnetic field.
Exposure to a high level of ELF magnetic field may mediate the connection between welding and endocrine gland tumors.
The confusions of solvent exposure do not explain this association, but the confusions of other factors cannot be ruled out.
The study was funded by the Swedish commission for work life and social studies2002-0463.
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