Letter to the editor regarding
Follow-up study of chrysotile textile workers: cohort mortality and
exposure-response by Hein MJ, Stayner LT, Lehman E, Dement JM in Occup
Environ Med 2007; 64: 616-625.
Bengt Sjögren
MD, PhD,
Work Environment Toxicology,
Institute of Environmental Medicine,
Karolinska Institutet,
SE-177 77 Stockholm,
Sweden,
Phone +46 8 524 822 29,
Fax +46 8 31 41 24,
E-mail bengt.sjogren@ki...
Letter to the editor regarding
Follow-up study of chrysotile textile workers: cohort mortality and
exposure-response by Hein MJ, Stayner LT, Lehman E, Dement JM in Occup
Environ Med 2007; 64: 616-625.
Bengt Sjögren
MD, PhD,
Work Environment Toxicology,
Institute of Environmental Medicine,
Karolinska Institutet,
SE-177 77 Stockholm,
Sweden,
Phone +46 8 524 822 29,
Fax +46 8 31 41 24,
E-mail bengt.sjogren@ki.se
Hein and coworkers followed a cohort of 3072 chrysotile textile
workers until 2001(1). One of the main messages was an excess mortality
from ischaemic heart disease (IHD), SMR 1.20 (95% CI 1.10-1.32). There
were altogether 469 deaths due to IHD which is higher than the total
number of cancers being 463, but there were no calculations of dose-
response regarding IHD.
Today health effects of general air pollutants have been studied
intensively. Exposure to airborne particulate matter has been associated
with increases in mortality and hospital admissions due to cardiovascular
diseases. These effects have been found in short-term studies, which
relate day-to-day variations in air pollution and health and in long-term
studies, which have followed cohorts of exposed individuals over
time(2,3). Short-term effects of air pollutants have been studied among 38
million persons in eight European cities. An increase of 10 µg/m3 in PM10
was associated with 0.5% (95%CI 0.2-0.8%) increase in hospital admissions
for cardiac causes(4). A cohort of approximately 500 000 persons was
formed in 1982 and followed for 16 years. Each 10 µg/m3 elevation of fine
particulate (PM2.5) was associated with a 6% increase of cardiopulmonary
deaths(5). In an intervention study the cardiovascular death rate
decreased by 10% in Dublin after the ban of coal sales in 1990, which
decreased the average black smoke by 36 µg/m3 in the city(6). Thus effects
have been observed at very low levels of exposure and it is unclear
whether a threshold concentration exists for particulate matter under
which no effects occur(3).
So far very few occupational studies have focused on the relation
between air pollutants and IHD and to my knowledge none has investigated
dose-response relations between air pollutants and IHD. It is urgent that
Hein and her coworkers take this opportunity to investigate the dose-
response relationship between chrysotile asbestos exposure and IHD.
References
1. Hein MJ, Stayner LT, Lehman E, Dement JM. Follow-up study of
chrysotile textile workers: cohort mortality and exposure-response. Occup
Environ Med 2007; 64: 616-625.
2. Brook RD, Franklin B, Cascio W, et al. Air pollution and
cardiovascular disease. A statement for healthcare professionals from the
expert panel on population and prevention science of the American Heart
Association. Circulation; 2004; 109: 2655-2671.
3. Brunekreef B, Holgate ST. Air pollution and health. Lancet 2002;
360: 1233-1242.
4. Le Tertre A, Medina S, Samoli E, et al. Short-term effects of
particulate air pollution on cardiovascular diseases in eight European
cities. J Epidemiol Community Health 2002; 56: 773-779.
5. Pope CA III, Burnett RT, Thun MJ, et al. Lung cancer,
cardiopulmonary mortality, and long-term exposure to fine particulate air
pollution. JAMA 2002; 287: 1132-1141.
6. Clancy L, Goodman P, Sinclair H, Dockery DW. Effect of air-
pollution control on death rates in Dublin, Ireland: an intervention
study. Lancet 2002; 360: 1210-1214.
Measuring uranium intake using urine isotope ratio studies has been
known for a decade to only be accurate up to a few weeks after exposure.
"Urine assay for uranium inhalation exposure can be useful, provided
that measurements are made soon after a known acute intake. The urinary
excretion rate falls substantially after exposure, particularly during the
first few days. If urine analysis is carried out on a routi...
Measuring uranium intake using urine isotope ratio studies has been
known for a decade to only be accurate up to a few weeks after exposure.
"Urine assay for uranium inhalation exposure can be useful, provided
that measurements are made soon after a known acute intake. The urinary
excretion rate falls substantially after exposure, particularly during the
first few days. If urine analysis is carried out on a routine basis not
related to the pattern of intake, then the errors in the assessment of
intake can be considerable." (Ansoborlo, E., et al. (1998) "Exposure
implications for uranium aerosols formed at a new laser enrichment
facility: application of the ICRP respiratory tract and systemic model"
Radiation Protection Dosimetry 79: 23-27.)
http://rpd.oxfordjournals.org/cgi/content/abstract/79/1-4/23
This paper is a valuable review of a neglected hazard (1). However,
the following points deserve additional emphasis.
There is limited evidence that exposure to keratin nail dust can
cause allergic conditions. Guinea pigs inhaling aerosolised nail dust
produced IgE against T. rubrum, and developed lung lesions similar to
hypersensitivity pneumonitis (2). A high prevalence of wheeze has be...
This paper is a valuable review of a neglected hazard (1). However,
the following points deserve additional emphasis.
There is limited evidence that exposure to keratin nail dust can
cause allergic conditions. Guinea pigs inhaling aerosolised nail dust
produced IgE against T. rubrum, and developed lung lesions similar to
hypersensitivity pneumonitis (2). A high prevalence of wheeze has been
reported in chiropodists (3). They also have precipitating antibodies to
nail dust, raised IgE (4), and positive skin tests & IgE RAST for
T.rubrum (2). The finding that 70% of nail-dust particles were of less
than 7 ìm in diameter raises concerns of high deposition rates in the lung
(5).
Occupational infections arising from inhalation are relatively
uncommon, but pulmonary tuberculosis & aspergillosis, and ocular
C.trachomatis have all been reported in health care workers (6,7).
Seroepidemiological studies (8,9) have shown a high seroprevalence for L.
pneumophila antibodies among dental personnel using drills, although this
was not confirmed in a more recent study (10). Aerosols of nail dust are
unlikely to contain tuberculosis or C. trachomatis, but moulds have been
found (1). Studies of nail dust exposure and infectious disease in
podiatrists have been of limited scope, and have not demonstrated a
convincing association (1). McLarnon measured exposure of podiatrists to
bacteria in terms of colony forming units in air (CFU/ m3), but this may
not be a useful parameter of infectious risk (11). Individual factors such
as compromised immunity, allergy or bronchiectasis may be more important
indicators of risk, particularly for Aspergillus (6).
There do not appear to be any reports in the literature of
measurements of airborne nail dust using standard gravimetric occupational
hygiene techniques (e.g. personal monitoring of exposure to inhalable and
respirable dust).
With regard to controlling dust exposure, the studies cited in the
article found that LEV reduced levels of dust, but did not use methods
which would allow comparison with HSE standards (1). Anecdotal reports
suggest that newer types of podiatric drills have more efficient dust
extraction systems than older models. The effectiveness of general room
ventilation has not been studied in podiatry. Studies show that both the
speed and type of tool used for nail reduction influence nail dust
production. Lower operating speeds appear to generate less dust, but at
the cost of lower amounts of nail removed (1). Thus using a tool at a
lower speed and for longer periods increases the treatment time, the
duration of dust production and possibly the total amount of dust
generated. The data presented in the cited papers makes it difficult to
discern the optimum tool types and operating speeds for of dust control
(1). Nails can also be reduced manually using a scalpel. However this
would also increase treatment times, and be associated with it’s own
risks: namely accidental blood exposure to the operator, patient injury
and work-related upper limb disorders.
The effectiveness of respiratory PPE has not been effectively studied
in podiatry (1). Because gravimetric studies of podiatric dust levels have
not been undertaken, the required mask protection factor is not known. For
small dust particles, high efficiency masks would be required. These would
have the usual drawbacks of user-discomfort, cost, fit-difficulties and
staff-training.
In conclusion, podiatric drills should be well maintained, and LEV
routinely used to minimise dust exposure. Quantitative measurements of
dust levels may be useful (i) to identify the most effective forms of LEV,
(ii) for comparison with the HSE recommendations for general dust levels,
and (iii) to provide a guide for respiratory PPE requirements. However, it
is important to note that levels of respirable dust below the general
Health & Safety Executive standard of 4 mg/m3 would not necessarily
protect against allergic conditions such as asthma. In view of the risks
of allergy, infectious disease in staff with pre-existing lung disease,
and the lack of information from studies; regular respiratory health
surveillance of podiatrists should be considered, to comply with the COSHH
regulations.
No competing interests.
References
1. Burrow JG & McLarnon NA, 2006. World at work: evidence based
risk management of nail dust in chiropodists and podiatrists. Occup Env
Med 63(10):713-6.
2. Alonso A et al, 2003. [Hypersensitivity to Trichophyton rubrum
antigens in atopic and non-atopic podiatrists]. Allergol Immunopathol
(Madr) Mar-Apr;31(2):70-6.
3. Gatley M, 1991. Human nail dust: hazard to chiropodists or merely
nuisance. J Soc Occup Med 41:121-125.
4. Abramson C & Wilton, 1992b. Nail dust from onychomycotic
toenails. Part II, clinical & serological aspects. J Am Pod Med Assoc
82(2):116-123.
5. Purkiss R, 1997. An assessment of the airborne dust in podiatric
treatment area, and its relevance to the use of respiratory protective
equipment. J Brit Pod Med 52(9):129-136.
6. Woodhead M, 1995. Infectious diseases and zoonoses. In Parkes RW
(editor). Occupational lung disorders, 3rd edition.
7. Midulla M et al, 1987. Infection by airborne Chlamydia trachomatis
in a dentist cured with rifampicin after failure with tetracycline and
doxycycline. Brit Med J 294:742.
8. Fotos PG et al, 1985. Prevalence of Legionella specific IgG and
IgM antibody in a dental clinic population. J Dent Res 64(12):1382-5.
9. Reinthaler FF, Mascher F & Stunzer D, 1988. Serological
examinations for antibodies against Legionella species in dental
personnel. J Dent Res 67(6):942-3.
10. Pankhurst CL et al, 2003. Prevalence of legionella waterline
contamination and
Legionella pneumophila antibodies in general dental practitioners in
London and rural Northern Ireland. Br Dent J 195(10):591-4.
11. McClarnon N et al. The use of an air filtration system in
podiatry clinics. Int J of Env Health Res 13:215-221.
We are writing in response to the editorial (1) relating to our
previously published paper on a consensus study defining occupational
asthma and confirming the diagnosis (2). We feel that the editorial reads
more into the RAND consensus approach than the technique allows. The RAND
process is a validated approach to develop consensus in situations where
no gold standard or formal agreement exists. It is not possible to de...
We are writing in response to the editorial (1) relating to our
previously published paper on a consensus study defining occupational
asthma and confirming the diagnosis (2). We feel that the editorial reads
more into the RAND consensus approach than the technique allows. The RAND
process is a validated approach to develop consensus in situations where
no gold standard or formal agreement exists. It is not possible to deviate
from the technique even if the researchers do not fully support the
consensus outcomes. We do not believe that the RAND technique is
sufficiently robust to interpret small differences in scores, for example
from 7-9 in our original paper.
We agreed that all the usual tests should be available in specialised
centres, including spirometry, peak flow monitoring and OASYS computer
plotting, non specific bronchial reactivity, specific IgE to occupational
allergens, workplace challenges, specific occupational challenge tests and
the availability to do workplace visits. We would also like to confirm
that the outcomes of the BOHRF document (3), with which our consensus
concurs, were unknown to the consensus panel at the time of the data
collection.
The editors reasonably reflect on international differences in
frequency of use of challenge testing. In the UK investigation of workers
with possible occupational asthma has to be done at the same cost as
routine respiratory outpatient visits. A premium tariff would be needed to
match countries where insurance funding of investigation and benefits
require a higher diagnostic rigour. Nevertheless, even if more adequate
funding were available, we doubt that the comments made about specific
challenge testing would alter significantly.
The use of sputum cytology and exhaled NO in the management or
diagnosis of constitutional and occupational asthma is not yet
established, hence it’s low ranking.
Another point in the editorial is the consensus agreement of the need
for other testing, such as physiological, radiological, biochemical and
immunological. We prefer a holistic and inclusive assessment of other co-
existing diseases which affect workability and disability. In addition,
some factors (such as total IgE) are required to interpret other tests,
for example specific IgE assays isocyanate-HSA conjugates which may be
confounded by non-specific binding with high levels of total IgE.
We do agree that some of the newer internet databases of occupational
asthma are useful in addition to the toxicological databases referred to
in our paper.
In summary, we feel that the RAND technique provided a method to
identify the weaknesses present in the general availability of UK
diagnostic services for occupational lung disease. Furthermore it has
helped to develop a “national standard of care” document, currently in
final publication review.
We believe our work has contributed to a better clarity of diagnostic
awareness within the UK. We wonder whether other countries less fortunate
in their funding provision for diagnostic services in comparison to
Finland, Canada and Belgium, may find our work reflective of the
practical problems faced locally when investigating workers with possible
occupational asthma.
References
1. Malo JL, Newman Taylor A. Defining occupational asthma and
confirming the diagnosis: what do experts suggest? Occup.Environ.Med.
2007;64:359-360.
3. Nicholson PJ, Newman Taylor A, et al. Evidence guidelines for the
prevention, identification, and management of occupational asthma.
Occup.Environ.Med. 2005;62:290-299.
This multicentre study confirms the idea that man made mineral fibres
(1), with exception of refractory ceramic fibres (2), are not associated
with lung cancer.
Modern monitoring techniques would allow a more exact determination
of fibre dose (1,2) so that a prospective study would be possible as to
the malignant disease risk also at other sites than respiratory tract (3).
This multicentre study confirms the idea that man made mineral fibres
(1), with exception of refractory ceramic fibres (2), are not associated
with lung cancer.
Modern monitoring techniques would allow a more exact determination
of fibre dose (1,2) so that a prospective study would be possible as to
the malignant disease risk also at other sites than respiratory tract (3).
1 Paananen H, Holopainen M, Kalliokoski P, et al. Evaluation of
exposure to man-made vitreous fibres by nasal lavage. J Occup Environ Hyg,
2004; 1: 82-87.
2 Linnainmaa M, Kangas J, Mäkinen M, et al. Exposure to refractory
ceramic fibres in the metal industry. Ann Occup Hyg, in press.
3 LeMasters GK, Lockey JE, Yin JH, et al. Mortality of workers
exposed to refractory ceramic fibers. J Occup Environ Med, 2003; 45: 440-
450.
We have read the interesting paper from Adam Simning and Edwin van
Wijngaarden about cancer in dentists. However, in their article, they
attribute the increased skin cancer occurrence in this occupation to
socioeconomic status.
In this sense, we would like to point out that, at least in Sweden,
our results showed a significant risk excess of melanoma in males dentists
[1] and female...
We have read the interesting paper from Adam Simning and Edwin van
Wijngaarden about cancer in dentists. However, in their article, they
attribute the increased skin cancer occurrence in this occupation to
socioeconomic status.
In this sense, we would like to point out that, at least in Sweden,
our results showed a significant risk excess of melanoma in males dentists
[1] and female dental nurses [2] even after socioeconomic adjustment.
Female dentists had also a non significant increase of risk. Higher
incidences of melanoma than expected by chance for dentistry, in both men
and women, have been found in pooled SIR of Nordic countries [3], in
England and Wales [4], but also in socioeconomic adjusted estimators for
men in US [5] and Switzerland, [6]. Dentists are exposed to certain agents
that have been related to this neoplasm, such as artificial sources of UV
radiation[7] and/or mercury[8]. Thus, occupational explanations for this
possible excess should also be kept in mind
1 Perez-Gomez B, Pollan M, Gustavsson P, et al. Cutaneous melanoma:
hints from occupational risks by anatomic site in Swedish men. Occup
Environ Med 2004;61:117-26.
2 Perez-Gomez B, Aragones N, Gustavsson P, et al. Cutaneous melanoma
in Swedish women: Occupational risks by anatomic site. Am J Ind Med
2005;48 (4):270-81.
3 Andersen A, Barlow L, Engeland A, et al. Work-related cancer in
the Nordic countries. Scand J Work Environ Health 1999;25 (Suppl 2):1-116.
4 Vagero D, Swerdlow AJ, Beral V. Occupation and malignant melanoma:
a study based on cancer registration data in England and Wales and in
Sweden. Br J Ind Med 1990;47 (5):317-24.
5 Goodman KJ, Bible ML, London S, et al. Proportional melanoma
incidence and occupation among white males in Los Angeles County
(California, United States). Cancer Causes Control 1995;6 (5):451-9.
6 Bouchardy C, Schuler G, Minder C, et al. Cancer risk by occupation
and socioeconomic group among men--a study by the Association of Swiss
Cancer Registries. Scand J Work Environ Health 2002;28 (Suppl 1):1-88.
7 Westerdahl J, Ingvar C, Masback A, et al. Risk of cutaneous
malignant melanoma in relation to use of sunbeds: further evidence for UV-
A carcinogenicity. Br J Cancer 2000;82 (9):1593-9.
8 Magnani C, Coggon D, Osmond C, et al. Occupation and five cancers:
a case-control study using death certificates. Br J Ind Med 1987;44
(11):769-76.
We thank Dr Preece for his comments. We believe that he is justified
in questioning the make up of the panel and that this has a significant
bias for tertiary assessment of occupational lung disease. However our
aim in performing this process was to get this group of experts to agree
on "definitions” with a view to unifying the label at this later clinical
stage of the process. In addition we hoped that the requirements...
We thank Dr Preece for his comments. We believe that he is justified
in questioning the make up of the panel and that this has a significant
bias for tertiary assessment of occupational lung disease. However our
aim in performing this process was to get this group of experts to agree
on "definitions” with a view to unifying the label at this later clinical
stage of the process. In addition we hoped that the requirements of a
specialist occupational lung disease assessment service would form a basis
for developing a standards of care document for those giving expert
medical advice in this specialist field. We felt that it was appropriate
to carry out the process from this stand-point, as if this body could not
agree on what constitutes occupational asthma or work aggravated asthma in
principal, how could we work towards an agreed process for evaluation at
all levels?
A similar exercise done in parallel using occupational physicians
would be a very interesting and valuable exercise. It is likely that the
view of work place based physicians will be different because of local
variations in perspectives. We reiterate that it was never intended for
this to be within the scope of this project. In carrying out the process
in this way we certainly did not wish to alienate our occupational
physician colleagues and in no way intend to imply that their viewpoint is
not valued. We felt it was valuable to share the perspectives from the
specialist occupational lung physician, in publishing our findings.
Finally we note the comment regarding the evidence based guidelines
and whilst there is some practical relevance of the consensus to the
guidelines and joint interested parties on the two documents, it was not
practical to include the consensus in the guidelines. Doing so would have
caused a significant delay in publishing the guidelines which was not
merited as after all consensus is the least important and lowest level of
evidence base.
We thank Dr Kalman for his views and understand his issues with
regard to context, a point similar to that made by Dr Preece. We performed
this study, specifically to deal with producing the definition on which
specialist centres should base their assessment of cases of possible work
related asthma. The facilities required component was specifically aimed
at identifying standards of care for this process. Whilst the definitions
are of relevance to the work site and legal situations, we felt that a
firm basis for discussion and minimum criteria required to assess
difficult cases appropriately was an important issue and the sole basis
for this study. The requirement of a breech of statutory duty of care
does not affect the clinical diagnosis or management of a worker in the
workplace. We feel that a medical diagnosis (such as occupational asthma)
should be based on what is wrong with the patient and what is the cause.
I found the recent paper “Reducing healthy worker survivor bias by
restricting date of hire in a cohort study of Vermont granite workers” by
Applebaum, Malloy and Eisen to be of great interest, especially as my
colleagues and I are currently conducting a mortality study of Vermont
granite workers. The cohort used by Applebaum et al., which was assembled
and followed by W.G.B. Graham and J. Costel...
I found the recent paper “Reducing healthy worker survivor bias by
restricting date of hire in a cohort study of Vermont granite workers” by
Applebaum, Malloy and Eisen to be of great interest, especially as my
colleagues and I are currently conducting a mortality study of Vermont
granite workers. The cohort used by Applebaum et al., which was assembled
and followed by W.G.B. Graham and J. Costello, has been used in several
previous studies.(1-3) Our current study includes this cohort, but we
have endeavored to identify workers who were not in the Graham cohort
because they did not have a chest X-ray as part of a medical surveillance
program. From our efforts to date, it appears that they constituted about
a third of all workers. Because the exclusion of these individuals may
have introduced considerable selection bias, the results of all studies
based on the Graham cohort should be interpreted with caution.
Sincerely,
Pamela M. Vacek
References:
1. Costello J, Graham WGB. Vermont granite workers’ mortality
study. Am J Ind Med 1988; 13:483-97.
2. Graham WGB, Costello J, Vacek PM: Vermont granite mortality
study: an update with an emphasis on lung cancer. J Occup Environ Med
2004; 46:459-66.
3. Attfield MD, Costello J. Quantitative exposure-response for
silica dust and lung cancer in Vermont granite workers. Am J Ind Med
2004; 45:129-38.
Sir
Francis and her colleagues have completed an interesting and useful piece
of work in relation to a definition of, and diagnostic resources required
for occupational asthma. It is, in my view, however important to identify,
in full, the context of such definitions if they are not to be used for
unintended purposes or, perhaps, inappropriately.
Is it possible to suggest that the term 'occupational asthma' used in
term...
Sir
Francis and her colleagues have completed an interesting and useful piece
of work in relation to a definition of, and diagnostic resources required
for occupational asthma. It is, in my view, however important to identify,
in full, the context of such definitions if they are not to be used for
unintended purposes or, perhaps, inappropriately.
Is it possible to suggest that the term 'occupational asthma' used in
terms of identifying work factors important to be controlled in that
individual's protection could be different from a definition of
occupational asthma in terms of regulatory or litigation issues where,
perhaps, part of the definition could be in relation to a breech of a
statutory duty of care?
I, at least, do not believe that these 2 issues are the same in relation
to asthma, and in relation to a number of other health conditions which
have some work relation. I wonder if the authors would agree that the
deliberations in terms of scope might have been different if their
starting definition had included considerations of employers' liability,
as well as a clinical basis?
Chris Kalman
Mr. Darby raises some interesting points regarding the prevention of
discomfort and pain among computer users. The main topic is whether the
suggestion to limit computer time (IJmker et al., 2007) has validity in
preventing hand-arm-wrist and neck-shoulder symptoms.
We agree with Mr Darby that reducing the duration of computer use
without breaks may not be the solution for all workers. At present, there
is unc...
Mr. Darby raises some interesting points regarding the prevention of
discomfort and pain among computer users. The main topic is whether the
suggestion to limit computer time (IJmker et al., 2007) has validity in
preventing hand-arm-wrist and neck-shoulder symptoms.
We agree with Mr Darby that reducing the duration of computer use
without breaks may not be the solution for all workers. At present, there
is uncertainty regarding the positive effects of breaks in preventing hand
-arm-wrist and neck-shoulder symptoms, since high quality intervention
studies are lacking and the results from the available evidence are
inconsistent (Brewer et al., 2006; Bongers et al., 2006). In addition, a
study by Veiersted (1994) among assembly line workers might fit into the
idea that rest breaks might not be productive in preventing symptoms for
some workers. He found that during forced machine stops future patients
showed higher muscle tension compared to employees who remained healthy.
In addition, Blangsted and co-workers (2003) showed that increasing the
duration of rest breaks does not per se cause muscle relaxation. High
quality studies are needed in this field.
Mr Darby also notes that reducing time alone may be
“superficial�, given the supposed underlying mechanism (i.e. sustained
muscle activation). Mr. Darby notes a number of factors that might relate
to muscle tension during mouse use. We agree on these factors. However, in
our opinion there are other factors to be considered as well, if we assume
that sustained muscle activation plays a leading role in the development
of symptoms. Factors to be added to the list might be cognitive demands
(Waersted, Bjorklund and Westgaard, 1991) and psychosocial demands (i.e.
time pressure, see Visser et al., 2004). Despite the indications from
experimental lab studies, longitudinal field studies studying the additive
and or multiplicative effect of these factors, in combination with the
duration of mouse use per se, are lacking. Currently several longitudinal
studies are in progress that use software to register computer use and
associated factors. We hope that these studies will provide more insight
into these issues.
Contrary to what Mr. Darby states, modern break reminder software
already registers mouse use. This information is integrated with
information on keyboard use into algorithms to provide feedback to the
user to take a break from computer work. However this kind of software
does not register all the factors listed by Mr Darby. For example, the
gripforce while pointing the mouse is not registered.
Finally, we would like to note that the review included a limited
number of studies, which where all based on self-reported duration of
computer use. Future studies, especially those with objective recordings
of computer use, might change our conclusions. Also, the
pathophysiological link we made between mouse use, sustained muscle
activation and symptoms, has been criticized (Knardahl, 2002).
References
IJmker S, Huysmans MA, Blatter BM, van der Beek AJ, van Mechelen W,
Bongers PM. Should office workers spend fewer hours at their computer? A
systematic review of the literature. Occup Environ Med. 2007;64(4):211-22.
Veiersted KB. Sustained muscle tension as a risk factor for trapezius
myalgia. Int J Ind Ergon. 1994;14:333-339.
Blangsted AK, Sogaard K, Christensen H, Sjogaard G. The effect of
physical and psychosocial loads on the trapezius muscle activity during
computer keying tasks and rest periods. Eur J Appl Physiol. 2004;91(2-
3):253-8.
Brewer S, Van Eerd D, Amick BC 3rd, Irvin E, Daum KM, Gerr F, Moore
JS, Cullen K, Rempel D. Workplace interventions to prevent musculoskeletal
and visual symptoms and disorders among computer users: a systematic
review. J Occup Rehabil. 2006;16(3):325-58.
Bongers PM, Ijmker S, van den Heuvel S, Blatter BM. Epidemiology of
work related neck and upper limb problems: psychosocial and personal risk
factors (part I) and effective interventions from a bio behavioural
perspective (part II). J Occup Rehabil. 2006;16(3):279-302.
Waersted M, Bjorklund RA, Westgaard RH. Shoulder muscle tension
induced by two VDU-based tasks of different complexity. Ergonomics.
1991;34(2):137-50.
Visser B, De Looze M, De Graaff M, Van Dieen J. Effects of precision
demands and mental pressure on muscle activation and hand forces in
computer mouse tasks.
Ergonomics. 2004;47(2):202-17.
Knardahl S. Psychophysiological mechanisms of pain in computer work:
the blood vessel-nociceptor interaction hypothesis. Work & Stress
2002;16(2):179-189.
Letter to the editor regarding Follow-up study of chrysotile textile workers: cohort mortality and exposure-response by Hein MJ, Stayner LT, Lehman E, Dement JM in Occup Environ Med 2007; 64: 616-625.
Bengt Sjögren MD, PhD, Work Environment Toxicology, Institute of Environmental Medicine, Karolinska Institutet, SE-177 77 Stockholm, Sweden, Phone +46 8 524 822 29, Fax +46 8 31 41 24, E-mail bengt.sjogren@ki...
Measuring uranium intake using urine isotope ratio studies has been known for a decade to only be accurate up to a few weeks after exposure.
"Urine assay for uranium inhalation exposure can be useful, provided that measurements are made soon after a known acute intake. The urinary excretion rate falls substantially after exposure, particularly during the first few days. If urine analysis is carried out on a routi...
Dear Sir
This paper is a valuable review of a neglected hazard (1). However, the following points deserve additional emphasis.
There is limited evidence that exposure to keratin nail dust can cause allergic conditions. Guinea pigs inhaling aerosolised nail dust produced IgE against T. rubrum, and developed lung lesions similar to hypersensitivity pneumonitis (2). A high prevalence of wheeze has be...
We are writing in response to the editorial (1) relating to our previously published paper on a consensus study defining occupational asthma and confirming the diagnosis (2). We feel that the editorial reads more into the RAND consensus approach than the technique allows. The RAND process is a validated approach to develop consensus in situations where no gold standard or formal agreement exists. It is not possible to de...
Dear Editor,
This multicentre study confirms the idea that man made mineral fibres (1), with exception of refractory ceramic fibres (2), are not associated with lung cancer.
Modern monitoring techniques would allow a more exact determination of fibre dose (1,2) so that a prospective study would be possible as to the malignant disease risk also at other sites than respiratory tract (3).
1 Paana...
To the Editor:
We have read the interesting paper from Adam Simning and Edwin van Wijngaarden about cancer in dentists. However, in their article, they attribute the increased skin cancer occurrence in this occupation to socioeconomic status.
In this sense, we would like to point out that, at least in Sweden, our results showed a significant risk excess of melanoma in males dentists [1] and female...
We thank Dr Preece for his comments. We believe that he is justified in questioning the make up of the panel and that this has a significant bias for tertiary assessment of occupational lung disease. However our aim in performing this process was to get this group of experts to agree on "definitions” with a view to unifying the label at this later clinical stage of the process. In addition we hoped that the requirements...
To the Editor:
I found the recent paper “Reducing healthy worker survivor bias by restricting date of hire in a cohort study of Vermont granite workers” by Applebaum, Malloy and Eisen to be of great interest, especially as my colleagues and I are currently conducting a mortality study of Vermont granite workers. The cohort used by Applebaum et al., which was assembled and followed by W.G.B. Graham and J. Costel...
Sir Francis and her colleagues have completed an interesting and useful piece of work in relation to a definition of, and diagnostic resources required for occupational asthma. It is, in my view, however important to identify, in full, the context of such definitions if they are not to be used for unintended purposes or, perhaps, inappropriately. Is it possible to suggest that the term 'occupational asthma' used in term...
Mr. Darby raises some interesting points regarding the prevention of discomfort and pain among computer users. The main topic is whether the suggestion to limit computer time (IJmker et al., 2007) has validity in preventing hand-arm-wrist and neck-shoulder symptoms.
We agree with Mr Darby that reducing the duration of computer use without breaks may not be the solution for all workers. At present, there is unc...
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