Chen et al [1] reported the positive association between
environmental tobacco smoke (ETS) and severe dementia syndromes. They
mentioned that Cox regression model was applied to detect statistical
significance.
I have two queries on their study. First, they conducted cross-
sectional study and Cox regression analysis was applied to detect relative
risk by adjusting several confounders. They described the methodol...
Chen et al [1] reported the positive association between
environmental tobacco smoke (ETS) and severe dementia syndromes. They
mentioned that Cox regression model was applied to detect statistical
significance.
I have two queries on their study. First, they conducted cross-
sectional study and Cox regression analysis was applied to detect relative
risk by adjusting several confounders. They described the methodological
explanation in the 4th paragraph of the discussion, mainly avoiding
overestimation of the association. Although they quoted one reference [2]
with their previous two papers to select Cox regression analysis,
estimation of odds ratio by logistic regression analysis seems appropriate
in their cross-sectional study, because statistical advantage of handling
censored cases and duration from baseline to event occurrence was not
considered for their analysis.
Second, in their Table 1, 791 current smokers were categorized as no
ETS exposure group. There is no difference of ETS exposure from others or
from himself/herself, and ETS can be applied to never smokers or former
smokers in general. This also related to the content in Table 3, which
presents risk assessment of ETS to all participants, including current
smokers, with severe dementia syndromes. As Table 3 contains results for
3769 never smokers, their conclusion that highest ETS exposure by
cumulative dose is a significant risk factor for severe dementia syndromes
is acceptable.
The mean age is over 70 years in their study, and the validation of
ETS exposure for long-term period should also be evaluated. As there is a
report that heavy smoking in midlife becomes a risk of Alzheimer disease
[3], cause-effect relationship between ETS and severe dementia syndromes
by longer follow-up study with adjustment of several confounders should be
conducted to validate their results.
REFERENCES
1. Chen R, Wilson K, Chen Y, et al. Association between environmental
tobacco smoke exposure and dementia syndromes. Occup Environ Med
2013;70:63-9.
2. Zhang J, Yu KF. What's the relative risk? A method of correcting
the odds ratio in cohort studies of common outcomes. JAMA 1998;280:1690-1.
3. Rusanen M, Kivipelto M, Quesenberry CP Jr, et al. Heavy smoking in
midlife and long-term risk of Alzheimer disease and vascular dementia.
Arch Intern Med 2011;171:333-9.
Hambach et al [1] have published cross-sectional study on the
associations between cadmium (Cd) exposure and renal or oxidative stress
biomarkers in 36 solderers. They adopted multiple regression analysis to
detect statistical significance with adjustment of age and pack-years of
smoking. In contrast, there is a significant relationship between low
levels of Cd exposure and N-acetyl-beta-D-glucosaminidase (NAG) [2,3],
w...
Hambach et al [1] have published cross-sectional study on the
associations between cadmium (Cd) exposure and renal or oxidative stress
biomarkers in 36 solderers. They adopted multiple regression analysis to
detect statistical significance with adjustment of age and pack-years of
smoking. In contrast, there is a significant relationship between low
levels of Cd exposure and N-acetyl-beta-D-glucosaminidase (NAG) [2,3],
with special emphasis on smoking status [4,5].
I have two queries on their study. First, they used pack-years of
smoking as independent variables to know the effect of occupational Cd
exposure by excluding the effect of Cd exposure by smoking. In their
tables 3 and 4, explanation rate expressed by the square values of
multiple regression coefficient (R) were under 0.3, and significant levels
were near the borderline. I have some doubt on the validity of non-
occupational Cd exposure by pack-years of smoking, especially for
populations with low levels of Cd exposure. I want to recommend Hambach et
al to add the information on the relationship between Cd exposure and
renal or oxidative stress markers without adjustment by pack-years of
smoking. In addition, regression coefficients and standard errors of age
and pack-years of smoking should also be presented to know the effect of
age and smoking on several biomarkers.
Second, Hambach et al described in their Table 3 that urinary NAG was
normally distributed and logarithmic transformation was not conducted. In
addition, some of the gradients of three renal markers except IAP showed
negative values, which is difficult to explain biologically.
I suppose that the separation of occupational and non-occupational Cd
exposure is not easy in workers with low level of Cd exposure, and direct
relationship between Cd exposure and biological markers with only
adjustment of age would be informative to make comparison of their results
with past reports.
REFERENCES
1. Hambach R, Lison D, D'Haese P, et al. Adverse effects of low
occupational cadmium exposure on renal and oxidative stress biomarkers in
solderers. Occup Environ Med 2013;70:108-13.
2. Kawada T, Koyama H, Suzuki S. Cadmium, NAG activity, and beta 2-
microglobulin in the urine of cadmium pigment workers. Br J Ind Med
1989;46:52-5.
3. Noonan CW, Sarasua SM, Campagna D, et al. Effects of exposure to
low levels of environmental cadmium on renal biomarkers. Environ Health
Perspect 2002;110:151-5.
4. Akesson A, Lundh T, Vahter M, et al. Tubular and glomerular kidney
effects in Swedish women with low environmental cadmium exposure. Environ
Health Perspect 2005;113:1627-31.
5. Koyama H, Satoh H, Suzuki S, et al. Increased urinary cadmium
excretion and its relationship to urinary N-acetyl-beta-D-glucosaminidase
activity in smokers. Arch Toxicol 1992;66:598-601.
We read the article by Njoku and Orisakwe comparing blood lead levels
(BLL) in rural and urban pregnant women in Eastern Nigeria with great
interest [1]. The authors found that BLL were substantially higher in
rural areas than urban areas (135+/-160 vs 77+/-100 ug/dl). This in itself
is an important finding: it may reflect a stronger reliance on locally
grown foodstuffs in rural areas, combined with the effect of lead expo...
We read the article by Njoku and Orisakwe comparing blood lead levels
(BLL) in rural and urban pregnant women in Eastern Nigeria with great
interest [1]. The authors found that BLL were substantially higher in
rural areas than urban areas (135+/-160 vs 77+/-100 ug/dl). This in itself
is an important finding: it may reflect a stronger reliance on locally
grown foodstuffs in rural areas, combined with the effect of lead exposure
from soil and dust from farming. However, the authors understate the
importance of the overall BLL in this area of Eastern Nigeria (99+/-123
ug/dl). This level is substantially higher than has been found during
pregnancy in other developing countries (e.g. Mumbai, India (geometric
mean 6.4+/-1.69 ug/dl [2]) or in developed countries where there is a high
environmental exposure (e.g. Sweden (smelter) 2.63+/-0.31 ug/dl [3]), or
even in other countries in Africa (e.g. South Africa (median 2.3 ug/dl
[4]). The reported levels are sufficient to cause overt symptoms of lead
toxicity. As the authors note, there is free flow of lead though the
placenta, with the ratio of fetal:maternal lead being about 0.7-0.9. Thus,
the BLL of the newborn infants of these mothers will be about 80 ug/dl,
and will rise further with exposure from breast-milk and local foods, and
from the environment. These children are at extremely high risk of
neurological damage and impaired growth and development, as stated by the
authors. It is of note that the Centers for Disease Control and Prevention
(CDC) in the USA recommends chelation therapy for BLL of >45 ug/dl in
children [5]. The authors provide some data on the lead levels in local
staple foods: the high levels in these foods must reflect severe
contamination of farmland. The BLL in these pregnant women is of great
public health concern, not only for themselves, but also for their
children and subsequent generations.
References
1. Njoku CO, Orisakwe OE. Higher blood lead levels in rural than
urban pregnant women in Eastern Nigeria. Occ Environ Med 2012.doi
10.1136/oemed-2012-100947.
2. Raghunath R, Tripathi RM, Sastry VN, Krishnamurthy TM. Heavy
metals in maternal and cord blood. Sci Total Environ 2000;250:135-41.
3. Lagerkvist BJ, Ekesrydh S, Englyst V, Nordberg GF, Soderberg HA,
Wiklund DE. Increased blood lead and decreased calcium levels during
pregnancy: A prospective study of Swedish women living near a smelter. Am
J Pub Health 1996;86:1247-52.
4. Rudge CV, Rollin HB, Nogueira CM, Thomassen Y, Rudge MC, Odland
JO. The placenta as a barrier for toxic and essential elements in paired
maternal and cord blood samples of South African delivering women. J
Environ Monitor 2009;11:1322-30.
5. Centres for Disease Control. Lead. Managing elevated blood lead
levels among young children: recommendations from the Advisory Committee
on Childhood Lead Poisoning Prevention Committee 2002. Available at:
http://www.cdc.gov/nceh/lead/CaseManagement/caseManage_chap3.htm (accessed
20 September 2012).
The Editor
Occupational and Environmental Medicine
14th September, 2012
Cadmium, arsenic and lung cancer: A complete picture?
Were the occupational lung cancers among former employees at the
cadmium recovery plant located near Denver, CO, USA due to cadmium
exposures, arsenic exposures or both? One of us recently suggested that a
"simultaneous analysis of lung cancer risks in relation to both...
The Editor
Occupational and Environmental Medicine
14th September, 2012
Cadmium, arsenic and lung cancer: A complete picture?
Were the occupational lung cancers among former employees at the
cadmium recovery plant located near Denver, CO, USA due to cadmium
exposures, arsenic exposures or both? One of us recently suggested that a
"simultaneous analysis of lung cancer risks in relation to both recent and
distant cadmium and arsenic exposures" was required, and that researchers
should "let the data speak and not design an analysis that assumes in
advance which of these variables is important".[1] Although the new paper
from Robert Park and co-workers [2] does not appear to respond to these
suggestions, we believe their data could assist with authoritative
interpretation.
Findings from the only other cohort study to carry out an analysis of
occupational lung cancer risks in relation to quantitative estimates of
cadmium and arsenic exposures (and exposures to other metals) were
consistent with the hypotheses that recent arsenic exposures are more
important than distant exposures, and that cadmium exposures are
unimportant.[3] In addition indirect evidence that a late stage
carcinogen was operating at the Globe plant has already been provided.[4]
Analyses of recent exposures in the current study could be illuminating
and need to be carried out.
In addition, analyses in which the size of the arsenic effect is not
constrained need to be reported. Some of the later stages of processing
at the Globe plant would only have had exposures to cadmium because the
arsenic had already been removed (e.g. solution, pigment). This contrast
provides a cell with cadmium effects only. Therefore, there is the
potential for separating the independent effects of arsenic and cadmium,
without applying constraints to the modelling.
Reference
1. Sorahan T. Cadmium, arsenic and lung cancer: the bigger picture. Occup Med (Lond) 2010;60:236.
2. Park RM, Stayner LT, Petersen MR, et al. Cadmium and lung cancer mortality accounting for simultaneous arsenic exposure. Occup Environ Med 2012;69:303-9.
3. Jones SR, Atkin P, Holroyd C et al. Lung cancer mortality at a UK tin smelter. Occup Med (Lond) 2007;57:238-45.
4. Sorahan T. Lung cancer morality in arsenic-exposed workers from a cadmium recovery plant. Occup Med (Lond) 2009;59:264-6.
1Institute of Occupational and Environmental Medicine, University of
Birmingham, Edgbaston, Birmingham, B15 2TT, UK;
2Environmental and Occupational Health Sciences, University of Illinois at Chicago, School of Public Health (W) M/C 922, 2121 West Taylor St., Chicago, IL 60612, USA
We appreciate the interest of Dr. Garlantezec and colleagues in our
article on the association between maternal occupational exposure to
organic solvents (chlorinated, aromatic and Stoddard) and birth defects.
We reported a positive association between chlorinated solvents and neural
tube defects, particularly spina bifida; we did not observe an association
between solvent exposure and orofacial clefts.
We appreciate the interest of Dr. Garlantezec and colleagues in our
article on the association between maternal occupational exposure to
organic solvents (chlorinated, aromatic and Stoddard) and birth defects.
We reported a positive association between chlorinated solvents and neural
tube defects, particularly spina bifida; we did not observe an association
between solvent exposure and orofacial clefts.
As noted in their comment, our exposure assessment did not include
oxygenated solvents such as glycol ethers, which have been previously
linked with an increased prevalence of some birth defects, including both
oral clefts and neural tube defects. Garlantezec et al. suggest that our
exclusion of oxygenated solvents may explain our null findings for oral
clefts because women exposed to such solvents may be included in our
reference group, thereby introducing bias. Though potentially a plausible
explanation for our findings, we believe that bias due to the lack of
assessment for oxygenated solvents is unlikely. Based on preliminary,
unpublished data from an expert industrial hygienist review-based
assessment for the National Birth Defects Prevention Study, only 0.4
percent of working women in our study population had any exposure to
glycol ethers during pregnancy or the 3 months before conception. Because
the prevalence of occupational exposure to glycol ethers in our study
population is exceedingly rare, its omission would not result in a
meaningful underestimate of our effect measure estimates. However,
estimated exposure to other oxygenated solvents such as aliphatic
alcohols, ketones, esters and aldehydes in our study population is
unknown.
We agree with Dr. Garlantezec and colleagues that differences in the
definition of exposure (characterized by solvent type, formulation or
mixture, frequency and intensity, etc., as noted in our Discussion) may
explain apparent "inconsistencies" in reported results across studies. We
encourage further dialogue and research aimed at elucidating the true
underlying relation between exposure to distinct classes of organic
solvents and birth defects.
We read with interest the report by Desrosiers et al of the
association between maternal occupational exposure to organic solvents and
some birth defects [1]. Their case-control study examined occupational
exposure to three classes of solvents (chlorinated, aromatic and Stoddard)
and found one association -- between neural tube defects (mainly spinal
bifida) and maternal occupational exposure to chlorinated solvents, but n...
We read with interest the report by Desrosiers et al of the
association between maternal occupational exposure to organic solvents and
some birth defects [1]. Their case-control study examined occupational
exposure to three classes of solvents (chlorinated, aromatic and Stoddard)
and found one association -- between neural tube defects (mainly spinal
bifida) and maternal occupational exposure to chlorinated solvents, but no
association with the other solvent classes or with oral clefts. In their
discussion, the authors noted that previous findings of maternal
occupational exposure to solvents and oral clefts were from European,
mainly French, populations and hypothesized that the inconsistency between
their results and these previous studies might be due to different
exposure profiles (e.g., intensity, solvent formulation). Although this
explanation is plausible, another must be discussed: differences in the
definition of exposure. Our research team conducted four of the five
studies with positive results cited by Desrosiers et al[2][3][4][5]. All
four were population based and included, in addition to the solvent
classes considered by Desrosiers et al, oxygenated solvents, for example
alcohols or glycol ethers. Exposure limited to only oxygenated solvents
appears to be very frequent among working women: more than half of the
solvent exposure group in Chevrier et al [4] were exposed only to that
solvent class. Because previous studies found the increased risk of oral
clefts to be associated principally with that specific exposure, the
failure to consider this association could explain the negative findings
for oral clefts. Moreover, women who were exposed only to oxygenated
solvents are included in the reference ('non-exposed') group here, which
would result in underestimating associations with chlorinated and
petroleum solvents. For both these reasons, we think that the failure to
consider oxygenated solvents led to underestimating the risk estimates for
oral clefts.
1. Desrosiers, T.A., et al., Maternal occupational exposure to
organic solvents during early pregnancy and risks of neural tube defects
and orofacial clefts. Occup Environ Med 2012;69:7 493-499 Published Online
First: 23 March 2012 doi:10.1136/oemed-2011-100245.
2. Cordier, S., et al., Maternal occupational exposure and congenital
malformations. Scand J Work Environ Health, 1992. 18(1): p. 11-7.
3. Lorente, C., et al., Maternal occupational risk factors for oral
clefts. Occupational Exposure and Congenital Malformation Working Group.
Scand J Work Environ Health, 2000. 26(2): p. 137-45.
4. Chevrier, C., et al., Occupational exposure to organic solvent mixtures
during pregnancy and the risk of non-syndromic oral clefts. Occup Environ
Med, 2006. 63(9): p. 617-23.
5. Garlantezec, R., et al., Maternal occupational exposure to solvents and
congenital malformations: a prospective study in the general population.
Occup Environ Med, 2009. 66(7): p. 456-63.
We thanks Barratt and colleagues for their comments. We agree that
"care should be taken to validate model estimates with empirical
measurements wherever possible". Barratt and colleagues cite two stations
from the European Environment Agency database as located in the Railway
Ring and they report increasing NO2 concentrations from 2001 to 2005.
However, one station (IT0953A) is actually located i...
We thanks Barratt and colleagues for their comments. We agree that
"care should be taken to validate model estimates with empirical
measurements wherever possible". Barratt and colleagues cite two stations
from the European Environment Agency database as located in the Railway
Ring and they report increasing NO2 concentrations from 2001 to 2005.
However, one station (IT0953A) is actually located in the middle of a
large park within the Railway Ring, and thus reflecting urban background
concentrations, while the other station is not located in the Railway
Ring, making a direct validation nearly impossible. The correct code of
another traffic station located within the Railway Ring is IT0828A and the
annual mean NO2 concentration went from 80 ?g/m3 in 2001 to 68 ?g/m3 in
2005, which is a clear decrease supporting our work.
Moreover, official data from the Regional Environmental Agency
document that in Rome there was a decrease in nitrogen dioxide (NO2)
concentrations in most of the fixed monitoring stations from 2001 to
2005.[1] Moreover, Cattani et al. have documented a decrease in both NO2
and PM concentrations, especially in sites located near traffic, over a
longer period.[2]
That NOx emission standards of the different EURO vehicle classes are
much smaller than initially anticipated when the policy was formulated is
discovered very recently, and was not known at the time of this study.
Modelling studies are hampered by assumptions about for example emission
factors which may not be correct. Policy evaluation by measurements will
encounter difficulties as well, particularly by other developments
unrelated to the policy (for example an increase in the proportion of
diesel vehicles in the London congestion charging zone). Apart from
traffic other sources of air pollution on both the local and regional
scale, coupled with varying meteorological conditions could all confuse
air pollution trends. Therefore, multiple time windows surrounding the
policy and inclusion of sites not affected by the policy should be
evaluated in a proper empirical evaluation. Since this data was not
readily available at the time of this study, we performed a modelling
approach, reflecting real word conditions as close as possible.
2. Cattani G, Di Menno di Bucchianico A, Dina D, et al. Evaluation of
the temporal variation of air quality in Rome, Italy, from 1999 to 2008.
Ann Ist Super Sanita. 2010;46:242-53.
It is good to see some scientific rigour applied in this important
area. It is interesting to note however that there is no definition of
occupational dermatitis. It is a reportable and prescribed disease in the
UK, and can cause major impact on workers who suffer from it, but the
question is whether healthcare workers who have perhaps a period of dry
skin managed with ease, should be regarded has suffering from an
occu...
It is good to see some scientific rigour applied in this important
area. It is interesting to note however that there is no definition of
occupational dermatitis. It is a reportable and prescribed disease in the
UK, and can cause major impact on workers who suffer from it, but the
question is whether healthcare workers who have perhaps a period of dry
skin managed with ease, should be regarded has suffering from an
occupational disease. The answer to such a question is important to the
context of this paper and to the subject as a whole.
The title of the paper is on 'management' therefore relates to those who
have the condition, but there are of course in addition, major issues of
risk reduction and control, which must run in parallel. While the paper
makes mention of sensitisation in its background section, this important
group does not feature in the review.
In its later sections the term occupational dermatitis, is often reduced
just to 'dermatitis'. Does this mean that the recommendations apply
equally to workers with non occupational skin problems, such as psoriasis
or eczema, both in the pre-employment and in service situations?
Cesaroni et al make an assessment of the health benefits of a traffic management scheme in Rome based on changes in vehicle emissions and associated chronic risk factors(1). The authors estimate that a combination of the policy intervention and unrelated fleet changes caused a 38% reduction in the annual mean exposure of NO2 and a 29% reduction of PM10 within the 'railway ring' restricted zone bet...
Cesaroni et al make an assessment of the health benefits of a traffic management scheme in Rome based on changes in vehicle emissions and associated chronic risk factors(1). The authors estimate that a combination of the policy intervention and unrelated fleet changes caused a 38% reduction in the annual mean exposure of NO2 and a 29% reduction of PM10 within the 'railway ring' restricted zone between 2001 and 2005. The majority of this decrease was unrelated to the intervention, however, NO2 reductions specifically driven by the policy, were translated to 1387 years of life gained per 100,000 residents.
We strongly believe that such statements based solely on modelled and hence theoretical decreases in pollution require validation using empirical data. Measurements from the European Environment Agency's air quality database(2) show that measured annual mean NO2 concentrations within the 'railway ring' zone actually increased between 2001 and 2005 (80 ug/m3 to 82 ug/m3 at roadside site IT0946A and 39 ug/m3 to 41 ug/m3 at background site IT0953A). It is therefore evident that the assumptions used in the analysis did not reflect real world conditions.
Similarly, in studying the impacts of the London Congestion Charging Scheme, Kelly et al, found little evidence of a beneficial effect on monitored concentrations of NO2 and PM10, despite a large and sustained reduction in vehicle numbers(3). This was attributed to the relatively small area of the zone and an increase in the proportion of the vehicle fleet using diesel engines. It is also now widely accepted that the Euro emission standards are not delivering the predicted reductions in NOX(4).
While theoretical estimations of the health benefits of policy interventions are welcome, care should be taken to validate these estimates with empirical measurements wherever possible as man and machine rarely behave as predicted.
References:
1 Cesaroni G, Boogaard H, Jonkers S, Porta D, Badaloni C, Cattani G, Forastiere F, Hoek G. Health benefits of traffic-related air pollution reduction in different socioeconomic groups: the effect of low-emission zoning in Rome. Occup Environ Med. 2012;69(2):133-9.
3 Kelly F.J., Anderson H.R., Armstrong B., Atkinson R, Barratt B., Beevers S.D, Derwent D., Green D., Mudway I., Wilkinson P., 2011. The Impact of the Congestion Charging Scheme on Air Quality in London. Research Report Number 155. Health Effects Institute, Boston, MA, USA. April 2011. Available from http://pubs.healtheffects.org/types.php?type=1.
4 Carslaw D.C., Beevers S.D., Westmoreland E., Williams W., Tate J., Murrells T., Stedman J., Li Y., Grice S., Kent A., Tsagatakis I., 2011. Trends in NOX and NO2 emissions and ambient measurements in the UK. Report for Defra, March 2011. Available from http://uk-air.defra.gov.uk/library/reports?report_id=645.
High temperatures and mortality - even more relevant in desert
environments.
Your editorial on exposure to high ambient temperatures and mortality
is timely [1]. The Gasparrini et al.[2] paper on ambient air temperatures
and mortality in temperate England and Wales provides further support for
population-level preventive measures to reduce the likelihood of adverse
health effects from elev...
High temperatures and mortality - even more relevant in desert
environments.
Your editorial on exposure to high ambient temperatures and mortality
is timely [1]. The Gasparrini et al.[2] paper on ambient air temperatures
and mortality in temperate England and Wales provides further support for
population-level preventive measures to reduce the likelihood of adverse
health effects from elevated environmental temperatures.
The risk of heat-related illness and death is especially relevant to
desert environments, such as in the United Arab Emirates (UAE), where
summer temperatures can often exceed 50 degrees Celsius. In recent years,
the risk of morbidity and mortality from heat exposure was compounded when
the holy month of Ramadan coincided with summer in the Middle East. During
Ramadan, Muslims abstain from consuming fluids or food during daylight
hours. Additional risk factors for these workers are prolonged day shifts,
strenuous outdoor manual work and inadequate rest breaks. Muslim workers
constitute a majority of the expatriate workforce in several Middle
Eastern countries. Preventive measures to reduce the likelihood of
morbidity and/or mortality in this group are particularly pertinent over
the next few years when Ramadan will again fall during summer. In the UAE,
the Health Authority of Abu Dhabi developed a "Safety in the Heat"
campaign which distributed educational materials in five different
languages to over 800,000 outdoor workers focusing on self-monitoring
hydration status using urine colour, adequate hydration before and after
fasting, and self-pacing strategies whilst performing physical activity
[3]. An environmental early warning system could be developed using a
composite index of thermal stress incorporating several environmental
parameters (i.e. dry bulb temperature, wet bulb temperature, wind speed
and radiant heat). Another index is the Thermal Work Limit [4] which is a
good indicator of heat stress in outdoor workers and would be a useful
addendum to the Department of Health's Heatwave environmental monitoring
plan [5].
1. Ebi KL. High temperatures and cause-specific mortality. Occup
Environ Med 2012;69:3-4.
2. Gasparrini A, Armstrong B, Kovats S, Wilkinson P. The effect of
high temperatures on cause-specific mortality in England and Wales. Occup
Environ Med 2012;69:56-61.
3. Joubert D, Thomsen J, Harrison O. Safety in the Heat: A
Comprehensive Program for Prevention of Heat Illness Among Workers in Abu
Dhabi, United Arab Emirates, Am J Public Hlth 2011;101(3):395-398.
4. Brake DJ, Bates GP. Limiting metabolic rate (Thermal Work Limit)
as an Index of Thermal Stress. App Occup Environ Hyg 2002;17(3):176-186.
5. Department of Health. Heatwave: Plan for England - Protecting
Health and Reducing Harm From Extreme Heat and Heatwave. London:
Department of Health, 2009.
Chen et al [1] reported the positive association between environmental tobacco smoke (ETS) and severe dementia syndromes. They mentioned that Cox regression model was applied to detect statistical significance.
I have two queries on their study. First, they conducted cross- sectional study and Cox regression analysis was applied to detect relative risk by adjusting several confounders. They described the methodol...
Hambach et al [1] have published cross-sectional study on the associations between cadmium (Cd) exposure and renal or oxidative stress biomarkers in 36 solderers. They adopted multiple regression analysis to detect statistical significance with adjustment of age and pack-years of smoking. In contrast, there is a significant relationship between low levels of Cd exposure and N-acetyl-beta-D-glucosaminidase (NAG) [2,3], w...
We read the article by Njoku and Orisakwe comparing blood lead levels (BLL) in rural and urban pregnant women in Eastern Nigeria with great interest [1]. The authors found that BLL were substantially higher in rural areas than urban areas (135+/-160 vs 77+/-100 ug/dl). This in itself is an important finding: it may reflect a stronger reliance on locally grown foodstuffs in rural areas, combined with the effect of lead expo...
The Editor Occupational and Environmental Medicine
14th September, 2012
Cadmium, arsenic and lung cancer: A complete picture?
Were the occupational lung cancers among former employees at the cadmium recovery plant located near Denver, CO, USA due to cadmium exposures, arsenic exposures or both? One of us recently suggested that a "simultaneous analysis of lung cancer risks in relation to both...
We appreciate the interest of Dr. Garlantezec and colleagues in our article on the association between maternal occupational exposure to organic solvents (chlorinated, aromatic and Stoddard) and birth defects. We reported a positive association between chlorinated solvents and neural tube defects, particularly spina bifida; we did not observe an association between solvent exposure and orofacial clefts.
As noted...
We read with interest the report by Desrosiers et al of the association between maternal occupational exposure to organic solvents and some birth defects [1]. Their case-control study examined occupational exposure to three classes of solvents (chlorinated, aromatic and Stoddard) and found one association -- between neural tube defects (mainly spinal bifida) and maternal occupational exposure to chlorinated solvents, but n...
Dear Editor,
We thanks Barratt and colleagues for their comments. We agree that "care should be taken to validate model estimates with empirical measurements wherever possible". Barratt and colleagues cite two stations from the European Environment Agency database as located in the Railway Ring and they report increasing NO2 concentrations from 2001 to 2005. However, one station (IT0953A) is actually located i...
It is good to see some scientific rigour applied in this important area. It is interesting to note however that there is no definition of occupational dermatitis. It is a reportable and prescribed disease in the UK, and can cause major impact on workers who suffer from it, but the question is whether healthcare workers who have perhaps a period of dry skin managed with ease, should be regarded has suffering from an occu...
Cesaroni et al make an assessment of the health benefits of a traffic management scheme in Rome based on changes in vehicle emissions and associated chronic risk factors(1). The authors estimate that a combination of the policy intervention and unrelated fleet changes caused a 38% reduction in the annual mean exposure of NO2 and a 29% reduction of PM10 within the 'railway ring' restricted zone bet...
Dear Editor,
High temperatures and mortality - even more relevant in desert environments.
Your editorial on exposure to high ambient temperatures and mortality is timely [1]. The Gasparrini et al.[2] paper on ambient air temperatures and mortality in temperate England and Wales provides further support for population-level preventive measures to reduce the likelihood of adverse health effects from elev...
Pages