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*Corresponding author: E-mail: aishasamir@yahoo.com, aishasamir@kasralainy.edu.eg;
British Journal of Applied Science & Technology
4(11): 1634-1643, 2014
SCIENCEDOMAIN international
www.sciencedomain.org
Occupational Health Hazards among Double
Sided Printed Circuit Board Manufacturers
A. El Safty1, S. Helal1, N. Abdel Maksoud1and A. Samir1*
1Occupational and Environmental Medicine Department, Faculty of Medicine, Cairo
University, Egypt.
Authors’ contributions
This work was carried out in collaboration between all authors. Authors AES, AS, SH and
NAM designed the study, performed the statistical analysis, wrote the protocol and wrote the
first draft of the manuscript. Authors AS, SH and NAM designed the patient files and
managed the literature searches. Authors AS, NAM and SH managed the analyses of the
study, wrote the discussion and recommendations of this study. Author AES revised the
discussion and recommendations. All authors read and approved the final manuscript.
Received 15th November 2013
Accepted 1st February 2014
Published 15th February 2014
ABSTRACT
Workers in printed circuit boards (PrCBs) industry have a long history of occupational
exposures to toxic substances, however little is known about the long-term health
consequences of such exposure.
Aims: To determine the prevalence of some health problems among manufacturers of
printed circuit boards and to formulate recommendations for occupational safety and
health at this factory. Subjects and Methods: A case-control study was conducted in the
first double sided printed circuit board manufacturing factory in Egypt, during the period
from December 2012 to January 2013. Fifty three workers engaged in the process of
printed circuit board manufacture were matched with sixty six referent subjects from the
administrative department. All workers were personally interviewed filling a special
questionnaire involving occupational history and full clinical examination. Investigations
as Lead, Cadmium, serum copper and zinc levels were measured.
Results: Eighten exposed workers (34%), had occupational asthma; 7 (13.2%) had
contact dermatitis; 8 (15.1%) had ocular manifestations versus 11 (16.7%); 1 (1.5%); 4
(6.1%); 1 (1.5%) respectively for the control group. Blood levels of lead (48.84±10.0
Original Research Article
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1635
versus. 13.60±4.70, p<0.001), cadmium (35.09±14.0 versus 23.90±5.70, p<0.001), and
copper (1.32±0.64 versus 0.94±0.33, p<0.001), were statistically significantly higher
among the exposed group than controls, while zinc levels (40.75±19.34 versus
77.31±15.21, p<0.001) were statistically significantly lower among the exposed group
than controls. Blood levels of lead (r=. 543; p<. 001) and copper (r=. 463; p<. 001) were
found to be positively correlated with the duration of employment.
Conclusion: PrCBs manufacturing has been implicated with many health problems.
Recommendations: Proper safety measures should be enforced in the workplace. Pre-
employment and periodic medical examination should be done for exposed workers.
Further studies are recommended for PrCBs workers.
Key words: Printed circuit boards; Heavy metals-Occupational asthma; Contact dermatitis;
Health Hazards.
1. INTRODUCTION
Printed circuit boards (PrCBs) are essential components of electronic equipments. They are
also called printed wiring boards. PrCBs development has revolutionized the electronics
industry. In recent years, the average rate of world -wide PrCBs manufacture is increased.
They can be used to mechanically support and electrically connect electronic components
using conductive pathways, tracks or signal traces. They are involved in the manufacturing
of business machines, computers, as well as communication, control and home
entertainment equipment [1]. They essentially re-placed electrical wiring with a landscape of
conductive paths on a rigid surface. PrCBs consisted of patterns of conductive material
formed onto a non-conductive base. The conductor is generally copper, although aluminum,
chrome, nickel and other metals have been used. The metal is fixed to the base through the
use of adhesives, pressure, heat bonding, and sometimes screws. Those materials and
metals along with electronic parts are attached to the board by a solder containing lead and
tin [2]. Although developments in such semi-conductor components as memory chips and
microprocessors gain the public attention, PrCBs have quietly evolved to meet the needs of
those components, including changes in their size, density, weight, and stre ngth and power
requirements [3]. PrCBs manufacturing entails many potential health and safety hazards.
These hazards can be classified into three broad categories: chemical, physical and
psychosoical. Chemical hazards are including organic solvents (such as formaldehyde,
dimethylformamide, ethylene glycol monomethyl ether and methoxyacetic acid), acids,
bases and metal fumes;physical hazards include covering electric shock, noise, vibration,
high temperature operation fire and explosion [4]. PrCBs workers are exposed to a variety of
chemicals quiet similar to those of other microelectronics workers, however little is known
about the outcome of such exposures. In Egypt, health hazards among workers in electronic
industry, were not thoroughly studied. This is the first health survey conducted in a factory
that is a pioneer in the PrCBs industry in Egypt. This study was designed to assess health
implication of PrCBs process on exposed workers. To execute this task, we designed our
objectives as follow: To determine the prevalence of some health problems among
manufacturers of printed circuit boards. To measure some of heavy metals encountered in
this industry. To propose recommendations for occupational safety and health in this
industry.
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1636
2. SUBJECTS AND METHODS
2.1 Study Population
The study was carried out in the first factory for manufacturing printed circuit boards in Giza,
Egypt during the period from December 2012 to January 2013. This study was conducted on
two groups: an exposed and a control group. The total working force was 122 male workers,
constituting the whole workforce of the factory. The exposed group consisted of 56 male
workers occupationally exposed to the printed circuit board process. The control group
included 66 male workers in administrative departments of the company, who have never
been occupationally involved in PrCBs manufacturing. The control group was matched to
the exposed group as regards age, sex, socioeconomic status and smoking habit. Upon their
request, three of the exposed workers refused to take part in this study. The remaining 53
workers were involved in printed circuit boards (PrCBs) manufacturing, double sided board,
for more than one year, working in 12 hours based shift. The process is accomplished by
producing patterns of conductive material on a non- conductive substrate by subtractive or
additive process (the conductor is usually copper, the base can be pressed epoxy, Teflon, or
glass). The steps of manufacturing the board are cleaning, surface preparation of the base,
electrolysis, copper plating, map or pattern printing, masking, electroplating and etching. The
study protocol was first approved by the Occupational and Environmental department ethical
committee, Kasr Al Ainy Hospital, Faculty of Medicine, Cairo Uni versity. Prior to this study, a
written consent to participate in the study and an approval to give blood samples were
obtained. During the study, the ethical guidelines of good clinical practices (GCPs) and strict
confidentiality were observed throughout sample collection, coding, testing, and recording of
the results.
2.2 Methods
The studied groups were subjected to a specially designed detailed questionnaire including:
socio-demographic data including age, residence, marital status, and special habi ts, present,
past and family history. Occupational history included: current job and its nature, previous
jobs, duration of employment in years; Health complaints: onset, duration and relation to
work; Clinical examination: comprehensive general examination including the chest, skin and
ocular examination. Blood samples were collected for measuring a complete blood picture,
kidney functions (urea, creatinine) and blood levels of lead, cadmium, copper and zinc. All
heavy metals were detected using the atomic absorption spectrophotometry. Ventilatory
function assessment was conducted for all workers included in this study using calibrated
electronic spirometer.
2.3 Statistical Analysis
Data obtained from the study were coded and entered using the statistical package SPSS
version 16. The mean values, standard deviation (SD) and ranges were then estimated for
quantitative variables, as for the qualitative variables, the frequency distribution was
calculated. Comparisons between exposed and control groups were done using the
independent simple t-test. The correlations between individual variables were calculated
using Pearson correlation coefficient. P values less than 0.05 were considered statistically
significant.
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1637
3. RESULTS
The exposed group consisted of 53 workers all were men their mean age was 39.20±4.8
years ranging from 30 to 53 years. Mean duration of exposure was 13.71±3.0 years, ranging
from 5 to 20 years. The mean age of the control group was 39.18±5.8 years, ranging from 32
to 52 years, showing no statistically significant difference between the exposed group and
the controls. Systolic and diastolic blood pressure was statistically significantly elevated
among PrCBs workers compared to the control subjects, but both groups showed levels
within normal range. Other sociodemographic characteristics of printed circuit board workers
and control group are shown in Table 1.
Table 1. Sociodemographic characteristics of printed circuit board workers and
control group
General Characteristics
PrCB
Workers
n=53
Control
n=66
Statistical
tests
Pvalue
Age (yrs) (Mean±SD)
39.20±4.8
39.18±5.8
.026*
.979
Duration of work (yrs.) (Mean±SD)
13.71±3.0
-------
-------
-------
Blood pressure (Mean±SD)
SBP
DBP
124.94±14.0
79.60±10.0
106.52±21.7
73.40±9.1
5.361*
3.486*
< .001
.001
Smoking habit
Smokers n(%)
Nonsmokers n (%)
19(64.2)
34 (35.8)
30(45.5)
36(54.5)
2.202* *
.138
Marital status
Married n(%)
Unmarried n (%)
7(88.7)
6(11.3)
57(86.4)
9(13.6)
.143* *
.705
* Independent simple t-test value; significantly (2 tailed) p<0.001
** Pearson Chi-Square
History of typical asthma was found among 18 exposed subjects (34%) Table 2, however,
only 13 (24.5%) showed obstructive manifestations by ventilatory function test res ults.
Restrictive pulmonary impairment was detected in 8 exposed workers (15.1%) and
combined restrictive and obstructive among 5 cases (9.5 %) Table 3. History of contact
dermatitis that resolved by being away from exposure was found among 7 subjects (13.2
%), only one case showed residual skin manifestations that didn’t improve by removal from
exposure and needed medical intervention. History of conjunctivitis and upper respiratory
tract irritation were found in 8 cases (15.1%) and ophthalmic examination showed chronic
conjunctivitis in 4 cases (6.1%). All encountered health complaints had exposure -response
relationships that were emphasized by a detailed history taking Table 2.
The mean values of the complete blood picture and kidney function tests among printed
circuit boards' workers and control group were shown in Table 4.
The mean levels of lead, cadmium and copper among PrCBs workers showed statistically
significantly higher values compared to that in the control as presented in Table 5.
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1638
Table 2. Frequency distribution of clinical manifestations among PrCB Workers and
control group
Clinical manifestations
PrCB Workers
n=53
Control
n=66
X2*
Pvalue
Occupational asthma
18(34)
11(16.7)
4.765
.029
Contact Dermatitis
7(13.2)
1(1.5)
6.907
.009
Conjunctivitis
8(15.1)
4(6.1)
2.649
.104
Upper respiratory tract irritation1
8(15.1)
1(1.5)
7.753
<.001
* Fisher’s exact chi-square
Table 3. Results of ventilatory function test between printed circuit boar ds workers
and control group
Ventilatory function
impairment
PrCB Workers
(n=53)
n(%)
Control
(n=66)
n(%)
X2*
Pvalue
Obstructive
13(24.5)
3(4.5)
10.086
.001
Restrictive
8(15.1)
1(1.5)
7.753
.005
Combined
5(9.5)
1(1.5)
3.850
.050
* Fisher’s exact chi-square
Table 4. Complete blood picture and kidney functions tests among printed circuit
board workers and control group
PrCB Workers
(n=53)
Control (n=66)
t-test *
P value
RBCs
4.34±0.63
4.30±0.60
.466
.642
WBCS
6.79±1.29
7.08±1.46
-1.015
.312
Hb gm/dl
13.71±0.67
13.50±0.71
1.615
.109
Urea
18.33±3.7
18.04±2.69
.500
.618
Creatinine
1.04±0.32
0.99±0.21
.875
.383
* Independent simple t-test value; significantly (2 tailed) p<0.001
Table 5. Blood levels of measured heavy metals and trace elements a mong printed
circuit board workers and control group
PrCB Workers
(n=53)
Control
(n=66)
t-test*
P
value
Lead Ug/dL
48.84±10.0
13.60±4.70
3.909
<0.001
Copper(serum) Ug/dL
35.09±14.0
23.90±5.70
5.926
<0.001
Cadmium Ug/dL
1.32±0.64
0.94±0.33
4.455
<0.001
Zinc (serum) Ug/dL
40.75±19.34
77.31±15.21
-11.54
<0.001
* Independent simple t-test value; significantly (2 tailed) p<0.001
Serum zinc levels showed lower values among PrCBs workers compared with the controls.
The correlation between different variables revealed a positive significant correlation
between duration of employment in PrCBs and both lead and copper (r= 0.543, p<0.001;
r=0.0463, p<0.001 respectively). There were negative correlations between duration of
employment in PrCBs and each of hemoglobin; urea and creatine level Table 6.
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1639
Table 6. Correlation coefficient between duration of employment and different
investigations among printed circuit board exposed workers
r
Pvalue
SBP*
.325
.018
DBP**
.208
.135
Lead
.543
< .001
Cadmium
.137
.328
Copper
.463
< .001
Zinc
-.080
.570
Hb
-.230
.097
Urea
-.335
.014
Creatinine
-.088
.531
* SBP: Systolic blood pressure., ** DBP: Diastolic blood pressure
4. DISCUSSION
The manufacture and use of electrical and electronic products have increased dramatically
over the past several decades. One of the major health concerns in the PrCBs manufacture
process is exposure to the fumes generated during soldering and electronics assembly.
Respiratory irritants encountered during these processes contributed to the high prevalence
of occupational asthma among exposed workers as shown in Table 1. Some of these
irritants are heavy metals, machining fluids, lubricants, solvents, paints and coatings,
adhesives, soldering fluxes and other various chemicals. The fumes generated from the
fluxes used in solders and liquid fluxes used in dip soldering are known respiratory
sensitizers that are liable to cause occupational asthma, rhinitis and conjunctivitis. La dou,
[4], similarly concluded the presence of high doses of heavy metals in the electronics
products industry. Several studies have reported that the inhalation of metal dust and
fumes is associated with adverse health effects such as metal fume fever and other
respiratory diseases [5,6]. Adding to the hazardous material exposure, poor industrial
hygiene and long work shift in confined poorly ventilated workplace may aggravate work
related health complaints. Most of PrCBs, require soldering mask. The solder mask
application is found in the surface finish. The manufactures use cluster, sets of chemicals
processes and technologies that can substitute for one another to perform a speci fic
function. In the current study, smoking habit didn't contribute to the higher prevalence of
ventilatory function test impairment among exposed compared with the controls, no
statistically significant difference as regards smoking habits between both groups was found
Table 1. Asthma is characterized by the presence of reversible airflow obstruction; however,
irreversible airflow obstruction develops in some patients [7]. In our study, ventilatory
function testing demonstrated statistically significantly higher impairment among PrCBs
workers compared with the control subjects (p<0.001). Diagnosis of occupational asthma
due to exposure to fumes generated from soldering flux during manufacturing PrCBs, was
evident among 13 workers based on pulmonary function test, however 18 cases gave a
typical history of asthma among exposed workers versus 11 control subjects. In our cou ntry
patients are treated mostly by clinical history, sign and symptoms and their lung function test
are rarely assessed. This study provides evidence that exposure to fumes and dust
encountered during the process of printed circuit board manufacture, increases the risk of
respiratory complaints. The present findings were with the perception that asthma is a
chronic inflammatory disease in which ongoing tissue injury and repair result in irreversible
fibrotic changes in the airways leading to decline in lung functions. Skin irritation and
sensitization among workers in the electronics industry are associated with a variety of
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1640
physical, chemical and psychosocial causes. Causal agents for skin diseases in electronics
workers were studied by many researchers and inc lude epoxy resins, acrylates, solvents,
metals, fiberglass and flux [4,8-10],. In the current study, we found that 7 workers (13.2%)
had hand contact dermatitis and none had allergic dermatitis, Table 2. Our results agreed
with Shiao et al. [11], who conducted a field investigation to determine the prevalence,
patterns and risk factors of occupational hand dermatitis among electronics workers. The
survey was conducted in five electronics plants using a self-administered questionnaire on
skin symptoms and risk factors. Skin examination and patch test were followed for those with
symptoms compatible with hand dermatitis. A total of 3070 workers completed the
questionnaire. Among them, 302 (9.8%) reported to have symptoms (itching with either
redness/scaling) compatible with contact dermatitis on hands.
Recently, Szoboszlai et al. [12], investigated the elemental composition and mass size
distribution of indoor aerosol particles in a working environment where soldering of PrCBs
took place. They reported that, based on the elemental ratios, correlations, size distribution
data and single particle analysis e.g. soldering, fluxing, etching and cleaning. The
concentration of particulate matter (PM) and the elemental components increased at the
wave solders. The main constituents of the leaded and the unleaded melt were recognized
in the indoor aerosols. In the case of PM10, the Pb levels in the workplace were
approximately 3.8 times higher on average than the outer Pb levels. Flux -related and
etching-related elemental compositions were also identified at work place. This is in
resemblance to the results of our study, that found higher blood levels of heavy metals as
lead and cadmium, among exposed workers, Table 5. Lead is the most widely used in
electronic devices for various purposes, especially during soldering, resulting in a variety of
health hazards attribute to environmental contamination. The advantages of lead include low
melting point, freedom from whiskers, in susceptibility to tin – pest, slowing down on the inter
metallic phase formation or copper dissolution, technical reliability and cost-effectiveness
[13-15]. Huo et al. [16], found that primitive electronic-waste recycling activities contribute to
the elevated blood lead levels in children living in Gui yu in China. Recently, Yang et al. [17],
investigated the association between Pb and Cd exposure, physical growth, bone and
calcium metabolism in children of an electronic waste (e-waste) processing area in Guiyu,
China. They found the mean values of blood lead levels (BLLs) 7.30 μg/dl and blood
cadmium levels (BCLs) 0.69 μg/L. They concluded that primitive e-waste recycling can
threaten the health of children with elevated BLLs and BCLs that may eventually cause
adult osteoporosis. Similarly, our results re vealed high BLLs (48.84±10.0 μg/dl) and BCLs
(1.32±0.64 μg/dl), and statistically positive correlation between duration of employment and
their blood lead levels Table 6.
Cadmium and zinc are similar in structure and function in the human body. Cadmium
displaces zinc in some of its important enzymatic and organ functions; thus, it interferes with
these functions. In the current study, we found higher levels of cadmium among exposed
workers compared with the controls. Regarding what we have mentioned above , we have
found in our study that serum levels of zinc are lower than those of the controls, this because
of the competitive action of divalent cations between zinc and cadmium.
Other metals used in PrCBs, rather than lead, are copper, aluminum, tin, iron , nickel, zinc,
gold and silver. Among them, copper is the primary metal enriched in the four size fractions
that is between 0.15 and 1.25 mm [18]. This can be explained by exposure to copper during
the process of plating. In the current study we found hig h serum levels of copper among
exposed workers Table 5 and statistically significant positive correlation between its levels
and duration of employment as demonstrated in the Table 6. This can be explained by
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1641
exposure to copper during the process of plating, etching or soldering. Serum zinc levels
showed lower values among our workers relative to that among the controls. This is
supported by the results of Soleo et al. [19], who studied health risk assessment of exposure
to metals in workers of steel foundry. They found that Zn showed significantly higher urinary
concentrations in controls than in the exposed subjects. This could be explained by the
competitive action of divalent cations. Ayinde et al. [20], mentioned that occupational and
environmental exposures to lead remain a public health problem as lead alters physiological
processes by inducing oxidative stress and mimicking divalent cations. On the other hand,
Kasperczyk et al. [21], evaluated the effect of occupational lead exposure on blood
concentrations of zinc. They found that zinc level was unchanged in the exposed group
compared with the control group.
LaDou, [4], presented the wide range of occupational, environmental health and regulations
controlling this industry. He also stated that, PrC Bs industry had received remarkably little
regulatory and enforcement attention in the United States and elsewhere . Szoboszlai et al.
[12], concluded that, although the concentrations of Pb were less than the limit value of the
OSHA and WHO, there was a maximum in the fine mode and the mass size distributions of
Pb and other metals that increase the risk of adverse effects among exposed workers in
PrCBs. In 2003, the European Union (EU) [22] enacted the Restriction on Hazardous
Substances (ROHS) Directive that bans the use of lead, mercury, cadmium, hexavalent
chromium, and certain brominated flame retardants (BFRs) in most electronics products sold
in the EU market beginning July 1, 2006. However, in Egypt we still broadly use these toxic
metals and chemicals in PrCBs industry. It is understood that, the electronics industry
provides valuable jobs, nonetheless, attention is needed to identify greener and safer
alternatives and controls.
One of the limitations of this study, is we can't assume a cause effect relationship between
exposure to heavy metals during manufacturing of PrCBs and the health effects found in our
study. Because little is known about the long-term health consequences of exposure to
chemicals by semiconductor workers; nothing is known of long-term exposure to low levels
of these chemicals and also nothing is known about long-term exposure to low levels of
combinations of chemicals and reaction products. Despite documented evidence of adverse
health effects of electronic industries from the W orld Health Organization (WHO), the
International Labor Organization (ILO), various government agencies and individual
scientists, no uniform set of protective standards for workers in the electronics sector is
found.
5. CONCLUSION AND RECOMMENDATION
We can conclude that the fumes emitted during the industrial process pose a health hazard.
There is considerable exposure to heavy metals and solvents during the process of
manufacturing printed circuit boards, especially during electrolysis, etching, drilling and
electroplating. So, proper safety measures should be insured during the industrial process.
Hierarchy of Hazard control of the workplace should be applied to protect the workers from
health hazards associated with this industry as shown in a flow chart below.
British Journal of Applied Science & Technology, 4(11): 1634-1643, 2014
1642
Hierarchy of Hazard Control
Substitution and even elimination of these hazardous substances at sources of heavy metals
and solvent exposure during, electrolysis, etching, drilling and electroplating are important.
Proper engineering measures to reduce the effect of the fumes as enclosed systems and
proper maintenance of machinery together with proper and effective ventilation at work place
are necessary. Good and proper ventilation is a must at work place. The fumes must be
given appropriate extraction and cleaning before being discharged to the atmosphere.
Further down the hierarchy is to apply administrative controls providing specialist training or
putting a supervisor in place to monitor the work environment. A last resort control, is
personal protective equipment such as safety goggles and glasses will minimize the risk but
not address the hazards. Pre-employment and periodic medical examination for exposed
workers, for early detection of health affection are needed. One year follow up by measuring
blood levels of lead, cadmium and copper are also recommended. The magnitude of this
problem has to be studied on a large scale to support our findings.
COMPETING INTERESTS
There is no conflict of interest in this research.
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© 2014 Safty et al.; This is an Open Access article distributed under the terms of the Creative Commons Attribution
License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction
in any medium, provided the original work is properly cited.
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