Blood Lead Level in Relation to Awareness and Self Reported Symptoms among Gasoline Station Workers in the Gaza Strip

Background: Leaded gasoline is being used in Gaza Strip. Measurements of blood lead level (BLL) and relate it to awareness of gasoline station workers would be helpful in lead protection programs. Purpose: To determine BLL and to assess its relation to awareness and self reported symptoms among gasoline station workers in the Gaza Strip. Methods: A cross section of 72 workers was asked to fill in a questionnaire. BLL was determined by atomic absorption spectrometry. Results: Thirty four (47.2%) workers had BLL>10 μg/dl. The mean BLL was inversely related to the education level (p=0.001). Workers worked d”5 years in the station had lower BLL than those worked >5 years (7.8±5.6 v 12.5±5.8 μg/dl, p=0.004). The variation in workers’ knowledge by their BLL was not significant. Higher BLL was generally found in workers who did not practice protective measures compared to those who did, with significant difference for respiratory mask (12.4±5.9 v 5.6±1.6 μg/dl, p=0.001), gloves (13.1±6.0 v 8.6±4.9 μg/dl, p=0.001) and frequent milk drink (13.5±6.0 v 9.3±5.2 μg/dl, p=0.018). Higher BLL was also found in workers who reported symptoms than in those who did not, with significant differences for irritability (12.4±5.4 v 9.2±5.6 μg/dl, p=0.031), headache (12.2±5.8 v 9.0±5.9 μg/ dl, p=0.046), concentration difficulties (12.9±5.8 v 9.4±5.6 μg/dl, p=0.015), sleep disturbances (14.1±5.8 v 8.9±5.0 μg/dl, p=0.001) and hypertension (13.3±6.4 v 8.1±2.9 μg/dl, p=0.001). Conclusions: High BLL was associated with low education level, long work duration, lack of protective measures and increase self reported symptoms. Educational programs on protective measures practices are recommended.

education, work duration and house location?; (2) what is the level of workers' knowledge on route of lead entry into the body, lead health effects and lead as an environmental pollutant?, and is there a relationship between BLL and such knowledge?;(3) Do workers have practices towards the protective measures?, and which of them relate to BLL?; (4) what are the self reported symptoms among workers?; and is there an association between BLL and such symptoms?

Study area
The Gaza Strip is a part of the Palestinian coastal plain bordered by Egypt from the South, the green line from the North, Nagev desert from the East and the Mediterranean Sea from the West.The total surface area of the Gaza Strip is 360 km 2 , where about 1.64 million Palestinian people live and work 17 .The Gaza Strip is divided geographically into five Governorates: Northern, Gaza, Mid Zone, Khan Younis and Rafah.
Gaza Strip is a poor area suffering from a long-term pattern of economic stagnation and plummeting development indicators 18 .The situation becomes even worse since Israel imposed extreme restrictions on the movement of goods and people in response to the new political situation in the Gaza Strip.The unemployment rate in the Gaza Strip is 32.2% 19 .
The Gaza Strip suffers from many environmental problems including extensive use/misuse of pesticides, water pollution and lack of sewage and solid waste treatment [20][21][22] .Air pollution is another environmental burden in the Gaza Strip caused to a large extent by carbon monoxide, nitrogen oxide and lead emitted by petrol vehicles.Leaded gasoline imported from Israel and Egypt is still the predominant fuel grade in the Gaza Strip 23,24 .Lead emitted from such fuel imposes serious health problems on both general population and gasoline station workers in the Gaza Strip.

Study design and target population
This investigation was a cross sectional study.The target population was gasoline station workers in the five Governorates of the Gaza Strip during the spring of 2006.For ethical consideration, the necessary approval to conduct the study was obtained from Helsinki committee in the Gaza Strip in January, 2006.

Sample size and sampling
The estimated number of legal gasoline stations registered in the Gaza Strip in the year 2006 was 81 distributed in the five Governorates of the Gaza Strip as follows: Northern (17), Gaza (27), Mid Zone (10), Khan Yunis (19) and Rafah (8).According to the municipalities of Gaza Governorates, Palestinian National Authority (Personal communication), the estimated total number of workers in Gaza Governorates was 208, distributed as follows: Northern (36), Gaza (77), Mid Zone (24), Khan Yunis (45), and Rafah (26).A stratified sample was used based on the formula: No. of workers/Governorate X Sample size = No. of required Total No. of workers workers/Governorate Therefore, our sample size of 105 gasoline station workers was distributed according to the number of workers in each Governorate as follows: Northern (18), Gaza (39), Mid Zone (12), Khan Yunis (23), and Rafah (13).Out of the 105 workers, 72 freely gave blood samples for BLL analysis and answered a questionnaire questions i.e. the response rate was 68.6%.

Questionnaire interview
A meeting interview was used for filling in the questionnaire.A total of 72 workers were questioned.All interviews were conducted face to face.The questionnaire was based on adult lead poisoning questionnaire with some modifications 25 .The questionnaire was validated by four specialists in the fields of environment and public health.Most questions were one of two types: the yes/no question, which offers a dichotomous choice; and the multiple choice question, which offers several fixed alternatives 26 .A questionnaire was piloted among 10 gasoline station workers not included in the sample, and modified as necessary for improving reliability.The questionnaire included questions related to: personal profile such as age and education; work duration; house location to other lead facility; and knowledge on the route of lead entry into the human body, health effects of leaded gasoline exposure and lead as an environmental pollutant.Practice questions included: the wearing of protective gear; smoking; drinking and eating during work; chewing gum; whether they drink milk frequently or not; and whether to have a water bath or not at work place.Selfreported symptoms questions were also included in the questionnaire.

Determination of blood lead level
Blood samples were collected from the median cubital vein by a well trained nurse.About 3 ml blood was drawn from each worker by plastic metallic-free disposable syringe (SANWOO coroporation-Korea) into vacutainer vial containing potassium ethylenediamine tetracetic acid "EDTA (K3)" as anticoagulant produced by AFMA-DISPO-Jordan.Blood lead level was determined by atomic absorption spectrometry based on the method described by Miller and his colleagues 27 .Quantification was based on the measurement of light absorbed at 283.3 nm by ground state atoms of lead from either an electrode-less discharge lamp or from a hollow-cathode lamp source.Blood samples human and bovine blood quality control pools, and aqueous standards were diluted with a matrix modifier (nitric acid, Triton X -100, and ammonium phosphate).The lead content was determined by using a Perkin-Elmer model 5100 atomic absorption spectrophotometer with Zeeman Effect background correction.Lead contamination was carefully avoided throughout all procedures.

Data analysis
Data were computer analyzed using SPSS/PC (Statistical Package for the Social Science Inc. Chicago, lllinois USA, version 13.0) statistical package.Simple distribution of the study variables, the cross tabulation and the mean of the BLL were applied 28 .The one-way ANOVA test was used for analysis of variance for average BLL as quantitative dependant variable by qualitative variables.The independent-sample t-test procedure was used to compare means of quantitative variables by the separated cases into two qualitative groups.The result was accepted as statistically significant when the p-value was less than 5% (p<0.05).

Blood lead level in relation to house location to other lead facility
None of the workers was found to live near lead smelter (Table IV).In addition, there were no significant differences in the mean blood levels of workers in relation to house location to other lead facilities including battery workshop, auto radiator workshop and garage of cars (p>0.05). ) and mouth 18 (25.0%)as routes of lead entry.However, the variation in such workers' knowledge by their BLLs was not significant (p>0.05).

Blood lead level in relation to protective gear in use
As illustrated in Table VI, the protective gear was poorly used during work at the station where the highest number of workers (n=27, 37.5%) wore gloves and the lowest number (n=4, 5.6%) wore hats or special boots.In general, the mean BLL was found to be higher in workers who did not use protective gear than in those who did with significant differences for respiratory mask and gloves (12.4±5.9 v 5.6±1.6 µg/dl, t=3.609, p=0.001 and 13.1±6.0v 8.6±4.9 µg/dl, t=3.316, p=0.001, respectively).

Blood lead level in relation to personal habits
Table VII provides the personal habits of workers (n=72) practiced at work place.The mean BLL of workers who were smoked, drunk, ate and chewed gum was higher than that of workers who were not.However, the difference was not significant (p>0.05).The higher BLL was also found in workers who did not frequently drink milk, but the difference was significant (13.5±6.0 v 9.3±5.2µg/dl, t=3.162, p=0.018).

Blood lead level in relation to self reported symptoms
The recall period was shortened to three months preceding the interview to minimize the possibility of recall bias.

Discussion:
Although leaded gasoline is still the predominant fuel grade in the Gaza Strip, no previous research have been determined BLL in gasoline station workers and relate it to their awareness and self reported symptoms.Blood lead level is the most widely used measure and powerful indicator for occupationally lead exposure.Several authors used BLL as a direct indicator for lead exposure in gasoline station workers as well as an indication of potential for adverse effect on health. 10,291][32] The higher BLL recorded in Gaza Strip workers may be attributed to poor use of protective measures and lack of awareness programs, 15 which implemented in other countries.In Greater Beirut even higher mean BLL (18.4 µg/dl) was found compared to Gaza workers 29 , which was attributed to frequent sniffing of cars in such traffic busy city.
The result that none of the workers found to be illiterate do reflect a well educated community.Such finding may give the impression that the high rate of educated workers is a result of them not getting another job because of the unemployment crisis in the Gaza Strip. 18The level of education was inversely related to BLL of workers i.e. the higher educational level of the workers, the lower BLL they had.This means that the more educated workers were more aware of the risk of lead exposure.Similar result was obtained in lead workers in Taiwan. 33garding work duration, the finding that more than two thirds of the workers worked in the gasoline station for more than 5 years, and all workers had no history of other lead-related job may imply that most of lead exposure coming from the workplace.The insignificant differences in mean BLLs of workers in relation to their houses location to other lead facilities probably support this view.The mean BLL was significantly increased with increased work duration at the station.This positive association more likely put workers health at a higher risk.Lead toxicity was more frequently encountered with longer term occupational lead exposure. 34e finding that a higher proportion of gasoline station workers were more aware of inhalational of leaded gasoline than other routes of exposure agrees with other studies which have found that most occupational exposure to lead occur through inhalation. 14,35The high level of workers' knowledge on the health effects of leaded gasoline exposure was previously reported 15 .When BLL was related to workers' knowledge, no significant association was found.This implies that knowledge on lead hazards alone may be not enough to significantly decrease BLL among workers.It was indicated that lead awareness knowledge doesn't necessarily guarantee positive behavior change. 36Knowledge of lead hazards together with good hygiene and education of correct work practice may be the preferential way to reduce lead exposure 12,37 .
The protective gear was poorly used.In general, the mean BLL was higher in workers who did not use protective gears than in those who did, with significant difference only for respiratory mask and gloves.The protective effect of respiratory mask and gloves against lead exposure do confirm that inhalation and hand contamination are important routes of lead exposure in gasoline station.Increasing of BLL was found in occupational lead workers who neglected protective measures including face masks 38 .
Personal protective equipment was consider as an essential component in any occupational health and safety program and as a mean of preventing occupational lead absorption. 39e mean BLL was not significantly associated with the personal habits of workers except for drinking milk, where BLL was significantly higher in workers who did not frequently drink milk.It was reported that milk drinking by workers who occupationally exposed to lead reduced BLL. 40The degree of lead absorption is increased in person, whose diet is deficient in calcium, since calcium competes with lead for intestinal absorption 41 .Thus, the milk consumption is recommended as a dietary supplement for lead exposed workers in Gaza Strip to minimize lead absorption.
Regarding self reported symptoms, the mean BLL was generally higher in workers who reported symptoms than in those who did not with significant difference for irritability, headache, concentration difficulties, sleep disturbance and hypertension.This coincides with the idea that the nervous system is the primary target of lead toxicity. 42Such finding necessitates urgent prevention, intervention, and protection from the Ministry of Health and other non-governmental organizations.It was reported that workers with high BLL have a higher prevalence of most of the symptoms of lead toxicity than did workers with lower BLL in many countries including the neighboring ones. 43

Conclusion:
Gasoline station workers in the Gaza Strip are still exposed to leaded gasoline.The mean BLL increased significantly in less educated and longer work duration-engaged workers.The variation in workers' knowledge on route of lead entry into the body, and its health and environmental effects by their BLLs was not significant.Use of protective measures was poor.Higher BLL was found in workers who did not practice protective measures with significant difference for respiratory mask, gloves and frequent milk drink.In general, higher BLL was also found in workers who reported symptoms than in those who did not with significant difference for irritability, headache, concentration difficulties, sleep disturbance and hypertension.Prevention and intervention programs regarding the use of protective measures and monitoring the health status of gasoline station workers should be implemented.
Strip The mean BLL decreased with increasing education level, where BLL of workers who had a university degree was 8.0±4.3 µg/dl and of those who had passed primary school it was 16.2±7.3µg/dl.This inverse relationship was statistically significant (F=10.120,p=0.001).
Blood lead level was expressed as mean ±SD Blood lead level in relation to age and education of workers As indicated in TableII, the highest mean BLL (15.7±6.5 µg/ dl) was found in workers aged >50 years old whereas the lowest (8.7±5.3 µg/dl) was found in those aged 19-26 years old.However, there was no significant relationship between BLL and age of the workers (F=1.874,p=0.125).Analysis of the educational status of the workers (n=72) showed that none of them was illiterate.Blood lead level was expressed as mean ±SD, P<0.05: significantBlood lead level in relation to work durationAs depicted from TableIII, the mean BLL of workers who worked in the station for 1-5 years was significantly lower than that of workers who worked for >5 years (7.8±5.6 v 12.5±5.8µg/dl, t=2.945, p=0.004).It is worth mentioning that, all interviewed workers had no history of other lead-related job.
Blood Lead Level in Relation to Awareness and Self Reported Symptoms among Gasoline Station Workers