Water Pipe Smoking Affects Young Females and Males Differently with Some Effects on Immune System Cells, but None for C-reactive Protein, Thyroid Hormones, and Vitamin D.

INTRODUCTION: Water pipe smoking (WPS) is a major health threat leading to higher mortality, morbidity, and incidence of many diseases, such as inflammatory, respiratory and cardiovascular diseases; and cancers. This study aimed to determine the differences in the effects of WPS on the immune system, inflammatory markers, lipids, vitamin D, and thyroid hormones in female and male WP smokers, and compared to nonsmokers of both sexes. No other studies showed the differences between female and male WP smokers for the parameters investigated here, with the exception of the lipid profile.
METHODOLOGY: The study was carried on 76 randomly chosen subjects (17 female and 17 male WP smokers, 21 female and 21 male nonsmokers) living in Saudi Arabia with an age range of 20-35 years. Blood samples were collected to determine the differential complete blood counts; lipid profiles; and C-reactive protein, triiodothyronine, thyroxine, and vitamin D concentrations.
RESULTS: Results showed no significant differences between female smokers and nonsmokers for all parameters. Male smokers had a significantly lower mean monocytes count and a significantly higher mean red blood cell count and hemoglobin concentration compared to male nonsmokers. Comparing females and males among smokers and nonsmokers separately, the only significant difference in the parameters that was not found in both comparisons was a significantly lower mean basophil count in female nonsmokers compared to male nonsmokers.
CONCLUSION: It may be concluded that the effects of WPS were limited to males with immune cells and hematology minimally affected, and that females and males were affected differently by WPS. Copyright:

INTRODUCTION

Tobacco smoking is a major health threat in many parts of the world, especially the developing world. It has long been accepted that tobacco use and smoking are the leading causes of preventable death worldwide. The World Health Organization (WHO)[1] estimates that more than six million people are killed yearly by smoking. One common form of tobacco smoking is water pipe smoking (WPS), which was previously mainly confined to the Middle East, Africa, and some parts of Asia. WPS has been gaining increased popularity in Western developed countries, especially among the youth of both sexes.[2] Smoking the water pipe (WP), also known as arghile, shisha, narghile, bory, hookah, and hubble bubble, involves the use of tobacco in different forms with the inhaled smoke passing through water before inhalation. Studies have shown that WPS is more harmful than cigarette smoking as it delivers more toxic and harmful substances[2] and leads to increased incidence of the same types of diseases and cancers as ones linked to cigarettes.

Tobacco smoke contains thousands of toxic and carcinogenic substances that cause respiratory diseases, cardiovascular disease (CVD), chronic obstructive pulmonary disease, and different types of cancer, especially lung cancer and also bladder, colon, and oral cancers.[3] These diseases are caused by the effects of smoking tobacco on many different cells, organs, processes, and different systems of the body that lead to changes in the counts of cells and concentrations of different substances or hormones secreted by cells or tissues in the body that affect mainly the respiratory, cardiovascular, immunological, hematological, and reproductive systems.[34567] Many studies have been carried out on the effects of cigarette smoking, and to a much lesser extent, on WPS on general health, immunity, and their link to inflammatory diseases and other related diseases, although the findings are contradictory.

C-reactive protein (CRP), an acute phase protein and an inflammatory disease marker, is strongly linked to inflammation and many of the same diseases that are linked to smoking tobacco. It is also linked to some lifestyles, such as increased weight and a lack of exercise.[89] White blood cells (WBCs) are known to increase in conditions of inflammation as they are mediators of inflammation. The levels of CRP and WBCs, both important in inflammation and the immune system, have been studied[671011] in tobacco smokers, and the findings are contradictory. The platelet is another blood constituent that is involved in inflammation and in innate and acquired immune responses, in addition to its role in blood coagulation.[12] As for the lipid profile in tobacco smokers, most studies, but not all, agree that smokers have dyslipidemia and that smoking is atherogenic leading to increased risk for cardiovascular, heart, inflammatory, and other related diseases.[131415]

Tobacco smoking has been shown to influence the concentrations of some hormones in the body leading to some related diseases and conditions, although not all studies agree on the occurrence of these changes and their direction. Some hormones that have been shown to be affected by tobacco smoking are the major thyroid gland hormones and vitamin D,[716] which are also implicated in immunity and inflammation. The major thyroid gland hormones, triiodothyronine (T3) and thyroxine (T4), are important for normal growth and development, metabolism, general health, proper development of all cells in the body,[17] modulation of the immune system,[17] and inflammation.[1618] Vitamin D is important for bone health, mineral metabolism, and the immune system.[19] Smoking has been shown to lead to low vitamin D levels.[20] Low levels of vitamin D and thyroid hormones are linked to the development of many diseases including CVD, cancers, autoimmune diseases, and inflammatory bowel disease.[21]

Saudi Arabia has a high prevalence of smoking and it is a major consumer of tobacco products. WPS has been increasing in popularity in all age groups and in both sexes in Saudi Arabia,[22] nevertheless studies on WP smokers in Saudi Arabia are few. In addition, there are no studies that showed the differences between female and male WP smokers for the parameters investigated here, with the exception of the lipid profile. Therefore, the aims of this study were to determine the effects of WPS on health in general, the immune system, and inflammation in healthy young female and male Saudis compared to nonsmokers of both sexes and to determine the differences in the effects of WPS on females and males. This was achieved by determining the differential and complete blood counts, the lipid profile, and concentrations of CRP, T3, T4, and vitamin D in the subjects.

MATERIALS AND METHODS

Subjects and categorization

For this study, 76 randomly chosen subjects, living in Jeddah and Al-Muzaylef, Saudi Arabia, with an age range of 20–35 years, were recruited. None of the subjects were taking any medications on a regular basis, nor having any allergic or chronic diseases (such as diabetes, immune diseases, blood pressure, hereditary diseases, anemia, or heart disease). The subjects were 17 female WP smokers, 21 female non-WP smokers (control), 17 male WP smokers, and 21 male non-WP smokers (control). None of the WP smokers smoked other tobacco products in addition to the WP. Female subjects were not pregnant or menstruating at the time of blood collection. Each subject signed a consent form and filled a lifestyle questionnaire to assess health status and lifestyle factors that may influence the parameters. Ethical approval for the study and for blood collection was obtained from the King Abdulaziz University Hospital, Jeddah, Saudi Arabia.

Blood collection

Blood was collected in plain Vacutainer tubes, which were centrifuged at 1370 × g for 5min to separate the serum from the blood clot. These samples were used for the CRP, thyroid hormones, and vitamin D analyses. Blood was also collected in ethylenediaminetetraacetic acid Vacutainer tubes for the differential complete blood counts. Finally, blood samples were also collected in lithium heparin Vacutainer tubes for the determination of lipid profiles. These samples were centrifuged at 1370 × g for 5min to separate the plasma from the cells.

Determination of parameters

All blood analyses were carried out at the King Abdulaziz Hospital, Jeddah, Saudi Arabia, and Al-Muzaylef General Hospital, Al-Muzaylef, Saudi Arabia.

The differential and complete CBC for all blood samples was carried out on a Sysmex XT 2000i Automated Hematology Analyzer (Sysmex, Kobe, Japan) using the Sysmex reagents (Sysmex, Norderstedt, Germany). A CRP Latex Test Kit (Crescent Diagnostics, Jeddah, Saudi Arabia) was used to determine the concentrations of CRP, as per the manufacturer’s instructions. The determination of the lipid profile for the subjects was carried out on a Beckman UniCel DxC 600 Chemistry Analyzer (Beckman Coulter, Brea, California), using chemicals from the same company. Vitamin D, T3, and T4 concentrations were determined on a Cobas e 411 Analyzer (Hitachi High-Technologies, Tokyo, Japan) using the Roche Diagnostic reagents (Mannheim, Germany).

Statistical methods

The MegaStat (version 9.4) statistical program was used for the calculation of the mean (), standard deviation (±SD), and the minimum and maximum values for all parameters. For the normally distributed parameters, the t-test was used to test for the significance in the differences between the groups, whereas the Mann–Whitney U-test was used for the non-normally distributed parameters. A P value less than or equal to 0.05 is considered a significant (S) difference.

RESULTS

Subjects

Ages of female smokers and nonsmokers ranged from 20 to 35 years, whereas ages for male smokers ranged from 25 to 35 years and for male nonsmokers from 23 to 35 years [Table 1]. The median age for female smokers was 27 years and for male smokers it was 29 years. Both female and male nonsmokers had a median age of 28 years.

Table 1

Age ranges, medians, and means for all groups

Group	Age range (years)	Media (n)	Mean	±SD
Female smokers	20–35	27	26.88	5.57
Female nonsmokers	20–35	28	27.24	4.78
Male smokers	25–35	29	29.47	3.12
Male nonsmokers	23–35	28	28.90	3.88

Lifestyle questionnaire

As shown in Table 2, more than half of female smokers and nonsmokers and most male smokers and nonsmokers were Saudi Arabian. The remaining subjects were of different nationalities. The majority of female smokers and nonsmokers were single, whereas the majority of male smokers and nonsmokers were married.

Table 2

Information on the subjects provided by the questionnaire

Factor	Females				Males
	Smokers		Nonsmokers		Smokers		Nonsmokers
	Frequency	%	Frequency	%	Frequency	%	Frequency	%
Nationality
Saudi	10	58.82	9	42.86	16	94.12	18	85.71
Non-Saudi	7	41.18	12	57.14	1	5.88	3	14.29
Marital status
Single	12	70.59	14	66.67	5	29.41	9	42.86
Married	5	29.41	7	33.33	12	70.59	12	57.14
Drinking tea and coffee
Tea only	1	5.88	4	19.05	7	41.18	7	33.33
Coffee only	7	41.18	8	38.10	0	0.00	3	14.29
Coffee and tea	7	41.18	6	28.57	8	47.06	11	52.38
None	2	11.76	3	14.29	2	11.76	0	0.00
Exercise
Daily	1	5.88	1	4.76	7	41.18	5	23.81
Weekly	3	17.65	2	9.52	1	5.88	7	33.33
Monthly	0	0.00	0	0.00	0	0.00	2	9.52
Rare	7	41.18	10	47.62	8	47.06	7	33.33
Never	6	35.29	8	38.10	1	5.88	0	0.00
Income level
<5,000	7	41.18	17	80.95	2	11.76	8	38.10
5,001–10,000	8	47.06	4	23.53	10	58.82	9	42.86
10,001–15,000	2	11.76	0	0.00	3	17.65	4	19.05
>15,000	0	0.00	0	0.00	2	11.76	0	0.00
Education
Less than high school	2	11.76	3	14.29	0	0.00	0	0.00
High school	7	41.18	7	33.33	7	41.18	3	14.29
Diploma	1	5.88	2	9.52	3	17.65	6	28.57
Bachelor’s	6	35.29	8	38.10	7	41.18	12	57.14
Master’s	1	5.88	1	4.76	0	0.00	0	0.00
PhD	0	0.00	0	0.00	0	0.00	0	0.00
Years of WPS
5	11	64.71	-	-	7	41.18	-	-
6–10	4	23.53	-	-	6	35.29	-	-
11–15	1	5.88	-	-	2	11.76	-	-
16–20	1	5.88	-	-	2	11.76	-	-
Frequency of WPS
Once daily	3	17.65	-	-	4	23.53	-	-
Twice daily	4	23.53	-	-	3	17.65	-	-
Thrice daily	3	17.65	-	-	4	23.53	-	-
Four times daily	0	0.00	-	-	2	11.76	-	-
Once weekly	0	0.00	-	-	0	0.00	-	-
Twice weekly	0	0.00	-	-	1	5.88	-	-
Thrice weekly	7	41.18	-	-	3	17.65	-	-
Exposure to secondhand smoke
At home	10	58.82	3	14.29	1	5.88	1	4.76
At work	5	29.41	1	4.76	7	41.18	9	42.86
None	2	11.76	17	80.95	9	52.94	11	52.38

Comparing female smokers and nonsmokers and male smokers and nonsmokers

Comparing the parameters between female smokers and nonsmokers [Tables 3 and 4], none of the parameters showed significant differences. Comparing male smokers and nonsmokers [Tables 5 and 6], it was found that smokers had a significantly lower mean monocyte count and a significantly higher mean red blood cell (RBC) count and hemoglobin concentration.

Table 3

Descriptive statistics and test of significance for the differences between female smokers and nonsmokers for the total and differential complete blood counts and C-reactive protein concentrations

Parameter	Group	n	Min	Max	Mean	±SD	±SE	P value
WBC* (103/µL)	Smokers	17	4.45	11.50	7.45	2.23	0.54	0.501NS
	Nonsmokers	21	3.72	11.15	6.95	2.28	0.50
Neutrophil* (103/µL)	Smokers	16	1.59	7.95	3.79	1.72	0.43	0.749NS
	Nonsmokers	16	1.37	6.45	3.98	1.58	0.40
Lymphocyte* (103/µL)	Smokers	16	1.49	4.92	2.99	0.86	0.22	0.289NS
	Nonsmokers	16	1.62	4.85	2.65	0.89	0.22
Monocyte* (103/µL)	Smokers	16	0.34	0.83	0.57	0.14	0.03	0.707NS
	Nonsmokers	16	0.31	0.79	0.56	0.13	0.03
Eosinophil** (103/µL)	Smokers	16	0.04	0.47	0.18	0.12	0.03	0.449NS
	Nonsmokers	16	0.03	0.47	0.16	0.13	0.03
Basophil** (103/µL)	Smokers	16	0.00	0.08	0.03	0.02	0.00	0.600NS
	Nonsmokers	16	0.00	0.18	0.03	0.04	0.01
RBC* (106/µL)	Smokers	17	3.21	5.22	4.53	0.53	0.13	0.481NS
	Nonsmokers	21	3.90	5.10	4.43	0.32	0.07
Platelets* (103/µL)	Smokers	17	193	455	321	67	16	0.093NS
	Nonsmokers	21	169	460	282	71	15
Hemoglobin* (g/dL)	Smokers	17	6.7	14.8	11.7	2.3	0.5	0.167NS
	Nonsmokers	21	10.3	13.9	12.5	0.9	0.2
CRP** (mg/L)	Smokers	17	5.99	24.00	7.40	4.52	1.10	0.484NS
	Nonsmokers	21	5.99	12.00	6.56	1.81	0.39

S = significant (P ≤ 0.05), NS = not significant (P > 0.05), Max = maximum, Min = minimum *t-test was used for the significance test **Mann–Whitney U-test was used for the significance test

Table 4

Descriptive statistics and test of significance for the differences between female smokers and nonsmokers for the thyroid hormones, vitamin D, and lipid profile concentrations

Parameter (mmol/L)	Group	N	Min	Max	Mean	±SD	±SE	P value
T3*	Smokers	17	3.07	6.26	4.86	0.78	0.19	0.775NS
	Nonsmokers	21	3.96	6	4.8	0.48	0.1
T4*	Smokers	17	10.12	19.3	15.19	2.14	0.52	0.855NS
	Nonsmokers	21	12.79	19.11	15.31	1.84	0.4
Vitamin D**	Smokers	17	4.82	27.12	13.46	7.39	1.79	0.883NS
	Nonsmokers	21	3.55	34.54	14.51	8.36	1.82
Cholesterol*	Smokers	17	3.16	6.6	5.04	0.86	0.21	0.121NS
	Nonsmokers	21	3.21	6.15	4.62	0.78	0.17
Triglyceride**	Smokers	17	0.37	2.91	0.91	0.59	0.14	0.103NS
	Nonsmokers	21	0.28	2.09	0.74	0.53	0.12
HDL**	Smokers	17	1	2.21	1.39	0.37	0.09	0.681NS
	Nonsmokers	21	0.84	2.68	1.45	0.43	0.09
LDL*	Smokers	17	1.6	4.4	3.3	0.8	0.2	0.119NS
	Nonsmokers	21	1.8	4.5	2.9	0.8	0.2

NS = not significant (P > 0.05), Max = maximum, Min = minimum *t-test was used for the significance test **Mann–Whitney U-test was used for the significance test

Table 5

Descriptive statistics and test of significance for the differences between male smokers and nonsmokers for the total and differential complete blood counts and C-reactive protein concentrations

Parameter	Group	n	Min	Max	Mean	±SD	±SE	P value
WBC*	Smokers	17	3.26	11.14	6.28	2.13	0.52	0.743NS
(103/µL)
	Nonsmokers	21	3.71	11.76	6.51	2.06	0.45
Neutrophil**	Smokers	17	0.6	7.56	2.9	1.82	0.44	0.618NS
(103/µL)	Nonsmokers	21	1.2	7.48	3.1	1.64	0.36
Lymphocyte*	Smokers	17	1.76	4.52	2.61	0.66	0.16	0.685NS
(103/µL)	Nonsmokers	21	1.62	4	2.52	0.68	0.15
Monocyte*	Smokers	17	0.19	0.85	0.53	0.19	0.05	0.047S
(103/µL)	Nonsmokers	21	0.4	1.01	0.65	0.16	0.04
Eosinophil**	Smokers	17	0.06	0.45	0.21	0.11	0.03	0.955NS
(103/µL)	Nonsmokers	21	0.05	0.56	0.2	0.13	0.03
Basophil**	Smokers	17	0.01	0.1	0.04	0.02	0.01	0.988NS
(103/µL)	Nonsmokers	21	0.02	0.07	0.03	0.02	0
RBC*	Smokers	17	4.49	7.08	5.52	0.56	0.14	0.023S
(106/µL)	Nonsmokers	21	4.67	5.73	5.21	0.22	0.05
Platelets*	Smokers	17	150	333	227	42	10	0.483NS
(103/µL)	Nonsmokers	21	161	317	236	44	10
Hemoglobin*	Smokers	17	12.9	18.4	15.5	1.4	0.3	0.005HS
(g/dL)	Nonsmokers	21	12.8	15.6	14.4	0.9	0.2
CRP**	Smokers	17	5.99	12	6.7	1.1	0.48	0.595NS
(mg/L)	Nonsmokers	21	5.99	48	8.28	9.2	2.01

HS = highly significant (P < 0.01), S = significant (P ≤ 0.05), NS = not significant (P > 0.05), Max = maximum, Min = minimum *t-test was used for the significance test **Mann–Whitney U-test was used for the significance test

Table 6

Descriptive statistics and test of significance for the differences between male smokers and nonsmokers for the thyroid hormones, vitamin D, and lipid profile concentrations

Parameter (mmol/L)	Group	n	Min	Max	Mean	±SD	±SE	P value
T3*	Smokers	17	4.67	6.60	5.47	0.54	0.13	0.639NS
	Nonsmokers	21	4.43	7.06	5.57	0.70	0.15
T4*	Smokers	17	13.72	19.44	16.29	1.54	0.37	0.200NS
	Nonsmokers	21	11.54	20.67	15.37	2.55	0.56
Vitamin D**	Smokers	17	8.29	30.52	14.34	5.75	1.39	0.587NS
	Nonsmokers	21	7.98	36.78	15.95	7.67	1.67
Cholesterol*	Smokers	15	3.66	5.34	4.66	0.47	0.12	0.890NS
	Nonsmokers	22	3.29	6.20	4.63	0.72	0.15
Triglyceride**	Smokers	15	0.78	4.65	2.08	1.29	0.33	0.228NS
	Nonsmokers	22	0.17	3.79	1.46	0.75	0.16
HDL*	Smokers	15	0.71	1.81	1.12	0.28	0.07	0.493NS
	Nonsmokers	21	0.71	1.49	1.06	0.22	0.05
LDL*	Smokers	15	2.2	4.0	3.1	0.6	0.2	0.270NS
	Nonsmokers	21	2.1	4.7	3.3	0.7	0.2

NS = not significant (P > 0.05), Max = maximum, Min = minimum *-test was used for the significance test **Mann–Whitney U-test was used for the significance test

Comparing female and male smokers and female and male nonsmokers

In both smokers and nonsmokers [Tables 7 and 8], females had significantly higher mean platelet counts and high-density lipoprotein (HDL) concentrations and significantly lower mean RBC counts and mean hemoglobin, T3, and triglyceride concentrations compared to male smokers and nonsmokers, respectively. In addition, female nonsmokers had significantly lower mean basophil counts compared to male nonsmokers [Table 7].

Table 7

Descriptive statistics and test of significance for the differences between female and male smokers and nonsmokers for the total and differential complete blood count and C-reactive protein concentrations

Parameter	Smokers					Nonsmokers
	Group	n	Mean	±SD	P value	n	Mean	±SD	P value
WBC*	Females	17	7.45	2.23	0.127NS	21	6.95	2.28	0.510NS
(103/µL)	Males	17	6.28	2.13		21	6.51	2.06
Neutrophil*	Females	16	3.79	1.72	0.159NS	16	3.98	1.58	0.110NS
(103/µL)	Males	17	2.9	1.82		21	3.10	1.64
Lymphocyte*	Females	16	2.99	0.86	0.163NS	16	2.65	0.89	0.602NS
(103/µL)	Males	17	2.61	0.66		21	2.52	0.68
Monocyte*	Females	16	0.57	0.14	0.476NS	16	0.56	0.13	0.069NS
(103/µL)	Males	17	0.53	0.19		21	0.65	0.16
Eosinophil*,**	Females	16	0.18	0.12	0.457NS	16	0.16	0.13	0.059NS
(103/µL)	Males	17	0.21	0.11		21	0.20	0.13
Basophil**	Females	16	0.03	0.02	0.198NS	16	0.031	0.04	0.042S
(103/µL)	Males	17	0.04	0.02		21	0.032	0.02
RBC**,*	Females	17	4.53	0.53	0.000S	21	4.43	0.32	0.000S
(106/µL)	Males	17	5.52	0.56		21	5.21	0.22
Platelet*	Females	17	321	67	0.000S	21	282	71	0.016S
(103/µL)	Males	17	227	42		21	236	44
Hemoglobin*	Females	17	11.7	2.3	0.000S	21	12.5	0.9	0.000S
(g/dL)	Males	17	15.5	1.4		21	14.4	0.9
CRP**	Females	17	7.40	4.52	0.655NS	21	6.56	1.81	0.420NS
(mg/L)	Males	17	6.70	1.10		21	8.28	9.2

S = significant (P ≤ 0.05), NS = not significant (P > 0.05) *t-test was used for the significance test **Mann–Whitney U-test was used for the significance test *,**t-test was used for smokers and Mann–Whitney U-test was used for nonsmokers **,*Mann–Whitney U-was used for smokers and t-test was used for nonsmokers

Table 8

Descriptive statistics and test of significance for the differences between female and male smokers and nonsmokers for the thyroid hormones, vitamin D, and lipid profile concentrations

Parameter (mmol/L)	Smokers					Nonsmokers
	Group	n	Mean	±SD	P value	n	Mean	±SD	P value
T3*	Females	17	4.86	0.78	0.012S	21	4.80	0.48	0.000S
	Males	17	5.47	0.54		21	5.57	0.70
T4*	Females	17	15.19	2.14	0.095NS	21	15.31	1.84	0.931NS
	Males	17	16.29	1.54		21	15.37	2.55
Vitamin D**,*	Females	17	13.46	7.39	0.605NS	21	14.51	8.36	0.565NS
	Males	17	14.34	5.75		21	15.95	7.67
Cholesterol*	Females	17	5.04	0.86	0.133NS	21	4.62	0.78	0.975NS
	Males	15	4.66	0.47		21	4.63	0.72
Triglyceride**	Females	17	0.91	0.59	0.002S	21	0.74	0.53	0.001S
	Males	15	2.08	1.29		21	1.46	0.75
HDL**,*	Females	17	1.39	0.37	0.017S	21	1.45	0.43	0.001S
	Males	15	1.12	0.28		21	1.06	0.22
LDL*	Females	17	3.3	0.8	0.433NS	21	2.9	0.8	0.053NS
	Males	15	3.1	0.6		21	3.3	0.7

S = significant (P ≤ 0.05), NS = not significant (P > 0.05) *t-test was used for the significance test **Mann–Whitney U-test was used for the significance test **,* Mann–Whitney U-test was used for smokers and t-test was used for nonsmokers

DISCUSSION

This study was carried out on female and male WP smokers and nonsmokers living in Jeddah and Al-Muzaylef, Saudi Arabia, to determine the effects of WPS on female and male smokers and the gender differential effects of WPS on the immune system, some hormones, and other health-related parameters. Thus, each parameter was compared between smokers and nonsmokers in females and males each to determine the influence of smoking on the studied parameters. In addition, comparisons were made between female and male smokers and female and male nonsmokers separately to determine the gender-dependent effects of WPS. The results were compared to the findings of other research studies that were carried out mainly on cigarette smokers, rather than on WP smokers, due to the scarcity of studies on WP smokers. In addition, no other studies showed the differences between female and male WP smokers for the parameters investigated here, with the exception of the lipid profile.

The results for the subjects’ mean ages showed a lower mean age for female smokers compared to that for female nonsmokers and a higher mean age for male smokers than that for male nonsmokers. From information that was collected using the lifestyle questionnaire, most female smokers drank coffee only or coffee and tea, whereas most female nonsmokers drank coffee only. Most male smokers and nonsmokers drank coffee and tea. The majority of female and male smokers and female nonsmokers rarely exercised, whereas most male nonsmokers were equally divided between exercising weekly and rarely. About twice as many male smokers exercised daily compared to male nonsmokers. This may lead to health benefits and a reduction in the ill effects of smoking in male smokers.

Most female and male smokers and male nonsmokers had incomes in the lower intermediate range (5001–10,000 Saudi Riyals), whereas the majority of female nonsmokers had low incomes. As for education level, more female nonsmokers had earned a bachelor’s or master’s degree compared to most female smokers having high school diploma only or a bachelor’s or master’s degree. For male smokers, an equal percent had earned a high school diploma only or a bachelor’s degree, whereas most male nonsmokers had attained a bachelor’s degree.

The majority of female and male smokers have been smoking for five years at the time of the study. Thus, more males than females had been smoking for six years or more. Most female smokers smoked three times per week, whereas for male smokers most subjects smoked either once per day or three times per day. More than three-quarters of male smokers smoked the WP daily (one to four times per day), whereas a little more than half of females smoked daily (one to three times per day). The majority of female smokers were exposed to secondhand smoke (mainly at home), whereas the majority of female nonsmokers and male smokers and nonsmokers were not exposed to any secondhand smoke.

There were no significant differences in the mean total WBC counts between smokers and nonsmokers in both females and males nor between females and males among smokers and nonsmokers, separately. Contradictory findings were reported earlier by several investigators[23242526] who found significantly higher levels of WBC in female and male cigarette and WP smokers. On the contrary, other studies[727] found no difference in WBC counts between male WP smokers and nonsmokers, in agreement with the findings here.

For the differential WBC counts, there were no significant differences between smokers and nonsmokers in females and males, separately, for all mean cell counts, with the exception of a significantly lower mean monocyte count for male smokers compared with male nonsmokers. Comparing females and males among smokers and nonsmokers each, no significant differences were observed for the mean counts of the WBC types, except for a significantly lower mean basophil cell count for female nonsmokers compared with male nonsmokers.

The results obtained for the differential WBC counts in female and male WP smokers do not correlate with other studies that showed significantly lower neutrophil,[711] lymphocyte,[25] and eosinophil counts,[28] and significantly higher lymphocyte,[1011] total granulocyte,[25] neutrophil,[10] monocyte,[1011] basophil,[10] and eosinophil[1011] counts in female and male smokers compared to nonsmokers. Some studies found no differences between the monocyte cell counts for female[25] and male[725] cigarette smokers compared to nonsmokers, which agree with our results for female smokers but not for male smokers who had a lower mean monocyte count. On the contrary, the results were in agreement with the finding of no significant differences in the cell counts for lymphocytes,[7] eosinophils,[7] and basophils[711] in male smokers compared to those in nonsmokers.

Comparing female smokers and nonsmokers, it was found that the results for mean RBC and platelet counts and mean hemoglobin concentrations did not show any significant differences. For males, mean RBC counts and hemoglobin concentrations for smokers were significantly higher compared with nonsmokers. As for the mean platelet counts, no significant difference was observed between male smokers and nonsmokers. Comparing female and male smokers and nonsmokers separately, it was found that mean RBC counts and hemoglobin concentrations were significantly lower, and mean platelet counts were significantly higher for both female smokers and nonsmokers compared to those for male smokers and nonsmokers, respectively. Thus, compared to female smokers and nonsmokers, male smokers and nonsmokers, respectively, had higher RBC counts and hemoglobin levels along with lower platelet counts, which is normal in males.

Compared to nonsmokers, the current findings for mean hemoglobin concentrations for female smokers disagree, whereas for male smokers they agree with the findings of other researchers’ of significantly higher hemoglobin levels for female[25] and male[24252628] cigarette and WP smokers compared with those for nonsmokers. The hemoglobin results for males disagree with the results of previous studies that found no significant differences in the hemoglobin concentrations of male WP smokers[27] and male cigarette smokers[727] compared to those of nonsmokers.

Other researchers found no differences in RBC counts for female and male cigarette smokers[2527] and male WP smokers[27] compared to nonsmokers, which is in agreement with the results of this study for females but not for males. On the contrary, in agreement with the current results for males, other studies found significantly higher RBC counts in male WP smokers[26] and male cigarette smokers[72426] compared to nonsmokers. Higher hemoglobin concentrations and RBC counts in smokers have been speculated to be due to hypoxic hypoxia, which is an insufficient amount of oxygen reaching the lungs that results from the effects of smoking or respiratory diseases.[2930] Elevated levels of hemoglobin correlate with the increased number and size of RBCs[24] as found in the results for male smokers compared to that for nonsmokers.

In this study, the lack of differences in platelet counts between smokers and nonsmokers in females and males agrees with the findings of other research studies on male WP smokers[27] and on female[2531] and male[725] cigarette smokers compared to nonsmokers. Contrary to the current findings, other researchers observed lower numbers of circulating platelets in female WP smokers,[3233] female cigarette smokers,[34] and male WP and cigarette smokers[27] compared to those in nonsmokers. Also contrary to the current results, a previous study[34] found that platelet counts were slightly higher in male cigarette smokers than those in nonsmokers. Lower platelet counts may be due to platelet aggregation that may result in smokers due to the effects of smoking.

The results for the mean CRP concentrations did not show any significant differences between smokers and nonsmokers in both females and males nor between females and males among smokers and nonsmokers, separately. As has been reported in previous studies and in agreement with the current results, CRP concentrations were not significantly different for male WP smokers[33] nor in female[23] and male[735] cigarette smokers compared to nonsmokers. Contrary to the current results, other research studies found higher CRP levels in male[233637] and female[36] cigarette smokers compared to those in nonsmokers. It is well known that high CRP levels are strongly associated with a higher risk for CVD and other inflammatory diseases that are all prevalent in tobacco smokers.[36] Therefore, it was expected, contrary to our findings, that smokers would have had significantly higher CRP levels.

Mean T3, T4, and vitamin D concentrations did not show any significant differences between smokers and nonsmokers in females and males, separately. For the comparisons between female and male smokers and nonsmokers each, no significant differences were observed for mean T4 and vitamin D concentrations. Mean T3 concentrations in female smokers and nonsmokers were significantly lower compared to levels in male smokers and nonsmokers, respectively. A previous study on female[38] and male[738] cigarette smokers showed that smoking has no effect on T3 and T4 concentrations, which is in agreement with this study, whereas other studies[3940] observed that female and male cigarette smokers have higher T3 and T4 levels than nonsmokers. A study carried out on rats exposed to WP smoke[41] found that serum T3 and T4 levels were significantly increased compared to control rats.

No significant differences were observed between smokers and nonsmokers in both females and males for mean serum cholesterol, triglyceride, HDL, and low-density lipoprotein (LDL) concentrations. On the contrary, comparing female and male smokers and nonsmokers, separately, mean serum triglyceride concentrations were significantly lower and mean serum HDL concentrations were significantly higher for female smokers and nonsmokers compared to the respective levels for male smokers and nonsmokers, respectively. Finally, no significant differences were observed between females and males in both the smokers and nonsmokers groups for mean cholesterol and LDL concentrations.

The lipid profile results disagree with several other studies that found significantly higher levels of cholesterol,[15273742] LDL,[273742] HDL,[15] and triglyceride,[152527323742] and significantly lower HDL levels[27323742] in female and male WP and cigarette smokers compared to nonsmokers. The study by Kuzuya et al.[32] disagrees with these studies in finding significantly lower cholesterol and LDL levels in female and male cigarette smokers compared to those in nonsmokers. In agreement with our findings, other studies found no significant differences between female and male cigarette smokers compared to those in nonsmokers, in cholesterol,[25] LDL,[1525] HDL,[2537] and triglyceride concentrations.[2537]

It was expected that there would be more significant differences between smokers and nonsmokers in both females and males. One explanation for these unexpected findings is that most females (64.71%) had been smoking the WP for five years only, whereas most males (58.81%) had been smoking the WP for more than five years. In addition, a greater number of male smokers smoked the WP more often and on a daily basis compared to female smokers. In addition, as discussed earlier, the current results disagree with the findings of some previous studies by other researchers. One possible reason for this, other than the obvious ones such as racial and age differences, may be the fact that most previous studies either included females in cohorts of mixed genders or they only studied male smokers.

CONCLUSION

In conclusion, none of the determined parameters were significantly different between female smokers and nonsmokers. On the contrary, compared to male nonsmokers, male smokers had significantly lower monocytes counts and significantly higher RBC counts and hemoglobin concentrations, whereas the remaining parameters did not show any significant differences. In addition to these observed gender-specific differences, the parameters were compared between female and male smokers and nonsmokers separately. The few significant differences that were found between females and males were present in both smokers and nonsmokers, with the exception of a significantly lower basophil cell count in female compared to the count in male nonsmokers. Thus, it may be concluded that the basophil cell count is the only parameter that behaved differently between female and male smokers compared to that between female and male nonsmokers. Therefore, it is apparent that females and males are affected differently by WPS with only some immune system cells being effected but none of the other parameters.

Ethical considerations

Ethical approval for the study and for blood collection was obtained from the King Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia.

Financial support and sponsorship

Partial funding for this research study was provided by a grant from King Abdulaziz City for Science and Technology, Riyadh, Kingdom of Saudi Arabia.

Conflicts of interest

There are no conflicts of interest.