groups. Furthermore, subanalysis indicated that, regard- less of age or gender, significant alterations in the hema- tological profiles were seen in those children exposed to benzene. Overall, the findings of the hematological pro- files confirmed the pilot study findings indicating that children who have been exposed to benzene have sig- nificantly increased health risks compared with unex- posed children.
Effect of Benzene Exposure on Hepatic Function in Children
Currently, there are no published studies in literature that evaluated the clinical effect of benzene exposure on the liver function in children except 2 recent reports published by the authors.35,36 The initial pilot study included 157 benzene-exposed and 155 unexposed chil- dren and assessed their liver function enzymes such as alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT). The study findings revealed that benzene-exposed children had clinically significantly higher levels of ALP (P = .04), AST (P = .015), and ALT (P = .005) compared with the unexposed children.
Subsequently, the larger cohort study36 assessed the liver function enzymes in 641 benzene-exposed children and compared with the 258 unexposed children. Serum ALP, AST, and ALT levels were reported to be increased significantly in children exposed to benzene compared with the unexposed children (P = .001). Furthermore, subgroup analysis indicated that, regardless of age or gender, significant alterations in hepatic enzymes were seen in children exposed to benzene. Overall, the find- ings of the hepatic profiles confirmed the pilot study findings indicating that children who have been exposed to benzene have significantly increased health risks compared with unexposed children.
Benzene Exposure and Illness Symptom Profiles in Children
Among all, respiratory illness symptoms are the most often studied health complaints in children exposed to benzene or petrochemicals/urban traffic pollutants. Upper respiratory symptoms were the most (67%) fre- quently reported, followed by neurological symptoms (57%), diarrhea (25%), and cough (24%). Logistic regression analysis indicated that neurological symptoms (R2 = 0.75), chest pain (R2 = 0.64), joint pain (R2 = 0.57), and vision difficulty (R2 = 0.54) were positively associ- ated with increasing age. Other studies have shown that asthma symptoms such as those related to wheezing, cough, and shortness of breath or chest tightness were the most frequently reported respiratory illness symptoms in
in a Spanish birth cohort of 2199 infants. These authors observed that during the second trimester of pregnancy, an increase in 1.0 µg/m3 of benzene exposure was asso- ciated with an increased risk of lower respiratory tract infections in those infants.
In a panel study, Delfino et al42 examined the longitu- dinal relationship of the daily asthma severity among asthmatic children exposed to volatile organic com- pounds such as benzene. The study included 21 asth- matic children between 10 and 16 years of age. The study revealed that increased mean concentrations of benzene (5.7 µg/m3) levels were associated with increased asthma and poor lung function among the children. Martins and coauthors43 evaluated the relationship between air pol- luted by benzene exposure and airway changes in a group of wheezing children. The investigators included a total of 51 wheezing children with a mean age of 7.3 years from Viseu, Portugal. Benzene levels were monitored for 4 weeks, and using a dispersion model, personal expo- sure was determined based on time-activity patterns according to the estimations. These authors reported that an increase in 10.0 µg/m3 of benzene exposure was asso- ciated with deteriorated lung function-related outcomes in wheezing children.
In a pilot study, we investigated the clinical presenta- tion of the illness symptoms experienced by children who were exposed to benzene following a flaring inci- dent at the BP refinery in Texas City, Texas.35 The study included a total of 157 children who were exposed to benzene. Among the illness symptoms, neurological symptoms such as unsteady gait, memory loss, and headaches were the most (80%) frequently reported symptoms in children exposed to benzene. Upper respi- ratory symptoms were reported by 48% of the benzene- exposed children followed by cough (48%), nausea/ vomiting (43%), dermatological (36%), shortness of
breath (32%), wheezing (27%), dizziness (22%), chest
pain (15%), painful joints (15%), and weight loss (13%). To complement these findings, recently we conducted a full-fledged study in 641 children who were exposed to benzene following a flaring incident at the BP refinery in Texas City, Texas.44 A total of 1790 illness symptoms were observed in 641 children exposed to benzene.
Among all clinically presented illness symptoms, upper respiratory symptoms occurred as the most fre- quently (67%) followed by neurological symptoms (57%), diarrhea (25%), and cough (24%). Logistic regression analysis indicated that neurological symptoms (R2 = 0.75), chest pain (R2 = 0.64), joint pain (R2 = 0.57), and vision difficulty (R2 = 0.54) were positively associ- ated with increasing age of the children. Overall, the findings revealed that children exposed to benzene expe- rienced range of illness symptoms indicating their vul- nerability to increased risks and health complications.
dehydrogenases are important enzymes in the biological processes. They are involved in the detoxification, metabolism, and biosynthesis of energetic macromole- cules for different essential functions. Any interference in these enzymes leads to biochemical impairment and changes in the tissue and cellular function. Thus, the measurement of these liver enzyme such as ALP, AST, and ALT are routinely assessed as indicators for hepatic dysfunction and damage.46,47 In normal conditions, these enzymes are confined to the cells but are released into circulating blood when there is necrosis or injury. Despite its importance, until recently, there were no published studies available in the literature evaluating the effect of benzene exposure on the hepatic function in children. The 2 recent studies reported by the authors35,36 revealed that the serum levels of ALP, AST, and ALT were found to be elevated among those children who were exposed to benzene indicating hepatic abnormali- ties in these children. The increase in the levels of these liver enzymes in their serum suggests the impairment of the hepatic function in children exposed to benzene.
Studies assessing the somatic or clinically presenting illness symptoms such as respiratory, neurological, gas- trointestinal, and other symptoms in children exposed to benzene were also limited in the published literature. However, evidence from available studies suggests that benzene exposure is associated clinically with sickness symptoms in children. The most common clinical pre- sentations of the illness symptoms include neurological, respiratory, shortness of breath, wheezing, dizziness, chest pain, and painful joints.
Conclusions
Together, studies evaluating the clinical changes in the hematologic, cardiac, hepatic, renal, and other vital organ functions in children who were exposed to ben- zene are sparse. We have yet to learn and understand the full extent of all the adverse effects that benzene expo- sure has on pediatric populations. Findings from the cur- rently available studies reveal that benzene exposure is associated with clinical abnormalities in the hemato- logic, hepatic, respiratory, and pulmonary functions in children. The hematological abnormalities were charac- terized by changes in RBC, WBC, absolute lympho- cytes, platelets, hemoglobin, hematocrit, and creatinine in benzene-exposed children. Similarly, the hepatic abnormalities were characterized by elevated levels of ALP, AST, and ALT enzymes in the serum of the chil- dren exposed to benzene. Few studies have evaluated the somatic or illness symptoms such as respiratory, neurological, gastrointestinal, and other symptoms in children exposed to benzene. These findings indicate