Naturally, benzene comes from crude oil. For example benzene, found at concentrations up to 4g/L in petroleum content, is also found in seawater with concentrations up to 0.8ppb in the vicinity of natural gas and petroleum storage.1 Measurement of benzene exposure for a population is quite difficult to quantify because the lifestyle of each individual varies widely, environmental weather conditions can also affect, and the environment in which they live varies.2

Workers in industries that make or use benzene such as petrochemicals, petroleum refining, coal mining, tire manufacturing, benzene storage and distribution, fuel storage and distribution can be exposed to high levels. Other occupations that have the potential to be exposed to benzene are workers working in coal furnaces in the steel industry, printing, shoe factories, laboratory technicians, firefighters, and gas station operators.3

The effects of acute exposure to high levels of benzene (to nerves, skin, respiration, and digestion) can occur immediately after exposure. Neurological effects due to the anesthetic nature of benzene which directly attacks the central nervous system/preceded by feelings of drift, depression, and if exposure to high levels of benzene continues, it can cause death. The effects of moderate concentrations of benzene exposure can cause headaches, dizziness, nausea, dizziness, and eye burning. The effects of continued exposure can cause tremors, shortness of breath, confusion, loss of consciousness, coma, and death.4

In Indonesia, standards have been established for the determination of the threshold value (NAV) for physical and chemical factors in the workplace. In the Regulation of the Minister of Manpower of the Republic of Indonesia No. 5 of 2018 concerning Work Safety in the Work Environment stipulates that benzene is included in group A1 or a chemical substance that is proven to have a carcinogenic health effect for humans with a threshold value (TLV) of 0.5ppm for 8h of exposure. Meanwhile, for a short exposure for 15min of 2.5ppm.5

The source of benzene in the control room comes from the waste pit which is an open oil pool, so that with the help of sunlight, evaporation will occur and produce a strong benzene smell that can be carried by wind.

The working hours of the control room workers consist of 3 shifts were 1-morning shift, 1-night shift, and 1-holiday shift which changes every 3 days continuously. 1 shift has 12h of working hours, holidays do not affect them because the machines and tools on-site must always be maintained for 24h because if there is any damage, they can be immediately resolved and do not interfere with oil production.

Calculation of cancer and non-cancer intakes

The calculation of the intake of non-cancer exposure is carried out to take into account the non-cancer effects that can occur on workers in 2 different times of exposure, namely real time and lifetime. In real time, real time figures are used, namely the length of time they have worked in that place, while the non-cancerous lifetime exposure is 40 years, which is obtained from workers starting to work until they retire (Tables 4 and 5).

Table 4.

The value of intake (intake) of non-carcinogenic and carcinogenic effects in control room A employees.

Participants	Non-carcinogenic		Carcinogenic
	Real time	Lifetime	Real time	Lifetime
A1	0.0104	0.0160	0.0045	0.0069
A2	0.0104	0.0181	0.0045	0.0078
A3	0.0067	0.0207	0.0029	0.0089
A4	0.0116	0.0193	0.0050	0.0083
A5	0.0136	0.0227	0.0058	0.0097
A6	0.0074	0.0164	0.0032	0.0070
A7	0.0113	0.0181	0.0049	0.0078
A8	0.0002	0.0190	0.0001	0.0081
A9	0.0050	0.0168	0.0022	0.0072
A10	0.0050	0.0181	0.0021	0.0078
A11	0.0129	0.0184	0.0055	0.0079
A12	0.0028	0.0188	0.0012	0.0081

Table 5.

The value of intake (intake) of non-carcinogenic and carcinogenic effects in control room B employees.

Participants	Non-carcinogenic		Carcinogenic
	Real time	Lifetime	Real time	Lifetime
B1	0.0131	0.0175	0.0056	0.0075
B2	0.0012	0.0155	0.0005	0.0066
B3	0.0118	0.0163	0.0051	0.0070
B4	0.0112	0.0173	0.0048	0.0074
B5	0.0111	0.0171	0.0048	0.0073
B6	0.0034	0.0152	0.0015	0.0065
B7	0.0093	0.0161	0.0040	0.0069
B8	0.0012	0.0164	0.0005	0.0070
B9	0.0030	0.0169	0.0013	0.0073
B10	0.0091	0.0152	0.0039	0.0065

Risk characterization

The risk characteristics are used to distinguish the health effects of non-cancer and cancer from the parameters tested, namely benzene. The risk characteristics for non-cancerous effects can be determined using the following formula:

After getting the RQ value, it can be assumed as follows:

• •

  If RQ<1, then the hazard concentration is not at risk of causing non-carcinogenic health effects.

• •

  If RQ>1, then the hazard concentration is already at risk of causing non-carcinogenic health effects.

The characteristics for the cancer effect can be determined by multiplying the carcinogenic intake value by the CSF value (Tables 6–9).

Table 6.

Distribution of risk quotient (RQ) values in control room A.

Participants	Real time	Risk level	Life time	Risk level
A1	1.210	B	1.861	B
A2	1.211	B	2.106	B
A3	0.784	TB	2.412	B
A4	1.349	B	2.248	B
A5	1.583	B	2.638	B
A6	0.857	TB	1.905	B
A7	1.316	B	2.106	B
A8	0.023	TB	2.205	B
A9	0.585	TB	1.951	B
A10	0.579	TB	2.106	B
A11	1.501	B	2.145	B
A12	0.328	TB	2.185	B
Average	0.944	TB	2.156	B

Table 7.

Distribution of risk quotient (RQ) values in control room B.

Participants	Real time	Risk level	Life time	Risk level
B1	1.524	B	2.032	B
B2	0.135	TB	1.804	B
B3	1.371	B	1.891	B
B4	1.307	B	2.010	B
B5	1.293	B	1.989	B
B6	0.399	TB	1.771	B
B7	1.077	B	1.873	B
B8	0.143	TB	1.910	B
B9	0.345	TB	1.969	B
B10	1.063	B	1.771	B
Average	0.866	TB	1.902	B

Table 8.

Distribution of excess cancer risk (ECR) values in control room A.

Participants	Real time	Risk level	Life time	Risk level
A1	0.00012	B	0.00019	B
A2	0.00012	B	0.00021	B
A3	0.00008	TB	0.00024	B
A4	0.00014	B	0.00023	B
A5	0.00016	B	0.00027	B
A6	0.00009	TB	0.00019	B
A7	0.00013	B	0.00021	B
A8	0.00000	TB	0.00022	B
A9	0.00006	TB	0.00020	B
A10	0.00006	TB	0.00021	B
A11	0.00015	B	0.00022	B
A12	0.00003	TB	0.00022	B
Average	0.00009	TB	0.00022	B

Table 9.

Distribution of excess cancer risk (ECR) values in control room B.

Participants	Real time	Risk level	Life time	Risk level
A1	0.00015	B	0.00020	B
A2	0.00001	TB	0.00018	B
A3	0.00014	B	0.00019	B
A4	0.00013	B	0.00020	B
A5	0.00013	B	0.00020	B
A6	0.00004	TB	0.00018	B
A7	0.00011	B	0.00019	B
A8	0.00001	TB	0.00019	B
A9	0.00003	TB	0.00020	B
A10	0.00011	B	0.00018	B
Average	0.00009	TB	0.00019	B

Notes: B: risk of carcinogenic health effects; TB: no risk of carcinogenic effects.

After getting the ECR value, the following assumptions are used:

• •

  If the ECR <10-4, then the hazard concentration has not caused a carcinogenic health effect.

• •

  If the ECR >10-4, then the hazard concentration values have already caused carcinogenic health effects.

Risk management

Risk management is an effort to protect the object of research, in this case, workers from the influence of benzene, which can cause non-carcinogenic and carcinogenic health effects. The first way to do after a risk analysis is to reduce the concentration of benzene exposure and reduce the contact time of workers with benzene (Table 10).8

Table 10.

Data from the calculation of risk control options for the effects of cancer on safe benzene exposure in the employee population of control room A and B.

Component	Preliminary data	Safe variable
Concentration (C)	0.191mg/m3	0.1mg/m3
Time exposure (tE)	12h/day	6h/day
Frequency exposure (fE)	243day/year	115day/year

Reduces concentration during life time exposure

Reduces the length of exposure (tE) during lifetime exposure

Reduces frequency of exposure (fE) during lifetime exposure

The results of individual calculations for the non-carcinogenic effect of benzene, the results obtained for control room A on real time exposure, 6 people who had an RQ value ≤1 and 6 people had an RQ value >1, at lifetime exposure there were no people who had an RQ value ≤1 would but there are 12 people who have an RQ value >1. In control room B on real time exposure, 4 people who have an RQ value ≤1 and 6 people have an RQ value >1, on lifetime exposure there are no people who have an RQ value ≤1 but there are 10 people who have an RQ value >1.

The results of individual calculations for the carcinogenic effect of benzene, the results obtained for control room A on real time exposure, 6 people had ECR values ≤10−4, and 6 people had ECR values >10−4, at lifetime exposure there were no people who had ECR values. ≤10−4 but 12 people who have ECR values >10−4. In control room B, on real time exposure, 4 people have an ECR value ≤10−4 and 6 people have an ECR value >10−4, at lifetime exposure there are no people who have an ECR value ≤10−4 but there are 10 people who have a value ECR >10−4.

The toxic effects of benzene exposure can be felt by the body in the short and long term. In the short term, benzene exposure will have an effect on throat problems and eye irritation. However, if the exposure is short term but the concentration is high enough the benzene exposure will cause narcosis: dizziness, headache, drowsiness, confusion, tremor, unconsciousness. In long-term exposure, the health effects due to benzene toxicity are on the bone marrow which is responsible for making blood cells so that it can cause leucopenia, anemia, and thrombocytopenia and prolonged exposure to benzene can cause leukemia.9

Provides more specific risk control guidelines for OHS hazards using approaches such as elimination, substitution, engineering control (technical approach), administrative control, and use of personal protective equipment (PPE). Since the benzene exposure in control rooms A and B came from a fixed source that could not be eliminated because it was used for the benefit of each company, the elimination and substitution approach could not be applied.10

The concentration of benzene exposure to control room A and B employees depends on the benzene content in crude oil (crude oil). Meanwhile, the time variable relates to the work rules/regulations that have been agreed upon between the employees and the management of control rooms A and B, which submit to labor regulations. The results of the calculation of risk management measures for concentration, duration, and frequency are for control room A and B 0.1mg/m3, 6h/day, 115days/year.

Therefore, risk control that can be done is by using engineering control (technical approach), administrative control (administrative control), and use of personal protective equipment (PPE). The first engineering control (technical approach) is to isolate the waste pit by adding a cover like a greenhouse with a gas channel and air suction so that the benzene content can be sucked up and disposed of in areas with less population.11

The risk control that can be done is to carry out administrative control by adding an existing shift that previously had 3 shifts to 4 or 8 shifts so that workers can work with the ON-OFF-ON system because by adding this shift it can reduce exposure time to 6h/day and exposure frequency to 122 days/year. The second is engineering control, it is recommended that PT X build a cover in each waste pit like a greenhouse so that the benzene content in the air does not pollute the environment, the use and supervision of PPE must be carried out to discipline workers to always use complete PPE while working to protect the health of workers.

The authors declare no conflict of interest.