Carbon disulphide

Toxicological Summary

Workers - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

15.8 mg/m³

DNEL related information

Overall assessment factor (AF):

1

Acute/short term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

48 mg/m³

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Workers - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Acute/short term exposure

Hazard assessment conclusion:

low hazard (no threshold derived)

Workers - Hazard for the eyes

Local effects

Hazard assessment conclusion:

low hazard (no threshold derived)

Additional information - workers

There is ample information available on the effects of CS2 exposure on humans in occupational settings, in particular the production of viscose/rayon. The effects found generally fall in three categories: neurotoxicity, reproduction toxicity and cardiovascular toxicity. Most experimental studies with CS2 are concerned with elucidating the mechanistic background of the effects observed in humans.

Epidemiological studies (see Section 7.10) clearly indicate that long-term occupational exposure at or below 5 ppm (15.8 mg/m3) does not give rise to adverse effects belonging to these three categories. These studies were used by national and international institutions and competent authorities to derive occupational exposure limits for CS2. For instance, the SCOEL (Scientific Committee on Occupational Exposure Limits of the European Union) derived a value of 5 ppm (15.8 mg/m3) as a time weighted average (TWA) for 8 hours exposure. Because the effects observed in the epidemiological studies could only be linked with "working with CS2" and not with "inhalation of CS2", "skin contact with liquid/dissolved CS2" or "absorption of CS2 vapour from the air through the skin", this inhalation concentration should be regarded as a proxy for the total exposure. As dermal exposure in viscose/rayon production may be higher than in other occupational settings, the application of this concentration can be regarded as to protect all workers. Well-conducted studies linking personal monitoring data to biological monitoring data (TTCA excretion) in the viscose rayon industry have demonstrated that the CS2 concentration in air correlates well with the total body load.

Starting point for the derivation of the long-term occupational exposure DNEL is the air concentration of 5 ppm (15.8 mg/m3). This value is assumed to adequately protect all workers against the adverse health effects of long term exposure to CS2 via inhalation, the skin and eyes. It can thus be directly adopted as the inhalation DNEL, while it makes the dermal DNEL superfluous because it is a proxy for total exposure.

General Population - Hazard via inhalation route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

1.88 mg/m³

DNEL related information

Explanation for the modification of the dose descriptor starting point:

The OEL of 5 ppm (15.8 mg/m3) for workers was used as starting point. The following DNEL was obtained for the general population:15.8 mg/m3 x 5/7 (days) x 8/24 (daily duration) x 1/2 = 1.88 mg/m3 (0.6 ppm). The factor 1/2 was used to account for the larger intraspecies variation (intraspecies assesment factor 5 for workers versus 10 for the general population).

The World Health Organization has set an air quality guideline for carbon disulfide of 100 µg/m3 (0.03 ppm) averaged over 24 h (WHO, 2001). This was based on the lowest concentration of carbon disulfide at which an adverse effect was observed in the occupational environment being considered by WHO to be about 10 mg/m3 (3 ppm) and an uncertainty factor of 100, to take into account the expected variability in the susceptibility of the general population. However, the use of an intraspecies factor of 100 (WHO) for the general population is very conservative in comparison to the intraspecies factor used in REACH which is only 2x times the value for workers (5 for workers and 10 for the general population). Nevertheless, the exposure assessments for the general population (secondary poisoning) were assessed using the conservative value of 100 ug/m3 showing there was no risk for the general population.

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard via dermal route

Systemic effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

Local effects

Long term exposure

Hazard assessment conclusion:

no hazard identified

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

General Population - Hazard via oral route

Systemic effects

Long term exposure

Hazard assessment conclusion:

DNEL (Derived No Effect Level)

Value:

0.2 mg/kg bw/day

Most sensitive endpoint:

repeated dose toxicity

Route of original study:

Oral

DNEL related information

DNEL derivation method:

ECHA REACH Guidance

Overall assessment factor (AF):

200

Dose descriptor starting point:

LOAEL

Explanation for the modification of the dose descriptor starting point:

The LOAEL in the EOGRTS study was 120 mg/kg bw (systemic effects, no local effects); NOAEL = 12 mg/kg bw. However, due to limited effects seen at the LOAEL, an assessment factor of 3 was chosen to arrive from the LOAEL to the NOAEL as the factor 10 difference between dose levels is cosidered too large, thus the NOAEL was set at 40 mg/kg bw/day.

AF for dose response relationship:

1

Justification:

Clear dose-response study

AF for differences in duration of exposure:

2

Justification:

Extrapolation from subchronic to chronic

AF for interspecies differences (allometric scaling):

4

Justification:

Standard factor

AF for other interspecies differences:

2.5

Justification:

Standard factor in case of systemic effects

AF for intraspecies differences:

10

Justification:

Standard factor

AF for the quality of the whole database:

1

Justification:

Well performed GLP study, supported by other studies

AF for remaining uncertainties:

1

Justification:

No uncertainties

Acute/short term exposure

Hazard assessment conclusion:

no hazard identified

DNEL related information

General Population - Hazard for the eyes

Local effects

Hazard assessment conclusion:

no hazard identified

Additional information - General Population

The only relevant exposure of the general population to CS2 is possible via emission of this compound as vapour via stacks to the air by viscose/rayon factories. This implies that the general population will never be exposed at any appreciable level by skin or eye contact with CS2 in liquid form or dissolved in water. Thus no DNELs have to be derived for dermal exposure (local or systemic and for acute or long-term exposure). However. for the gastrointestinal tract (exposure via crops) a DNEL LT (systemic effects) has been derived based on the recently performed EOGRTS.

The inhalation DNEL derived for workers is linked to the effects in humans that are the result of occupational exposure via inhalation AND via skin contact (absorption via the skin of vapour and/or incidental exposure to (diluted) liquid). This DNEL could be used as starting point for the derivation of the DNEL for the exposure of the general population to CS2 that is emitted via stacks. The derived DNEL thus also covers absorption of vapour through the skin, and no separate dermal DNEL has to be derived for that route. Because the general population is not exposed by skin contact with liquid or dissolved CS2, the DNEL for the general population represents an overestimation of the hazard of CS2. The absence of local effects in occupational settings indicates that no DNEL has to be derived for local effects for the general population exposed via the air.