Distillates (petroleum), full-range straight-run middle

Endpoint summary

Description of key information

Key acute oral (OECD 401), dermal (OECD 402), and inhalation (OECD 403) studies were identified for straight run gas oils.  LD50 and LC50 values were as follows:

• The oral LD50 was > 5000 mg/kg bw in male and female rats.

• The dermal LD50 was > 2000 mg/kg bw in male and female rabbits.

• The LC50 was > 2.53 mg/L in male and female rats.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

5 000 mg/kg bw

Quality of whole database:

Based on one key and one supporting study with straight-run gas oils

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

2 530 mg/m³ air

Quality of whole database:

Based on one key inhalation study with straight-run gas oil

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Based on one key and one supporting study with straight-run gas oils

Additional information

Key acute oral, dermal, and inhalation studies were identified. Based on the results of the studies, straight run gas oils are of low acute oral and dermal toxicity, with an oral LD50 greater than 5000 mg/kg (rat) and a dermal LD50 greater than 2000 mg/kg (rabbit). In a key rat inhalation study the LC50 was greater than 2.53 mg/L. Additional detail on the studies are reported below.

Acute Oral Toxicity

In an acute oral toxicity study (API, 1985a), five male and five female fasted Sprague-Dawley rats were given a single oral dose of straight run middle distillate (petroleum). Clinical signs observed during the study period included hypoactivity, ataxia, diarrhoea, lacrimation, oily yellow-stained coat, and hair loss. No mortality was observed. Body weights in both males and females increased at day 7 and continued to increase at 14 days post-treatment. The oral LD50 for straight run middle distillate in male and female rats was calculated to be greater than 5000 mg/kg body weight.

Acute Dermal Toxicity

In an acute dermal toxicity study (API, 1985a), 4 male and 4 female albino New Zealand rabbits were exposed to straight run middle distillate (petroleum) for 24 hours to approximately 10% of their body surface, at 2000 mg/kg bw. No signs of systemic toxicity or mortality were observed at this dosage level. Slight to moderate dermal irritation for erythema, oedema, atonia, desquamation, and fissuring, and slight coriaceousness was observed. The dermal LD50 was determined to be >2000 mg/kg in males and females.

Acute Inhalation Toxicity

In a key acute inhalation toxicity study (EMBSI, 1991), a sample of SRGO (CAS no. 64741-44-2) was administered to Sprague-Dawley rats (5/sex/dose) via inhalation (in air; nose only) at a concentration of 2.53 mg/L for a period of 4 hours. Post-exposure animals were observed every 15 minutes for the first hour, and then at hourly intervals during the exposure period. Detailed individual observations on all animals were recorded pre-exposure, immediately post-exposure and then daily for fourteen days. Bodyweights were recorded for all animals pre-exposure (day 0) and on days 7 and 14 of the study period. Necroscopy was conducted for all surviving animals at termination and means and standard deviations calculated.

A few animals exhibited laboured breathing starting approximately thirty minutes into the exposure. Incidences of laboured breathing increased as the exposure progressed, and during the last two hours all animals exhibited laboured breathing. Individual animals also displayed decreased activity, a closed eye, clear ocular discharge, brown ano-genital staining of the fur, and brown material on the fur of the dorsal lumbar area. Most animals were observed to have recovered by Day 1 post-exposure (although one male exhibited laboured breathing). Other abnormalities observed on Day 1 included ungroomed fur, dry red material around the left eye, brown or yellow ano-genital staining, and brown material on the fur of the dorsal lumbar area. All animals appeared normal by Day 3 post-exposure. One animal developed alopecia on the head from Day 5 through Day 13 and exfoliation on the dorsal cervical area from Day 5 through Day 9. Another animal had alopecia of the extremities from Day 7 through 14 post-exposure. Also observed, were single scattered incidences of scabs on the extremities and dorsal cervical area. These observations were considered incidental and probably not related to exposure to the test material. All animals gained weight throughout the study; weight gains were slightly lower for the first week than the second week in both sexes.

There were no deaths during the study. Necroscopy revealed that 5 animals had slightly discoloured lungs (mottled in 2 rats and single or small numbers of dark red foci in 3 rats). This was probably related to exposure. Other minor abnormalities included single incidences of enlarged kidneys, discoloured mandibular lymph nodes and alopecia on the extremities. 4 animals had no macroscopic abnormalities.Based upon the results of this study, the four hour acute inhalation LC₅₀for the test material was determined to be greater than 2.53 mg/L.

 

Supporting studies on acute oral and dermal toxicity offer further support that straight run gas oils are not acute oral or dermal toxicants, with the reported oral LD50 value being greater than 5000 mg/kg in male and female rats and the dermal LD₅₀ value being greater than 2000 mg/kg in male and female rabbits (ARCO, 1990a, 1990b).

Justification for selection of acute toxicity – oral endpoint

Well conducted guideline study

Justification for selection of acute toxicity – inhalation endpoint

Well conducted guideline study

Justification for selection of acute toxicity – dermal endpoint

Well conducted guideline study

Justification for classification or non-classification

Based on evaluation of all the acute toxicity data discussed above, straight run gas oils do not meet the criteria for classification as an acute oral or dermal toxicant under the EU CLP Regulation (EC No. 1272/2008), because the LD50 values are greater than the limits for classification defined in the legislation. Straight run gas oil aerosols are considered to meet the criteria for classification as an acute inhalation toxicant under the EU CLP Regulation (EC No. 1272/2008) and are classified as H332.

Regulatory classification and labelling for aspiration toxicity relies on the measured or calculated kinematic viscosity of a substance at 40°C rather than results from toxicological studies with animals. Hydrocarbons with kinematic viscosities = 20.5 mm²/sec are classified for aspiration toxicity according to EU CLP criteria. As members of this category may exist as low viscosity liquids that meet these criteria, substances in this category are classified for aspiration hazard unless the viscosity at 40^oC is greater than the regulatory thresholds. Straight run gas oils with kinematic viscosities = 20.5 mm²/sec are classified as aspiration hazards (H304) according to the EU CLP Regulation (EC No. 1272/2008).