Proxan-sodium

Sensitisation data (human)

Administrative data

Endpoint:

sensitisation data (humans)

Type of information:

other: Human observational study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Justification for type of information:

The Sodium O-isopropyl dithiocarbonate (CAS No. 140-93-2), the subject of this dossier) is expected to exhibit very similar toxicity to sodium O-ethyl dithiocarbonate CAS No 140-90-9, which is also xanthate compound. Comparable metabolism would occur.

Data source

Reference

Reference 1

Reference Type:

publication

Title:

Case report - carbon disulphide absorption during xanthate reagent mixing in a gold mine concentrator

Author:

Donoghue AM

Year:

1998

Bibliographic source:

Occup Med, 48(7):469-470.

Reference 2

Reference Type:

study report

Title:

Unnamed

Year:

2000

Materials and methods

Type of sensitisation studied:

skin

Study type:

case report

Test guideline

Qualifier:

no guideline followed

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

Sodium O-ethyl dithiocarbonate

EC Number:

205-440-9

EC Name:

Sodium O-ethyl dithiocarbonate

Cas Number:

140-90-9

Molecular formula:

C3H6OS2.Na

IUPAC Name:

sodium O-ethyl dithiocarbonate

Test material form:

solid: compact

Details on test material:

- Name of test material (as cited in study report):sodium ethyl xanthate

Method

Type of population:

occupational

Ethical approval:

confirmed, but no further information available

Subjects:

Worker exposed to xanthate powder and solution during the mixing process

Clinical history:

A 32-year-old male reagent mixer was using an inversion cradle to discharge powdered xanthate from a drum into the hopper of a mixing tank at a gold mine. This particular drum's contents had become severely compacted in the lower third and he resorted to hammering the drum, scraping out the xanthate and washing the inside of the drum with hose water. In the process he was covered in xanthate powder and aqueous xanthate solution. He was wearing disposable paper overalls over the top of cotton overalls, PVC gloves, and an acid-gas/particulate full-face negative pressure respirator. On completion of the mixing task he went for a shower and discovered his skin stained green from the chest down. This degree of skin contamination was much greater than he had ever experienced previously.
Twenty hours later, on the following day, before any exposure to chemicals, he developed epigastric 'burning', central abdominal 'tightness', anorexia, nausea, vomiting, fatigue, headache and felt 'faint'. He went home to rest, the vomiting ceased and he was able to eat later that evening. He remained nauseated and fatigued and his sleep was disturbed by acid reflux and epigastric/retrosternal discomfort. He denied visual disturbances and did not complain of weakness or numbness of the limbs or of psychotic symptoms. Somewhat surprisingly he did not experience skin irritation except for some mild pruritus at the wrists. He never developed diarrhoea. His symptoms resolved gradually over the next four days, at which point he returned to work. His previous medical history was unremarkable, his pre-employment health assessment denied nausea, indigestion or other gastrointestinal symptoms

Route of administration:

dermal

Details on study design:

A 32-year-old male reagent mixer was using an inversion cradle to discharge powdered xanthate from a drum into the hopper of a mixing tank at a gold mine. This particular drum's contents had become severely compacted in the lower third and he resorted to hammering the drum, scraping out the xanthate and washing the inside of the drum with hose water. In the process he was covered in xanthate powder and aqueous xanthate solution. He was wearing disposable paper overalls over the top of cotton overalls, PVC gloves, and an acid-gas/particulate full-face negative pressure respirator. On completion of the mixing task he went for a shower and discovered his skin stained green from the chest down. This degree of skin contamination was much greater than he had ever experienced previously.

Results and discussion

Results of examinations:

Extensive skin contamination of the worker’s chest area was evident (green staining) post exposure. The worker developed an illness, consisting predominantly of gastrointestinal symptoms, which began 20 h after exposure and lasted for 3 days. Carbon disulfide body burden was confirmed by the detection of urinary TTCA (<4 mg/L measured approximately 68 h after exposure). Drager tube testing, during subsequent mixing operations, recorded an airborne concentration of at least 60 ppm CS2.
The worker was wearing cotton overalls, PVC gloves and an acid gas/particulate full-face respirator. It was not clear whether symptoms were the result of CS2 inhalation or xanthate/CS2 skin absorption as although the respirator did not include an organic vapour cartridge, the worker apparently did not experience any eye irritation, which suggests that the level of CS2 within the respirator was not particularly high.

Any other information on results incl. tables

The presence of TTCA in this case confirmed the absorption of carbon disulphide. Previous biological monitoring of xanthate mixers at this site had not detectedTTCA. This suggests that normally the exposure tocarbon disulphide in this job is low and that the unusualand very extensive skin contamination which occurred inthis case was the most likely cause for the carbon disulphidea bsorption. Carbon disulphide is readily absorbedthrough the skin and would have been generated at theskin surface by the decomposition of both solid andaqueous xanthate. The need for impervious protective clothing and work procedures or engineering controlswhich avoid splashing is clear.

Although skin contamination was probably the majorcontributor in this case, it is possible that inhalation mayalso have contributed, because spot air levels beyond theSTEL were obtained after the event, and the respiratoryprotection did not include an organic vapour cartridge. Itis interesting to note however that he did not experienceirritation of the eyes, which suggests that the level ofcarbon disulphide within his full-face respirator was

probably not very high.

The maximum spot air level obtained after the eventwas more than 60 ppm, which is significantly greater thanthe highest previously published level I am aware of— 16 ppm.This level was recorded while water wasbeing added to a tank in which the xanthate had beendeposited. After a change in procedure, whereby the tankwas filled with water before the addition of xanthate, theair levels were reported to be below 10 ppm.

Applicant's summary and conclusion

Conclusions:

A xanthate reagent mixer at a gold mine concentrator was exposed to carbon disulphide by extensive skin contamination with xanthate powder and solution during the reagent mixing process. Absorption of carbon disulphide was confirmed by the detection of urinary 2-thiothiazolidine-4-carboxylic acid (TTCA). Drager colorimetric tube testing during subsequent mixing recorded a maximum concentration of at least 60 ppm carbon disulphide. An illness consisting of predominantly gastrointestinal symptoms began 20 h after the exposure. Although this may have been due to carbon disulphide toxicity this is by no means certain. The need for engineering controls, impervious protective clothing and full-face respirators with particulate and organic vapour cartridges is discussed. This episode occurred at another mine site, unrelated to Mount Isa Mines Limited.

Executive summary:

A single case report of a worker exposed to xanthate powder and solution(specific compound not specified) during the mixing process was reported byDonoghue (1998).

Extensive skin contamination of the worker’s chest area wasevident (green staining) post exposure.The worker developed an illness, consisting predominantly of gastrointestinalsymptoms, which began 20 h after exposure and lasted for 3 days. Carbondisulfide body burden was confirmed by the detection of urinary TTCA (<4 mg/Lmeasured approximately 68 h after exposure). Drager tube testing, duringsubsequent mixing operations, recorded an airborne concentration of at least 60ppm CS2.

The worker was wearing cotton overalls, PVC gloves and an acid gas/particulatefull-face respirator. It was not clear whether symptoms were the result of CS2inhalation orxanthate/CS2 skin absorption as although the respirator did notinclude an organic vapour cartridge, the worker apparently did not experience anyeye irritation, which suggests that the level of CS2 within the respirator was notparticularly high.