Wood preservation facilities, creosote: chapter D-6

6. Protection of Personnel

6.1 First Aid, Precautions and Hygiene for Creosote Exposure

The general rule applies: for work with creosote, creosote/oil mixtures and/or sludge, the higher the concentration of a preservative to which a worker is exposed, the greater the need for protective measures and immediate response if contact occurs.

Facility staff should have access to product labels and appropriate training to apply first aid.

Artificial respiration should not be performed without the use of a barrier device, as the injured person may be contaminated (on skin) with Creosote solution, making the first aider the next victim if direct mouth-to-mouth contact is made. First aid personnel should periodically verify up-to-date response measures with chemical suppliers and/or industrial physicians

Table 5 contains the recommended actions in case of creosote exposure. Potential exposure to creosote in pressure treatment facilities includes exposure to creosote, creosote treating solutions and sludge, contaminated aqueous solutions and treated wood. Inhalation exposure can occur from vapours or aerosols.

6.2 Regulatory Controls

The labels for pesticide products contain information on the minimum necessary protective equipment and practices necessary for using the product. The worker protection measures on the pesticide label are mandatory. Provincial or municipal regulations may require additional measures that may enhance, but not reduce, protection. Table 7 in Chapter A can be used to summarize the local regulatory threshold limit values (TLVs) and/or biological exposure indices (BEIs) applicable to the plant.

Most regulatory criteria established by worker protection agencies are based on TLVs and BEIs, as recommended by the American Conference of Governmental Industrial Hygienists (ACGIH). Creosote per se is not addressed by the ACGIH. The ACGIH suggests the use of benzene soluble fractions of coal tar pitch volatiles as a measure of exposure (20).

The ACGIHTLV-TWAs for chemicals are defined with the following provisos:

• “The limits are intended for use in the practice of industrial hygiene as guidelines for good practices or recommendations in the control of potential health hazards and for no other use” (i.e. proof or disproof of the cause of an existing disease or physical condition).
• “The limits are not fine lines between safe and dangerous concentration.”
• “In spite of the fact that serious injury is not believed likely as a result of exposure to the Threshold Limit concentrations, the best practice is to maintain concentrations of all atmospheric contaminants as low as is practical.”
• “When two or more hazardous substances, which act upon the same organ system, are present, their combined effect, rather than that of either individually, should be given primary consideration.”

Recently, the ACGIH has suggested augmenting TLV workplace evaluations by using “biological exposure indices (which) may be useful as a guide to safe exposure” (20).

Skin and Eye Contact

A wide range of dermal exposures to creosote can potentially be encountered in the workplace, from exposure to “pure” creosote, to creosote/oil mixtures or to waters containing a few parts per million of creosote. A minimal level of protection and hygiene--for example, impermeable gloves and regular clothing changes--should be maintained by all facility workers who could have dermal exposure to creosote, creosote/oil and aqueous solutions of creosote or freshly treated wood. The level of protection should increase with increasing potential for exposure.

Inhalation

The ACGIH recommended threshold limit value - time weighted average (TLV-TWA) for creosote represents a TWA concentration “for a normal 8-hour workday and a 40-hour workweek, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect.” The recommended TLV-TWA value for benzene-soluble fractions of coal tar pitch volatiles is 0.2 mg/m³.

The ACGIHTLV-TWA values for coal tar pitch volatiles are applicable as maximum allowable values for inhalation. Adequate design and operational procedures (e.g. adequate local ventilation and use of appropriate respiratory equipment, where necessary) will minimize worker exposure to vapours. Other potential sources of inhaled coal tar pitch volatiles include vapours in the vicinity of charge removal areas and in the vicinity of freshly treated wood, and aerosols at improperly maintained facilities (e.g. from leaking seals) or at inadequately designed facilities (e.g. from vacuum pump discharges to work area).

Ingestion

Oral intake of creosote must be avoided. Ingestion of creosote or creosote-containing liquids is unlikely if workers follow elementary rules of good hygiene. Acceptable limits of ingestion are not prescribed by regulation since there is no valid reason for any such intake to occur. The single dose level of creosote suggested to be fatal is in the order of 0.1 g creosote per 1 kg of body weight (18).

6.3 Safety Precautions

Workers need to familiarize themselves with the safety precautions presented in Table 8 in addition to those mentioned in Chapter A, Section 6.3. Sensitive individuals should take special care to avoid exposure.

6.4 Biological Monitoring of Exposed Workers

Biological monitoring is a useful tool for evaluating the long-term effectiveness of the protective measures applied. Routine biological monitoring of exposed workers (primarily those who handle preservatives and treated wood, e.g., plant operators and quality control personnel) is recommended. Refer to Chapter A, Section 6.4.