Carcinogen and Pesticide Branch
1. General Discussion
This evaluation was undertaken to determine the effectiveness of the OVS-2 tube as a sampling device for heptachlor. It follows the procedure developed for chlordane. (Ref. 5.1.)
1.1.2. Toxic effects (This section is for information only and should not be taken as the basis of OSHA policy.)
Heptachlor has an acute oral LD50 of 40-188 mg/kg and an acute dermal LD50 of 119-320 mg/kg for rats. (Ref. 5.2. to 5.4.) Animal studies indicating clearly the carcinogenicity in mice and rats have been reported. (Ref. 5.2. to 5.4.) Due to these and other factors the ACGIH has set a threshold limit value (TLV) of 0.5 mg/m3 for heptachlor with a skin notation. (Ref. 5.4.) This level has also been adopted as the OSHA PEL.
1.1.3. Potential workplace exposure
Heptachlor is used as an insecticide. In the United States a total of 2.3 million kg of heptachlor was produced in 1980. (Ref. 5.2.) No information could be found on the number of workers exposed to heptachlor.
1.2. Limit defining parameters
The detection limit of the analytical procedure, including a 17:1 split ratio, is 0.43 pg per injection. This is the amount of analyte which will give a peak whose height is approximately five times the baseline noise.
2. Sampling Procedure
2.1.2. OVS-2 tubes, which are specially made
No sampling reagents are required.
2.3. Sampling technique
2.3.2. Attach the small end of the tube to the sampling pump with flexible tubing.
2.3.3. Attach the tube vertically in the employee's breathing zone in such a manner that it does not impede work performance.
2.3.4. After sampling for the appropriate time, remove the tube and seal with plastic caps.
2.3.5. Wrap each sample end-to-end with an OSHA seal (Form 21).
2.3.6. Record the air volume for each sample, and list any possible interferences.
2.3.7. Submit at least one blank for each set of samples. Handle the blank in the same manner as the samples, except no air is drawn through it.
2.3.8. Submit bulk samples for analysis in a separate container. Limit the amount of bulk submitted to one gram or one ml. Do not ship them with air samples.
2.4. Desorption efficiency (glass fiber filter and XAD-2 adsorbent)
Fifteen vials, each containing a 13-mm glass fiber filter and
2.5. Retention efficiency
Six OVS-2 tubes were each liquid spiked with 20 µl (2× PEL) of a 2.95 mg/ml solution of heptachlor in toluene. These were allowed to dry for 2 hours and then 60 L of humid air (~80% relative humidity) were drawn through each tube at 1 L/min. The tubes were stored overnight in a drawer at ambient temperature, desorbed vith 4.0 mL of toluene, shaken for 30 min and then analyzed as in Section 3. The results are listed in Table 2.5.
2.6. Sample storage
Twenty four OVS-2 tubes were each liquid spiked with 10 µl (1× PEL) of 2.95 mg/ml of heptachlor. These were allowed to dry for 2 hours and then 60 L of humid air (~80% relative humidity) were drawn through each tube at 1 L/min. Half of the tubes were stored in a drawer at ambient temperature, and the other half were stored in a freezer (-5°C). They were extracted and analyzed as in Section 3. The results are given in Tables 2.6.1. and 2.6.2.
2.7. Recommended air volume and sampling rate
2.7.2. The recommended flow rate is 1.0 L/min.
2.8. Interferences (sampling)
It is not known if any compounds will interfere with the collection of heptachlor. Any suspected interferences should be reported to the laboratory.
2.9. Safety precautions (sampling)
2.9.2. Follow all safety practices that apply to the work area being sampled.
3. Analytical Procedure
3.1.2. A mechanical shaker.
3.1.3. A GC equipped with an ECD. A Hewlett Packard (HP) 5890 equipped with an autosampler was used in this evaluation.
3.1.4. A GC column capable of separating heptachlor from any interferences. A 45 m × 0.25 mm i.d. (0.25 µm film) SE-54 capillary column was used in this evaluation.
3.1.5. An electronic integrator, or some other suitable means for measuring detector response. The Hewlett-Packard 3357 Laboratory Data System was used in this evaluation.
3.1.6. Volumetric flasks and pipets.
3.1.7. Vials, 2-mL, and 4-mL.
3.2.2. Heptachlor, reagent grade. A standard obtained from EPA (EPA # 3860, 99.8% purity) was used in this evaluation. .
3.3. Standard preparation
Prepare stock standards by adding toluene to preweighed amounts of heptachlor. Prepare working range standards by diluting stock standards with toluene. Store stock and working standards in a freezer.
3.4. Sample preparation
3.4.2. Add 4.0 mL of toluene to each vial and seal with a Teflon-lined cap.
3.4.3. Shake the vials for 30 minutes on a mechanical shaker.
3.4.4. If necessary, transer the samples to 2-mL vials for use on an HP autosampler.
3.5.2. Chromatogram (Figure 2.)
3.6. Interferences (analytical)
3.6.2. GC conditions may generally be varied to circumvent interferences.
3.6.3. Retention time on a single column is not proof of chemical identity. Analysis by an alternate GC column, high performance liquid chromatography (HPLC) and confirmation by mass spectrometry are additional means of identification.
3.7.2. Determine the µg/mL of heptachlor in both sections of each sample and blank from the calibration curve.
3.7.3. Blank correct each sample by subtracting the µg/mL found in each section of the blank from the µg/mL found in the corresponding sections of the sample and then add the two sample sections together.
3.7.4. Determine the air concentration by using the following formula.
3.8. Safety precautions (analytical)
3.8.2. Avoid skin contact with all solvents.
3.8.3. Wear safety glasses at all times.
4. Recommendation for Further Study
This method should be fully validated.
5.2. IARC Monographs on the Evaluation of the
Carcinogenic Risk of Chemicals to Humans; International Agency for
Research on Cancer: Lyon, 1979; Vol. 20, pp
5.3. Registry of Toxic Effects of Chemical
5.4. Documentation of the Threshold Limit Values and Biological Exposure Indices, American Conference of Governmental Industrial Hygienist INC., fifth edition, 1986; p 296.
5.5. Farm Chemicals Handbook; Berg, Gordon L. Ed.; Meister: Willoughby, Ohio, 1986; p C123.
5.6. Merck Index, 10th ed.; Windholz, Martha ED.; Merck: Rahway, N.J., 1983; p 673.