Roundup and Cancer by Meriel Watts

Soil & Health, May/June 1998, Vol 58. No.3, p.16

1. Non-Hodgkin lymphoma (NHL)

A recent population-based study in Sweden1, of links between exposure to pesticides and incidence of non-Hodgkin lymphoma, established an increase risk of NHL for people exposed to herbicides and to fungicides (but not insecticides). Of the herbicides the strongest link was demonstrated with the phenoxy herbicide MCPA. This confirms the findings of a number of other studies over the years since 1979 which have linked NHL with exposure to phenoxy herbicides including 2,4-D2-7, according to the authors. The study also found a significant increase in risk of NHL following exposure to glyphosate. The authors warn that definite conclusions cannot be drawn because of the low numbers of exposed subjects: 4 for glyphosate, with 3 control subjects. However they also state that the results might be of concern as the usage of glyphosate has increased drastically since the time period for diagnosis that was used in this study. They draw attention to reports of gene mutations8-10 and chromosomal aberrations11 in mouse lymphoma cells exposed to glyphosate; to the increased incidence of hepatocellular carcinoma, leukemia and lymphoma in one study on mice12, and to the increased number of sister chromatid exchanges in a study on human lymphocytes13. Based on these reported studies, their findings and an earlier study that demonstrated a link between glyphosate and hairy cell leukemia (see below), the authors believe that "glyphosate deserves further epidemiological studies".

2. Hairy cell leukemia

An earlier population-based study in Sweden14 also found an elevated risk of non-Hodgkin lymphoma - this time of the hairy cell leukemia subgroup of NHL - resulting from exposure to herbicides and fungicides. The results are very similar to the above study, with exposure to all herbicides analysed for showing a strong correlation to incidence of hairy cell leukemia - the incidence was strongest for exposure to glyphosate and MCPA, and then for 2,4-D. Again the results cannot be viewed as conclusive because of the small number of subjects - for glyphosate 4 cases and 5 controls.

The results of these two studies fail to confirm the US EPA's classification of glyphosate as non-carcinogenic and do indicate the valid possibility of a link between glyphosate and non-Hodgkin lymphoma, a possibility that can no longer be ignored. That being the case, it can be concluded that a precautionary approach should be taken to any further use of glyphosate in New Zealand until a definite link can be established or refuted with certainty.

In 1993 the US EPA15 declared glyphosate as being non-carcinogenic to humans on the basis of only 3 studies on rats and mice. These studies all showed a variety of carcinogenic effects which, however, were considered to be not statistically significant:

• increased thyroid C-cell carcinomas - at high dose levels
• increased interstitial cell testicular tumours - at high dose levels
• increased pancreatic islet cell carcinomas, at low and high doses
• increased liver adenomas - at low and high doses
• increased thyroid C-cell carcinomas - at mid and high doses
• slight increase in incidence of renal tubular adenomas - at high doses.

References:

1. Hardell L, Eriksson M. 1999. A case-control study of non-Hodgkin lymphoma and exposure to pesticides. Cancer 85(6): 1353-1360.
2. Hardell L. 1979. Malignant lymphoma of histiocytic type and exposure to phenoxyacetic acids or chlorophenols. Lancet 1:55-6.
3. Hardell L, Eriksson M, Lenner P, Lundgren E. 1981. Malignant lymphoma and exposure to chemicals, especially organic solvents, chlorophenols and phenoxy acids: a case-control study. British Journal of Cancer 43:169-76.
4. Hoar SK., Blair A., Holmes FF, Boysen CD, Robel RJ, Hoover R, Fraumeni JF, Jr. 1986. Agricultural herbicide use and risk of lymphoma and soft-tissue sarcoma. Journal of American Medical Association 256:1141-7
5. Zahm SH, Weisenburger DD, Babbitt PA, Saul RC, Vaught JB, Cantor KP, Blair A. 1990. A case-control study of non-Hodgkin's lymphoma and the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) in Eastern Nebraska. Epidemiology l(5):349-356. Kogevinas M, Kauppinen T, Winkelmann R, Johnson ES, Bertazzi PA, Buneo de Mesquita BH. 1995. Soft tissue sarcoma and non-Hodgkin's lymphoma in workers exposed to phenoxy herbicides, chlorophenols and dioxins: two nested case-control studies. Epidemiology
6. 396-402 7. Becher H, Flesch-Janys D, Kauppinen T, Kogevinas M, Steindorf K, Manz A, et al. 1996. Cancer mortality in German male workers exposed to phenoxy herbicides and dioxins. Cancer Causes Control
7. 312-21. 8. Majeska JB, Matheson DW. 1982. R-50224: mutagenicity evaluation in mouse lymphoma multiple endpoint test. A forward mutagenicity assay T-1084
8. Farmington: Stauffer Chemical Company.
9. Majeska JB, Matheson DW. 1982. R-50224, sample 3: mutagenicity evaluation in mouse lymphoma multiple endpoint test. Forward mutation assay T-11018. Farmington: Stauffer Chemical Company.
10. Majeska JB, Matheson DW. 1985. SC-0224: mutagenicity evaluation in mouse lymphoma multiple endpoint test. Forward mutation assay T-12661. Farmington: Stauffer Chemical Company.
11. Majeska JB, Matheson DW. 1985. SC-0224: mutagenicity evaluation in mouse lymphoma multiple endpoint test, cytogenetic assay T-12662. Farmington: Stauffer Chemical Company.
12. Pavkov KL, Turnier JC. 1986. 2-year chronic toxicity and oncogenicity dietary study with SC-0224 in mice. T-11813. Farmington: Stauffer Chemical Company.
13. Vigfusson NV, Vyse ER. 1980. The effect of the pesticides Dexon, Captan, and Roundup, on sister-chromatid exchanges in human lymphocytes in vitro. Mutation Research 79:53-7.
14. Nordstrom M, Hardell L, Magnuson A, Hagberg H, Rask-Anderson A. 1998. Occupational exposures, animal exposure and smoking as risk factors for hairy cell leukaemia evaluated in a case-control study. British Journal of Cancer 77(11):2048-2052. 15. US EPA, 1993. EPA Reregistration Eligibility Document. Glyphosate. Office of Prevention, Pesticides and Toxic Substances. September 1993.