Residues of 18 organochlorine pesticides in 30 traditional Chinese medicines

We analyzed 30 different traditional Chinese medicines (TCMs) to determine levels of contamination with organochlorine pesticides (OCPs). We tested for 18 pesticides: benzene hexachloride (BHC, including alpha-BHC, beta-BHC, gamma-BHC, delta-BHC), heptachlor, heptachlor epoxide, tecnazene, pentachloronitrobenzene (PCNB), hexachlorobenzene, aldrin, methyl pentachlorophenyl sulphide (MPCPS), alpha-endosulfan, trans-chlorodane, cis-chlorodane, p,p'-DDE, o,p'-DDT, p,p'-DDD, and p,p'-DDT. The sample extracts were analyzed by GC-ECD. A total of 280 samples of 30 different TCMs were analyzed. Our results showed that 75.8% of samples contained at least one of the above pesticides. The pesticides detected were tecnazene, hexachlorobenzene, PCNB, heptachlor, aldrin, alpha-BHC, beta-BHC, gamma-BHC, delta-BHC, p,p'-DDE, o,p'-DDT, p,p'-DDD p,p'-DDT. More than 50% of samples contained alpha-BHC (55.8%) and PCNB (55.8%); hexachlorobenzene was detected in 40.9% of samples, tecnazene in 19.5%, gamma-BHC in 16.7% and p,p'-DDE in 16.0%. Less than 10% of samples contained beta-BHC, delta-BHC, heptachlor, aldrin, o,p'-DDT, p,p'-DDT and p,p'-DDD. None of the 280 samples contained heptachlor epoxide, MPCPS, alpha-endosulfan, trans-chlorodane, or cis-chlorodane. Concentrations of OCPs in four samples exceeded the maximum allowable residue limits (MRLs) specified in the PRC Pharmacopoeia 2005. The results indicate that the most common contaminants among the 280 samples were alpha-BHC, PCNB, hexachlorobenzene, and tecnazene. Our results suggest that contamination of TCMs with OCPs is widespread. The MRLs for other OCPs commonly found in TCMs (e.g. hexachlorobenzene and tecnazene) should be set as quickly as possible, and the MRLs of OCPs in other TCMs should be established.