Pesticide Residues in Milk and Milk Products - Pesticides: Evaluation of Environmental Pollution - page 576

impacts. Pesticides should be managed to avoid their migration into off-site land or
water environment by implementing an integrated pest management (IPM) strategy
and as documented in a pesticide management plan (PMP). When designing and
implementing an IPM strategy, preference should be given to alternative pest manage-
ment strategies, and the use of synthetic chemical pesticides should be the last option.
18.2 Entry of Pesticide Residues into Milk
Milk can be contaminated by the residues of pesticides through a variety of sources. The
major source of organochlorine pesticide (OCP) residues is fodder and soil, while organo-
phosphorus residues are mainly associated with ingestion through licking of insecticides
used to control parasites on animals.
After ingestion, the active ingredient is mostly metabolized in the liver or stored in the
fat. Excretion through milk can lead to residues in milk and milk products. The active
ingredients that are soluble in water will be mostly eliminated through urine and feces.
However, the substances that are soluble in fat will be eliminated mainly through milk. Fat
solubility can be estimated by log P, which is the logarithm of the octanol-water partition
coefficient. log P is the prime indicator of fat solubility and, by consequence, of the poten-
tial transfer to milk. When the log P exceeds 3, the compound is designated as fat-soluble
(Bertrand 2010).
In Table 18.1 , physicochemical properties of some pesticide residues are summed up
(Tomlin 2000).
18.3 Hazardous Nature of Pesticide Residues in
Milk Compared to Other Sources
Different studies have reported the presence of toxic residues in milk as well as in veg-
etables and meat products, which may cause serious, acute or chronic health hazards,
depending on the length of exposure.
A higher level of contamination (63.38% of 325 samples) by OCPs in bovine milk has
been reported in India (Nag and Raikwar 2008). Similar findings for dairy products
(milk, cheese, labneh, yogurt, and butter) have been reported in Jordan (Salem et al. 2009).
OCPs used in agriculture may reach aquatic bodies and finally humans through the food
web. OCPs, for instance, are suspected to have a high affinity for the testicular androgen
receptors, causing the dysfunction of the reproductive system (Singh et al. 2008), and to
be associated with Parkinson disease, type 2 diabetes, and malarial infection (through
the depletion of liver reserves of vitamin A) (Stuetz et al. 2006). In addition, DDT, mirex,
toxaphene, HCH, and HCB are considered possible carcinogens (IARC 2006). Fat-soluble
pesticides are accumulated in animal tissues and are excreted into milk but not into urine.
These pesticides are more resistant to degradation compared to polar pesticides. Therefore,
the pesticides present in milk are more hazardous compared to those in other matrices.